t/lib-pack.sh

   1 # Support routines for hand-crafting weird or malicious packs.
   2 #
   3 # You can make a complete pack like:
   4 #
   5 #   pack_header 2 >foo.pack &&
   6 #   pack_obj e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 >>foo.pack &&
   7 #   pack_obj e68fe8129b546b101aee9510c5328e7f21ca1d18 >>foo.pack &&
   8 #   pack_trailer foo.pack
   9
  10 # Print the big-endian 4-byte octal representation of $1
  11 uint32_octal () {
  12         n=$1
  13         printf '\\%o' $(($n / 16777216)); n=$((n % 16777216))
  14         printf '\\%o' $(($n /    65536)); n=$((n %    65536))
  15         printf '\\%o' $(($n /      256)); n=$((n %      256))
  16         printf '\\%o' $(($n           ));
  17 }
  18
  19 # Print the big-endian 4-byte binary representation of $1
  20 uint32_binary () {
  21         printf "$(uint32_octal "$1")"
  22 }
  23
  24 # Print a pack header, version 2, for a pack with $1 objects
  25 pack_header () {
  26         printf 'PACK' &&
  27         printf '\0\0\0\2' &&
  28         uint32_binary "$1"
  29 }
  30
  31 # Print the pack data for object $1, as a delta against object $2 (or as a full
  32 # object if $2 is missing or empty). The output is suitable for including
  33 # directly in the packfile, and represents the entirety of the object entry.
  34 # Doing this on the fly (especially picking your deltas) is quite tricky, so we
  35 # have hardcoded some well-known objects. See the case statements below for the
  36 # complete list.
  37 pack_obj () {
  38         case "$1" in
  39         # empty blob
  40         $EMPTY_BLOB)
  41                 case "$2" in
  42                 '')
  43                         printf '\060\170\234\003\0\0\0\0\1'
  44                         return
  45                         ;;
  46                 esac
  47                 ;;
  48
  49         # blob containing "\7\76"
  50         $(test_oid packlib_7_76))
  51                 case "$2" in
  52                 '')
  53                         printf '\062\170\234\143\267\3\0\0\116\0\106'
  54                         return
  55                         ;;
  56                 01d7713666f4de822776c7622c10f1b07de280dc)
  57                         printf '\165\1\327\161\66\146\364\336\202\47\166' &&
  58                         printf '\307\142\54\20\361\260\175\342\200\334\170' &&
  59                         printf '\234\143\142\142\142\267\003\0\0\151\0\114'
  60                         return
  61                         ;;
  62                 37c8e2c15bb22b912e59b43fd51a4f7e9465ed0b5084c5a1411d991cbe630683)
  63                         printf '\165\67\310\342\301\133\262\53\221\56\131' &&
  64                         printf '\264\77\325\32\117\176\224\145\355\13\120' &&
  65                         printf '\204\305\241\101\35\231\34\276\143\6\203\170' &&
  66                         printf '\234\143\142\142\142\267\003\0\0\151\0\114'
  67                         return
  68                         ;;
  69                 esac
  70                 ;;
  71
  72         # blob containing "\7\0"
  73         $(test_oid packlib_7_0))
  74                 case "$2" in
  75                 '')
  76                         printf '\062\170\234\143\147\0\0\0\20\0\10'
  77                         return
  78                         ;;
  79                 e68fe8129b546b101aee9510c5328e7f21ca1d18)
  80                         printf '\165\346\217\350\22\233\124\153\20\32\356' &&
  81                         printf '\225\20\305\62\216\177\41\312\35\30\170\234' &&
  82                         printf '\143\142\142\142\147\0\0\0\53\0\16'
  83                         return
  84                         ;;
  85                 5d8e6fc40f2dab00e6983a48523fe57e621f46434cb58dbd4422fba03380d886)
  86                         printf '\165\135\216\157\304\17\55\253\0\346\230\72' &&
  87                         printf '\110\122\77\345\176\142\37\106\103\114\265' &&
  88                         printf '\215\275\104\42\373\240\63\200\330\206\170\234' &&
  89                         printf '\143\142\142\142\147\0\0\0\53\0\16'
  90                         return
  91                         ;;
  92                 esac
  93                 ;;
  94         # blob containing "\3\326"
  95         471819e8c52bf11513f100b2810a8aa0622d5cd3d1c913758a071dd4b3bad8fe)
  96                 case "$2" in
  97                 '')
  98                         printf '\062\170\234\143\276\006\000\000\336\000\332'
  99                         return
 100                         ;;
 101                 esac
 102         esac
 103
 104         # If it's not a delta, we can convince pack-objects to generate a pack
 105         # with just our entry, and then strip off the header (12 bytes) and
 106         # trailer (20 bytes).
 107         if test -z "$2"
 108         then
 109                 echo "$1" | git pack-objects --stdout >pack_obj.tmp &&
 110                 size=$(wc -c <pack_obj.tmp) &&
 111                 dd if=pack_obj.tmp bs=1 count=$((size - $(test_oid rawsz) - 12)) skip=12 &&
 112                 rm -f pack_obj.tmp
 113                 return
 114         fi
 115
 116         echo >&2 "BUG: don't know how to print $1${2:+ (from $2)}"
 117         return 1
 118 }
 119
 120 # Compute and append pack trailer to "$1"
 121 pack_trailer () {
 122         test-tool $(test_oid algo) -b <"$1" >trailer.tmp &&
 123         cat trailer.tmp >>"$1" &&
 124         rm -f trailer.tmp
 125 }
 126
 127 # Remove any existing packs to make sure that
 128 # whatever we index next will be the pack that we
 129 # actually use.
 130 clear_packs () {
 131         rm -f .git/objects/pack/*
 132 }
 133
 134 test_oid_cache <<-EOF
 135 packlib_7_0 sha1:01d7713666f4de822776c7622c10f1b07de280dc
 136 packlib_7_0 sha256:37c8e2c15bb22b912e59b43fd51a4f7e9465ed0b5084c5a1411d991cbe630683
 137
 138 packlib_7_76 sha1:e68fe8129b546b101aee9510c5328e7f21ca1d18
 139 packlib_7_76 sha256:5d8e6fc40f2dab00e6983a48523fe57e621f46434cb58dbd4422fba03380d886
 140 EOF