+/* forward declaration for a mutually recursive function */
+static int packed_object_info(struct pack_entry *entry,
+ char *type, unsigned long *sizep);
+
+static int packed_delta_info(unsigned char *base_sha1,
+ unsigned long delta_size,
+ unsigned long left,
+ char *type,
+ unsigned long *sizep,
+ struct packed_git *p)
+{
+ struct pack_entry base_ent;
+
+ if (left < 20)
+ die("truncated pack file");
+
+ /* The base entry _must_ be in the same pack */
+ if (!find_pack_entry_one(base_sha1, &base_ent, p))
+ die("failed to find delta-pack base object %s",
+ sha1_to_hex(base_sha1));
+
+ /* We choose to only get the type of the base object and
+ * ignore potentially corrupt pack file that expects the delta
+ * based on a base with a wrong size. This saves tons of
+ * inflate() calls.
+ */
+
+ if (packed_object_info(&base_ent, type, NULL))
+ die("cannot get info for delta-pack base");
+
+ if (sizep) {
+ const unsigned char *data;
+ unsigned char delta_head[64];
+ unsigned long result_size;
+ z_stream stream;
+ int st;
+
+ memset(&stream, 0, sizeof(stream));
+
+ data = stream.next_in = base_sha1 + 20;
+ stream.avail_in = left - 20;
+ stream.next_out = delta_head;
+ stream.avail_out = sizeof(delta_head);
+
+ inflateInit(&stream);
+ st = inflate(&stream, Z_FINISH);
+ inflateEnd(&stream);
+ if ((st != Z_STREAM_END) &&
+ stream.total_out != sizeof(delta_head))
+ die("delta data unpack-initial failed");
+
+ /* Examine the initial part of the delta to figure out
+ * the result size.
+ */
+ data = delta_head;
+ get_delta_hdr_size(&data); /* ignore base size */
+
+ /* Read the result size */
+ result_size = get_delta_hdr_size(&data);
+ *sizep = result_size;
+ }
+ return 0;
+}
+
+static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
+ enum object_type *type, unsigned long *sizep)
+{
+ unsigned shift;
+ unsigned char *pack, c;
+ unsigned long size;
+
+ if (offset >= p->pack_size)
+ die("object offset outside of pack file");
+
+ pack = p->pack_base + offset;
+ c = *pack++;
+ offset++;
+ *type = (c >> 4) & 7;
+ size = c & 15;
+ shift = 4;
+ while (c & 0x80) {
+ if (offset >= p->pack_size)
+ die("object offset outside of pack file");
+ c = *pack++;
+ offset++;
+ size += (c & 0x7f) << shift;
+ shift += 7;
+ }
+ *sizep = size;
+ return offset;
+}
+
+void packed_object_info_detail(struct pack_entry *e,
+ char *type,
+ unsigned long *size,
+ unsigned long *store_size,
+ int *delta_chain_length,
+ unsigned char *base_sha1)
+{
+ struct packed_git *p = e->p;
+ unsigned long offset, left;
+ unsigned char *pack;
+ enum object_type kind;
+
+ offset = unpack_object_header(p, e->offset, &kind, size);
+ pack = p->pack_base + offset;
+ left = p->pack_size - offset;
+ if (kind != OBJ_DELTA)
+ *delta_chain_length = 0;
+ else {
+ int chain_length = 0;
+ memcpy(base_sha1, pack, 20);
+ do {
+ struct pack_entry base_ent;
+ unsigned long junk;
+
+ find_pack_entry_one(pack, &base_ent, p);
+ offset = unpack_object_header(p, base_ent.offset,
+ &kind, &junk);
+ pack = p->pack_base + offset;
+ chain_length++;
+ } while (kind == OBJ_DELTA);
+ *delta_chain_length = chain_length;
+ }
+ switch (kind) {
+ case OBJ_COMMIT:
+ strcpy(type, "commit");
+ break;
+ case OBJ_TREE:
+ strcpy(type, "tree");
+ break;
+ case OBJ_BLOB:
+ strcpy(type, "blob");
+ break;
+ case OBJ_TAG:
+ strcpy(type, "tag");
+ break;
+ default:
+ die("corrupted pack file %s containing object of kind %d",
+ p->pack_name, kind);
+ }
+ *store_size = 0; /* notyet */
+}
+
+static int packed_object_info(struct pack_entry *entry,
+ char *type, unsigned long *sizep)
+{
+ struct packed_git *p = entry->p;
+ unsigned long offset, size, left;
+ unsigned char *pack;
+ enum object_type kind;
+ int retval;
+
+ if (use_packed_git(p))
+ die("cannot map packed file");
+
+ offset = unpack_object_header(p, entry->offset, &kind, &size);
+ pack = p->pack_base + offset;
+ left = p->pack_size - offset;
+
+ switch (kind) {
+ case OBJ_DELTA:
+ retval = packed_delta_info(pack, size, left, type, sizep, p);
+ unuse_packed_git(p);
+ return retval;
+ case OBJ_COMMIT:
+ strcpy(type, "commit");
+ break;
+ case OBJ_TREE:
+ strcpy(type, "tree");
+ break;
+ case OBJ_BLOB:
+ strcpy(type, "blob");
+ break;
+ case OBJ_TAG:
+ strcpy(type, "tag");
+ break;
+ default:
+ die("corrupted pack file %s containing object of kind %d",
+ p->pack_name, kind);
+ }
+ if (sizep)
+ *sizep = size;
+ unuse_packed_git(p);
+ return 0;
+}
+
+/* forward declaration for a mutually recursive function */
+static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
+
+static void *unpack_delta_entry(unsigned char *base_sha1,
+ unsigned long delta_size,
+ unsigned long left,
+ char *type,
+ unsigned long *sizep,
+ struct packed_git *p)
+{
+ struct pack_entry base_ent;
+ void *data, *delta_data, *result, *base;
+ unsigned long data_size, result_size, base_size;
+ z_stream stream;
+ int st;
+
+ if (left < 20)
+ die("truncated pack file");
+ data = base_sha1 + 20;
+ data_size = left - 20;
+ delta_data = xmalloc(delta_size);
+
+ memset(&stream, 0, sizeof(stream));
+
+ stream.next_in = data;
+ stream.avail_in = data_size;
+ stream.next_out = delta_data;
+ stream.avail_out = delta_size;
+
+ inflateInit(&stream);
+ st = inflate(&stream, Z_FINISH);
+ inflateEnd(&stream);
+ if ((st != Z_STREAM_END) || stream.total_out != delta_size)
+ die("delta data unpack failed");
+
+ /* The base entry _must_ be in the same pack */
+ if (!find_pack_entry_one(base_sha1, &base_ent, p))
+ die("failed to find delta-pack base object %s",
+ sha1_to_hex(base_sha1));
+ base = unpack_entry_gently(&base_ent, type, &base_size);
+ if (!base)
+ die("failed to read delta-pack base object %s",
+ sha1_to_hex(base_sha1));
+ result = patch_delta(base, base_size,
+ delta_data, delta_size,
+ &result_size);
+ if (!result)
+ die("failed to apply delta");
+ free(delta_data);
+ free(base);
+ *sizep = result_size;
+ return result;
+}
+
+static void *unpack_non_delta_entry(unsigned char *data,
+ unsigned long size,
+ unsigned long left)
+{
+ int st;
+ z_stream stream;
+ unsigned char *buffer;
+
+ buffer = xmalloc(size + 1);
+ buffer[size] = 0;
+ memset(&stream, 0, sizeof(stream));
+ stream.next_in = data;
+ stream.avail_in = left;
+ stream.next_out = buffer;
+ stream.avail_out = size;
+
+ inflateInit(&stream);
+ st = inflate(&stream, Z_FINISH);
+ inflateEnd(&stream);
+ if ((st != Z_STREAM_END) || stream.total_out != size) {
+ free(buffer);
+ return NULL;
+ }
+
+ return buffer;
+}
+
+static void *unpack_entry(struct pack_entry *entry,
+ char *type, unsigned long *sizep)
+{
+ struct packed_git *p = entry->p;
+ void *retval;
+
+ if (use_packed_git(p))
+ die("cannot map packed file");
+ retval = unpack_entry_gently(entry, type, sizep);
+ unuse_packed_git(p);
+ if (!retval)
+ die("corrupted pack file %s", p->pack_name);
+ return retval;
+}
+
+/* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
+void *unpack_entry_gently(struct pack_entry *entry,
+ char *type, unsigned long *sizep)
+{
+ struct packed_git *p = entry->p;
+ unsigned long offset, size, left;
+ unsigned char *pack;
+ enum object_type kind;
+ void *retval;
+
+ offset = unpack_object_header(p, entry->offset, &kind, &size);
+ pack = p->pack_base + offset;
+ left = p->pack_size - offset;
+ switch (kind) {
+ case OBJ_DELTA:
+ retval = unpack_delta_entry(pack, size, left, type, sizep, p);
+ return retval;
+ case OBJ_COMMIT:
+ strcpy(type, "commit");
+ break;
+ case OBJ_TREE:
+ strcpy(type, "tree");
+ break;
+ case OBJ_BLOB:
+ strcpy(type, "blob");
+ break;
+ case OBJ_TAG:
+ strcpy(type, "tag");
+ break;
+ default:
+ return NULL;
+ }
+ *sizep = size;
+ retval = unpack_non_delta_entry(pack, size, left);
+ return retval;
+}
+
+int num_packed_objects(const struct packed_git *p)
+{
+ /* See check_packed_git_idx() */
+ return (p->index_size - 20 - 20 - 4*256) / 24;
+}
+
+int nth_packed_object_sha1(const struct packed_git *p, int n,
+ unsigned char* sha1)
+{
+ void *index = p->index_base + 256;
+ if (n < 0 || num_packed_objects(p) <= n)
+ return -1;
+ memcpy(sha1, (index + 24 * n + 4), 20);
+ return 0;
+}
+
+int find_pack_entry_one(const unsigned char *sha1,
+ struct pack_entry *e, struct packed_git *p)
+{
+ unsigned int *level1_ofs = p->index_base;
+ int hi = ntohl(level1_ofs[*sha1]);
+ int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
+ void *index = p->index_base + 256;
+
+ do {
+ int mi = (lo + hi) / 2;
+ int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
+ if (!cmp) {
+ e->offset = ntohl(*((int*)(index + 24 * mi)));
+ memcpy(e->sha1, sha1, 20);
+ e->p = p;
+ return 1;
+ }
+ if (cmp > 0)
+ hi = mi;
+ else
+ lo = mi+1;
+ } while (lo < hi);
+ return 0;
+}
+
+static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
+{
+ struct packed_git *p;
+ prepare_packed_git();
+
+ for (p = packed_git; p; p = p->next) {
+ if (find_pack_entry_one(sha1, e, p))
+ return 1;
+ }
+ return 0;
+}
+
+struct packed_git *find_sha1_pack(const unsigned char *sha1,
+ struct packed_git *packs)
+{
+ struct packed_git *p;
+ struct pack_entry e;
+
+ for (p = packs; p; p = p->next) {
+ if (find_pack_entry_one(sha1, &e, p))
+ return p;
+ }
+ return NULL;
+
+}
+