pack-objects: allow "fixing" a corrupted pack without a full repack

When the pack data to be reused is found to be bad, let's fall back to
full object access through the generic path which has its own strategies
to find alternate object sources in that case.  This allows for "fixing"
a corrupted pack simply by copying either another pack containing the
object(s) found to be bad, or the loose object itself, into the object
store and launch a repack without the need for -f.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 04a5a55ef94d411c99287e9c9ac5c75f73051e16..5be6664c7294157c669e1b73de4698e81655d460 100644 (file)
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -277,6 +277,7 @@ static unsigned long write_object(struct sha1file *f,
                                 */
 
        if (!to_reuse) {
+               no_reuse:
                if (!usable_delta) {
                        buf = read_sha1_file(entry->idx.sha1, &type, &size);
                        if (!buf)
@@ -358,20 +359,30 @@ static unsigned long write_object(struct sha1file *f,
                struct revindex_entry *revidx;
                off_t offset;
 
-               if (entry->delta) {
+               if (entry->delta)
                        type = (allow_ofs_delta && entry->delta->idx.offset) ?
                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
-                       reused_delta++;
-               }
                hdrlen = encode_header(type, entry->size, header);
+
                offset = entry->in_pack_offset;
                revidx = find_pack_revindex(p, offset);
                datalen = revidx[1].offset - offset;
                if (!pack_to_stdout && p->index_version > 1 &&
-                   check_pack_crc(p, &w_curs, offset, datalen, revidx->nr))
-                       die("bad packed object CRC for %s", sha1_to_hex(entry->idx.sha1));
+                   check_pack_crc(p, &w_curs, offset, datalen, revidx->nr)) {
+                       error("bad packed object CRC for %s", sha1_to_hex(entry->idx.sha1));
+                       unuse_pack(&w_curs);
+                       goto no_reuse;
+               }
+
                offset += entry->in_pack_header_size;
                datalen -= entry->in_pack_header_size;
+               if (!pack_to_stdout && p->index_version == 1 &&
+                   check_pack_inflate(p, &w_curs, offset, datalen, entry->size)) {
+                       error("corrupt packed object for %s", sha1_to_hex(entry->idx.sha1));
+                       unuse_pack(&w_curs);
+                       goto no_reuse;
+               }
+
                if (type == OBJ_OFS_DELTA) {
                        off_t ofs = entry->idx.offset - entry->delta->idx.offset;
                        unsigned pos = sizeof(dheader) - 1;
@@ -383,21 +394,19 @@ static unsigned long write_object(struct sha1file *f,
                        sha1write(f, header, hdrlen);
                        sha1write(f, dheader + pos, sizeof(dheader) - pos);
                        hdrlen += sizeof(dheader) - pos;
+                       reused_delta++;
                } else if (type == OBJ_REF_DELTA) {
                        if (limit && hdrlen + 20 + datalen + 20 >= limit)
                                return 0;
                        sha1write(f, header, hdrlen);
                        sha1write(f, entry->delta->idx.sha1, 20);
                        hdrlen += 20;
+                       reused_delta++;
                } else {
                        if (limit && hdrlen + datalen + 20 >= limit)
                                return 0;
                        sha1write(f, header, hdrlen);
                }
-
-               if (!pack_to_stdout && p->index_version == 1 &&
-                   check_pack_inflate(p, &w_curs, offset, datalen, entry->size))
-                       die("corrupt packed object for %s", sha1_to_hex(entry->idx.sha1));
                copy_pack_data(f, p, &w_curs, offset, datalen);
                unuse_pack(&w_curs);
                reused++;
@@ -1074,6 +1083,7 @@ static void check_object(struct object_entry *entry)
                         */
                        entry->type = entry->in_pack_type;
                        entry->delta = base_entry;
+                       entry->delta_size = entry->size;
                        entry->delta_sibling = base_entry->delta_child;
                        base_entry->delta_child = entry;
                        unuse_pack(&w_curs);