Imported Upstream version 2.25.1
[platform/upstream/git.git] / dir.c
diff --git a/dir.c b/dir.c
index fcb6872..b460211 100644 (file)
--- a/dir.c
+++ b/dir.c
@@ -2,21 +2,22 @@
  * This handles recursive filename detection with exclude
  * files, index knowledge etc..
  *
- * See Documentation/technical/api-directory-listing.txt
- *
  * Copyright (C) Linus Torvalds, 2005-2006
  *              Junio Hamano, 2005-2006
  */
 #include "cache.h"
+#include "config.h"
 #include "dir.h"
+#include "object-store.h"
+#include "attr.h"
 #include "refs.h"
 #include "wildmatch.h"
 #include "pathspec.h"
-
-struct path_simplify {
-       int len;
-       const char *path;
-};
+#include "utf8.h"
+#include "varint.h"
+#include "ewah/ewok.h"
+#include "fsmonitor.h"
+#include "submodule-config.h"
 
 /*
  * Tells read_directory_recursive how a file or directory should be treated.
@@ -31,27 +32,45 @@ enum path_treatment {
        path_untracked
 };
 
+/*
+ * Support data structure for our opendir/readdir/closedir wrappers
+ */
+struct cached_dir {
+       DIR *fdir;
+       struct untracked_cache_dir *untracked;
+       int nr_files;
+       int nr_dirs;
+
+       const char *d_name;
+       int d_type;
+       const char *file;
+       struct untracked_cache_dir *ucd;
+};
+
 static enum path_treatment read_directory_recursive(struct dir_struct *dir,
-       const char *path, int len,
-       int check_only, const struct path_simplify *simplify);
-static int get_dtype(struct dirent *de, const char *path, int len);
+       struct index_state *istate, const char *path, int len,
+       struct untracked_cache_dir *untracked,
+       int check_only, int stop_at_first_file, const struct pathspec *pathspec);
+static int resolve_dtype(int dtype, struct index_state *istate,
+                        const char *path, int len);
 
-/* helper string functions with support for the ignore_case flag */
-int strcmp_icase(const char *a, const char *b)
+int count_slashes(const char *s)
 {
-       return ignore_case ? strcasecmp(a, b) : strcmp(a, b);
+       int cnt = 0;
+       while (*s)
+               if (*s++ == '/')
+                       cnt++;
+       return cnt;
 }
 
-int strncmp_icase(const char *a, const char *b, size_t count)
+int fspathcmp(const char *a, const char *b)
 {
-       return ignore_case ? strncasecmp(a, b, count) : strncmp(a, b, count);
+       return ignore_case ? strcasecmp(a, b) : strcmp(a, b);
 }
 
-int fnmatch_icase(const char *pattern, const char *string, int flags)
+int fspathncmp(const char *a, const char *b, size_t count)
 {
-       return wildmatch(pattern, string,
-                        flags | (ignore_case ? WM_CASEFOLD : 0),
-                        NULL);
+       return ignore_case ? strncasecmp(a, b, count) : strncmp(a, b, count);
 }
 
 int git_fnmatch(const struct pathspec_item *item,
@@ -74,13 +93,11 @@ int git_fnmatch(const struct pathspec_item *item,
        if (item->magic & PATHSPEC_GLOB)
                return wildmatch(pattern, string,
                                 WM_PATHNAME |
-                                (item->magic & PATHSPEC_ICASE ? WM_CASEFOLD : 0),
-                                NULL);
+                                (item->magic & PATHSPEC_ICASE ? WM_CASEFOLD : 0));
        else
                /* wildmatch has not learned no FNM_PATHNAME mode yet */
                return wildmatch(pattern, string,
-                                item->magic & PATHSPEC_ICASE ? WM_CASEFOLD : 0,
-                                NULL);
+                                item->magic & PATHSPEC_ICASE ? WM_CASEFOLD : 0);
 }
 
 static int fnmatch_icase_mem(const char *pattern, int patternlen,
@@ -104,7 +121,7 @@ static int fnmatch_icase_mem(const char *pattern, int patternlen,
 
        if (ignore_case)
                flags |= WM_CASEFOLD;
-       match_status = wildmatch(use_pat, use_str, flags, NULL);
+       match_status = wildmatch(use_pat, use_str, flags);
 
        strbuf_release(&pat_buf);
        strbuf_release(&str_buf);
@@ -121,7 +138,7 @@ static size_t common_prefix_len(const struct pathspec *pathspec)
         * ":(icase)path" is treated as a pathspec full of
         * wildcard. In other words, only prefix is considered common
         * prefix. If the pathspec is abc/foo abc/bar, running in
-        * subdir xyz, the common prefix is still xyz, not xuz/abc as
+        * subdir xyz, the common prefix is still xyz, not xyz/abc as
         * in non-:(icase).
         */
        GUARD_PATHSPEC(pathspec,
@@ -130,7 +147,8 @@ static size_t common_prefix_len(const struct pathspec *pathspec)
                       PATHSPEC_LITERAL |
                       PATHSPEC_GLOB |
                       PATHSPEC_ICASE |
-                      PATHSPEC_EXCLUDE);
+                      PATHSPEC_EXCLUDE |
+                      PATHSPEC_ATTR);
 
        for (n = 0; n < pathspec->nr; n++) {
                size_t i = 0, len = 0, item_len;
@@ -168,19 +186,24 @@ char *common_prefix(const struct pathspec *pathspec)
        return len ? xmemdupz(pathspec->items[0].match, len) : NULL;
 }
 
-int fill_directory(struct dir_struct *dir, const struct pathspec *pathspec)
+int fill_directory(struct dir_struct *dir,
+                  struct index_state *istate,
+                  const struct pathspec *pathspec)
 {
-       size_t len;
+       const char *prefix;
+       size_t prefix_len;
 
        /*
         * Calculate common prefix for the pathspec, and
         * use that to optimize the directory walk
         */
-       len = common_prefix_len(pathspec);
+       prefix_len = common_prefix_len(pathspec);
+       prefix = prefix_len ? pathspec->items[0].match : "";
 
        /* Read the directory and prune it */
-       read_directory(dir, pathspec->nr ? pathspec->_raw[0] : "", len, pathspec);
-       return len;
+       read_directory(dir, istate, prefix, prefix_len, pathspec);
+
+       return prefix_len;
 }
 
 int within_depth(const char *name, int namelen,
@@ -198,22 +221,84 @@ int within_depth(const char *name, int namelen,
        return 1;
 }
 
-#define DO_MATCH_EXCLUDE   1
-#define DO_MATCH_DIRECTORY 2
+/*
+ * Read the contents of the blob with the given OID into a buffer.
+ * Append a trailing LF to the end if the last line doesn't have one.
+ *
+ * Returns:
+ *    -1 when the OID is invalid or unknown or does not refer to a blob.
+ *     0 when the blob is empty.
+ *     1 along with { data, size } of the (possibly augmented) buffer
+ *       when successful.
+ *
+ * Optionally updates the given oid_stat with the given OID (when valid).
+ */
+static int do_read_blob(const struct object_id *oid, struct oid_stat *oid_stat,
+                       size_t *size_out, char **data_out)
+{
+       enum object_type type;
+       unsigned long sz;
+       char *data;
+
+       *size_out = 0;
+       *data_out = NULL;
+
+       data = read_object_file(oid, &type, &sz);
+       if (!data || type != OBJ_BLOB) {
+               free(data);
+               return -1;
+       }
+
+       if (oid_stat) {
+               memset(&oid_stat->stat, 0, sizeof(oid_stat->stat));
+               oidcpy(&oid_stat->oid, oid);
+       }
+
+       if (sz == 0) {
+               free(data);
+               return 0;
+       }
+
+       if (data[sz - 1] != '\n') {
+               data = xrealloc(data, st_add(sz, 1));
+               data[sz++] = '\n';
+       }
+
+       *size_out = xsize_t(sz);
+       *data_out = data;
+
+       return 1;
+}
+
+#define DO_MATCH_EXCLUDE   (1<<0)
+#define DO_MATCH_DIRECTORY (1<<1)
+#define DO_MATCH_LEADING_PATHSPEC (1<<2)
 
 /*
- * Does 'match' match the given name?
- * A match is found if
+ * Does the given pathspec match the given name?  A match is found if
  *
- * (1) the 'match' string is leading directory of 'name', or
- * (2) the 'match' string is a wildcard and matches 'name', or
- * (3) the 'match' string is exactly the same as 'name'.
+ * (1) the pathspec string is leading directory of 'name' ("RECURSIVELY"), or
+ * (2) the pathspec string has a leading part matching 'name' ("LEADING"), or
+ * (3) the pathspec string is a wildcard and matches 'name' ("WILDCARD"), or
+ * (4) the pathspec string is exactly the same as 'name' ("EXACT").
  *
- * and the return value tells which case it was.
+ * Return value tells which case it was (1-4), or 0 when there is no match.
  *
- * It returns 0 when there is no match.
+ * It may be instructive to look at a small table of concrete examples
+ * to understand the differences between 1, 2, and 4:
+ *
+ *                              Pathspecs
+ *                |    a/b    |   a/b/    |   a/b/c
+ *          ------+-----------+-----------+------------
+ *          a/b   |  EXACT    |  EXACT[1] | LEADING[2]
+ *  Names   a/b/  | RECURSIVE |   EXACT   | LEADING[2]
+ *          a/b/c | RECURSIVE | RECURSIVE |   EXACT
+ *
+ * [1] Only if DO_MATCH_DIRECTORY is passed; otherwise, this is NOT a match.
+ * [2] Only if DO_MATCH_LEADING_PATHSPEC is passed; otherwise, not a match.
  */
-static int match_pathspec_item(const struct pathspec_item *item, int prefix,
+static int match_pathspec_item(const struct index_state *istate,
+                              const struct pathspec_item *item, int prefix,
                               const char *name, int namelen, unsigned flags)
 {
        /* name/namelen has prefix cut off by caller */
@@ -253,6 +338,10 @@ static int match_pathspec_item(const struct pathspec_item *item, int prefix,
            strncmp(item->match, name - prefix, item->prefix))
                return 0;
 
+       if (item->attr_match_nr &&
+           !match_pathspec_attrs(istate, name, namelen, item))
+               return 0;
+
        /* If the match was just the prefix, we matched */
        if (!*match)
                return MATCHED_RECURSIVELY;
@@ -274,6 +363,40 @@ static int match_pathspec_item(const struct pathspec_item *item, int prefix,
                         item->nowildcard_len - prefix))
                return MATCHED_FNMATCH;
 
+       /* Perform checks to see if "name" is a leading string of the pathspec */
+       if (flags & DO_MATCH_LEADING_PATHSPEC) {
+               /* name is a literal prefix of the pathspec */
+               int offset = name[namelen-1] == '/' ? 1 : 0;
+               if ((namelen < matchlen) &&
+                   (match[namelen-offset] == '/') &&
+                   !ps_strncmp(item, match, name, namelen))
+                       return MATCHED_RECURSIVELY_LEADING_PATHSPEC;
+
+               /* name doesn't match up to the first wild character */
+               if (item->nowildcard_len < item->len &&
+                   ps_strncmp(item, match, name,
+                              item->nowildcard_len - prefix))
+                       return 0;
+
+               /*
+                * name has no wildcard, and it didn't match as a leading
+                * pathspec so return.
+                */
+               if (item->nowildcard_len == item->len)
+                       return 0;
+
+               /*
+                * Here is where we would perform a wildmatch to check if
+                * "name" can be matched as a directory (or a prefix) against
+                * the pathspec.  Since wildmatch doesn't have this capability
+                * at the present we have to punt and say that it is a match,
+                * potentially returning a false positive
+                * The submodules themselves will be able to perform more
+                * accurate matching to determine if the pathspec matches.
+                */
+               return MATCHED_RECURSIVELY_LEADING_PATHSPEC;
+       }
+
        return 0;
 }
 
@@ -292,7 +415,8 @@ static int match_pathspec_item(const struct pathspec_item *item, int prefix,
  * pathspec did not match any names, which could indicate that the
  * user mistyped the nth pathspec.
  */
-static int do_match_pathspec(const struct pathspec *ps,
+static int do_match_pathspec(const struct index_state *istate,
+                            const struct pathspec *ps,
                             const char *name, int namelen,
                             int prefix, char *seen,
                             unsigned flags)
@@ -305,7 +429,8 @@ static int do_match_pathspec(const struct pathspec *ps,
                       PATHSPEC_LITERAL |
                       PATHSPEC_GLOB |
                       PATHSPEC_ICASE |
-                      PATHSPEC_EXCLUDE);
+                      PATHSPEC_EXCLUDE |
+                      PATHSPEC_ATTR);
 
        if (!ps->nr) {
                if (!ps->recursive ||
@@ -337,7 +462,7 @@ static int do_match_pathspec(const struct pathspec *ps,
                 */
                if (seen && ps->items[i].magic & PATHSPEC_EXCLUDE)
                        seen[i] = MATCHED_FNMATCH;
-               how = match_pathspec_item(ps->items+i, prefix, name,
+               how = match_pathspec_item(istate, ps->items+i, prefix, name,
                                          namelen, flags);
                if (ps->recursive &&
                    (ps->magic & PATHSPEC_MAXDEPTH) &&
@@ -361,22 +486,79 @@ static int do_match_pathspec(const struct pathspec *ps,
        return retval;
 }
 
-int match_pathspec(const struct pathspec *ps,
+int match_pathspec(const struct index_state *istate,
+                  const struct pathspec *ps,
                   const char *name, int namelen,
                   int prefix, char *seen, int is_dir)
 {
        int positive, negative;
        unsigned flags = is_dir ? DO_MATCH_DIRECTORY : 0;
-       positive = do_match_pathspec(ps, name, namelen,
+       positive = do_match_pathspec(istate, ps, name, namelen,
                                     prefix, seen, flags);
        if (!(ps->magic & PATHSPEC_EXCLUDE) || !positive)
                return positive;
-       negative = do_match_pathspec(ps, name, namelen,
+       negative = do_match_pathspec(istate, ps, name, namelen,
                                     prefix, seen,
                                     flags | DO_MATCH_EXCLUDE);
        return negative ? 0 : positive;
 }
 
+/**
+ * Check if a submodule is a superset of the pathspec
+ */
+int submodule_path_match(const struct index_state *istate,
+                        const struct pathspec *ps,
+                        const char *submodule_name,
+                        char *seen)
+{
+       int matched = do_match_pathspec(istate, ps, submodule_name,
+                                       strlen(submodule_name),
+                                       0, seen,
+                                       DO_MATCH_DIRECTORY |
+                                       DO_MATCH_LEADING_PATHSPEC);
+       return matched;
+}
+
+int report_path_error(const char *ps_matched,
+                     const struct pathspec *pathspec)
+{
+       /*
+        * Make sure all pathspec matched; otherwise it is an error.
+        */
+       int num, errors = 0;
+       for (num = 0; num < pathspec->nr; num++) {
+               int other, found_dup;
+
+               if (ps_matched[num])
+                       continue;
+               /*
+                * The caller might have fed identical pathspec
+                * twice.  Do not barf on such a mistake.
+                * FIXME: parse_pathspec should have eliminated
+                * duplicate pathspec.
+                */
+               for (found_dup = other = 0;
+                    !found_dup && other < pathspec->nr;
+                    other++) {
+                       if (other == num || !ps_matched[other])
+                               continue;
+                       if (!strcmp(pathspec->items[other].original,
+                                   pathspec->items[num].original))
+                               /*
+                                * Ok, we have a match already.
+                                */
+                               found_dup = 1;
+               }
+               if (found_dup)
+                       continue;
+
+               error(_("pathspec '%s' did not match any file(s) known to git"),
+                     pathspec->items[num].original);
+               errors++;
+       }
+       return errors;
+}
+
 /*
  * Return the length of the "simple" part of a path match limiter.
  */
@@ -397,9 +579,9 @@ int no_wildcard(const char *string)
        return string[simple_length(string)] == '\0';
 }
 
-void parse_exclude_pattern(const char **pattern,
+void parse_path_pattern(const char **pattern,
                           int *patternlen,
-                          int *flags,
+                          unsigned *flags,
                           int *nowildcardlen)
 {
        const char *p = *pattern;
@@ -407,20 +589,20 @@ void parse_exclude_pattern(const char **pattern,
 
        *flags = 0;
        if (*p == '!') {
-               *flags |= EXC_FLAG_NEGATIVE;
+               *flags |= PATTERN_FLAG_NEGATIVE;
                p++;
        }
        len = strlen(p);
        if (len && p[len - 1] == '/') {
                len--;
-               *flags |= EXC_FLAG_MUSTBEDIR;
+               *flags |= PATTERN_FLAG_MUSTBEDIR;
        }
        for (i = 0; i < len; i++) {
                if (p[i] == '/')
                        break;
        }
        if (i == len)
-               *flags |= EXC_FLAG_NODIR;
+               *flags |= PATTERN_FLAG_NODIR;
        *nowildcardlen = simple_length(p);
        /*
         * we should have excluded the trailing slash from 'p' too,
@@ -430,80 +612,223 @@ void parse_exclude_pattern(const char **pattern,
        if (*nowildcardlen > len)
                *nowildcardlen = len;
        if (*p == '*' && no_wildcard(p + 1))
-               *flags |= EXC_FLAG_ENDSWITH;
+               *flags |= PATTERN_FLAG_ENDSWITH;
        *pattern = p;
        *patternlen = len;
 }
 
-void add_exclude(const char *string, const char *base,
-                int baselen, struct exclude_list *el, int srcpos)
+int pl_hashmap_cmp(const void *unused_cmp_data,
+                  const struct hashmap_entry *a,
+                  const struct hashmap_entry *b,
+                  const void *key)
+{
+       const struct pattern_entry *ee1 =
+                       container_of(a, struct pattern_entry, ent);
+       const struct pattern_entry *ee2 =
+                       container_of(b, struct pattern_entry, ent);
+
+       size_t min_len = ee1->patternlen <= ee2->patternlen
+                        ? ee1->patternlen
+                        : ee2->patternlen;
+
+       if (ignore_case)
+               return strncasecmp(ee1->pattern, ee2->pattern, min_len);
+       return strncmp(ee1->pattern, ee2->pattern, min_len);
+}
+
+static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern *given)
+{
+       struct pattern_entry *translated;
+       char *truncated;
+       char *data = NULL;
+
+       if (!pl->use_cone_patterns)
+               return;
+
+       if (given->flags & PATTERN_FLAG_NEGATIVE &&
+           given->flags & PATTERN_FLAG_MUSTBEDIR &&
+           !strcmp(given->pattern, "/*")) {
+               pl->full_cone = 0;
+               return;
+       }
+
+       if (!given->flags && !strcmp(given->pattern, "/*")) {
+               pl->full_cone = 1;
+               return;
+       }
+
+       if (given->patternlen > 2 &&
+           !strcmp(given->pattern + given->patternlen - 2, "/*")) {
+               if (!(given->flags & PATTERN_FLAG_NEGATIVE)) {
+                       /* Not a cone pattern. */
+                       pl->use_cone_patterns = 0;
+                       warning(_("unrecognized pattern: '%s'"), given->pattern);
+                       goto clear_hashmaps;
+               }
+
+               truncated = xstrdup(given->pattern);
+               truncated[given->patternlen - 2] = 0;
+
+               translated = xmalloc(sizeof(struct pattern_entry));
+               translated->pattern = truncated;
+               translated->patternlen = given->patternlen - 2;
+               hashmap_entry_init(&translated->ent,
+                                  ignore_case ?
+                                  strihash(translated->pattern) :
+                                  strhash(translated->pattern));
+
+               if (!hashmap_get_entry(&pl->recursive_hashmap,
+                                      translated, ent, NULL)) {
+                       /* We did not see the "parent" included */
+                       warning(_("unrecognized negative pattern: '%s'"),
+                               given->pattern);
+                       free(truncated);
+                       free(translated);
+                       goto clear_hashmaps;
+               }
+
+               hashmap_add(&pl->parent_hashmap, &translated->ent);
+               hashmap_remove(&pl->recursive_hashmap, &translated->ent, &data);
+               free(data);
+               return;
+       }
+
+       if (given->flags & PATTERN_FLAG_NEGATIVE) {
+               warning(_("unrecognized negative pattern: '%s'"),
+                       given->pattern);
+               goto clear_hashmaps;
+       }
+
+       translated = xmalloc(sizeof(struct pattern_entry));
+
+       translated->pattern = xstrdup(given->pattern);
+       translated->patternlen = given->patternlen;
+       hashmap_entry_init(&translated->ent,
+                          ignore_case ?
+                          strihash(translated->pattern) :
+                          strhash(translated->pattern));
+
+       hashmap_add(&pl->recursive_hashmap, &translated->ent);
+
+       if (hashmap_get_entry(&pl->parent_hashmap, translated, ent, NULL)) {
+               /* we already included this at the parent level */
+               warning(_("your sparse-checkout file may have issues: pattern '%s' is repeated"),
+                       given->pattern);
+               hashmap_remove(&pl->parent_hashmap, &translated->ent, &data);
+               free(data);
+               free(translated);
+       }
+
+       return;
+
+clear_hashmaps:
+       warning(_("disabling cone pattern matching"));
+       hashmap_free_entries(&pl->parent_hashmap, struct pattern_entry, ent);
+       hashmap_free_entries(&pl->recursive_hashmap, struct pattern_entry, ent);
+       pl->use_cone_patterns = 0;
+}
+
+static int hashmap_contains_path(struct hashmap *map,
+                                struct strbuf *pattern)
+{
+       struct pattern_entry p;
+
+       /* Check straight mapping */
+       p.pattern = pattern->buf;
+       p.patternlen = pattern->len;
+       hashmap_entry_init(&p.ent,
+                          ignore_case ?
+                          strihash(p.pattern) :
+                          strhash(p.pattern));
+       return !!hashmap_get_entry(map, &p, ent, NULL);
+}
+
+int hashmap_contains_parent(struct hashmap *map,
+                           const char *path,
+                           struct strbuf *buffer)
+{
+       char *slash_pos;
+
+       strbuf_setlen(buffer, 0);
+
+       if (path[0] != '/')
+               strbuf_addch(buffer, '/');
+
+       strbuf_addstr(buffer, path);
+
+       slash_pos = strrchr(buffer->buf, '/');
+
+       while (slash_pos > buffer->buf) {
+               strbuf_setlen(buffer, slash_pos - buffer->buf);
+
+               if (hashmap_contains_path(map, buffer))
+                       return 1;
+
+               slash_pos = strrchr(buffer->buf, '/');
+       }
+
+       return 0;
+}
+
+void add_pattern(const char *string, const char *base,
+                int baselen, struct pattern_list *pl, int srcpos)
 {
-       struct exclude *x;
+       struct path_pattern *pattern;
        int patternlen;
-       int flags;
+       unsigned flags;
        int nowildcardlen;
 
-       parse_exclude_pattern(&string, &patternlen, &flags, &nowildcardlen);
-       if (flags & EXC_FLAG_MUSTBEDIR) {
-               char *s;
-               x = xmalloc(sizeof(*x) + patternlen + 1);
-               s = (char *)(x+1);
-               memcpy(s, string, patternlen);
-               s[patternlen] = '\0';
-               x->pattern = s;
+       parse_path_pattern(&string, &patternlen, &flags, &nowildcardlen);
+       if (flags & PATTERN_FLAG_MUSTBEDIR) {
+               FLEXPTR_ALLOC_MEM(pattern, pattern, string, patternlen);
        } else {
-               x = xmalloc(sizeof(*x));
-               x->pattern = string;
+               pattern = xmalloc(sizeof(*pattern));
+               pattern->pattern = string;
        }
-       x->patternlen = patternlen;
-       x->nowildcardlen = nowildcardlen;
-       x->base = base;
-       x->baselen = baselen;
-       x->flags = flags;
-       x->srcpos = srcpos;
-       ALLOC_GROW(el->excludes, el->nr + 1, el->alloc);
-       el->excludes[el->nr++] = x;
-       x->el = el;
+       pattern->patternlen = patternlen;
+       pattern->nowildcardlen = nowildcardlen;
+       pattern->base = base;
+       pattern->baselen = baselen;
+       pattern->flags = flags;
+       pattern->srcpos = srcpos;
+       ALLOC_GROW(pl->patterns, pl->nr + 1, pl->alloc);
+       pl->patterns[pl->nr++] = pattern;
+       pattern->pl = pl;
+
+       add_pattern_to_hashsets(pl, pattern);
 }
 
-static void *read_skip_worktree_file_from_index(const char *path, size_t *size)
+static int read_skip_worktree_file_from_index(const struct index_state *istate,
+                                             const char *path,
+                                             size_t *size_out, char **data_out,
+                                             struct oid_stat *oid_stat)
 {
        int pos, len;
-       unsigned long sz;
-       enum object_type type;
-       void *data;
 
        len = strlen(path);
-       pos = cache_name_pos(path, len);
+       pos = index_name_pos(istate, path, len);
        if (pos < 0)
-               return NULL;
-       if (!ce_skip_worktree(active_cache[pos]))
-               return NULL;
-       data = read_sha1_file(active_cache[pos]->sha1, &type, &sz);
-       if (!data || type != OBJ_BLOB) {
-               free(data);
-               return NULL;
-       }
-       *size = xsize_t(sz);
-       return data;
+               return -1;
+       if (!ce_skip_worktree(istate->cache[pos]))
+               return -1;
+
+       return do_read_blob(&istate->cache[pos]->oid, oid_stat, size_out, data_out);
 }
 
 /*
- * Frees memory within el which was allocated for exclude patterns and
- * the file buffer.  Does not free el itself.
+ * Frees memory within pl which was allocated for exclude patterns and
+ * the file buffer.  Does not free pl itself.
  */
-void clear_exclude_list(struct exclude_list *el)
+void clear_pattern_list(struct pattern_list *pl)
 {
        int i;
 
-       for (i = 0; i < el->nr; i++)
-               free(el->excludes[i]);
-       free(el->excludes);
-       free(el->filebuf);
+       for (i = 0; i < pl->nr; i++)
+               free(pl->patterns[i]);
+       free(pl->patterns);
+       free(pl->filebuf);
 
-       el->nr = 0;
-       el->excludes = NULL;
-       el->filebuf = NULL;
+       memset(pl, 0, sizeof(*pl));
 }
 
 static void trim_trailing_spaces(char *buf)
@@ -529,41 +854,135 @@ static void trim_trailing_spaces(char *buf)
                *last_space = '\0';
 }
 
-int add_excludes_from_file_to_list(const char *fname,
-                                  const char *base,
-                                  int baselen,
-                                  struct exclude_list *el,
-                                  int check_index)
+/*
+ * Given a subdirectory name and "dir" of the current directory,
+ * search the subdir in "dir" and return it, or create a new one if it
+ * does not exist in "dir".
+ *
+ * If "name" has the trailing slash, it'll be excluded in the search.
+ */
+static struct untracked_cache_dir *lookup_untracked(struct untracked_cache *uc,
+                                                   struct untracked_cache_dir *dir,
+                                                   const char *name, int len)
+{
+       int first, last;
+       struct untracked_cache_dir *d;
+       if (!dir)
+               return NULL;
+       if (len && name[len - 1] == '/')
+               len--;
+       first = 0;
+       last = dir->dirs_nr;
+       while (last > first) {
+               int cmp, next = first + ((last - first) >> 1);
+               d = dir->dirs[next];
+               cmp = strncmp(name, d->name, len);
+               if (!cmp && strlen(d->name) > len)
+                       cmp = -1;
+               if (!cmp)
+                       return d;
+               if (cmp < 0) {
+                       last = next;
+                       continue;
+               }
+               first = next+1;
+       }
+
+       uc->dir_created++;
+       FLEX_ALLOC_MEM(d, name, name, len);
+
+       ALLOC_GROW(dir->dirs, dir->dirs_nr + 1, dir->dirs_alloc);
+       MOVE_ARRAY(dir->dirs + first + 1, dir->dirs + first,
+                  dir->dirs_nr - first);
+       dir->dirs_nr++;
+       dir->dirs[first] = d;
+       return d;
+}
+
+static void do_invalidate_gitignore(struct untracked_cache_dir *dir)
+{
+       int i;
+       dir->valid = 0;
+       dir->untracked_nr = 0;
+       for (i = 0; i < dir->dirs_nr; i++)
+               do_invalidate_gitignore(dir->dirs[i]);
+}
+
+static void invalidate_gitignore(struct untracked_cache *uc,
+                                struct untracked_cache_dir *dir)
+{
+       uc->gitignore_invalidated++;
+       do_invalidate_gitignore(dir);
+}
+
+static void invalidate_directory(struct untracked_cache *uc,
+                                struct untracked_cache_dir *dir)
+{
+       int i;
+
+       /*
+        * Invalidation increment here is just roughly correct. If
+        * untracked_nr or any of dirs[].recurse is non-zero, we
+        * should increment dir_invalidated too. But that's more
+        * expensive to do.
+        */
+       if (dir->valid)
+               uc->dir_invalidated++;
+
+       dir->valid = 0;
+       dir->untracked_nr = 0;
+       for (i = 0; i < dir->dirs_nr; i++)
+               dir->dirs[i]->recurse = 0;
+}
+
+static int add_patterns_from_buffer(char *buf, size_t size,
+                                   const char *base, int baselen,
+                                   struct pattern_list *pl);
+
+/*
+ * Given a file with name "fname", read it (either from disk, or from
+ * an index if 'istate' is non-null), parse it and store the
+ * exclude rules in "pl".
+ *
+ * If "ss" is not NULL, compute SHA-1 of the exclude file and fill
+ * stat data from disk (only valid if add_patterns returns zero). If
+ * ss_valid is non-zero, "ss" must contain good value as input.
+ */
+static int add_patterns(const char *fname, const char *base, int baselen,
+                       struct pattern_list *pl, struct index_state *istate,
+                       struct oid_stat *oid_stat)
 {
        struct stat st;
-       int fd, i, lineno = 1;
+       int r;
+       int fd;
        size_t size = 0;
-       char *buf, *entry;
+       char *buf;
 
        fd = open(fname, O_RDONLY);
        if (fd < 0 || fstat(fd, &st) < 0) {
-               if (errno != ENOENT)
-                       warn_on_inaccessible(fname);
-               if (0 <= fd)
+               if (fd < 0)
+                       warn_on_fopen_errors(fname);
+               else
                        close(fd);
-               if (!check_index ||
-                   (buf = read_skip_worktree_file_from_index(fname, &size)) == NULL)
+               if (!istate)
                        return -1;
-               if (size == 0) {
-                       free(buf);
-                       return 0;
-               }
-               if (buf[size-1] != '\n') {
-                       buf = xrealloc(buf, size+1);
-                       buf[size++] = '\n';
-               }
+               r = read_skip_worktree_file_from_index(istate, fname,
+                                                      &size, &buf,
+                                                      oid_stat);
+               if (r != 1)
+                       return r;
        } else {
                size = xsize_t(st.st_size);
                if (size == 0) {
+                       if (oid_stat) {
+                               fill_stat_data(&oid_stat->stat, &st);
+                               oidcpy(&oid_stat->oid, the_hash_algo->empty_blob);
+                               oid_stat->valid = 1;
+                       }
                        close(fd);
                        return 0;
                }
-               buf = xmalloc(size+1);
+               buf = xmallocz(size);
                if (read_in_full(fd, buf, size) != size) {
                        free(buf);
                        close(fd);
@@ -571,16 +990,53 @@ int add_excludes_from_file_to_list(const char *fname,
                }
                buf[size++] = '\n';
                close(fd);
+               if (oid_stat) {
+                       int pos;
+                       if (oid_stat->valid &&
+                           !match_stat_data_racy(istate, &oid_stat->stat, &st))
+                               ; /* no content change, ss->sha1 still good */
+                       else if (istate &&
+                                (pos = index_name_pos(istate, fname, strlen(fname))) >= 0 &&
+                                !ce_stage(istate->cache[pos]) &&
+                                ce_uptodate(istate->cache[pos]) &&
+                                !would_convert_to_git(istate, fname))
+                               oidcpy(&oid_stat->oid,
+                                      &istate->cache[pos]->oid);
+                       else
+                               hash_object_file(buf, size, "blob",
+                                                &oid_stat->oid);
+                       fill_stat_data(&oid_stat->stat, &st);
+                       oid_stat->valid = 1;
+               }
        }
 
-       el->filebuf = buf;
+       add_patterns_from_buffer(buf, size, base, baselen, pl);
+       return 0;
+}
+
+static int add_patterns_from_buffer(char *buf, size_t size,
+                                   const char *base, int baselen,
+                                   struct pattern_list *pl)
+{
+       int i, lineno = 1;
+       char *entry;
+
+       hashmap_init(&pl->recursive_hashmap, pl_hashmap_cmp, NULL, 0);
+       hashmap_init(&pl->parent_hashmap, pl_hashmap_cmp, NULL, 0);
+
+       pl->filebuf = buf;
+
+       if (skip_utf8_bom(&buf, size))
+               size -= buf - pl->filebuf;
+
        entry = buf;
+
        for (i = 0; i < size; i++) {
                if (buf[i] == '\n') {
                        if (entry != buf + i && entry[0] != '#') {
                                buf[i - (i && buf[i-1] == '\r')] = 0;
                                trim_trailing_spaces(entry);
-                               add_exclude(entry, base, baselen, el, lineno);
+                               add_pattern(entry, base, baselen, pl, lineno);
                        }
                        lineno++;
                        entry = buf + i + 1;
@@ -589,43 +1045,81 @@ int add_excludes_from_file_to_list(const char *fname,
        return 0;
 }
 
-struct exclude_list *add_exclude_list(struct dir_struct *dir,
+int add_patterns_from_file_to_list(const char *fname, const char *base,
+                                  int baselen, struct pattern_list *pl,
+                                  struct index_state *istate)
+{
+       return add_patterns(fname, base, baselen, pl, istate, NULL);
+}
+
+int add_patterns_from_blob_to_list(
+       struct object_id *oid,
+       const char *base, int baselen,
+       struct pattern_list *pl)
+{
+       char *buf;
+       size_t size;
+       int r;
+
+       r = do_read_blob(oid, NULL, &size, &buf);
+       if (r != 1)
+               return r;
+
+       add_patterns_from_buffer(buf, size, base, baselen, pl);
+       return 0;
+}
+
+struct pattern_list *add_pattern_list(struct dir_struct *dir,
                                      int group_type, const char *src)
 {
-       struct exclude_list *el;
+       struct pattern_list *pl;
        struct exclude_list_group *group;
 
        group = &dir->exclude_list_group[group_type];
-       ALLOC_GROW(group->el, group->nr + 1, group->alloc);
-       el = &group->el[group->nr++];
-       memset(el, 0, sizeof(*el));
-       el->src = src;
-       return el;
+       ALLOC_GROW(group->pl, group->nr + 1, group->alloc);
+       pl = &group->pl[group->nr++];
+       memset(pl, 0, sizeof(*pl));
+       pl->src = src;
+       return pl;
 }
 
 /*
  * Used to set up core.excludesfile and .git/info/exclude lists.
  */
-void add_excludes_from_file(struct dir_struct *dir, const char *fname)
+static void add_patterns_from_file_1(struct dir_struct *dir, const char *fname,
+                                    struct oid_stat *oid_stat)
 {
-       struct exclude_list *el;
-       el = add_exclude_list(dir, EXC_FILE, fname);
-       if (add_excludes_from_file_to_list(fname, "", 0, el, 0) < 0)
-               die("cannot use %s as an exclude file", fname);
+       struct pattern_list *pl;
+       /*
+        * catch setup_standard_excludes() that's called before
+        * dir->untracked is assigned. That function behaves
+        * differently when dir->untracked is non-NULL.
+        */
+       if (!dir->untracked)
+               dir->unmanaged_exclude_files++;
+       pl = add_pattern_list(dir, EXC_FILE, fname);
+       if (add_patterns(fname, "", 0, pl, NULL, oid_stat) < 0)
+               die(_("cannot use %s as an exclude file"), fname);
+}
+
+void add_patterns_from_file(struct dir_struct *dir, const char *fname)
+{
+       dir->unmanaged_exclude_files++; /* see validate_untracked_cache() */
+       add_patterns_from_file_1(dir, fname, NULL);
 }
 
 int match_basename(const char *basename, int basenamelen,
                   const char *pattern, int prefix, int patternlen,
-                  int flags)
+                  unsigned flags)
 {
        if (prefix == patternlen) {
                if (patternlen == basenamelen &&
-                   !strncmp_icase(pattern, basename, basenamelen))
+                   !fspathncmp(pattern, basename, basenamelen))
                        return 1;
-       } else if (flags & EXC_FLAG_ENDSWITH) {
+       } else if (flags & PATTERN_FLAG_ENDSWITH) {
                /* "*literal" matching against "fooliteral" */
                if (patternlen - 1 <= basenamelen &&
-                   !strncmp_icase(pattern + 1,
+                   !fspathncmp(pattern + 1,
                                   basename + basenamelen - (patternlen - 1),
                                   patternlen - 1))
                        return 1;
@@ -641,7 +1135,7 @@ int match_basename(const char *basename, int basenamelen,
 int match_pathname(const char *pathname, int pathlen,
                   const char *base, int baselen,
                   const char *pattern, int prefix, int patternlen,
-                  int flags)
+                  unsigned flags)
 {
        const char *name;
        int namelen;
@@ -662,7 +1156,7 @@ int match_pathname(const char *pathname, int pathlen,
         */
        if (pathlen < baselen + 1 ||
            (baselen && pathname[baselen] != '/') ||
-           strncmp_icase(pathname, base, baselen))
+           fspathncmp(pathname, base, baselen))
                return 0;
 
        namelen = baselen ? pathlen - baselen - 1 : pathlen;
@@ -676,7 +1170,7 @@ int match_pathname(const char *pathname, int pathlen,
                if (prefix > namelen)
                        return 0;
 
-               if (strncmp_icase(pattern, name, prefix))
+               if (fspathncmp(pattern, name, prefix))
                        return 0;
                pattern += prefix;
                patternlen -= prefix;
@@ -703,77 +1197,138 @@ int match_pathname(const char *pathname, int pathlen,
  * any, determines the fate.  Returns the exclude_list element which
  * matched, or NULL for undecided.
  */
-static struct exclude *last_exclude_matching_from_list(const char *pathname,
+static struct path_pattern *last_matching_pattern_from_list(const char *pathname,
                                                       int pathlen,
                                                       const char *basename,
                                                       int *dtype,
-                                                      struct exclude_list *el)
+                                                      struct pattern_list *pl,
+                                                      struct index_state *istate)
 {
+       struct path_pattern *res = NULL; /* undecided */
        int i;
 
-       if (!el->nr)
+       if (!pl->nr)
                return NULL;    /* undefined */
 
-       for (i = el->nr - 1; 0 <= i; i--) {
-               struct exclude *x = el->excludes[i];
-               const char *exclude = x->pattern;
-               int prefix = x->nowildcardlen;
+       for (i = pl->nr - 1; 0 <= i; i--) {
+               struct path_pattern *pattern = pl->patterns[i];
+               const char *exclude = pattern->pattern;
+               int prefix = pattern->nowildcardlen;
 
-               if (x->flags & EXC_FLAG_MUSTBEDIR) {
-                       if (*dtype == DT_UNKNOWN)
-                               *dtype = get_dtype(NULL, pathname, pathlen);
+               if (pattern->flags & PATTERN_FLAG_MUSTBEDIR) {
+                       *dtype = resolve_dtype(*dtype, istate, pathname, pathlen);
                        if (*dtype != DT_DIR)
                                continue;
                }
 
-               if (x->flags & EXC_FLAG_NODIR) {
+               if (pattern->flags & PATTERN_FLAG_NODIR) {
                        if (match_basename(basename,
                                           pathlen - (basename - pathname),
-                                          exclude, prefix, x->patternlen,
-                                          x->flags))
-                               return x;
+                                          exclude, prefix, pattern->patternlen,
+                                          pattern->flags)) {
+                               res = pattern;
+                               break;
+                       }
                        continue;
                }
 
-               assert(x->baselen == 0 || x->base[x->baselen - 1] == '/');
+               assert(pattern->baselen == 0 ||
+                      pattern->base[pattern->baselen - 1] == '/');
                if (match_pathname(pathname, pathlen,
-                                  x->base, x->baselen ? x->baselen - 1 : 0,
-                                  exclude, prefix, x->patternlen, x->flags))
-                       return x;
+                                  pattern->base,
+                                  pattern->baselen ? pattern->baselen - 1 : 0,
+                                  exclude, prefix, pattern->patternlen,
+                                  pattern->flags)) {
+                       res = pattern;
+                       break;
+               }
        }
-       return NULL; /* undecided */
+       return res;
 }
 
 /*
- * Scan the list and let the last match determine the fate.
- * Return 1 for exclude, 0 for include and -1 for undecided.
+ * Scan the list of patterns to determine if the ordered list
+ * of patterns matches on 'pathname'.
+ *
+ * Return 1 for a match, 0 for not matched and -1 for undecided.
  */
-int is_excluded_from_list(const char *pathname,
-                         int pathlen, const char *basename, int *dtype,
-                         struct exclude_list *el)
+enum pattern_match_result path_matches_pattern_list(
+                               const char *pathname, int pathlen,
+                               const char *basename, int *dtype,
+                               struct pattern_list *pl,
+                               struct index_state *istate)
 {
-       struct exclude *exclude;
-       exclude = last_exclude_matching_from_list(pathname, pathlen, basename, dtype, el);
-       if (exclude)
-               return exclude->flags & EXC_FLAG_NEGATIVE ? 0 : 1;
-       return -1; /* undecided */
+       struct path_pattern *pattern;
+       struct strbuf parent_pathname = STRBUF_INIT;
+       int result = NOT_MATCHED;
+       const char *slash_pos;
+
+       if (!pl->use_cone_patterns) {
+               pattern = last_matching_pattern_from_list(pathname, pathlen, basename,
+                                                       dtype, pl, istate);
+               if (pattern) {
+                       if (pattern->flags & PATTERN_FLAG_NEGATIVE)
+                               return NOT_MATCHED;
+                       else
+                               return MATCHED;
+               }
+
+               return UNDECIDED;
+       }
+
+       if (pl->full_cone)
+               return MATCHED;
+
+       strbuf_addch(&parent_pathname, '/');
+       strbuf_add(&parent_pathname, pathname, pathlen);
+
+       if (hashmap_contains_path(&pl->recursive_hashmap,
+                                 &parent_pathname)) {
+               result = MATCHED_RECURSIVE;
+               goto done;
+       }
+
+       slash_pos = strrchr(parent_pathname.buf, '/');
+
+       if (slash_pos == parent_pathname.buf) {
+               /* include every file in root */
+               result = MATCHED;
+               goto done;
+       }
+
+       strbuf_setlen(&parent_pathname, slash_pos - parent_pathname.buf);
+
+       if (hashmap_contains_path(&pl->parent_hashmap, &parent_pathname)) {
+               result = MATCHED;
+               goto done;
+       }
+
+       if (hashmap_contains_parent(&pl->recursive_hashmap,
+                                   pathname,
+                                   &parent_pathname))
+               result = MATCHED_RECURSIVE;
+
+done:
+       strbuf_release(&parent_pathname);
+       return result;
 }
 
-static struct exclude *last_exclude_matching_from_lists(struct dir_struct *dir,
-               const char *pathname, int pathlen, const char *basename,
-               int *dtype_p)
+static struct path_pattern *last_matching_pattern_from_lists(
+               struct dir_struct *dir, struct index_state *istate,
+               const char *pathname, int pathlen,
+               const char *basename, int *dtype_p)
 {
        int i, j;
        struct exclude_list_group *group;
-       struct exclude *exclude;
+       struct path_pattern *pattern;
        for (i = EXC_CMDL; i <= EXC_FILE; i++) {
                group = &dir->exclude_list_group[i];
                for (j = group->nr - 1; j >= 0; j--) {
-                       exclude = last_exclude_matching_from_list(
+                       pattern = last_matching_pattern_from_list(
                                pathname, pathlen, basename, dtype_p,
-                               &group->el[j]);
-                       if (exclude)
-                               return exclude;
+                               &group->pl[j], istate);
+                       if (pattern)
+                               return pattern;
                }
        }
        return NULL;
@@ -783,11 +1338,14 @@ static struct exclude *last_exclude_matching_from_lists(struct dir_struct *dir,
  * Loads the per-directory exclude list for the substring of base
  * which has a char length of baselen.
  */
-static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
+static void prep_exclude(struct dir_struct *dir,
+                        struct index_state *istate,
+                        const char *base, int baselen)
 {
        struct exclude_list_group *group;
-       struct exclude_list *el;
+       struct pattern_list *pl;
        struct exclude_stack *stk = NULL;
+       struct untracked_cache_dir *untracked;
        int current;
 
        group = &dir->exclude_list_group[EXC_DIRS];
@@ -801,17 +1359,17 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
                if (stk->baselen <= baselen &&
                    !strncmp(dir->basebuf.buf, base, stk->baselen))
                        break;
-               el = &group->el[dir->exclude_stack->exclude_ix];
+               pl = &group->pl[dir->exclude_stack->exclude_ix];
                dir->exclude_stack = stk->prev;
-               dir->exclude = NULL;
-               free((char *)el->src); /* see strbuf_detach() below */
-               clear_exclude_list(el);
+               dir->pattern = NULL;
+               free((char *)pl->src); /* see strbuf_detach() below */
+               clear_pattern_list(pl);
                free(stk);
                group->nr--;
        }
 
        /* Skip traversing into sub directories if the parent is excluded */
-       if (dir->exclude)
+       if (dir->pattern)
                return;
 
        /*
@@ -825,10 +1383,16 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
        /* Read from the parent directories and push them down. */
        current = stk ? stk->baselen : -1;
        strbuf_setlen(&dir->basebuf, current < 0 ? 0 : current);
+       if (dir->untracked)
+               untracked = stk ? stk->ucd : dir->untracked->root;
+       else
+               untracked = NULL;
+
        while (current < baselen) {
-               struct exclude_stack *stk = xcalloc(1, sizeof(*stk));
                const char *cp;
+               struct oid_stat oid_stat;
 
+               stk = xcalloc(1, sizeof(*stk));
                if (current < 0) {
                        cp = base;
                        current = 0;
@@ -837,11 +1401,16 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
                        if (!cp)
                                die("oops in prep_exclude");
                        cp++;
+                       untracked =
+                               lookup_untracked(dir->untracked, untracked,
+                                                base + current,
+                                                cp - base - current);
                }
                stk->prev = dir->exclude_stack;
                stk->baselen = cp - base;
                stk->exclude_ix = group->nr;
-               el = add_exclude_list(dir, EXC_DIRS, NULL);
+               stk->ucd = untracked;
+               pl = add_pattern_list(dir, EXC_DIRS, NULL);
                strbuf_add(&dir->basebuf, base + current, stk->baselen - current);
                assert(stk->baselen == dir->basebuf.len);
 
@@ -849,35 +1418,70 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
                if (stk->baselen) {
                        int dt = DT_DIR;
                        dir->basebuf.buf[stk->baselen - 1] = 0;
-                       dir->exclude = last_exclude_matching_from_lists(dir,
+                       dir->pattern = last_matching_pattern_from_lists(dir,
+                                                                       istate,
                                dir->basebuf.buf, stk->baselen - 1,
                                dir->basebuf.buf + current, &dt);
                        dir->basebuf.buf[stk->baselen - 1] = '/';
-                       if (dir->exclude &&
-                           dir->exclude->flags & EXC_FLAG_NEGATIVE)
-                               dir->exclude = NULL;
-                       if (dir->exclude) {
+                       if (dir->pattern &&
+                           dir->pattern->flags & PATTERN_FLAG_NEGATIVE)
+                               dir->pattern = NULL;
+                       if (dir->pattern) {
                                dir->exclude_stack = stk;
                                return;
                        }
                }
 
                /* Try to read per-directory file */
-               if (dir->exclude_per_dir) {
+               oidclr(&oid_stat.oid);
+               oid_stat.valid = 0;
+               if (dir->exclude_per_dir &&
+                   /*
+                    * If we know that no files have been added in
+                    * this directory (i.e. valid_cached_dir() has
+                    * been executed and set untracked->valid) ..
+                    */
+                   (!untracked || !untracked->valid ||
+                    /*
+                     * .. and .gitignore does not exist before
+                     * (i.e. null exclude_oid). Then we can skip
+                     * loading .gitignore, which would result in
+                     * ENOENT anyway.
+                     */
+                    !is_null_oid(&untracked->exclude_oid))) {
                        /*
                         * dir->basebuf gets reused by the traversal, but we
                         * need fname to remain unchanged to ensure the src
-                        * member of each struct exclude correctly
+                        * member of each struct path_pattern correctly
                         * back-references its source file.  Other invocations
-                        * of add_exclude_list provide stable strings, so we
+                        * of add_pattern_list provide stable strings, so we
                         * strbuf_detach() and free() here in the caller.
                         */
                        struct strbuf sb = STRBUF_INIT;
                        strbuf_addbuf(&sb, &dir->basebuf);
                        strbuf_addstr(&sb, dir->exclude_per_dir);
-                       el->src = strbuf_detach(&sb, NULL);
-                       add_excludes_from_file_to_list(el->src, el->src,
-                                                      stk->baselen, el, 1);
+                       pl->src = strbuf_detach(&sb, NULL);
+                       add_patterns(pl->src, pl->src, stk->baselen, pl, istate,
+                                    untracked ? &oid_stat : NULL);
+               }
+               /*
+                * NEEDSWORK: when untracked cache is enabled, prep_exclude()
+                * will first be called in valid_cached_dir() then maybe many
+                * times more in last_matching_pattern(). When the cache is
+                * used, last_matching_pattern() will not be called and
+                * reading .gitignore content will be a waste.
+                *
+                * So when it's called by valid_cached_dir() and we can get
+                * .gitignore SHA-1 from the index (i.e. .gitignore is not
+                * modified on work tree), we could delay reading the
+                * .gitignore content until we absolutely need it in
+                * last_matching_pattern(). Be careful about ignore rule
+                * order, though, if you do that.
+                */
+               if (untracked &&
+                   !oideq(&oid_stat.oid, &untracked->exclude_oid)) {
+                       invalidate_gitignore(dir->untracked, untracked);
+                       oidcpy(&untracked->exclude_oid, &oid_stat.oid);
                }
                dir->exclude_stack = stk;
                current = stk->baselen;
@@ -891,20 +1495,21 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
  * Returns the exclude_list element which matched, or NULL for
  * undecided.
  */
-struct exclude *last_exclude_matching(struct dir_struct *dir,
-                                            const char *pathname,
-                                            int *dtype_p)
+struct path_pattern *last_matching_pattern(struct dir_struct *dir,
+                                     struct index_state *istate,
+                                     const char *pathname,
+                                     int *dtype_p)
 {
        int pathlen = strlen(pathname);
        const char *basename = strrchr(pathname, '/');
        basename = (basename) ? basename+1 : pathname;
 
-       prep_exclude(dir, pathname, basename-pathname);
+       prep_exclude(dir, istate, pathname, basename-pathname);
 
-       if (dir->exclude)
-               return dir->exclude;
+       if (dir->pattern)
+               return dir->pattern;
 
-       return last_exclude_matching_from_lists(dir, pathname, pathlen,
+       return last_matching_pattern_from_lists(dir, istate, pathname, pathlen,
                        basename, dtype_p);
 }
 
@@ -913,12 +1518,13 @@ struct exclude *last_exclude_matching(struct dir_struct *dir,
  * scans all exclude lists to determine whether pathname is excluded.
  * Returns 1 if true, otherwise 0.
  */
-int is_excluded(struct dir_struct *dir, const char *pathname, int *dtype_p)
+int is_excluded(struct dir_struct *dir, struct index_state *istate,
+               const char *pathname, int *dtype_p)
 {
-       struct exclude *exclude =
-               last_exclude_matching(dir, pathname, dtype_p);
-       if (exclude)
-               return exclude->flags & EXC_FLAG_NEGATIVE ? 0 : 1;
+       struct path_pattern *pattern =
+               last_matching_pattern(dir, istate, pathname, dtype_p);
+       if (pattern)
+               return pattern->flags & PATTERN_FLAG_NEGATIVE ? 0 : 1;
        return 0;
 }
 
@@ -926,25 +1532,27 @@ static struct dir_entry *dir_entry_new(const char *pathname, int len)
 {
        struct dir_entry *ent;
 
-       ent = xmalloc(sizeof(*ent) + len + 1);
+       FLEX_ALLOC_MEM(ent, name, pathname, len);
        ent->len = len;
-       memcpy(ent->name, pathname, len);
-       ent->name[len] = 0;
        return ent;
 }
 
-static struct dir_entry *dir_add_name(struct dir_struct *dir, const char *pathname, int len)
+static struct dir_entry *dir_add_name(struct dir_struct *dir,
+                                     struct index_state *istate,
+                                     const char *pathname, int len)
 {
-       if (cache_file_exists(pathname, len, ignore_case))
+       if (index_file_exists(istate, pathname, len, ignore_case))
                return NULL;
 
        ALLOC_GROW(dir->entries, dir->nr+1, dir->alloc);
        return dir->entries[dir->nr++] = dir_entry_new(pathname, len);
 }
 
-struct dir_entry *dir_add_ignored(struct dir_struct *dir, const char *pathname, int len)
+struct dir_entry *dir_add_ignored(struct dir_struct *dir,
+                                 struct index_state *istate,
+                                 const char *pathname, int len)
 {
-       if (!cache_name_is_other(pathname, len))
+       if (!index_name_is_other(istate, pathname, len))
                return NULL;
 
        ALLOC_GROW(dir->ignored, dir->ignored_nr+1, dir->ignored_alloc);
@@ -962,31 +1570,18 @@ enum exist_status {
  * the directory name; instead, use the case insensitive
  * directory hash.
  */
-static enum exist_status directory_exists_in_index_icase(const char *dirname, int len)
+static enum exist_status directory_exists_in_index_icase(struct index_state *istate,
+                                                        const char *dirname, int len)
 {
-       const struct cache_entry *ce = cache_dir_exists(dirname, len);
-       unsigned char endchar;
-
-       if (!ce)
-               return index_nonexistent;
-       endchar = ce->name[len];
+       struct cache_entry *ce;
 
-       /*
-        * The cache_entry structure returned will contain this dirname
-        * and possibly additional path components.
-        */
-       if (endchar == '/')
+       if (index_dir_exists(istate, dirname, len))
                return index_directory;
 
-       /*
-        * If there are no additional path components, then this cache_entry
-        * represents a submodule.  Submodules, despite being directories,
-        * are stored in the cache without a closing slash.
-        */
-       if (!endchar && S_ISGITLINK(ce->ce_mode))
+       ce = index_file_exists(istate, dirname, len, ignore_case);
+       if (ce && S_ISGITLINK(ce->ce_mode))
                return index_gitdir;
 
-       /* This should never be hit, but it exists just in case. */
        return index_nonexistent;
 }
 
@@ -997,18 +1592,19 @@ static enum exist_status directory_exists_in_index_icase(const char *dirname, in
  * the files it contains) will sort with the '/' at the
  * end.
  */
-static enum exist_status directory_exists_in_index(const char *dirname, int len)
+static enum exist_status directory_exists_in_index(struct index_state *istate,
+                                                  const char *dirname, int len)
 {
        int pos;
 
        if (ignore_case)
-               return directory_exists_in_index_icase(dirname, len);
+               return directory_exists_in_index_icase(istate, dirname, len);
 
-       pos = cache_name_pos(dirname, len);
+       pos = index_name_pos(istate, dirname, len);
        if (pos < 0)
                pos = -pos-1;
-       while (pos < active_nr) {
-               const struct cache_entry *ce = active_cache[pos++];
+       while (pos < istate->cache_nr) {
+               const struct cache_entry *ce = istate->cache[pos++];
                unsigned char endchar;
 
                if (strncmp(ce->name, dirname, len))
@@ -1058,11 +1654,15 @@ static enum exist_status directory_exists_in_index(const char *dirname, int len)
  *  (c) otherwise, we recurse into it.
  */
 static enum path_treatment treat_directory(struct dir_struct *dir,
-       const char *dirname, int len, int exclude,
-       const struct path_simplify *simplify)
+       struct index_state *istate,
+       struct untracked_cache_dir *untracked,
+       const char *dirname, int len, int baselen, int exclude,
+       const struct pathspec *pathspec)
 {
+       int nested_repo = 0;
+
        /* The "len-1" is to strip the final '/' */
-       switch (directory_exists_in_index(dirname, len-1)) {
+       switch (directory_exists_in_index(istate, dirname, len-1)) {
        case index_directory:
                return path_recurse;
 
@@ -1070,12 +1670,42 @@ static enum path_treatment treat_directory(struct dir_struct *dir,
                return path_none;
 
        case index_nonexistent:
+               if ((dir->flags & DIR_SKIP_NESTED_GIT) ||
+                   !(dir->flags & DIR_NO_GITLINKS)) {
+                       struct strbuf sb = STRBUF_INIT;
+                       strbuf_addstr(&sb, dirname);
+                       nested_repo = is_nonbare_repository_dir(&sb);
+                       strbuf_release(&sb);
+               }
+               if (nested_repo)
+                       return ((dir->flags & DIR_SKIP_NESTED_GIT) ? path_none :
+                               (exclude ? path_excluded : path_untracked));
+
                if (dir->flags & DIR_SHOW_OTHER_DIRECTORIES)
                        break;
-               if (!(dir->flags & DIR_NO_GITLINKS)) {
-                       unsigned char sha1[20];
-                       if (resolve_gitlink_ref(dirname, "HEAD", sha1) == 0)
-                               return path_untracked;
+               if (exclude &&
+                       (dir->flags & DIR_SHOW_IGNORED_TOO) &&
+                       (dir->flags & DIR_SHOW_IGNORED_TOO_MODE_MATCHING)) {
+
+                       /*
+                        * This is an excluded directory and we are
+                        * showing ignored paths that match an exclude
+                        * pattern.  (e.g. show directory as ignored
+                        * only if it matches an exclude pattern).
+                        * This path will either be 'path_excluded`
+                        * (if we are showing empty directories or if
+                        * the directory is not empty), or will be
+                        * 'path_none' (empty directory, and we are
+                        * not showing empty directories).
+                        */
+                       if (!(dir->flags & DIR_HIDE_EMPTY_DIRECTORIES))
+                               return path_excluded;
+
+                       if (read_directory_recursive(dir, istate, dirname, len,
+                                                    untracked, 1, 1, pathspec) == path_excluded)
+                               return path_excluded;
+
+                       return path_none;
                }
                return path_recurse;
        }
@@ -1085,7 +1715,15 @@ static enum path_treatment treat_directory(struct dir_struct *dir,
        if (!(dir->flags & DIR_HIDE_EMPTY_DIRECTORIES))
                return exclude ? path_excluded : path_untracked;
 
-       return read_directory_recursive(dir, dirname, len, 1, simplify);
+       untracked = lookup_untracked(dir->untracked, untracked,
+                                    dirname + baselen, len - baselen);
+
+       /*
+        * If this is an excluded directory, then we only need to check if
+        * the directory contains any files.
+        */
+       return read_directory_recursive(dir, istate, dirname, len,
+                                       untracked, 1, exclude, pathspec);
 }
 
 /*
@@ -1093,25 +1731,35 @@ static enum path_treatment treat_directory(struct dir_struct *dir,
  * reading - if the path cannot possibly be in the pathspec,
  * return true, and we'll skip it early.
  */
-static int simplify_away(const char *path, int pathlen, const struct path_simplify *simplify)
+static int simplify_away(const char *path, int pathlen,
+                        const struct pathspec *pathspec)
 {
-       if (simplify) {
-               for (;;) {
-                       const char *match = simplify->path;
-                       int len = simplify->len;
+       int i;
 
-                       if (!match)
-                               break;
-                       if (len > pathlen)
-                               len = pathlen;
-                       if (!memcmp(path, match, len))
-                               return 0;
-                       simplify++;
-               }
-               return 1;
-       }
-       return 0;
-}
+       if (!pathspec || !pathspec->nr)
+               return 0;
+
+       GUARD_PATHSPEC(pathspec,
+                      PATHSPEC_FROMTOP |
+                      PATHSPEC_MAXDEPTH |
+                      PATHSPEC_LITERAL |
+                      PATHSPEC_GLOB |
+                      PATHSPEC_ICASE |
+                      PATHSPEC_EXCLUDE |
+                      PATHSPEC_ATTR);
+
+       for (i = 0; i < pathspec->nr; i++) {
+               const struct pathspec_item *item = &pathspec->items[i];
+               int len = item->nowildcard_len;
+
+               if (len > pathlen)
+                       len = pathlen;
+               if (!ps_strncmp(item, item->match, path, len))
+                       return 0;
+       }
+
+       return 1;
+}
 
 /*
  * This function tells us whether an excluded path matches a
@@ -1124,29 +1772,44 @@ static int simplify_away(const char *path, int pathlen, const struct path_simpli
  *   2. the path is a directory prefix of some element in the
  *      pathspec
  */
-static int exclude_matches_pathspec(const char *path, int len,
-               const struct path_simplify *simplify)
-{
-       if (simplify) {
-               for (; simplify->path; simplify++) {
-                       if (len == simplify->len
-                           && !memcmp(path, simplify->path, len))
-                               return 1;
-                       if (len < simplify->len
-                           && simplify->path[len] == '/'
-                           && !memcmp(path, simplify->path, len))
-                               return 1;
-               }
+static int exclude_matches_pathspec(const char *path, int pathlen,
+                                   const struct pathspec *pathspec)
+{
+       int i;
+
+       if (!pathspec || !pathspec->nr)
+               return 0;
+
+       GUARD_PATHSPEC(pathspec,
+                      PATHSPEC_FROMTOP |
+                      PATHSPEC_MAXDEPTH |
+                      PATHSPEC_LITERAL |
+                      PATHSPEC_GLOB |
+                      PATHSPEC_ICASE |
+                      PATHSPEC_EXCLUDE);
+
+       for (i = 0; i < pathspec->nr; i++) {
+               const struct pathspec_item *item = &pathspec->items[i];
+               int len = item->nowildcard_len;
+
+               if (len == pathlen &&
+                   !ps_strncmp(item, item->match, path, pathlen))
+                       return 1;
+               if (len > pathlen &&
+                   item->match[pathlen] == '/' &&
+                   !ps_strncmp(item, item->match, path, pathlen))
+                       return 1;
        }
        return 0;
 }
 
-static int get_index_dtype(const char *path, int len)
+static int get_index_dtype(struct index_state *istate,
+                          const char *path, int len)
 {
        int pos;
        const struct cache_entry *ce;
 
-       ce = cache_file_exists(path, len, 0);
+       ce = index_file_exists(istate, path, len, 0);
        if (ce) {
                if (!ce_uptodate(ce))
                        return DT_UNKNOWN;
@@ -1160,12 +1823,12 @@ static int get_index_dtype(const char *path, int len)
        }
 
        /* Try to look it up as a directory */
-       pos = cache_name_pos(path, len);
+       pos = index_name_pos(istate, path, len);
        if (pos >= 0)
                return DT_UNKNOWN;
        pos = -pos-1;
-       while (pos < active_nr) {
-               ce = active_cache[pos++];
+       while (pos < istate->cache_nr) {
+               ce = istate->cache[pos++];
                if (strncmp(ce->name, path, len))
                        break;
                if (ce->name[len] > '/')
@@ -1179,14 +1842,14 @@ static int get_index_dtype(const char *path, int len)
        return DT_UNKNOWN;
 }
 
-static int get_dtype(struct dirent *de, const char *path, int len)
+static int resolve_dtype(int dtype, struct index_state *istate,
+                        const char *path, int len)
 {
-       int dtype = de ? DTYPE(de) : DT_UNKNOWN;
        struct stat st;
 
        if (dtype != DT_UNKNOWN)
                return dtype;
-       dtype = get_index_dtype(path, len);
+       dtype = get_index_dtype(istate, path, len);
        if (dtype != DT_UNKNOWN)
                return dtype;
        if (lstat(path, &st))
@@ -1201,15 +1864,18 @@ static int get_dtype(struct dirent *de, const char *path, int len)
 }
 
 static enum path_treatment treat_one_path(struct dir_struct *dir,
+                                         struct untracked_cache_dir *untracked,
+                                         struct index_state *istate,
                                          struct strbuf *path,
-                                         const struct path_simplify *simplify,
-                                         int dtype, struct dirent *de)
+                                         int baselen,
+                                         const struct pathspec *pathspec,
+                                         int dtype)
 {
        int exclude;
-       int has_path_in_index = !!cache_file_exists(path->buf, path->len, ignore_case);
+       int has_path_in_index = !!index_file_exists(istate, path->buf, path->len, ignore_case);
+       enum path_treatment path_treatment;
 
-       if (dtype == DT_UNKNOWN)
-               dtype = get_dtype(de, path->buf, path->len);
+       dtype = resolve_dtype(dtype, istate, path->buf, path->len);
 
        /* Always exclude indexed files */
        if (dtype != DT_DIR && has_path_in_index)
@@ -1236,10 +1902,10 @@ static enum path_treatment treat_one_path(struct dir_struct *dir,
        if ((dir->flags & DIR_COLLECT_KILLED_ONLY) &&
            (dtype == DT_DIR) &&
            !has_path_in_index &&
-           (directory_exists_in_index(path->buf, path->len) == index_nonexistent))
+           (directory_exists_in_index(istate, path->buf, path->len) == index_nonexistent))
                return path_none;
 
-       exclude = is_excluded(dir, path->buf, &dtype);
+       exclude = is_excluded(dir, istate, path->buf, &dtype);
 
        /*
         * Excluded? If we don't explicitly want to show
@@ -1253,31 +1919,247 @@ static enum path_treatment treat_one_path(struct dir_struct *dir,
                return path_none;
        case DT_DIR:
                strbuf_addch(path, '/');
-               return treat_directory(dir, path->buf, path->len, exclude,
-                       simplify);
+               path_treatment = treat_directory(dir, istate, untracked,
+                                                path->buf, path->len,
+                                                baselen, exclude, pathspec);
+               /*
+                * If 1) we only want to return directories that
+                * match an exclude pattern and 2) this directory does
+                * not match an exclude pattern but all of its
+                * contents are excluded, then indicate that we should
+                * recurse into this directory (instead of marking the
+                * directory itself as an ignored path).
+                */
+               if (!exclude &&
+                   path_treatment == path_excluded &&
+                   (dir->flags & DIR_SHOW_IGNORED_TOO) &&
+                   (dir->flags & DIR_SHOW_IGNORED_TOO_MODE_MATCHING))
+                       return path_recurse;
+               return path_treatment;
        case DT_REG:
        case DT_LNK:
                return exclude ? path_excluded : path_untracked;
        }
 }
 
+static enum path_treatment treat_path_fast(struct dir_struct *dir,
+                                          struct untracked_cache_dir *untracked,
+                                          struct cached_dir *cdir,
+                                          struct index_state *istate,
+                                          struct strbuf *path,
+                                          int baselen,
+                                          const struct pathspec *pathspec)
+{
+       strbuf_setlen(path, baselen);
+       if (!cdir->ucd) {
+               strbuf_addstr(path, cdir->file);
+               return path_untracked;
+       }
+       strbuf_addstr(path, cdir->ucd->name);
+       /* treat_one_path() does this before it calls treat_directory() */
+       strbuf_complete(path, '/');
+       if (cdir->ucd->check_only)
+               /*
+                * check_only is set as a result of treat_directory() getting
+                * to its bottom. Verify again the same set of directories
+                * with check_only set.
+                */
+               return read_directory_recursive(dir, istate, path->buf, path->len,
+                                               cdir->ucd, 1, 0, pathspec);
+       /*
+        * We get path_recurse in the first run when
+        * directory_exists_in_index() returns index_nonexistent. We
+        * are sure that new changes in the index does not impact the
+        * outcome. Return now.
+        */
+       return path_recurse;
+}
+
 static enum path_treatment treat_path(struct dir_struct *dir,
-                                     struct dirent *de,
+                                     struct untracked_cache_dir *untracked,
+                                     struct cached_dir *cdir,
+                                     struct index_state *istate,
                                      struct strbuf *path,
                                      int baselen,
-                                     const struct path_simplify *simplify)
+                                     const struct pathspec *pathspec)
 {
-       int dtype;
-
-       if (is_dot_or_dotdot(de->d_name) || !strcmp(de->d_name, ".git"))
+       if (!cdir->d_name)
+               return treat_path_fast(dir, untracked, cdir, istate, path,
+                                      baselen, pathspec);
+       if (is_dot_or_dotdot(cdir->d_name) || !fspathcmp(cdir->d_name, ".git"))
                return path_none;
        strbuf_setlen(path, baselen);
-       strbuf_addstr(path, de->d_name);
-       if (simplify_away(path->buf, path->len, simplify))
+       strbuf_addstr(path, cdir->d_name);
+       if (simplify_away(path->buf, path->len, pathspec))
                return path_none;
 
-       dtype = DTYPE(de);
-       return treat_one_path(dir, path, simplify, dtype, de);
+       return treat_one_path(dir, untracked, istate, path, baselen, pathspec,
+                             cdir->d_type);
+}
+
+static void add_untracked(struct untracked_cache_dir *dir, const char *name)
+{
+       if (!dir)
+               return;
+       ALLOC_GROW(dir->untracked, dir->untracked_nr + 1,
+                  dir->untracked_alloc);
+       dir->untracked[dir->untracked_nr++] = xstrdup(name);
+}
+
+static int valid_cached_dir(struct dir_struct *dir,
+                           struct untracked_cache_dir *untracked,
+                           struct index_state *istate,
+                           struct strbuf *path,
+                           int check_only)
+{
+       struct stat st;
+
+       if (!untracked)
+               return 0;
+
+       /*
+        * With fsmonitor, we can trust the untracked cache's valid field.
+        */
+       refresh_fsmonitor(istate);
+       if (!(dir->untracked->use_fsmonitor && untracked->valid)) {
+               if (lstat(path->len ? path->buf : ".", &st)) {
+                       memset(&untracked->stat_data, 0, sizeof(untracked->stat_data));
+                       return 0;
+               }
+               if (!untracked->valid ||
+                       match_stat_data_racy(istate, &untracked->stat_data, &st)) {
+                       fill_stat_data(&untracked->stat_data, &st);
+                       return 0;
+               }
+       }
+
+       if (untracked->check_only != !!check_only)
+               return 0;
+
+       /*
+        * prep_exclude will be called eventually on this directory,
+        * but it's called much later in last_matching_pattern(). We
+        * need it now to determine the validity of the cache for this
+        * path. The next calls will be nearly no-op, the way
+        * prep_exclude() is designed.
+        */
+       if (path->len && path->buf[path->len - 1] != '/') {
+               strbuf_addch(path, '/');
+               prep_exclude(dir, istate, path->buf, path->len);
+               strbuf_setlen(path, path->len - 1);
+       } else
+               prep_exclude(dir, istate, path->buf, path->len);
+
+       /* hopefully prep_exclude() haven't invalidated this entry... */
+       return untracked->valid;
+}
+
+static int open_cached_dir(struct cached_dir *cdir,
+                          struct dir_struct *dir,
+                          struct untracked_cache_dir *untracked,
+                          struct index_state *istate,
+                          struct strbuf *path,
+                          int check_only)
+{
+       const char *c_path;
+
+       memset(cdir, 0, sizeof(*cdir));
+       cdir->untracked = untracked;
+       if (valid_cached_dir(dir, untracked, istate, path, check_only))
+               return 0;
+       c_path = path->len ? path->buf : ".";
+       cdir->fdir = opendir(c_path);
+       if (!cdir->fdir)
+               warning_errno(_("could not open directory '%s'"), c_path);
+       if (dir->untracked) {
+               invalidate_directory(dir->untracked, untracked);
+               dir->untracked->dir_opened++;
+       }
+       if (!cdir->fdir)
+               return -1;
+       return 0;
+}
+
+static int read_cached_dir(struct cached_dir *cdir)
+{
+       struct dirent *de;
+
+       if (cdir->fdir) {
+               de = readdir(cdir->fdir);
+               if (!de) {
+                       cdir->d_name = NULL;
+                       cdir->d_type = DT_UNKNOWN;
+                       return -1;
+               }
+               cdir->d_name = de->d_name;
+               cdir->d_type = DTYPE(de);
+               return 0;
+       }
+       while (cdir->nr_dirs < cdir->untracked->dirs_nr) {
+               struct untracked_cache_dir *d = cdir->untracked->dirs[cdir->nr_dirs];
+               if (!d->recurse) {
+                       cdir->nr_dirs++;
+                       continue;
+               }
+               cdir->ucd = d;
+               cdir->nr_dirs++;
+               return 0;
+       }
+       cdir->ucd = NULL;
+       if (cdir->nr_files < cdir->untracked->untracked_nr) {
+               struct untracked_cache_dir *d = cdir->untracked;
+               cdir->file = d->untracked[cdir->nr_files++];
+               return 0;
+       }
+       return -1;
+}
+
+static void close_cached_dir(struct cached_dir *cdir)
+{
+       if (cdir->fdir)
+               closedir(cdir->fdir);
+       /*
+        * We have gone through this directory and found no untracked
+        * entries. Mark it valid.
+        */
+       if (cdir->untracked) {
+               cdir->untracked->valid = 1;
+               cdir->untracked->recurse = 1;
+       }
+}
+
+static void add_path_to_appropriate_result_list(struct dir_struct *dir,
+       struct untracked_cache_dir *untracked,
+       struct cached_dir *cdir,
+       struct index_state *istate,
+       struct strbuf *path,
+       int baselen,
+       const struct pathspec *pathspec,
+       enum path_treatment state)
+{
+       /* add the path to the appropriate result list */
+       switch (state) {
+       case path_excluded:
+               if (dir->flags & DIR_SHOW_IGNORED)
+                       dir_add_name(dir, istate, path->buf, path->len);
+               else if ((dir->flags & DIR_SHOW_IGNORED_TOO) ||
+                       ((dir->flags & DIR_COLLECT_IGNORED) &&
+                       exclude_matches_pathspec(path->buf, path->len,
+                                                pathspec)))
+                       dir_add_ignored(dir, istate, path->buf, path->len);
+               break;
+
+       case path_untracked:
+               if (dir->flags & DIR_SHOW_IGNORED)
+                       break;
+               dir_add_name(dir, istate, path->buf, path->len);
+               if (cdir->fdir)
+                       add_untracked(untracked, path->buf + baselen);
+               break;
+
+       default:
+               break;
+       }
 }
 
 /*
@@ -1289,75 +2171,121 @@ static enum path_treatment treat_path(struct dir_struct *dir,
  * Also, we ignore the name ".git" (even if it is not a directory).
  * That likely will not change.
  *
+ * If 'stop_at_first_file' is specified, 'path_excluded' is returned
+ * to signal that a file was found. This is the least significant value that
+ * indicates that a file was encountered that does not depend on the order of
+ * whether an untracked or exluded path was encountered first.
+ *
  * Returns the most significant path_treatment value encountered in the scan.
+ * If 'stop_at_first_file' is specified, `path_excluded` is the most
+ * significant path_treatment value that will be returned.
  */
+
 static enum path_treatment read_directory_recursive(struct dir_struct *dir,
-                                   const char *base, int baselen,
-                                   int check_only,
-                                   const struct path_simplify *simplify)
+       struct index_state *istate, const char *base, int baselen,
+       struct untracked_cache_dir *untracked, int check_only,
+       int stop_at_first_file, const struct pathspec *pathspec)
 {
-       DIR *fdir;
+       /*
+        * WARNING WARNING WARNING:
+        *
+        * Any updates to the traversal logic here may need corresponding
+        * updates in treat_leading_path().  See the commit message for the
+        * commit adding this warning as well as the commit preceding it
+        * for details.
+        */
+
+       struct cached_dir cdir;
        enum path_treatment state, subdir_state, dir_state = path_none;
-       struct dirent *de;
        struct strbuf path = STRBUF_INIT;
 
        strbuf_add(&path, base, baselen);
 
-       fdir = opendir(path.len ? path.buf : ".");
-       if (!fdir)
+       if (open_cached_dir(&cdir, dir, untracked, istate, &path, check_only))
                goto out;
 
-       while ((de = readdir(fdir)) != NULL) {
+       if (untracked)
+               untracked->check_only = !!check_only;
+
+       while (!read_cached_dir(&cdir)) {
                /* check how the file or directory should be treated */
-               state = treat_path(dir, de, &path, baselen, simplify);
+               state = treat_path(dir, untracked, &cdir, istate, &path,
+                                  baselen, pathspec);
+
                if (state > dir_state)
                        dir_state = state;
 
                /* recurse into subdir if instructed by treat_path */
-               if (state == path_recurse) {
-                       subdir_state = read_directory_recursive(dir, path.buf,
-                               path.len, check_only, simplify);
+               if ((state == path_recurse) ||
+                       ((state == path_untracked) &&
+                        (resolve_dtype(cdir.d_type, istate, path.buf, path.len) == DT_DIR) &&
+                        ((dir->flags & DIR_SHOW_IGNORED_TOO) ||
+                         (pathspec &&
+                          do_match_pathspec(istate, pathspec, path.buf, path.len,
+                                            baselen, NULL, DO_MATCH_LEADING_PATHSPEC) == MATCHED_RECURSIVELY_LEADING_PATHSPEC)))) {
+                       struct untracked_cache_dir *ud;
+                       ud = lookup_untracked(dir->untracked, untracked,
+                                             path.buf + baselen,
+                                             path.len - baselen);
+                       subdir_state =
+                               read_directory_recursive(dir, istate, path.buf,
+                                                        path.len, ud,
+                                                        check_only, stop_at_first_file, pathspec);
                        if (subdir_state > dir_state)
                                dir_state = subdir_state;
+
+                       if (pathspec &&
+                           !match_pathspec(istate, pathspec, path.buf, path.len,
+                                           0 /* prefix */, NULL,
+                                           0 /* do NOT special case dirs */))
+                               state = path_none;
                }
 
                if (check_only) {
+                       if (stop_at_first_file) {
+                               /*
+                                * If stopping at first file, then
+                                * signal that a file was found by
+                                * returning `path_excluded`. This is
+                                * to return a consistent value
+                                * regardless of whether an ignored or
+                                * excluded file happened to be
+                                * encountered 1st.
+                                *
+                                * In current usage, the
+                                * `stop_at_first_file` is passed when
+                                * an ancestor directory has matched
+                                * an exclude pattern, so any found
+                                * files will be excluded.
+                                */
+                               if (dir_state >= path_excluded) {
+                                       dir_state = path_excluded;
+                                       break;
+                               }
+                       }
+
                        /* abort early if maximum state has been reached */
-                       if (dir_state == path_untracked)
+                       if (dir_state == path_untracked) {
+                               if (cdir.fdir)
+                                       add_untracked(untracked, path.buf + baselen);
                                break;
+                       }
                        /* skip the dir_add_* part */
                        continue;
                }
 
-               /* add the path to the appropriate result list */
-               switch (state) {
-               case path_excluded:
-                       if (dir->flags & DIR_SHOW_IGNORED)
-                               dir_add_name(dir, path.buf, path.len);
-                       else if ((dir->flags & DIR_SHOW_IGNORED_TOO) ||
-                               ((dir->flags & DIR_COLLECT_IGNORED) &&
-                               exclude_matches_pathspec(path.buf, path.len,
-                                       simplify)))
-                               dir_add_ignored(dir, path.buf, path.len);
-                       break;
-
-               case path_untracked:
-                       if (!(dir->flags & DIR_SHOW_IGNORED))
-                               dir_add_name(dir, path.buf, path.len);
-                       break;
-
-               default:
-                       break;
-               }
+               add_path_to_appropriate_result_list(dir, untracked, &cdir,
+                                                   istate, &path, baselen,
+                                                   pathspec, state);
        }
-       closedir(fdir);
+       close_cached_dir(&cdir);
  out:
        strbuf_release(&path);
 
        return dir_state;
 }
 
-static int cmp_name(const void *p1, const void *p2)
+int cmp_dir_entry(const void *p1, const void *p2)
 {
        const struct dir_entry *e1 = *(const struct dir_entry **)p1;
        const struct dir_entry *e2 = *(const struct dir_entry **)p2;
@@ -1365,105 +2293,343 @@ static int cmp_name(const void *p1, const void *p2)
        return name_compare(e1->name, e1->len, e2->name, e2->len);
 }
 
-static struct path_simplify *create_simplify(const char **pathspec)
-{
-       int nr, alloc = 0;
-       struct path_simplify *simplify = NULL;
-
-       if (!pathspec)
-               return NULL;
-
-       for (nr = 0 ; ; nr++) {
-               const char *match;
-               ALLOC_GROW(simplify, nr + 1, alloc);
-               match = *pathspec++;
-               if (!match)
-                       break;
-               simplify[nr].path = match;
-               simplify[nr].len = simple_length(match);
-       }
-       simplify[nr].path = NULL;
-       simplify[nr].len = 0;
-       return simplify;
-}
-
-static void free_simplify(struct path_simplify *simplify)
+/* check if *out lexically strictly contains *in */
+int check_dir_entry_contains(const struct dir_entry *out, const struct dir_entry *in)
 {
-       free(simplify);
+       return (out->len < in->len) &&
+               (out->name[out->len - 1] == '/') &&
+               !memcmp(out->name, in->name, out->len);
 }
 
 static int treat_leading_path(struct dir_struct *dir,
+                             struct index_state *istate,
                              const char *path, int len,
-                             const struct path_simplify *simplify)
+                             const struct pathspec *pathspec)
 {
+       /*
+        * WARNING WARNING WARNING:
+        *
+        * Any updates to the traversal logic here may need corresponding
+        * updates in read_directory_recursive().  See 777b420347 (dir:
+        * synchronize treat_leading_path() and read_directory_recursive(),
+        * 2019-12-19) and its parent commit for details.
+        */
+
        struct strbuf sb = STRBUF_INIT;
-       int baselen, rc = 0;
+       struct strbuf subdir = STRBUF_INIT;
+       int prevlen, baselen;
        const char *cp;
-       int old_flags = dir->flags;
+       struct cached_dir cdir;
+       enum path_treatment state = path_none;
+
+       /*
+        * For each directory component of path, we are going to check whether
+        * that path is relevant given the pathspec.  For example, if path is
+        *    foo/bar/baz/
+        * then we will ask treat_path() whether we should go into foo, then
+        * whether we should go into bar, then whether baz is relevant.
+        * Checking each is important because e.g. if path is
+        *    .git/info/
+        * then we need to check .git to know we shouldn't traverse it.
+        * If the return from treat_path() is:
+        *    * path_none, for any path, we return false.
+        *    * path_recurse, for all path components, we return true
+        *    * <anything else> for some intermediate component, we make sure
+        *        to add that path to the relevant list but return false
+        *        signifying that we shouldn't recurse into it.
+        */
 
        while (len && path[len - 1] == '/')
                len--;
        if (!len)
                return 1;
+
+       memset(&cdir, 0, sizeof(cdir));
+       cdir.d_type = DT_DIR;
        baselen = 0;
-       dir->flags &= ~DIR_SHOW_OTHER_DIRECTORIES;
+       prevlen = 0;
        while (1) {
-               cp = path + baselen + !!baselen;
+               prevlen = baselen + !!baselen;
+               cp = path + prevlen;
                cp = memchr(cp, '/', path + len - cp);
                if (!cp)
                        baselen = len;
                else
                        baselen = cp - path;
-               strbuf_setlen(&sb, 0);
+               strbuf_reset(&sb);
                strbuf_add(&sb, path, baselen);
                if (!is_directory(sb.buf))
                        break;
-               if (simplify_away(sb.buf, sb.len, simplify))
-                       break;
-               if (treat_one_path(dir, &sb, simplify,
-                                  DT_DIR, NULL) == path_none)
+               strbuf_reset(&sb);
+               strbuf_add(&sb, path, prevlen);
+               strbuf_reset(&subdir);
+               strbuf_add(&subdir, path+prevlen, baselen-prevlen);
+               cdir.d_name = subdir.buf;
+               state = treat_path(dir, NULL, &cdir, istate, &sb, prevlen,
+                                   pathspec);
+               if (state == path_untracked &&
+                   resolve_dtype(cdir.d_type, istate, sb.buf, sb.len) == DT_DIR &&
+                   (dir->flags & DIR_SHOW_IGNORED_TOO ||
+                    do_match_pathspec(istate, pathspec, sb.buf, sb.len,
+                                      baselen, NULL, DO_MATCH_LEADING_PATHSPEC) == MATCHED_RECURSIVELY_LEADING_PATHSPEC)) {
+                       if (!match_pathspec(istate, pathspec, sb.buf, sb.len,
+                                           0 /* prefix */, NULL,
+                                           0 /* do NOT special case dirs */))
+                               state = path_none;
+                       add_path_to_appropriate_result_list(dir, NULL, &cdir,
+                                                           istate,
+                                                           &sb, baselen,
+                                                           pathspec, state);
+                       state = path_recurse;
+               }
+
+               if (state != path_recurse)
                        break; /* do not recurse into it */
-               if (len <= baselen) {
-                       rc = 1;
+               if (len <= baselen)
                        break; /* finished checking */
-               }
        }
+       add_path_to_appropriate_result_list(dir, NULL, &cdir, istate,
+                                           &sb, baselen, pathspec,
+                                           state);
+
+       strbuf_release(&subdir);
        strbuf_release(&sb);
-       dir->flags = old_flags;
-       return rc;
+       return state == path_recurse;
+}
+
+static const char *get_ident_string(void)
+{
+       static struct strbuf sb = STRBUF_INIT;
+       struct utsname uts;
+
+       if (sb.len)
+               return sb.buf;
+       if (uname(&uts) < 0)
+               die_errno(_("failed to get kernel name and information"));
+       strbuf_addf(&sb, "Location %s, system %s", get_git_work_tree(),
+                   uts.sysname);
+       return sb.buf;
+}
+
+static int ident_in_untracked(const struct untracked_cache *uc)
+{
+       /*
+        * Previous git versions may have saved many NUL separated
+        * strings in the "ident" field, but it is insane to manage
+        * many locations, so just take care of the first one.
+        */
+
+       return !strcmp(uc->ident.buf, get_ident_string());
+}
+
+static void set_untracked_ident(struct untracked_cache *uc)
+{
+       strbuf_reset(&uc->ident);
+       strbuf_addstr(&uc->ident, get_ident_string());
+
+       /*
+        * This strbuf used to contain a list of NUL separated
+        * strings, so save NUL too for backward compatibility.
+        */
+       strbuf_addch(&uc->ident, 0);
+}
+
+static void new_untracked_cache(struct index_state *istate)
+{
+       struct untracked_cache *uc = xcalloc(1, sizeof(*uc));
+       strbuf_init(&uc->ident, 100);
+       uc->exclude_per_dir = ".gitignore";
+       /* should be the same flags used by git-status */
+       uc->dir_flags = DIR_SHOW_OTHER_DIRECTORIES | DIR_HIDE_EMPTY_DIRECTORIES;
+       set_untracked_ident(uc);
+       istate->untracked = uc;
+       istate->cache_changed |= UNTRACKED_CHANGED;
+}
+
+void add_untracked_cache(struct index_state *istate)
+{
+       if (!istate->untracked) {
+               new_untracked_cache(istate);
+       } else {
+               if (!ident_in_untracked(istate->untracked)) {
+                       free_untracked_cache(istate->untracked);
+                       new_untracked_cache(istate);
+               }
+       }
+}
+
+void remove_untracked_cache(struct index_state *istate)
+{
+       if (istate->untracked) {
+               free_untracked_cache(istate->untracked);
+               istate->untracked = NULL;
+               istate->cache_changed |= UNTRACKED_CHANGED;
+       }
 }
 
-int read_directory(struct dir_struct *dir, const char *path, int len, const struct pathspec *pathspec)
+static struct untracked_cache_dir *validate_untracked_cache(struct dir_struct *dir,
+                                                     int base_len,
+                                                     const struct pathspec *pathspec)
 {
-       struct path_simplify *simplify;
+       struct untracked_cache_dir *root;
+       static int untracked_cache_disabled = -1;
+
+       if (!dir->untracked)
+               return NULL;
+       if (untracked_cache_disabled < 0)
+               untracked_cache_disabled = git_env_bool("GIT_DISABLE_UNTRACKED_CACHE", 0);
+       if (untracked_cache_disabled)
+               return NULL;
+
+       /*
+        * We only support $GIT_DIR/info/exclude and core.excludesfile
+        * as the global ignore rule files. Any other additions
+        * (e.g. from command line) invalidate the cache. This
+        * condition also catches running setup_standard_excludes()
+        * before setting dir->untracked!
+        */
+       if (dir->unmanaged_exclude_files)
+               return NULL;
+
+       /*
+        * Optimize for the main use case only: whole-tree git
+        * status. More work involved in treat_leading_path() if we
+        * use cache on just a subset of the worktree. pathspec
+        * support could make the matter even worse.
+        */
+       if (base_len || (pathspec && pathspec->nr))
+               return NULL;
+
+       /* Different set of flags may produce different results */
+       if (dir->flags != dir->untracked->dir_flags ||
+           /*
+            * See treat_directory(), case index_nonexistent. Without
+            * this flag, we may need to also cache .git file content
+            * for the resolve_gitlink_ref() call, which we don't.
+            */
+           !(dir->flags & DIR_SHOW_OTHER_DIRECTORIES) ||
+           /* We don't support collecting ignore files */
+           (dir->flags & (DIR_SHOW_IGNORED | DIR_SHOW_IGNORED_TOO |
+                          DIR_COLLECT_IGNORED)))
+               return NULL;
+
+       /*
+        * If we use .gitignore in the cache and now you change it to
+        * .gitexclude, everything will go wrong.
+        */
+       if (dir->exclude_per_dir != dir->untracked->exclude_per_dir &&
+           strcmp(dir->exclude_per_dir, dir->untracked->exclude_per_dir))
+               return NULL;
 
        /*
-        * Check out create_simplify()
+        * EXC_CMDL is not considered in the cache. If people set it,
+        * skip the cache.
         */
-       if (pathspec)
-               GUARD_PATHSPEC(pathspec,
-                              PATHSPEC_FROMTOP |
-                              PATHSPEC_MAXDEPTH |
-                              PATHSPEC_LITERAL |
-                              PATHSPEC_GLOB |
-                              PATHSPEC_ICASE |
-                              PATHSPEC_EXCLUDE);
-
-       if (has_symlink_leading_path(path, len))
+       if (dir->exclude_list_group[EXC_CMDL].nr)
+               return NULL;
+
+       if (!ident_in_untracked(dir->untracked)) {
+               warning(_("untracked cache is disabled on this system or location"));
+               return NULL;
+       }
+
+       if (!dir->untracked->root) {
+               const int len = sizeof(*dir->untracked->root);
+               dir->untracked->root = xmalloc(len);
+               memset(dir->untracked->root, 0, len);
+       }
+
+       /* Validate $GIT_DIR/info/exclude and core.excludesfile */
+       root = dir->untracked->root;
+       if (!oideq(&dir->ss_info_exclude.oid,
+                  &dir->untracked->ss_info_exclude.oid)) {
+               invalidate_gitignore(dir->untracked, root);
+               dir->untracked->ss_info_exclude = dir->ss_info_exclude;
+       }
+       if (!oideq(&dir->ss_excludes_file.oid,
+                  &dir->untracked->ss_excludes_file.oid)) {
+               invalidate_gitignore(dir->untracked, root);
+               dir->untracked->ss_excludes_file = dir->ss_excludes_file;
+       }
+
+       /* Make sure this directory is not dropped out at saving phase */
+       root->recurse = 1;
+       return root;
+}
+
+int read_directory(struct dir_struct *dir, struct index_state *istate,
+                  const char *path, int len, const struct pathspec *pathspec)
+{
+       struct untracked_cache_dir *untracked;
+
+       trace_performance_enter();
+
+       if (has_symlink_leading_path(path, len)) {
+               trace_performance_leave("read directory %.*s", len, path);
                return dir->nr;
+       }
+
+       untracked = validate_untracked_cache(dir, len, pathspec);
+       if (!untracked)
+               /*
+                * make sure untracked cache code path is disabled,
+                * e.g. prep_exclude()
+                */
+               dir->untracked = NULL;
+       if (!len || treat_leading_path(dir, istate, path, len, pathspec))
+               read_directory_recursive(dir, istate, path, len, untracked, 0, 0, pathspec);
+       QSORT(dir->entries, dir->nr, cmp_dir_entry);
+       QSORT(dir->ignored, dir->ignored_nr, cmp_dir_entry);
 
        /*
-        * exclude patterns are treated like positive ones in
-        * create_simplify. Usually exclude patterns should be a
-        * subset of positive ones, which has no impacts on
-        * create_simplify().
+        * If DIR_SHOW_IGNORED_TOO is set, read_directory_recursive() will
+        * also pick up untracked contents of untracked dirs; by default
+        * we discard these, but given DIR_KEEP_UNTRACKED_CONTENTS we do not.
         */
-       simplify = create_simplify(pathspec ? pathspec->_raw : NULL);
-       if (!len || treat_leading_path(dir, path, len, simplify))
-               read_directory_recursive(dir, path, len, 0, simplify);
-       free_simplify(simplify);
-       qsort(dir->entries, dir->nr, sizeof(struct dir_entry *), cmp_name);
-       qsort(dir->ignored, dir->ignored_nr, sizeof(struct dir_entry *), cmp_name);
+       if ((dir->flags & DIR_SHOW_IGNORED_TOO) &&
+                    !(dir->flags & DIR_KEEP_UNTRACKED_CONTENTS)) {
+               int i, j;
+
+               /* remove from dir->entries untracked contents of untracked dirs */
+               for (i = j = 0; j < dir->nr; j++) {
+                       if (i &&
+                           check_dir_entry_contains(dir->entries[i - 1], dir->entries[j])) {
+                               FREE_AND_NULL(dir->entries[j]);
+                       } else {
+                               dir->entries[i++] = dir->entries[j];
+                       }
+               }
+
+               dir->nr = i;
+       }
+
+       trace_performance_leave("read directory %.*s", len, path);
+       if (dir->untracked) {
+               static int force_untracked_cache = -1;
+               static struct trace_key trace_untracked_stats = TRACE_KEY_INIT(UNTRACKED_STATS);
+
+               if (force_untracked_cache < 0)
+                       force_untracked_cache =
+                               git_env_bool("GIT_FORCE_UNTRACKED_CACHE", 0);
+               trace_printf_key(&trace_untracked_stats,
+                                "node creation: %u\n"
+                                "gitignore invalidation: %u\n"
+                                "directory invalidation: %u\n"
+                                "opendir: %u\n",
+                                dir->untracked->dir_created,
+                                dir->untracked->gitignore_invalidated,
+                                dir->untracked->dir_invalidated,
+                                dir->untracked->dir_opened);
+               if (force_untracked_cache &&
+                       dir->untracked == istate->untracked &&
+                   (dir->untracked->dir_opened ||
+                    dir->untracked->gitignore_invalidated ||
+                    dir->untracked->dir_invalidated))
+                       istate->cache_changed |= UNTRACKED_CHANGED;
+               if (dir->untracked != istate->untracked) {
+                       FREE_AND_NULL(dir->untracked);
+               }
+       }
        return dir->nr;
 }
 
@@ -1473,6 +2639,23 @@ int file_exists(const char *f)
        return lstat(f, &sb) == 0;
 }
 
+int repo_file_exists(struct repository *repo, const char *path)
+{
+       if (repo != the_repository)
+               BUG("do not know how to check file existence in arbitrary repo");
+
+       return file_exists(path);
+}
+
+static int cmp_icase(char a, char b)
+{
+       if (a == b)
+               return 0;
+       if (ignore_case)
+               return toupper(a) - toupper(b);
+       return a - b;
+}
+
 /*
  * Given two normalized paths (a trailing slash is ok), if subdir is
  * outside dir, return -1.  Otherwise return the offset in subdir that
@@ -1484,7 +2667,7 @@ int dir_inside_of(const char *subdir, const char *dir)
 
        assert(dir && subdir && *dir && *subdir);
 
-       while (*dir && *subdir && *dir == *subdir) {
+       while (*dir && *subdir && !cmp_icase(*dir, *subdir)) {
                dir++;
                subdir++;
                offset++;
@@ -1507,12 +2690,16 @@ int dir_inside_of(const char *subdir, const char *dir)
 
 int is_inside_dir(const char *dir)
 {
-       char cwd[PATH_MAX];
+       char *cwd;
+       int rc;
+
        if (!dir)
                return 0;
-       if (!getcwd(cwd, sizeof(cwd)))
-               die_errno("can't find the current directory");
-       return dir_inside_of(cwd, dir) >= 0;
+
+       cwd = xgetcwd();
+       rc = (dir_inside_of(cwd, dir) >= 0);
+       free(cwd);
+       return rc;
 }
 
 int is_empty_dir(const char *path)
@@ -1541,10 +2728,10 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
        int ret = 0, original_len = path->len, len, kept_down = 0;
        int only_empty = (flag & REMOVE_DIR_EMPTY_ONLY);
        int keep_toplevel = (flag & REMOVE_DIR_KEEP_TOPLEVEL);
-       unsigned char submodule_head[20];
+       struct object_id submodule_head;
 
        if ((flag & REMOVE_DIR_KEEP_NESTED_GIT) &&
-           !resolve_gitlink_ref(path->buf, "HEAD", submodule_head)) {
+           !resolve_gitlink_ref(path->buf, "HEAD", &submodule_head)) {
                /* Do not descend and nuke a nested git work tree. */
                if (kept_up)
                        *kept_up = 1;
@@ -1565,8 +2752,7 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
                else
                        return -1;
        }
-       if (path->buf[original_len - 1] != '/')
-               strbuf_addch(path, '/');
+       strbuf_complete(path, '/');
 
        len = path->len;
        while ((e = readdir(dir)) != NULL) {
@@ -1583,7 +2769,7 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
                                 * wanted anyway
                                 */
                                continue;
-                       /* fall thru */
+                       /* fall through */
                } else if (S_ISDIR(st.st_mode)) {
                        if (!remove_dir_recurse(path, flag, &kept_down))
                                continue; /* happy */
@@ -1615,28 +2801,33 @@ int remove_dir_recursively(struct strbuf *path, int flag)
        return remove_dir_recurse(path, flag, NULL);
 }
 
+static GIT_PATH_FUNC(git_path_info_exclude, "info/exclude")
+
 void setup_standard_excludes(struct dir_struct *dir)
 {
-       const char *path;
-       char *xdg_path;
-
        dir->exclude_per_dir = ".gitignore";
-       path = git_path("info/exclude");
-       if (!excludes_file) {
-               home_config_paths(NULL, &xdg_path, "ignore");
-               excludes_file = xdg_path;
-       }
-       if (!access_or_warn(path, R_OK, 0))
-               add_excludes_from_file(dir, path);
+
+       /* core.excludesfile defaulting to $XDG_CONFIG_HOME/git/ignore */
+       if (!excludes_file)
+               excludes_file = xdg_config_home("ignore");
        if (excludes_file && !access_or_warn(excludes_file, R_OK, 0))
-               add_excludes_from_file(dir, excludes_file);
+               add_patterns_from_file_1(dir, excludes_file,
+                                        dir->untracked ? &dir->ss_excludes_file : NULL);
+
+       /* per repository user preference */
+       if (startup_info->have_repository) {
+               const char *path = git_path_info_exclude();
+               if (!access_or_warn(path, R_OK, 0))
+                       add_patterns_from_file_1(dir, path,
+                                                dir->untracked ? &dir->ss_info_exclude : NULL);
+       }
 }
 
 int remove_path(const char *name)
 {
        char *slash;
 
-       if (unlink(name) && errno != ENOENT && errno != ENOTDIR)
+       if (unlink(name) && !is_missing_file_error(errno))
                return -1;
 
        slash = strrchr(name, '/');
@@ -1659,18 +2850,18 @@ void clear_directory(struct dir_struct *dir)
 {
        int i, j;
        struct exclude_list_group *group;
-       struct exclude_list *el;
+       struct pattern_list *pl;
        struct exclude_stack *stk;
 
        for (i = EXC_CMDL; i <= EXC_FILE; i++) {
                group = &dir->exclude_list_group[i];
                for (j = 0; j < group->nr; j++) {
-                       el = &group->el[j];
+                       pl = &group->pl[j];
                        if (i == EXC_DIRS)
-                               free((char *)el->src);
-                       clear_exclude_list(el);
+                               free((char *)pl->src);
+                       clear_pattern_list(pl);
                }
-               free(group->el);
+               free(group->pl);
        }
 
        stk = dir->exclude_stack;
@@ -1681,3 +2872,548 @@ void clear_directory(struct dir_struct *dir)
        }
        strbuf_release(&dir->basebuf);
 }
+
+struct ondisk_untracked_cache {
+       struct stat_data info_exclude_stat;
+       struct stat_data excludes_file_stat;
+       uint32_t dir_flags;
+};
+
+#define ouc_offset(x) offsetof(struct ondisk_untracked_cache, x)
+
+struct write_data {
+       int index;         /* number of written untracked_cache_dir */
+       struct ewah_bitmap *check_only; /* from untracked_cache_dir */
+       struct ewah_bitmap *valid;      /* from untracked_cache_dir */
+       struct ewah_bitmap *sha1_valid; /* set if exclude_sha1 is not null */
+       struct strbuf out;
+       struct strbuf sb_stat;
+       struct strbuf sb_sha1;
+};
+
+static void stat_data_to_disk(struct stat_data *to, const struct stat_data *from)
+{
+       to->sd_ctime.sec  = htonl(from->sd_ctime.sec);
+       to->sd_ctime.nsec = htonl(from->sd_ctime.nsec);
+       to->sd_mtime.sec  = htonl(from->sd_mtime.sec);
+       to->sd_mtime.nsec = htonl(from->sd_mtime.nsec);
+       to->sd_dev        = htonl(from->sd_dev);
+       to->sd_ino        = htonl(from->sd_ino);
+       to->sd_uid        = htonl(from->sd_uid);
+       to->sd_gid        = htonl(from->sd_gid);
+       to->sd_size       = htonl(from->sd_size);
+}
+
+static void write_one_dir(struct untracked_cache_dir *untracked,
+                         struct write_data *wd)
+{
+       struct stat_data stat_data;
+       struct strbuf *out = &wd->out;
+       unsigned char intbuf[16];
+       unsigned int intlen, value;
+       int i = wd->index++;
+
+       /*
+        * untracked_nr should be reset whenever valid is clear, but
+        * for safety..
+        */
+       if (!untracked->valid) {
+               untracked->untracked_nr = 0;
+               untracked->check_only = 0;
+       }
+
+       if (untracked->check_only)
+               ewah_set(wd->check_only, i);
+       if (untracked->valid) {
+               ewah_set(wd->valid, i);
+               stat_data_to_disk(&stat_data, &untracked->stat_data);
+               strbuf_add(&wd->sb_stat, &stat_data, sizeof(stat_data));
+       }
+       if (!is_null_oid(&untracked->exclude_oid)) {
+               ewah_set(wd->sha1_valid, i);
+               strbuf_add(&wd->sb_sha1, untracked->exclude_oid.hash,
+                          the_hash_algo->rawsz);
+       }
+
+       intlen = encode_varint(untracked->untracked_nr, intbuf);
+       strbuf_add(out, intbuf, intlen);
+
+       /* skip non-recurse directories */
+       for (i = 0, value = 0; i < untracked->dirs_nr; i++)
+               if (untracked->dirs[i]->recurse)
+                       value++;
+       intlen = encode_varint(value, intbuf);
+       strbuf_add(out, intbuf, intlen);
+
+       strbuf_add(out, untracked->name, strlen(untracked->name) + 1);
+
+       for (i = 0; i < untracked->untracked_nr; i++)
+               strbuf_add(out, untracked->untracked[i],
+                          strlen(untracked->untracked[i]) + 1);
+
+       for (i = 0; i < untracked->dirs_nr; i++)
+               if (untracked->dirs[i]->recurse)
+                       write_one_dir(untracked->dirs[i], wd);
+}
+
+void write_untracked_extension(struct strbuf *out, struct untracked_cache *untracked)
+{
+       struct ondisk_untracked_cache *ouc;
+       struct write_data wd;
+       unsigned char varbuf[16];
+       int varint_len;
+       const unsigned hashsz = the_hash_algo->rawsz;
+
+       ouc = xcalloc(1, sizeof(*ouc));
+       stat_data_to_disk(&ouc->info_exclude_stat, &untracked->ss_info_exclude.stat);
+       stat_data_to_disk(&ouc->excludes_file_stat, &untracked->ss_excludes_file.stat);
+       ouc->dir_flags = htonl(untracked->dir_flags);
+
+       varint_len = encode_varint(untracked->ident.len, varbuf);
+       strbuf_add(out, varbuf, varint_len);
+       strbuf_addbuf(out, &untracked->ident);
+
+       strbuf_add(out, ouc, sizeof(*ouc));
+       strbuf_add(out, untracked->ss_info_exclude.oid.hash, hashsz);
+       strbuf_add(out, untracked->ss_excludes_file.oid.hash, hashsz);
+       strbuf_add(out, untracked->exclude_per_dir, strlen(untracked->exclude_per_dir) + 1);
+       FREE_AND_NULL(ouc);
+
+       if (!untracked->root) {
+               varint_len = encode_varint(0, varbuf);
+               strbuf_add(out, varbuf, varint_len);
+               return;
+       }
+
+       wd.index      = 0;
+       wd.check_only = ewah_new();
+       wd.valid      = ewah_new();
+       wd.sha1_valid = ewah_new();
+       strbuf_init(&wd.out, 1024);
+       strbuf_init(&wd.sb_stat, 1024);
+       strbuf_init(&wd.sb_sha1, 1024);
+       write_one_dir(untracked->root, &wd);
+
+       varint_len = encode_varint(wd.index, varbuf);
+       strbuf_add(out, varbuf, varint_len);
+       strbuf_addbuf(out, &wd.out);
+       ewah_serialize_strbuf(wd.valid, out);
+       ewah_serialize_strbuf(wd.check_only, out);
+       ewah_serialize_strbuf(wd.sha1_valid, out);
+       strbuf_addbuf(out, &wd.sb_stat);
+       strbuf_addbuf(out, &wd.sb_sha1);
+       strbuf_addch(out, '\0'); /* safe guard for string lists */
+
+       ewah_free(wd.valid);
+       ewah_free(wd.check_only);
+       ewah_free(wd.sha1_valid);
+       strbuf_release(&wd.out);
+       strbuf_release(&wd.sb_stat);
+       strbuf_release(&wd.sb_sha1);
+}
+
+static void free_untracked(struct untracked_cache_dir *ucd)
+{
+       int i;
+       if (!ucd)
+               return;
+       for (i = 0; i < ucd->dirs_nr; i++)
+               free_untracked(ucd->dirs[i]);
+       for (i = 0; i < ucd->untracked_nr; i++)
+               free(ucd->untracked[i]);
+       free(ucd->untracked);
+       free(ucd->dirs);
+       free(ucd);
+}
+
+void free_untracked_cache(struct untracked_cache *uc)
+{
+       if (uc)
+               free_untracked(uc->root);
+       free(uc);
+}
+
+struct read_data {
+       int index;
+       struct untracked_cache_dir **ucd;
+       struct ewah_bitmap *check_only;
+       struct ewah_bitmap *valid;
+       struct ewah_bitmap *sha1_valid;
+       const unsigned char *data;
+       const unsigned char *end;
+};
+
+static void stat_data_from_disk(struct stat_data *to, const unsigned char *data)
+{
+       memcpy(to, data, sizeof(*to));
+       to->sd_ctime.sec  = ntohl(to->sd_ctime.sec);
+       to->sd_ctime.nsec = ntohl(to->sd_ctime.nsec);
+       to->sd_mtime.sec  = ntohl(to->sd_mtime.sec);
+       to->sd_mtime.nsec = ntohl(to->sd_mtime.nsec);
+       to->sd_dev        = ntohl(to->sd_dev);
+       to->sd_ino        = ntohl(to->sd_ino);
+       to->sd_uid        = ntohl(to->sd_uid);
+       to->sd_gid        = ntohl(to->sd_gid);
+       to->sd_size       = ntohl(to->sd_size);
+}
+
+static int read_one_dir(struct untracked_cache_dir **untracked_,
+                       struct read_data *rd)
+{
+       struct untracked_cache_dir ud, *untracked;
+       const unsigned char *data = rd->data, *end = rd->end;
+       const unsigned char *eos;
+       unsigned int value;
+       int i;
+
+       memset(&ud, 0, sizeof(ud));
+
+       value = decode_varint(&data);
+       if (data > end)
+               return -1;
+       ud.recurse         = 1;
+       ud.untracked_alloc = value;
+       ud.untracked_nr    = value;
+       if (ud.untracked_nr)
+               ALLOC_ARRAY(ud.untracked, ud.untracked_nr);
+
+       ud.dirs_alloc = ud.dirs_nr = decode_varint(&data);
+       if (data > end)
+               return -1;
+       ALLOC_ARRAY(ud.dirs, ud.dirs_nr);
+
+       eos = memchr(data, '\0', end - data);
+       if (!eos || eos == end)
+               return -1;
+
+       *untracked_ = untracked = xmalloc(st_add3(sizeof(*untracked), eos - data, 1));
+       memcpy(untracked, &ud, sizeof(ud));
+       memcpy(untracked->name, data, eos - data + 1);
+       data = eos + 1;
+
+       for (i = 0; i < untracked->untracked_nr; i++) {
+               eos = memchr(data, '\0', end - data);
+               if (!eos || eos == end)
+                       return -1;
+               untracked->untracked[i] = xmemdupz(data, eos - data);
+               data = eos + 1;
+       }
+
+       rd->ucd[rd->index++] = untracked;
+       rd->data = data;
+
+       for (i = 0; i < untracked->dirs_nr; i++) {
+               if (read_one_dir(untracked->dirs + i, rd) < 0)
+                       return -1;
+       }
+       return 0;
+}
+
+static void set_check_only(size_t pos, void *cb)
+{
+       struct read_data *rd = cb;
+       struct untracked_cache_dir *ud = rd->ucd[pos];
+       ud->check_only = 1;
+}
+
+static void read_stat(size_t pos, void *cb)
+{
+       struct read_data *rd = cb;
+       struct untracked_cache_dir *ud = rd->ucd[pos];
+       if (rd->data + sizeof(struct stat_data) > rd->end) {
+               rd->data = rd->end + 1;
+               return;
+       }
+       stat_data_from_disk(&ud->stat_data, rd->data);
+       rd->data += sizeof(struct stat_data);
+       ud->valid = 1;
+}
+
+static void read_oid(size_t pos, void *cb)
+{
+       struct read_data *rd = cb;
+       struct untracked_cache_dir *ud = rd->ucd[pos];
+       if (rd->data + the_hash_algo->rawsz > rd->end) {
+               rd->data = rd->end + 1;
+               return;
+       }
+       hashcpy(ud->exclude_oid.hash, rd->data);
+       rd->data += the_hash_algo->rawsz;
+}
+
+static void load_oid_stat(struct oid_stat *oid_stat, const unsigned char *data,
+                         const unsigned char *sha1)
+{
+       stat_data_from_disk(&oid_stat->stat, data);
+       hashcpy(oid_stat->oid.hash, sha1);
+       oid_stat->valid = 1;
+}
+
+struct untracked_cache *read_untracked_extension(const void *data, unsigned long sz)
+{
+       struct untracked_cache *uc;
+       struct read_data rd;
+       const unsigned char *next = data, *end = (const unsigned char *)data + sz;
+       const char *ident;
+       int ident_len;
+       ssize_t len;
+       const char *exclude_per_dir;
+       const unsigned hashsz = the_hash_algo->rawsz;
+       const unsigned offset = sizeof(struct ondisk_untracked_cache);
+       const unsigned exclude_per_dir_offset = offset + 2 * hashsz;
+
+       if (sz <= 1 || end[-1] != '\0')
+               return NULL;
+       end--;
+
+       ident_len = decode_varint(&next);
+       if (next + ident_len > end)
+               return NULL;
+       ident = (const char *)next;
+       next += ident_len;
+
+       if (next + exclude_per_dir_offset + 1 > end)
+               return NULL;
+
+       uc = xcalloc(1, sizeof(*uc));
+       strbuf_init(&uc->ident, ident_len);
+       strbuf_add(&uc->ident, ident, ident_len);
+       load_oid_stat(&uc->ss_info_exclude,
+                     next + ouc_offset(info_exclude_stat),
+                     next + offset);
+       load_oid_stat(&uc->ss_excludes_file,
+                     next + ouc_offset(excludes_file_stat),
+                     next + offset + hashsz);
+       uc->dir_flags = get_be32(next + ouc_offset(dir_flags));
+       exclude_per_dir = (const char *)next + exclude_per_dir_offset;
+       uc->exclude_per_dir = xstrdup(exclude_per_dir);
+       /* NUL after exclude_per_dir is covered by sizeof(*ouc) */
+       next += exclude_per_dir_offset + strlen(exclude_per_dir) + 1;
+       if (next >= end)
+               goto done2;
+
+       len = decode_varint(&next);
+       if (next > end || len == 0)
+               goto done2;
+
+       rd.valid      = ewah_new();
+       rd.check_only = ewah_new();
+       rd.sha1_valid = ewah_new();
+       rd.data       = next;
+       rd.end        = end;
+       rd.index      = 0;
+       ALLOC_ARRAY(rd.ucd, len);
+
+       if (read_one_dir(&uc->root, &rd) || rd.index != len)
+               goto done;
+
+       next = rd.data;
+       len = ewah_read_mmap(rd.valid, next, end - next);
+       if (len < 0)
+               goto done;
+
+       next += len;
+       len = ewah_read_mmap(rd.check_only, next, end - next);
+       if (len < 0)
+               goto done;
+
+       next += len;
+       len = ewah_read_mmap(rd.sha1_valid, next, end - next);
+       if (len < 0)
+               goto done;
+
+       ewah_each_bit(rd.check_only, set_check_only, &rd);
+       rd.data = next + len;
+       ewah_each_bit(rd.valid, read_stat, &rd);
+       ewah_each_bit(rd.sha1_valid, read_oid, &rd);
+       next = rd.data;
+
+done:
+       free(rd.ucd);
+       ewah_free(rd.valid);
+       ewah_free(rd.check_only);
+       ewah_free(rd.sha1_valid);
+done2:
+       if (next != end) {
+               free_untracked_cache(uc);
+               uc = NULL;
+       }
+       return uc;
+}
+
+static void invalidate_one_directory(struct untracked_cache *uc,
+                                    struct untracked_cache_dir *ucd)
+{
+       uc->dir_invalidated++;
+       ucd->valid = 0;
+       ucd->untracked_nr = 0;
+}
+
+/*
+ * Normally when an entry is added or removed from a directory,
+ * invalidating that directory is enough. No need to touch its
+ * ancestors. When a directory is shown as "foo/bar/" in git-status
+ * however, deleting or adding an entry may have cascading effect.
+ *
+ * Say the "foo/bar/file" has become untracked, we need to tell the
+ * untracked_cache_dir of "foo" that "bar/" is not an untracked
+ * directory any more (because "bar" is managed by foo as an untracked
+ * "file").
+ *
+ * Similarly, if "foo/bar/file" moves from untracked to tracked and it
+ * was the last untracked entry in the entire "foo", we should show
+ * "foo/" instead. Which means we have to invalidate past "bar" up to
+ * "foo".
+ *
+ * This function traverses all directories from root to leaf. If there
+ * is a chance of one of the above cases happening, we invalidate back
+ * to root. Otherwise we just invalidate the leaf. There may be a more
+ * sophisticated way than checking for SHOW_OTHER_DIRECTORIES to
+ * detect these cases and avoid unnecessary invalidation, for example,
+ * checking for the untracked entry named "bar/" in "foo", but for now
+ * stick to something safe and simple.
+ */
+static int invalidate_one_component(struct untracked_cache *uc,
+                                   struct untracked_cache_dir *dir,
+                                   const char *path, int len)
+{
+       const char *rest = strchr(path, '/');
+
+       if (rest) {
+               int component_len = rest - path;
+               struct untracked_cache_dir *d =
+                       lookup_untracked(uc, dir, path, component_len);
+               int ret =
+                       invalidate_one_component(uc, d, rest + 1,
+                                                len - (component_len + 1));
+               if (ret)
+                       invalidate_one_directory(uc, dir);
+               return ret;
+       }
+
+       invalidate_one_directory(uc, dir);
+       return uc->dir_flags & DIR_SHOW_OTHER_DIRECTORIES;
+}
+
+void untracked_cache_invalidate_path(struct index_state *istate,
+                                    const char *path, int safe_path)
+{
+       if (!istate->untracked || !istate->untracked->root)
+               return;
+       if (!safe_path && !verify_path(path, 0))
+               return;
+       invalidate_one_component(istate->untracked, istate->untracked->root,
+                                path, strlen(path));
+}
+
+void untracked_cache_remove_from_index(struct index_state *istate,
+                                      const char *path)
+{
+       untracked_cache_invalidate_path(istate, path, 1);
+}
+
+void untracked_cache_add_to_index(struct index_state *istate,
+                                 const char *path)
+{
+       untracked_cache_invalidate_path(istate, path, 1);
+}
+
+static void connect_wt_gitdir_in_nested(const char *sub_worktree,
+                                       const char *sub_gitdir)
+{
+       int i;
+       struct repository subrepo;
+       struct strbuf sub_wt = STRBUF_INIT;
+       struct strbuf sub_gd = STRBUF_INIT;
+
+       const struct submodule *sub;
+
+       /* If the submodule has no working tree, we can ignore it. */
+       if (repo_init(&subrepo, sub_gitdir, sub_worktree))
+               return;
+
+       if (repo_read_index(&subrepo) < 0)
+               die(_("index file corrupt in repo %s"), subrepo.gitdir);
+
+       for (i = 0; i < subrepo.index->cache_nr; i++) {
+               const struct cache_entry *ce = subrepo.index->cache[i];
+
+               if (!S_ISGITLINK(ce->ce_mode))
+                       continue;
+
+               while (i + 1 < subrepo.index->cache_nr &&
+                      !strcmp(ce->name, subrepo.index->cache[i + 1]->name))
+                       /*
+                        * Skip entries with the same name in different stages
+                        * to make sure an entry is returned only once.
+                        */
+                       i++;
+
+               sub = submodule_from_path(&subrepo, &null_oid, ce->name);
+               if (!sub || !is_submodule_active(&subrepo, ce->name))
+                       /* .gitmodules broken or inactive sub */
+                       continue;
+
+               strbuf_reset(&sub_wt);
+               strbuf_reset(&sub_gd);
+               strbuf_addf(&sub_wt, "%s/%s", sub_worktree, sub->path);
+               strbuf_addf(&sub_gd, "%s/modules/%s", sub_gitdir, sub->name);
+
+               connect_work_tree_and_git_dir(sub_wt.buf, sub_gd.buf, 1);
+       }
+       strbuf_release(&sub_wt);
+       strbuf_release(&sub_gd);
+       repo_clear(&subrepo);
+}
+
+void connect_work_tree_and_git_dir(const char *work_tree_,
+                                  const char *git_dir_,
+                                  int recurse_into_nested)
+{
+       struct strbuf gitfile_sb = STRBUF_INIT;
+       struct strbuf cfg_sb = STRBUF_INIT;
+       struct strbuf rel_path = STRBUF_INIT;
+       char *git_dir, *work_tree;
+
+       /* Prepare .git file */
+       strbuf_addf(&gitfile_sb, "%s/.git", work_tree_);
+       if (safe_create_leading_directories_const(gitfile_sb.buf))
+               die(_("could not create directories for %s"), gitfile_sb.buf);
+
+       /* Prepare config file */
+       strbuf_addf(&cfg_sb, "%s/config", git_dir_);
+       if (safe_create_leading_directories_const(cfg_sb.buf))
+               die(_("could not create directories for %s"), cfg_sb.buf);
+
+       git_dir = real_pathdup(git_dir_, 1);
+       work_tree = real_pathdup(work_tree_, 1);
+
+       /* Write .git file */
+       write_file(gitfile_sb.buf, "gitdir: %s",
+                  relative_path(git_dir, work_tree, &rel_path));
+       /* Update core.worktree setting */
+       git_config_set_in_file(cfg_sb.buf, "core.worktree",
+                              relative_path(work_tree, git_dir, &rel_path));
+
+       strbuf_release(&gitfile_sb);
+       strbuf_release(&cfg_sb);
+       strbuf_release(&rel_path);
+
+       if (recurse_into_nested)
+               connect_wt_gitdir_in_nested(work_tree, git_dir);
+
+       free(work_tree);
+       free(git_dir);
+}
+
+/*
+ * Migrate the git directory of the given path from old_git_dir to new_git_dir.
+ */
+void relocate_gitdir(const char *path, const char *old_git_dir, const char *new_git_dir)
+{
+       if (rename(old_git_dir, new_git_dir) < 0)
+               die_errno(_("could not migrate git directory from '%s' to '%s'"),
+                       old_git_dir, new_git_dir);
+
+       connect_work_tree_and_git_dir(path, new_git_dir, 0);
+}