Merge branch 'np/pack-safer'
authorJunio C Hamano <gitster@pobox.com>
Thu, 13 Nov 2008 06:26:35 +0000 (22:26 -0800)
committerJunio C Hamano <gitster@pobox.com>
Thu, 13 Nov 2008 06:26:35 +0000 (22:26 -0800)
* np/pack-safer:
t5303: fix printf format string for portability
t5303: work around printf breakage in dash
pack-objects: don't leak pack window reference when splitting packs
extend test coverage for latest pack corruption resilience improvements
pack-objects: allow "fixing" a corrupted pack without a full repack
make find_pack_revindex() aware of the nasty world
make check_object() resilient to pack corruptions
make packed_object_info() resilient to pack corruptions
make unpack_object_header() non fatal
better validation on delta base object offsets
close another possibility for propagating pack corruption

builtin-pack-objects.c
builtin-unpack-objects.c
cache.h
index-pack.c
pack-revindex.c
sha1_file.c
t/t5302-pack-index.sh
t/t5303-pack-corruption-resilience.sh
index 59ae64d83ff8ef28130384d4d6476ffd8a7715ad..67eefa2932717bfd4a5daa8ad3a4379af1ef78db 100644 (file)
@@ -286,6 +286,7 @@ 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)
@@ -367,46 +368,60 @@ 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;
                        dheader[pos] = ofs & 127;
                        while (ofs >>= 7)
                                dheader[--pos] = 128 | (--ofs & 127);
-                       if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit)
+                       if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
+                               unuse_pack(&w_curs);
                                return 0;
+                       }
                        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)
+                       if (limit && hdrlen + 20 + datalen + 20 >= limit) {
+                               unuse_pack(&w_curs);
                                return 0;
+                       }
                        sha1write(f, header, hdrlen);
                        sha1write(f, entry->delta->idx.sha1, 20);
                        hdrlen += 20;
+                       reused_delta++;
                } else {
-                       if (limit && hdrlen + datalen + 20 >= limit)
+                       if (limit && hdrlen + datalen + 20 >= limit) {
+                               unuse_pack(&w_curs);
                                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++;
@@ -1016,9 +1031,11 @@ static void check_object(struct object_entry *entry)
                 * We want in_pack_type even if we do not reuse delta
                 * since non-delta representations could still be reused.
                 */
-               used = unpack_object_header_gently(buf, avail,
+               used = unpack_object_header_buffer(buf, avail,
                                                   &entry->in_pack_type,
                                                   &entry->size);
+               if (used == 0)
+                       goto give_up;
 
                /*
                 * Determine if this is a delta and if so whether we can
@@ -1030,6 +1047,8 @@ static void check_object(struct object_entry *entry)
                        /* Not a delta hence we've already got all we need. */
                        entry->type = entry->in_pack_type;
                        entry->in_pack_header_size = used;
+                       if (entry->type < OBJ_COMMIT || entry->type > OBJ_BLOB)
+                               goto give_up;
                        unuse_pack(&w_curs);
                        return;
                case OBJ_REF_DELTA:
@@ -1046,19 +1065,25 @@ static void check_object(struct object_entry *entry)
                        ofs = c & 127;
                        while (c & 128) {
                                ofs += 1;
-                               if (!ofs || MSB(ofs, 7))
-                                       die("delta base offset overflow in pack for %s",
-                                           sha1_to_hex(entry->idx.sha1));
+                               if (!ofs || MSB(ofs, 7)) {
+                                       error("delta base offset overflow in pack for %s",
+                                             sha1_to_hex(entry->idx.sha1));
+                                       goto give_up;
+                               }
                                c = buf[used_0++];
                                ofs = (ofs << 7) + (c & 127);
                        }
-                       if (ofs >= entry->in_pack_offset)
-                               die("delta base offset out of bound for %s",
-                                   sha1_to_hex(entry->idx.sha1));
                        ofs = entry->in_pack_offset - ofs;
+                       if (ofs <= 0 || ofs >= entry->in_pack_offset) {
+                               error("delta base offset out of bound for %s",
+                                     sha1_to_hex(entry->idx.sha1));
+                               goto give_up;
+                       }
                        if (reuse_delta && !entry->preferred_base) {
                                struct revindex_entry *revidx;
                                revidx = find_pack_revindex(p, ofs);
+                               if (!revidx)
+                                       goto give_up;
                                base_ref = nth_packed_object_sha1(p, revidx->nr);
                        }
                        entry->in_pack_header_size = used + used_0;
@@ -1078,6 +1103,7 @@ 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);
@@ -1092,6 +1118,8 @@ static void check_object(struct object_entry *entry)
                         */
                        entry->size = get_size_from_delta(p, &w_curs,
                                        entry->in_pack_offset + entry->in_pack_header_size);
+                       if (entry->size == 0)
+                               goto give_up;
                        unuse_pack(&w_curs);
                        return;
                }
@@ -1101,6 +1129,7 @@ static void check_object(struct object_entry *entry)
                 * with sha1_object_info() to find about the object type
                 * at this point...
                 */
+               give_up:
                unuse_pack(&w_curs);
        }
 
@@ -1712,6 +1741,16 @@ static void prepare_pack(int window, int depth)
 
        get_object_details();
 
+       /*
+        * If we're locally repacking then we need to be doubly careful
+        * from now on in order to make sure no stealth corruption gets
+        * propagated to the new pack.  Clients receiving streamed packs
+        * should validate everything they get anyway so no need to incur
+        * the additional cost here in that case.
+        */
+       if (!pack_to_stdout)
+               do_check_packed_object_crc = 1;
+
        if (!nr_objects || !window || !depth)
                return;
 
index 9f4bdd3296d19b75211ca0f2434d227eafac44b6..47ed610677fe47f855beaac02f40fa84d132455e 100644 (file)
@@ -370,6 +370,8 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
                        base_offset = (base_offset << 7) + (c & 127);
                }
                base_offset = obj_list[nr].offset - base_offset;
+               if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
+                       die("offset value out of bound for delta base object");
 
                delta_data = get_data(delta_size);
                if (dry_run || !delta_data) {
diff --git a/cache.h b/cache.h
index c776f2f5ab718c920bba9d9c2734a3b3bd2ea9be..3b5f0c4c003a611b45e2ca9455681dc8a8347516 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -574,6 +574,9 @@ extern int force_object_loose(const unsigned char *sha1, time_t mtime);
 /* just like read_sha1_file(), but non fatal in presence of bad objects */
 extern void *read_object(const unsigned char *sha1, enum object_type *type, unsigned long *size);
 
+/* global flag to enable extra checks when accessing packed objects */
+extern int do_check_packed_object_crc;
+
 extern int check_sha1_signature(const unsigned char *sha1, void *buf, unsigned long size, const char *type);
 
 extern int move_temp_to_file(const char *tmpfile, const char *filename);
@@ -762,7 +765,7 @@ extern const unsigned char *nth_packed_object_sha1(struct packed_git *, uint32_t
 extern off_t nth_packed_object_offset(const struct packed_git *, uint32_t);
 extern off_t find_pack_entry_one(const unsigned char *, struct packed_git *);
 extern void *unpack_entry(struct packed_git *, off_t, enum object_type *, unsigned long *);
-extern unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep);
+extern unsigned long unpack_object_header_buffer(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep);
 extern unsigned long get_size_from_delta(struct packed_git *, struct pack_window **, off_t);
 extern const char *packed_object_info_detail(struct packed_git *, off_t, unsigned long *, unsigned long *, unsigned int *, unsigned char *);
 extern int matches_pack_name(struct packed_git *p, const char *name);
index fe75332a9cd492fa109d07904de39f0eafa75c7e..60ed41a993bf9e213b7dfde5ff43528eff6b6252 100644 (file)
@@ -338,7 +338,7 @@ static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_
                        base_offset = (base_offset << 7) + (c & 127);
                }
                delta_base->offset = obj->idx.offset - base_offset;
-               if (delta_base->offset >= obj->idx.offset)
+               if (delta_base->offset <= 0 || delta_base->offset >= obj->idx.offset)
                        bad_object(obj->idx.offset, "delta base offset is out of bound");
                break;
        case OBJ_COMMIT:
index 6096b6224ad551086afa346617eb714c15a51f78..1de53c8934c03b46604e94cbf4237ad5ffc57f83 100644 (file)
@@ -140,7 +140,8 @@ struct revindex_entry *find_pack_revindex(struct packed_git *p, off_t ofs)
                else
                        lo = mi + 1;
        } while (lo < hi);
-       die("internal error: pack revindex corrupt");
+       error("bad offset for revindex");
+       return NULL;
 }
 
 void discard_revindex(void)
index 491220572b8708a520aa54079a5246f9f2df033e..0fa65baa59de4db058ca6a41bba29ac78eab2643 100644 (file)
@@ -1122,7 +1122,8 @@ static int legacy_loose_object(unsigned char *map)
                return 0;
 }
 
-unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
+unsigned long unpack_object_header_buffer(const unsigned char *buf,
+               unsigned long len, enum object_type *type, unsigned long *sizep)
 {
        unsigned shift;
        unsigned char c;
@@ -1134,10 +1135,10 @@ unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned lon
        size = c & 15;
        shift = 4;
        while (c & 0x80) {
-               if (len <= used)
-                       return 0;
-               if (sizeof(long) * 8 <= shift)
+               if (len <= used || sizeof(long) * 8 <= shift) {
+                       error("bad object header");
                        return 0;
+               }
                c = buf[used++];
                size += (c & 0x7f) << shift;
                shift += 7;
@@ -1176,7 +1177,7 @@ static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned lon
         * really worth it and we don't write it any longer.  But we
         * can still read it.
         */
-       used = unpack_object_header_gently(map, mapsize, &type, &size);
+       used = unpack_object_header_buffer(map, mapsize, &type, &size);
        if (!used || !valid_loose_object_type[type])
                return -1;
        map += used;
@@ -1325,8 +1326,10 @@ unsigned long get_size_from_delta(struct packed_git *p,
        } 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))
-               die("delta data unpack-initial failed");
+       if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
+               error("delta data unpack-initial failed");
+               return 0;
+       }
 
        /* Examine the initial part of the delta to figure out
         * the result size.
@@ -1367,7 +1370,7 @@ static off_t get_delta_base(struct packed_git *p,
                        base_offset = (base_offset << 7) + (c & 127);
                }
                base_offset = delta_obj_offset - base_offset;
-               if (base_offset >= delta_obj_offset)
+               if (base_offset <= 0 || base_offset >= delta_obj_offset)
                        return 0;  /* out of bound */
                *curpos += used;
        } else if (type == OBJ_REF_DELTA) {
@@ -1393,15 +1396,32 @@ static int packed_delta_info(struct packed_git *p,
        off_t base_offset;
 
        base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
+       if (!base_offset)
+               return OBJ_BAD;
        type = packed_object_info(p, base_offset, NULL);
+       if (type <= OBJ_NONE) {
+               struct revindex_entry *revidx;
+               const unsigned char *base_sha1;
+               revidx = find_pack_revindex(p, base_offset);
+               if (!revidx)
+                       return OBJ_BAD;
+               base_sha1 = nth_packed_object_sha1(p, revidx->nr);
+               mark_bad_packed_object(p, base_sha1);
+               type = sha1_object_info(base_sha1, NULL);
+               if (type <= OBJ_NONE)
+                       return OBJ_BAD;
+       }
 
        /* 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 (sizep)
+       if (sizep) {
                *sizep = get_size_from_delta(p, w_curs, curpos);
+               if (*sizep == 0)
+                       type = OBJ_BAD;
+       }
 
        return type;
 }
@@ -1423,10 +1443,11 @@ static int unpack_object_header(struct packed_git *p,
         * insane, so we know won't exceed what we have been given.
         */
        base = use_pack(p, w_curs, *curpos, &left);
-       used = unpack_object_header_gently(base, left, &type, sizep);
-       if (!used)
-               die("object offset outside of pack file");
-       *curpos += used;
+       used = unpack_object_header_buffer(base, left, &type, sizep);
+       if (!used) {
+               type = OBJ_BAD;
+       } else
+               *curpos += used;
 
        return type;
 }
@@ -1510,8 +1531,9 @@ static int packed_object_info(struct packed_git *p, off_t obj_offset,
                        *sizep = size;
                break;
        default:
-               die("pack %s contains unknown object type %d",
-                   p->pack_name, type);
+               error("unknown object type %i at offset %"PRIuMAX" in %s",
+                     type, (uintmax_t)obj_offset, p->pack_name);
+               type = OBJ_BAD;
        }
        unuse_pack(&w_curs);
        return type;
@@ -1675,9 +1697,12 @@ static void *unpack_delta_entry(struct packed_git *p,
                 * This is costly but should happen only in the presence
                 * of a corrupted pack, and is better than failing outright.
                 */
-               struct revindex_entry *revidx = find_pack_revindex(p, base_offset);
-               const unsigned char *base_sha1 =
-                                       nth_packed_object_sha1(p, revidx->nr);
+               struct revindex_entry *revidx;
+               const unsigned char *base_sha1;
+               revidx = find_pack_revindex(p, base_offset);
+               if (!revidx)
+                       return NULL;
+               base_sha1 = nth_packed_object_sha1(p, revidx->nr);
                error("failed to read delta base object %s"
                      " at offset %"PRIuMAX" from %s",
                      sha1_to_hex(base_sha1), (uintmax_t)base_offset,
@@ -1706,6 +1731,8 @@ static void *unpack_delta_entry(struct packed_git *p,
        return result;
 }
 
+int do_check_packed_object_crc;
+
 void *unpack_entry(struct packed_git *p, off_t obj_offset,
                   enum object_type *type, unsigned long *sizep)
 {
@@ -1713,6 +1740,19 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
        off_t curpos = obj_offset;
        void *data;
 
+       if (do_check_packed_object_crc && p->index_version > 1) {
+               struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
+               unsigned long len = revidx[1].offset - obj_offset;
+               if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
+                       const unsigned char *sha1 =
+                               nth_packed_object_sha1(p, revidx->nr);
+                       error("bad packed object CRC for %s",
+                             sha1_to_hex(sha1));
+                       mark_bad_packed_object(p, sha1);
+                       return NULL;
+               }
+       }
+
        *type = unpack_object_header(p, &w_curs, &curpos, sizep);
        switch (*type) {
        case OBJ_OFS_DELTA:
@@ -1966,7 +2006,14 @@ int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
                if (!find_pack_entry(sha1, &e, NULL))
                        return status;
        }
-       return packed_object_info(e.p, e.offset, sizep);
+
+       status = packed_object_info(e.p, e.offset, sizep);
+       if (status < 0) {
+               mark_bad_packed_object(e.p, sha1);
+               status = sha1_object_info(sha1, sizep);
+       }
+
+       return status;
 }
 
 static void *read_packed_sha1(const unsigned char *sha1,
index b0b0fdaca5e9ddfda6b1625545b9ba7049cf1555..884e24253a0a9d262b39ae96ea5c03ecb7ba4072 100755 (executable)
@@ -196,7 +196,8 @@ test_expect_success \
 
 test_expect_success \
     '[index v2] 5) pack-objects refuses to reuse corrupted data' \
-    'test_must_fail git pack-objects test-5 <obj-list'
+    'test_must_fail git pack-objects test-5 <obj-list &&
+     test_must_fail git pack-objects --no-reuse-object test-6 <obj-list'
 
 test_expect_success \
     '[index v2] 6) verify-pack detects CRC mismatch' \
index 31b20b21d23c2066fd124bf6a33dbdc689930170..d4e30fc43c68ed9b0fc175f2a88a07de6458f58e 100755 (executable)
@@ -41,11 +41,17 @@ create_new_pack() {
     git verify-pack -v ${pack}.pack
 }
 
+do_repack() {
+    pack=`printf "$blob_1\n$blob_2\n$blob_3\n" |
+          git pack-objects $@ .git/objects/pack/pack` &&
+    pack=".git/objects/pack/pack-${pack}"
+}
+
 do_corrupt_object() {
     ofs=`git show-index < ${pack}.idx | grep $1 | cut -f1 -d" "` &&
     ofs=$(($ofs + $2)) &&
     chmod +w ${pack}.pack &&
-    dd if=/dev/zero of=${pack}.pack count=1 bs=1 conv=notrunc seek=$ofs &&
+    dd of=${pack}.pack count=1 bs=1 conv=notrunc seek=$ofs &&
     test_must_fail git verify-pack ${pack}.pack
 }
 
@@ -60,7 +66,7 @@ test_expect_success \
 
 test_expect_success \
     'create corruption in header of first object' \
-    'do_corrupt_object $blob_1 0 &&
+    'do_corrupt_object $blob_1 0 < /dev/zero &&
      test_must_fail git cat-file blob $blob_1 > /dev/null &&
      test_must_fail git cat-file blob $blob_2 > /dev/null &&
      test_must_fail git cat-file blob $blob_3 > /dev/null'
@@ -119,7 +125,7 @@ test_expect_success \
     'create corruption in header of first delta' \
     'create_new_pack &&
      git prune-packed &&
-     do_corrupt_object $blob_2 0 &&
+     do_corrupt_object $blob_2 0 < /dev/zero &&
      git cat-file blob $blob_1 > /dev/null &&
      test_must_fail git cat-file blob $blob_2 > /dev/null &&
      test_must_fail git cat-file blob $blob_3 > /dev/null'
@@ -133,6 +139,15 @@ test_expect_success \
      git cat-file blob $blob_2 > /dev/null &&
      git cat-file blob $blob_3 > /dev/null'
 
+test_expect_success \
+    '... and then a repack "clears" the corruption' \
+    'do_repack &&
+     git prune-packed &&
+     git verify-pack ${pack}.pack &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
 test_expect_success \
     'create corruption in data of first delta' \
     'create_new_pack &&
@@ -152,11 +167,20 @@ test_expect_success \
      git cat-file blob $blob_2 > /dev/null &&
      git cat-file blob $blob_3 > /dev/null'
 
+test_expect_success \
+    '... and then a repack "clears" the corruption' \
+    'do_repack &&
+     git prune-packed &&
+     git verify-pack ${pack}.pack &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
 test_expect_success \
     'corruption in delta base reference of first delta (OBJ_REF_DELTA)' \
     'create_new_pack &&
      git prune-packed &&
-     do_corrupt_object $blob_2 2 &&
+     do_corrupt_object $blob_2 2 < /dev/zero &&
      git cat-file blob $blob_1 > /dev/null &&
      test_must_fail git cat-file blob $blob_2 > /dev/null &&
      test_must_fail git cat-file blob $blob_3 > /dev/null'
@@ -171,17 +195,75 @@ test_expect_success \
      git cat-file blob $blob_3 > /dev/null'
 
 test_expect_success \
-    'corruption in delta base reference of first delta (OBJ_OFS_DELTA)' \
+    '... and then a repack "clears" the corruption' \
+    'do_repack &&
+     git prune-packed &&
+     git verify-pack ${pack}.pack &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
+test_expect_success \
+    'corruption #0 in delta base reference of first delta (OBJ_OFS_DELTA)' \
     'create_new_pack --delta-base-offset &&
      git prune-packed &&
-     do_corrupt_object $blob_2 2 &&
+     do_corrupt_object $blob_2 2 < /dev/zero &&
      git cat-file blob $blob_1 > /dev/null &&
      test_must_fail git cat-file blob $blob_2 > /dev/null &&
      test_must_fail git cat-file blob $blob_3 > /dev/null'
 
 test_expect_success \
-    '... and a redundant pack allows for full recovery too' \
+    '... but having a loose copy allows for full recovery' \
     'mv ${pack}.idx tmp &&
+     git hash-object -t blob -w file_2 &&
+     mv tmp ${pack}.idx &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
+test_expect_success \
+    '... and then a repack "clears" the corruption' \
+    'do_repack --delta-base-offset &&
+     git prune-packed &&
+     git verify-pack ${pack}.pack &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
+test_expect_success \
+    'corruption #1 in delta base reference of first delta (OBJ_OFS_DELTA)' \
+    'create_new_pack --delta-base-offset &&
+     git prune-packed &&
+     printf "\001" | do_corrupt_object $blob_2 2 &&
+     git cat-file blob $blob_1 > /dev/null &&
+     test_must_fail git cat-file blob $blob_2 > /dev/null &&
+     test_must_fail git cat-file blob $blob_3 > /dev/null'
+
+test_expect_success \
+    '... but having a loose copy allows for full recovery' \
+    'mv ${pack}.idx tmp &&
+     git hash-object -t blob -w file_2 &&
+     mv tmp ${pack}.idx &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
+test_expect_success \
+    '... and then a repack "clears" the corruption' \
+    'do_repack --delta-base-offset &&
+     git prune-packed &&
+     git verify-pack ${pack}.pack &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
+test_expect_success \
+    '... and a redundant pack allows for full recovery too' \
+    'do_corrupt_object $blob_2 2 < /dev/zero &&
+     git cat-file blob $blob_1 > /dev/null &&
+     test_must_fail git cat-file blob $blob_2 > /dev/null &&
+     test_must_fail git cat-file blob $blob_3 > /dev/null &&
+     mv ${pack}.idx tmp &&
      git hash-object -t blob -w file_1 &&
      git hash-object -t blob -w file_2 &&
      printf "$blob_1\n$blob_2\n" | git pack-objects .git/objects/pack/pack &&