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         test_oid_init
  39
  40         case "$1" in
  41         # empty blob
  42         $EMPTY_BLOB)
  43                 case "$2" in
  44                 '')
  45                         printf '\060\170\234\003\0\0\0\0\1'
  46                         return
  47                         ;;
  48                 esac
  49                 ;;
  50
  51         # blob containing "\7\76"
  52         $(test_oid packlib_7_76))
  53                 case "$2" in
  54                 '')
  55                         printf '\062\170\234\143\267\3\0\0\116\0\106'
  56                         return
  57                         ;;
  58                 01d7713666f4de822776c7622c10f1b07de280dc)
  59                         printf '\165\1\327\161\66\146\364\336\202\47\166' &&
  60                         printf '\307\142\54\20\361\260\175\342\200\334\170' &&
  61                         printf '\234\143\142\142\142\267\003\0\0\151\0\114'
  62                         return
  63                         ;;
  64                 37c8e2c15bb22b912e59b43fd51a4f7e9465ed0b5084c5a1411d991cbe630683)
  65                         printf '\165\67\310\342\301\133\262\53\221\56\131' &&
  66                         printf '\264\77\325\32\117\176\224\145\355\13\120' &&
  67                         printf '\204\305\241\101\35\231\34\276\143\6\203\170' &&
  68                         printf '\234\143\142\142\142\267\003\0\0\151\0\114'
  69                         return
  70                         ;;
  71                 esac
  72                 ;;
  73
  74         # blob containing "\7\0"
  75         $(test_oid packlib_7_0))
  76                 case "$2" in
  77                 '')
  78                         printf '\062\170\234\143\147\0\0\0\20\0\10'
  79                         return
  80                         ;;
  81                 e68fe8129b546b101aee9510c5328e7f21ca1d18)
  82                         printf '\165\346\217\350\22\233\124\153\20\32\356' &&
  83                         printf '\225\20\305\62\216\177\41\312\35\30\170\234' &&
  84                         printf '\143\142\142\142\147\0\0\0\53\0\16'
  85                         return
  86                         ;;
  87                 5d8e6fc40f2dab00e6983a48523fe57e621f46434cb58dbd4422fba03380d886)
  88                         printf '\165\135\216\157\304\17\55\253\0\346\230\72' &&
  89                         printf '\110\122\77\345\176\142\37\106\103\114\265' &&
  90                         printf '\215\275\104\42\373\240\63\200\330\206\170\234' &&
  91                         printf '\143\142\142\142\147\0\0\0\53\0\16'
  92                         return
  93                         ;;
  94                 esac
  95                 ;;
  96         esac
  97
  98         # If it's not a delta, we can convince pack-objects to generate a pack
  99         # with just our entry, and then strip off the header (12 bytes) and
 100         # trailer (20 bytes).
 101         if test -z "$2"
 102         then
 103                 echo "$1" | git pack-objects --stdout >pack_obj.tmp &&
 104                 size=$(wc -c <pack_obj.tmp) &&
 105                 dd if=pack_obj.tmp bs=1 count=$((size - $(test_oid rawsz) - 12)) skip=12 &&
 106                 rm -f pack_obj.tmp
 107                 return
 108         fi
 109
 110         echo >&2 "BUG: don't know how to print $1${2:+ (from $2)}"
 111         return 1
 112 }
 113
 114 # Compute and append pack trailer to "$1"
 115 pack_trailer () {
 116         test_oid_init &&
 117         test-tool $(test_oid algo) -b <"$1" >trailer.tmp &&
 118         cat trailer.tmp >>"$1" &&
 119         rm -f trailer.tmp
 120 }
 121
 122 # Remove any existing packs to make sure that
 123 # whatever we index next will be the pack that we
 124 # actually use.
 125 clear_packs () {
 126         rm -f .git/objects/pack/*
 127 }
 128
 129 test_oid_cache <<-EOF
 130 packlib_7_0 sha1:01d7713666f4de822776c7622c10f1b07de280dc
 131 packlib_7_0 sha256:37c8e2c15bb22b912e59b43fd51a4f7e9465ed0b5084c5a1411d991cbe630683
 132
 133 packlib_7_76 sha1:e68fe8129b546b101aee9510c5328e7f21ca1d18
 134 packlib_7_76 sha256:5d8e6fc40f2dab00e6983a48523fe57e621f46434cb58dbd4422fba03380d886
 135 EOF