Andrew's git - gitweb.git/blob

   1#!/bin/sh
   2#
   3# Support routines for hand-crafting weird or malicious packs.
   4#
   5# You can make a complete pack like:
   6#
   7#   pack_header 2 >foo.pack &&
   8#   pack_obj e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 >>foo.pack &&
   9#   pack_obj e68fe8129b546b101aee9510c5328e7f21ca1d18 >>foo.pack &&
  10#   pack_trailer foo.pack
  11
  12# Print the big-endian 4-byte octal representation of $1
  13uint32_octal () {
  14        n=$1
  15        printf '\\%o' $(($n / 16777216)); n=$((n % 16777216))
  16        printf '\\%o' $(($n /    65536)); n=$((n %    65536))
  17        printf '\\%o' $(($n /      256)); n=$((n %      256))
  18        printf '\\%o' $(($n           ));
  19}
  20
  21# Print the big-endian 4-byte binary representation of $1
  22uint32_binary () {
  23        printf "$(uint32_octal "$1")"
  24}
  25
  26# Print a pack header, version 2, for a pack with $1 objects
  27pack_header () {
  28        printf 'PACK' &&
  29        printf '\0\0\0\2' &&
  30        uint32_binary "$1"
  31}
  32
  33# Print the pack data for object $1, as a delta against object $2 (or as a full
  34# object if $2 is missing or empty). The output is suitable for including
  35# directly in the packfile, and represents the entirety of the object entry.
  36# Doing this on the fly (especially picking your deltas) is quite tricky, so we
  37# have hardcoded some well-known objects. See the case statements below for the
  38# complete list.
  39pack_obj () {
  40        case "$1" in
  41        # empty blob
  42        e69de29bb2d1d6434b8b29ae775ad8c2e48c5391)
  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        e68fe8129b546b101aee9510c5328e7f21ca1d18)
  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                esac
  65                ;;
  66
  67        # blob containing "\7\0"
  68        01d7713666f4de822776c7622c10f1b07de280dc)
  69                case "$2" in
  70                '')
  71                        printf '\062\170\234\143\147\0\0\0\20\0\10'
  72                        return
  73                        ;;
  74                e68fe8129b546b101aee9510c5328e7f21ca1d18)
  75                        printf '\165\346\217\350\22\233\124\153\20\32\356' &&
  76                        printf '\225\20\305\62\216\177\41\312\35\30\170\234' &&
  77                        printf '\143\142\142\142\147\0\0\0\53\0\16'
  78                        return
  79                        ;;
  80                esac
  81                ;;
  82        esac
  83
  84        echo >&2 "BUG: don't know how to print $1${2:+ (from $2)}"
  85        return 1
  86}
  87
  88# Compute and append pack trailer to "$1"
  89pack_trailer () {
  90        test-sha1 -b <"$1" >trailer.tmp &&
  91        cat trailer.tmp >>"$1" &&
  92        rm -f trailer.tmp
  93}
  94
  95# Remove any existing packs to make sure that
  96# whatever we index next will be the pack that we
  97# actually use.
  98clear_packs () {
  99        rm -f .git/objects/pack/*
 100}