+static void add_trailing_starstar_for_dir(struct strbuf *pat)
+{
+ if (pat->len && is_dir_sep(pat->buf[pat->len - 1]))
+ strbuf_addstr(pat, "**");
+}
+
+static int prepare_include_condition_pattern(struct strbuf *pat)
+{
+ struct strbuf path = STRBUF_INIT;
+ char *expanded;
+ int prefix = 0;
+
+ expanded = expand_user_path(pat->buf, 1);
+ if (expanded) {
+ strbuf_reset(pat);
+ strbuf_addstr(pat, expanded);
+ free(expanded);
+ }
+
+ if (pat->buf[0] == '.' && is_dir_sep(pat->buf[1])) {
+ const char *slash;
+
+ if (!cf || !cf->path)
+ return error(_("relative config include "
+ "conditionals must come from files"));
+
+ strbuf_realpath(&path, cf->path, 1);
+ slash = find_last_dir_sep(path.buf);
+ if (!slash)
+ BUG("how is this possible?");
+ strbuf_splice(pat, 0, 1, path.buf, slash - path.buf);
+ prefix = slash - path.buf + 1 /* slash */;
+ } else if (!is_absolute_path(pat->buf))
+ strbuf_insertstr(pat, 0, "**/");
+
+ add_trailing_starstar_for_dir(pat);
+
+ strbuf_release(&path);
+ return prefix;
+}
+
+static int include_by_gitdir(const struct config_options *opts,
+ const char *cond, size_t cond_len, int icase)
+{
+ struct strbuf text = STRBUF_INIT;
+ struct strbuf pattern = STRBUF_INIT;
+ int ret = 0, prefix;
+ const char *git_dir;
+ int already_tried_absolute = 0;
+
+ if (opts->git_dir)
+ git_dir = opts->git_dir;
+ else
+ goto done;
+
+ strbuf_realpath(&text, git_dir, 1);
+ strbuf_add(&pattern, cond, cond_len);
+ prefix = prepare_include_condition_pattern(&pattern);
+
+again:
+ if (prefix < 0)
+ goto done;
+
+ if (prefix > 0) {
+ /*
+ * perform literal matching on the prefix part so that
+ * any wildcard character in it can't create side effects.
+ */
+ if (text.len < prefix)
+ goto done;
+ if (!icase && strncmp(pattern.buf, text.buf, prefix))
+ goto done;
+ if (icase && strncasecmp(pattern.buf, text.buf, prefix))
+ goto done;
+ }
+
+ ret = !wildmatch(pattern.buf + prefix, text.buf + prefix,
+ WM_PATHNAME | (icase ? WM_CASEFOLD : 0));
+
+ if (!ret && !already_tried_absolute) {
+ /*
+ * We've tried e.g. matching gitdir:~/work, but if
+ * ~/work is a symlink to /mnt/storage/work
+ * strbuf_realpath() will expand it, so the rule won't
+ * match. Let's match against a
+ * strbuf_add_absolute_path() version of the path,
+ * which'll do the right thing
+ */
+ strbuf_reset(&text);
+ strbuf_add_absolute_path(&text, git_dir);
+ already_tried_absolute = 1;
+ goto again;
+ }
+done:
+ strbuf_release(&pattern);
+ strbuf_release(&text);
+ return ret;
+}
+
+static int include_by_branch(const char *cond, size_t cond_len)
+{
+ int flags;
+ int ret;
+ struct strbuf pattern = STRBUF_INIT;
+ const char *refname = !the_repository->gitdir ?
+ NULL : resolve_ref_unsafe("HEAD", 0, NULL, &flags);
+ const char *shortname;
+
+ if (!refname || !(flags & REF_ISSYMREF) ||
+ !skip_prefix(refname, "refs/heads/", &shortname))
+ return 0;
+
+ strbuf_add(&pattern, cond, cond_len);
+ add_trailing_starstar_for_dir(&pattern);
+ ret = !wildmatch(pattern.buf, shortname, WM_PATHNAME);
+ strbuf_release(&pattern);
+ return ret;
+}
+
+static int include_condition_is_true(const struct config_options *opts,
+ const char *cond, size_t cond_len)
+{
+
+ if (skip_prefix_mem(cond, cond_len, "gitdir:", &cond, &cond_len))
+ return include_by_gitdir(opts, cond, cond_len, 0);
+ else if (skip_prefix_mem(cond, cond_len, "gitdir/i:", &cond, &cond_len))
+ return include_by_gitdir(opts, cond, cond_len, 1);
+ else if (skip_prefix_mem(cond, cond_len, "onbranch:", &cond, &cond_len))
+ return include_by_branch(cond, cond_len);
+
+ /* unknown conditionals are always false */
+ return 0;
+}
+