+
+void *read_blob_data_from_index(const struct index_state *istate,
+ const char *path, unsigned long *size)
+{
+ int pos, len;
+ unsigned long sz;
+ enum object_type type;
+ void *data;
+
+ len = strlen(path);
+ pos = index_name_pos(istate, path, len);
+ if (pos < 0) {
+ /*
+ * We might be in the middle of a merge, in which
+ * case we would read stage #2 (ours).
+ */
+ int i;
+ for (i = -pos - 1;
+ (pos < 0 && i < istate->cache_nr &&
+ !strcmp(istate->cache[i]->name, path));
+ i++)
+ if (ce_stage(istate->cache[i]) == 2)
+ pos = i;
+ }
+ if (pos < 0)
+ return NULL;
+ data = read_object_file(&istate->cache[pos]->oid, &type, &sz);
+ if (!data || type != OBJ_BLOB) {
+ free(data);
+ return NULL;
+ }
+ if (size)
+ *size = sz;
+ return data;
+}
+
+void stat_validity_clear(struct stat_validity *sv)
+{
+ FREE_AND_NULL(sv->sd);
+}
+
+int stat_validity_check(struct stat_validity *sv, const char *path)
+{
+ struct stat st;
+
+ if (stat(path, &st) < 0)
+ return sv->sd == NULL;
+ if (!sv->sd)
+ return 0;
+ return S_ISREG(st.st_mode) && !match_stat_data(sv->sd, &st);
+}
+
+void stat_validity_update(struct stat_validity *sv, int fd)
+{
+ struct stat st;
+
+ if (fstat(fd, &st) < 0 || !S_ISREG(st.st_mode))
+ stat_validity_clear(sv);
+ else {
+ if (!sv->sd)
+ sv->sd = xcalloc(1, sizeof(struct stat_data));
+ fill_stat_data(sv->sd, &st);
+ }
+}
+
+void move_index_extensions(struct index_state *dst, struct index_state *src)
+{
+ dst->untracked = src->untracked;
+ src->untracked = NULL;
+ dst->cache_tree = src->cache_tree;
+ src->cache_tree = NULL;
+}
+
+struct cache_entry *dup_cache_entry(const struct cache_entry *ce,
+ struct index_state *istate)
+{
+ unsigned int size = ce_size(ce);
+ int mem_pool_allocated;
+ struct cache_entry *new_entry = make_empty_cache_entry(istate, ce_namelen(ce));
+ mem_pool_allocated = new_entry->mem_pool_allocated;
+
+ memcpy(new_entry, ce, size);
+ new_entry->mem_pool_allocated = mem_pool_allocated;
+ return new_entry;
+}
+
+void discard_cache_entry(struct cache_entry *ce)
+{
+ if (ce && should_validate_cache_entries())
+ memset(ce, 0xCD, cache_entry_size(ce->ce_namelen));
+
+ if (ce && ce->mem_pool_allocated)
+ return;
+
+ free(ce);
+}
+
+int should_validate_cache_entries(void)
+{
+ static int validate_index_cache_entries = -1;
+
+ if (validate_index_cache_entries < 0) {
+ if (getenv("GIT_TEST_VALIDATE_INDEX_CACHE_ENTRIES"))
+ validate_index_cache_entries = 1;
+ else
+ validate_index_cache_entries = 0;
+ }
+
+ return validate_index_cache_entries;
+}
+
+#define EOIE_SIZE (4 + GIT_SHA1_RAWSZ) /* <4-byte offset> + <20-byte hash> */
+#define EOIE_SIZE_WITH_HEADER (4 + 4 + EOIE_SIZE) /* <4-byte signature> + <4-byte length> + EOIE_SIZE */
+
+static size_t read_eoie_extension(const char *mmap, size_t mmap_size)
+{
+ /*
+ * The end of index entries (EOIE) extension is guaranteed to be last
+ * so that it can be found by scanning backwards from the EOF.
+ *
+ * "EOIE"
+ * <4-byte length>
+ * <4-byte offset>
+ * <20-byte hash>
+ */
+ const char *index, *eoie;
+ uint32_t extsize;
+ size_t offset, src_offset;
+ unsigned char hash[GIT_MAX_RAWSZ];
+ git_hash_ctx c;
+
+ /* ensure we have an index big enough to contain an EOIE extension */
+ if (mmap_size < sizeof(struct cache_header) + EOIE_SIZE_WITH_HEADER + the_hash_algo->rawsz)
+ return 0;
+
+ /* validate the extension signature */
+ index = eoie = mmap + mmap_size - EOIE_SIZE_WITH_HEADER - the_hash_algo->rawsz;
+ if (CACHE_EXT(index) != CACHE_EXT_ENDOFINDEXENTRIES)
+ return 0;
+ index += sizeof(uint32_t);
+
+ /* validate the extension size */
+ extsize = get_be32(index);
+ if (extsize != EOIE_SIZE)
+ return 0;
+ index += sizeof(uint32_t);
+
+ /*
+ * Validate the offset we're going to look for the first extension
+ * signature is after the index header and before the eoie extension.
+ */
+ offset = get_be32(index);
+ if (mmap + offset < mmap + sizeof(struct cache_header))
+ return 0;
+ if (mmap + offset >= eoie)
+ return 0;
+ index += sizeof(uint32_t);
+
+ /*
+ * The hash is computed over extension types and their sizes (but not
+ * their contents). E.g. if we have "TREE" extension that is N-bytes
+ * long, "REUC" extension that is M-bytes long, followed by "EOIE",
+ * then the hash would be:
+ *
+ * SHA-1("TREE" + <binary representation of N> +
+ * "REUC" + <binary representation of M>)
+ */
+ src_offset = offset;
+ the_hash_algo->init_fn(&c);
+ while (src_offset < mmap_size - the_hash_algo->rawsz - EOIE_SIZE_WITH_HEADER) {
+ /* After an array of active_nr index entries,
+ * there can be arbitrary number of extended
+ * sections, each of which is prefixed with
+ * extension name (4-byte) and section length
+ * in 4-byte network byte order.
+ */
+ uint32_t extsize;
+ memcpy(&extsize, mmap + src_offset + 4, 4);
+ extsize = ntohl(extsize);
+
+ /* verify the extension size isn't so large it will wrap around */
+ if (src_offset + 8 + extsize < src_offset)
+ return 0;
+
+ the_hash_algo->update_fn(&c, mmap + src_offset, 8);
+
+ src_offset += 8;
+ src_offset += extsize;
+ }
+ the_hash_algo->final_fn(hash, &c);
+ if (!hasheq(hash, (const unsigned char *)index))
+ return 0;
+
+ /* Validate that the extension offsets returned us back to the eoie extension. */
+ if (src_offset != mmap_size - the_hash_algo->rawsz - EOIE_SIZE_WITH_HEADER)
+ return 0;
+
+ return offset;
+}
+
+static void write_eoie_extension(struct strbuf *sb, git_hash_ctx *eoie_context, size_t offset)
+{
+ uint32_t buffer;
+ unsigned char hash[GIT_MAX_RAWSZ];
+
+ /* offset */
+ put_be32(&buffer, offset);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+
+ /* hash */
+ the_hash_algo->final_fn(hash, eoie_context);
+ strbuf_add(sb, hash, the_hash_algo->rawsz);
+}
+
+#define IEOT_VERSION (1)
+
+static struct index_entry_offset_table *read_ieot_extension(const char *mmap, size_t mmap_size, size_t offset)
+{
+ const char *index = NULL;
+ uint32_t extsize, ext_version;
+ struct index_entry_offset_table *ieot;
+ int i, nr;
+
+ /* find the IEOT extension */
+ if (!offset)
+ return NULL;
+ while (offset <= mmap_size - the_hash_algo->rawsz - 8) {
+ extsize = get_be32(mmap + offset + 4);
+ if (CACHE_EXT((mmap + offset)) == CACHE_EXT_INDEXENTRYOFFSETTABLE) {
+ index = mmap + offset + 4 + 4;
+ break;
+ }
+ offset += 8;
+ offset += extsize;
+ }
+ if (!index)
+ return NULL;
+
+ /* validate the version is IEOT_VERSION */
+ ext_version = get_be32(index);
+ if (ext_version != IEOT_VERSION) {
+ error("invalid IEOT version %d", ext_version);
+ return NULL;
+ }
+ index += sizeof(uint32_t);
+
+ /* extension size - version bytes / bytes per entry */
+ nr = (extsize - sizeof(uint32_t)) / (sizeof(uint32_t) + sizeof(uint32_t));
+ if (!nr) {
+ error("invalid number of IEOT entries %d", nr);
+ return NULL;
+ }
+ ieot = xmalloc(sizeof(struct index_entry_offset_table)
+ + (nr * sizeof(struct index_entry_offset)));
+ ieot->nr = nr;
+ for (i = 0; i < nr; i++) {
+ ieot->entries[i].offset = get_be32(index);
+ index += sizeof(uint32_t);
+ ieot->entries[i].nr = get_be32(index);
+ index += sizeof(uint32_t);
+ }
+
+ return ieot;
+}
+
+static void write_ieot_extension(struct strbuf *sb, struct index_entry_offset_table *ieot)
+{
+ uint32_t buffer;
+ int i;
+
+ /* version */
+ put_be32(&buffer, IEOT_VERSION);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+
+ /* ieot */
+ for (i = 0; i < ieot->nr; i++) {
+
+ /* offset */
+ put_be32(&buffer, ieot->entries[i].offset);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+
+ /* count */
+ put_be32(&buffer, ieot->entries[i].nr);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+ }
+}