- hash_sha1_file(map, size, type, real_sha1);
+ enum object_type obj_type;
+ struct git_istream *st;
+ git_SHA_CTX c;
+ char hdr[32];
+ int hdrlen;
+
+ if (map) {
+ hash_sha1_file(map, size, type, real_sha1);
+ return hashcmp(sha1, real_sha1) ? -1 : 0;
+ }
+
+ st = open_istream(sha1, &obj_type, &size, NULL);
+ if (!st)
+ return -1;
+
+ /* Generate the header */
+ hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
+
+ /* Sha1.. */
+ git_SHA1_Init(&c);
+ git_SHA1_Update(&c, hdr, hdrlen);
+ for (;;) {
+ char buf[1024 * 16];
+ ssize_t readlen = read_istream(st, buf, sizeof(buf));
+
+ if (!readlen)
+ break;
+ git_SHA1_Update(&c, buf, readlen);
+ }
+ git_SHA1_Final(real_sha1, &c);
+ close_istream(st);