diff options
| -rw-r--r-- | sha1_file.c | 231 |
1 files changed, 150 insertions, 81 deletions
diff --git a/sha1_file.c b/sha1_file.c index fb0506ea9e..b220a470f9 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -1864,68 +1864,6 @@ static void add_delta_base_cache(struct packed_git *p, off_t base_offset, static void *read_object(const unsigned char *sha1, enum object_type *type, unsigned long *size); -static void *unpack_delta_entry(struct packed_git *p, - struct pack_window **w_curs, - off_t curpos, - unsigned long delta_size, - off_t obj_offset, - enum object_type *type, - unsigned long *sizep) -{ - void *delta_data, *result, *base; - unsigned long base_size; - off_t base_offset; - - base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset); - if (!base_offset) { - error("failed to validate delta base reference " - "at offset %"PRIuMAX" from %s", - (uintmax_t)curpos, p->pack_name); - return NULL; - } - unuse_pack(w_curs); - base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0); - if (!base) { - /* - * We're probably in deep shit, but let's try to fetch - * the required base anyway from another pack or loose. - * This is costly but should happen only in the presence - * of a corrupted pack, and is better than failing outright. - */ - struct revindex_entry *revidx; - const unsigned char *base_sha1; - revidx = find_pack_revindex(p, base_offset); - if (!revidx) - return NULL; - base_sha1 = nth_packed_object_sha1(p, revidx->nr); - error("failed to read delta base object %s" - " at offset %"PRIuMAX" from %s", - sha1_to_hex(base_sha1), (uintmax_t)base_offset, - p->pack_name); - mark_bad_packed_object(p, base_sha1); - base = read_object(base_sha1, type, &base_size); - if (!base) - return NULL; - } - - delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size); - if (!delta_data) { - error("failed to unpack compressed delta " - "at offset %"PRIuMAX" from %s", - (uintmax_t)curpos, p->pack_name); - free(base); - return NULL; - } - result = patch_delta(base, base_size, - delta_data, delta_size, - sizep); - if (!result) - die("failed to apply delta"); - free(delta_data); - add_delta_base_cache(p, base_offset, base, base_size, *type); - return result; -} - static void write_pack_access_log(struct packed_git *p, off_t obj_offset) { static FILE *log_file; @@ -1946,48 +1884,179 @@ static void write_pack_access_log(struct packed_git *p, off_t obj_offset) int do_check_packed_object_crc; +#define UNPACK_ENTRY_STACK_PREALLOC 64 +struct unpack_entry_stack_ent { + off_t obj_offset; + off_t curpos; + unsigned long size; +}; + void *unpack_entry(struct packed_git *p, off_t obj_offset, - enum object_type *type, unsigned long *sizep) + enum object_type *final_type, unsigned long *final_size) { struct pack_window *w_curs = NULL; off_t curpos = obj_offset; - void *data; + void *data = NULL; + unsigned long size; + enum object_type type; + struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC]; + struct unpack_entry_stack_ent *delta_stack = small_delta_stack; + int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC; + int base_from_cache = 0; if (log_pack_access) write_pack_access_log(p, obj_offset); - if (do_check_packed_object_crc && p->index_version > 1) { - struct revindex_entry *revidx = find_pack_revindex(p, obj_offset); - unsigned long len = revidx[1].offset - obj_offset; - if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) { - const unsigned char *sha1 = - nth_packed_object_sha1(p, revidx->nr); - error("bad packed object CRC for %s", - sha1_to_hex(sha1)); - mark_bad_packed_object(p, sha1); - unuse_pack(&w_curs); - return NULL; + /* PHASE 1: drill down to the innermost base object */ + for (;;) { + off_t base_offset; + int i; + struct delta_base_cache_entry *ent; + + if (do_check_packed_object_crc && p->index_version > 1) { + struct revindex_entry *revidx = find_pack_revindex(p, obj_offset); + unsigned long len = revidx[1].offset - obj_offset; + if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) { + const unsigned char *sha1 = + nth_packed_object_sha1(p, revidx->nr); + error("bad packed object CRC for %s", + sha1_to_hex(sha1)); + mark_bad_packed_object(p, sha1); + unuse_pack(&w_curs); + return NULL; + } + } + + ent = get_delta_base_cache_entry(p, curpos); + if (eq_delta_base_cache_entry(ent, p, curpos)) { + type = ent->type; + data = ent->data; + size = ent->size; + clear_delta_base_cache_entry(ent); + base_from_cache = 1; + break; + } + + type = unpack_object_header(p, &w_curs, &curpos, &size); + if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA) + break; + + base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset); + if (!base_offset) { + error("failed to validate delta base reference " + "at offset %"PRIuMAX" from %s", + (uintmax_t)curpos, p->pack_name); + /* bail to phase 2, in hopes of recovery */ + data = NULL; + break; } + + /* push object, proceed to base */ + if (delta_stack_nr >= delta_stack_alloc + && delta_stack == small_delta_stack) { + delta_stack_alloc = alloc_nr(delta_stack_nr); + delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc); + memcpy(delta_stack, small_delta_stack, + sizeof(*delta_stack)*delta_stack_nr); + } else { + ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc); + } + i = delta_stack_nr++; + delta_stack[i].obj_offset = obj_offset; + delta_stack[i].curpos = curpos; + delta_stack[i].size = size; + + curpos = obj_offset = base_offset; } - *type = unpack_object_header(p, &w_curs, &curpos, sizep); - switch (*type) { + /* PHASE 2: handle the base */ + switch (type) { case OBJ_OFS_DELTA: case OBJ_REF_DELTA: - data = unpack_delta_entry(p, &w_curs, curpos, *sizep, - obj_offset, type, sizep); + if (data) + die("BUG in unpack_entry: left loop at a valid delta"); break; case OBJ_COMMIT: case OBJ_TREE: case OBJ_BLOB: case OBJ_TAG: - data = unpack_compressed_entry(p, &w_curs, curpos, *sizep); + if (!base_from_cache) + data = unpack_compressed_entry(p, &w_curs, curpos, size); break; default: data = NULL; error("unknown object type %i at offset %"PRIuMAX" in %s", - *type, (uintmax_t)obj_offset, p->pack_name); + type, (uintmax_t)obj_offset, p->pack_name); } + + /* PHASE 3: apply deltas in order */ + + /* invariants: + * 'data' holds the base data, or NULL if there was corruption + */ + while (delta_stack_nr) { + void *delta_data; + void *base = data; + unsigned long delta_size, base_size = size; + int i; + + data = NULL; + + if (base) + add_delta_base_cache(p, obj_offset, base, base_size, type); + + if (!base) { + /* + * We're probably in deep shit, but let's try to fetch + * the required base anyway from another pack or loose. + * This is costly but should happen only in the presence + * of a corrupted pack, and is better than failing outright. + */ + struct revindex_entry *revidx; + const unsigned char *base_sha1; + revidx = find_pack_revindex(p, obj_offset); + if (revidx) { + base_sha1 = nth_packed_object_sha1(p, revidx->nr); + error("failed to read delta base object %s" + " at offset %"PRIuMAX" from %s", + sha1_to_hex(base_sha1), (uintmax_t)obj_offset, + p->pack_name); + mark_bad_packed_object(p, base_sha1); + base = read_object(base_sha1, &type, &base_size); + } + } + + i = --delta_stack_nr; + obj_offset = delta_stack[i].obj_offset; + curpos = delta_stack[i].curpos; + delta_size = delta_stack[i].size; + + if (!base) + continue; + + delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size); + + if (!delta_data) { + error("failed to unpack compressed delta " + "at offset %"PRIuMAX" from %s", + (uintmax_t)curpos, p->pack_name); + free(base); + data = NULL; + continue; + } + + data = patch_delta(base, base_size, + delta_data, delta_size, + &size); + if (!data) + die("failed to apply delta"); + + free (delta_data); + } + + *final_type = type; + *final_size = size; + unuse_pack(&w_curs); return data; } |