extern int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *return_sha1);
extern int pretend_sha1_file(void *, unsigned long, enum object_type, unsigned char *);
extern int force_object_loose(const unsigned char *sha1, time_t mtime);
+extern void *map_sha1_file(const unsigned char *sha1, unsigned long *size);
+extern int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz);
+extern int parse_sha1_header(const char *hdr, unsigned long *sizep);
/* global flag to enable extra checks when accessing packed objects */
extern int do_check_packed_object_crc;