* we are going to reuse the existing object data as is.  make
  * sure it is not corrupt.
  */
-static int check_inflate(unsigned char *data, unsigned long len, unsigned long expect)
+static int check_pack_inflate(struct packed_git *p,
+               struct pack_window **w_curs,
+               unsigned long offset,
+               unsigned long len,
+               unsigned long expect)
+{
+       z_stream stream;
+       unsigned char fakebuf[4096], *in;
+       int st;
+
+       memset(&stream, 0, sizeof(stream));
+       inflateInit(&stream);
+       do {
+               in = use_pack(p, w_curs, offset, &stream.avail_in);
+               stream.next_in = in;
+               stream.next_out = fakebuf;
+               stream.avail_out = sizeof(fakebuf);
+               st = inflate(&stream, Z_FINISH);
+               offset += stream.next_in - in;
+       } while (st == Z_OK || st == Z_BUF_ERROR);
+       inflateEnd(&stream);
+       return (st == Z_STREAM_END &&
+               stream.total_out == expect &&
+               stream.total_in == len) ? 0 : -1;
+}
+
+static void copy_pack_data(struct sha1file *f,
+               struct packed_git *p,
+               struct pack_window **w_curs,
+               unsigned long offset,
+               unsigned long len)
+{
+       unsigned char *in;
+       unsigned int avail;
+
+       while (len) {
+               in = use_pack(p, w_curs, offset, &avail);
+               if (avail > len)
+                       avail = len;
+               sha1write(f, in, avail);
+               offset += avail;
+               len -= avail;
+       }
+}
+
+static int check_loose_inflate(unsigned char *data, unsigned long len, unsigned long expect)
 {
        z_stream stream;
        unsigned char fakebuf[4096];
                return -1;
        map += used;
        mapsize -= used;
-       return check_inflate(map, mapsize, size);
+       return check_loose_inflate(map, mapsize, size);
 }
 
 static unsigned long write_object(struct sha1file *f,
        else {
                struct packed_git *p = entry->in_pack;
                struct pack_window *w_curs = NULL;
+               unsigned long offset;
 
                if (entry->delta) {
                        obj_type = (allow_ofs_delta && entry->delta->offset) ?
                        hdrlen += 20;
                }
 
-               buf = use_pack(p, &w_curs, entry->in_pack_offset
-                       + entry->in_pack_header_size, NULL);
+               offset = entry->in_pack_offset + entry->in_pack_header_size;
                datalen = find_packed_object_size(p, entry->in_pack_offset)
                                - entry->in_pack_header_size;
-               if (!pack_to_stdout && check_inflate(buf, datalen, entry->size))
+               if (!pack_to_stdout && check_pack_inflate(p, &w_curs,
+                               offset, datalen, entry->size))
                        die("corrupt delta in pack %s", sha1_to_hex(entry->sha1));
-               sha1write(f, buf, datalen);
+               copy_pack_data(f, p, &w_curs, offset, datalen);
                unuse_pack(&w_curs);
                reused++;
        }
 
        void *index_base = p->index_base;
        SHA_CTX ctx;
        unsigned char sha1[20];
-       unsigned long pack_size = p->pack_size;
-       void *pack_base;
-       struct pack_header *hdr;
+       unsigned long offset = 0, pack_sig = p->pack_size - 20;
        int nr_objects, err, i;
 
-       /* Header consistency check */
-       pack_base = use_pack(p, w_curs, 0, NULL);
-       hdr = (struct pack_header*)pack_base;
-       if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
-               return error("Packfile %s signature mismatch", p->pack_name);
-       if (!pack_version_ok(hdr->hdr_version))
-               return error("Packfile version %d unsupported",
-                            ntohl(hdr->hdr_version));
-       nr_objects = ntohl(hdr->hdr_entries);
-       if (num_packed_objects(p) != nr_objects)
-               return error("Packfile claims to have %d objects, "
-                            "while idx size expects %d", nr_objects,
-                            num_packed_objects(p));
+       /* Note that the pack header checks are actually performed by
+        * use_pack when it first opens the pack file.  If anything
+        * goes wrong during those checks then the call will die out
+        * immediately.
+        */
 
        SHA1_Init(&ctx);
-       SHA1_Update(&ctx, pack_base, pack_size - 20);
+       while (offset < pack_sig) {
+               unsigned int remaining;
+               unsigned char *in = use_pack(p, w_curs, offset, &remaining);
+               offset += remaining;
+               if (offset > pack_sig)
+                       remaining -= offset - pack_sig;
+               SHA1_Update(&ctx, in, remaining);
+       }
        SHA1_Final(sha1, &ctx);
-       if (hashcmp(sha1, (unsigned char *)pack_base + pack_size - 20))
+       if (hashcmp(sha1, use_pack(p, w_curs, pack_sig, NULL)))
                return error("Packfile %s SHA1 mismatch with itself",
                             p->pack_name);
        if (hashcmp(sha1, (unsigned char *)index_base + index_size - 40))
                return error("Packfile %s SHA1 mismatch with idx",
                             p->pack_name);
+       unuse_pack(w_curs);
 
        /* Make sure everything reachable from idx is valid.  Since we
         * have verified that nr_objects matches between idx and pack,
         * we do not do scan-streaming check on the pack file.
         */
+       nr_objects = num_packed_objects(p);
        for (i = err = 0; i < nr_objects; i++) {
                unsigned char sha1[20];
                void *data;
 
 #define MAX_CHAIN 40
 
-static void show_pack_info(struct packed_git *p,
-               struct pack_window **w_curs)
+static void show_pack_info(struct packed_git *p)
 {
-       struct pack_header *hdr;
        int nr_objects, i;
        unsigned int chain_histogram[MAX_CHAIN];
 
-       hdr = (struct pack_header*)use_pack(p, w_curs, 0, NULL);
-       nr_objects = ntohl(hdr->hdr_entries);
+       nr_objects = num_packed_objects(p);
        memset(chain_histogram, 0, sizeof(chain_histogram));
 
        for (i = 0; i < nr_objects; i++) {
                if (ret)
                        printf("%s: bad\n", p->pack_name);
                else {
-                       struct pack_window *w_curs = NULL;
-                       show_pack_info(p, &w_curs);
-                       unuse_pack(&w_curs);
+                       show_pack_info(p);
                        printf("%s: ok\n", p->pack_name);
                }
        }
 
 
        if (sizep) {
                const unsigned char *data;
-               unsigned char delta_head[20];
+               unsigned char delta_head[20], *in;
                unsigned long result_size;
                z_stream stream;
                int st;
 
                memset(&stream, 0, sizeof(stream));
-
-               stream.next_in = use_pack(p, w_curs, offset, &stream.avail_in);
                stream.next_out = delta_head;
                stream.avail_out = sizeof(delta_head);
 
                inflateInit(&stream);
-               st = inflate(&stream, Z_FINISH);
+               do {
+                       in = use_pack(p, w_curs, offset, &stream.avail_in);
+                       stream.next_in = in;
+                       st = inflate(&stream, Z_FINISH);
+                       offset += stream.next_in - in;
+               } while ((st == Z_OK || st == Z_BUF_ERROR)
+                       && stream.total_out < sizeof(delta_head));
                inflateEnd(&stream);
                if ((st != Z_STREAM_END) &&
                    stream.total_out != sizeof(delta_head))
 {
        int st;
        z_stream stream;
-       unsigned char *buffer;
+       unsigned char *buffer, *in;
 
        buffer = xmalloc(size + 1);
        buffer[size] = 0;
        memset(&stream, 0, sizeof(stream));
-       stream.next_in = use_pack(p, w_curs, offset, &stream.avail_in);
        stream.next_out = buffer;
        stream.avail_out = size;
 
        inflateInit(&stream);
-       st = inflate(&stream, Z_FINISH);
+       do {
+               in = use_pack(p, w_curs, offset, &stream.avail_in);
+               stream.next_in = in;
+               st = inflate(&stream, Z_FINISH);
+               offset += stream.next_in - in;
+       } while (st == Z_OK || st == Z_BUF_ERROR);
        inflateEnd(&stream);
        if ((st != Z_STREAM_END) || stream.total_out != size) {
                free(buffer);