test case for pack resilience against corruptions

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

diff --git a/t/t5303-pack-corruption-resilience.sh b/t/t5303-pack-corruption-resilience.sh
new file mode 100755 (executable)
index 0000000..b0f5693
--- /dev/null
+++ b/t/t5303-pack-corruption-resilience.sh
@@ -0,0 +1,194 @@
+#!/bin/sh
+#
+# Copyright (c) 2008 Nicolas Pitre
+#
+
+test_description='resilience to pack corruptions with redundant objects'
+. ./test-lib.sh
+
+# Note: the test objects are created with knowledge of their pack encoding
+# to ensure good code path coverage, and to facilitate direct alteration
+# later on.  The assumed characteristics are:
+#
+# 1) blob_2 is a delta with blob_1 for base and blob_3 is a delta with blob2
+#    for base, such that blob_3 delta depth is 2;
+#
+# 2) the bulk of object data is uncompressible so the text part remains
+#    visible;
+#
+# 3) object header is always 2 bytes.
+
+create_test_files() {
+    test-genrandom "foo" 2000 > file_1 &&
+    test-genrandom "foo" 1800 > file_2 &&
+    test-genrandom "foo" 1800 > file_3 &&
+    echo " base " >> file_1 &&
+    echo " delta1 " >> file_2 &&
+    echo " delta delta2 " >> file_3 &&
+    test-genrandom "bar" 150 >> file_2 &&
+    test-genrandom "baz" 100 >> file_3
+}
+
+create_new_pack() {
+    rm -rf .git &&
+    git init &&
+    blob_1=`git hash-object -t blob -w file_1` &&
+    blob_2=`git hash-object -t blob -w file_2` &&
+    blob_3=`git hash-object -t blob -w file_3` &&
+    pack=`printf "$blob_1\n$blob_2\n$blob_3\n" |
+          git pack-objects $@ .git/objects/pack/pack` &&
+    pack=".git/objects/pack/pack-${pack}" &&
+    git verify-pack -v ${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 &&
+    test_must_fail git verify-pack ${pack}.pack
+}
+
+test_expect_success \
+    'initial setup validation' \
+    'create_test_files &&
+     create_new_pack &&
+     git prune-packed &&
+     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 header of first object' \
+    'do_corrupt_object $blob_1 0 &&
+     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'
+
+test_expect_success \
+    '... but having a loose copy allows for full recovery' \
+    'mv ${pack}.idx tmp &&
+     git hash-object -t blob -w file_1 &&
+     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 loose copy of first delta allows for partial recovery' \
+    'git prune-packed &&
+     test_must_fail git cat-file blob $blob_2 > /dev/null &&
+     mv ${pack}.idx tmp &&
+     git hash-object -t blob -w file_2 &&
+     mv tmp ${pack}.idx &&
+     test_must_fail 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 object' \
+    'create_new_pack &&
+     git prune-packed &&
+     chmod +w ${pack}.pack &&
+     perl -i -pe "s/ base /abcdef/" ${pack}.pack &&
+     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'
+
+test_expect_success \
+    '... but having a loose copy allows for full recovery' \
+    'mv ${pack}.idx tmp &&
+     git hash-object -t blob -w file_1 &&
+     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 loose copy of second object allows for partial recovery' \
+    'git prune-packed &&
+     test_must_fail git cat-file blob $blob_2 > /dev/null &&
+     mv ${pack}.idx tmp &&
+     git hash-object -t blob -w file_2 &&
+     mv tmp ${pack}.idx &&
+     test_must_fail 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 header of first delta' \
+    'create_new_pack &&
+     git prune-packed &&
+     do_corrupt_object $blob_2 0 &&
+     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 \
+    'create corruption in data of first delta' \
+    'create_new_pack &&
+     git prune-packed &&
+     chmod +w ${pack}.pack &&
+     perl -i -pe "s/ delta1 /abcdefgh/" ${pack}.pack &&
+     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 \
+    'corruption in delta base reference of first delta (OBJ_REF_DELTA)' \
+    'create_new_pack &&
+     git prune-packed &&
+     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 \
+    'corruption 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 &&
+     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' \
+    '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 &&
+     git prune-packed &&
+     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_done