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=$1 15printf'\%o'$(($n / 16777216)); n=$((n % 16777216)) 16printf'\%o'$(($n / 65536)); n=$((n % 65536)) 17printf'\%o'$(($n / 256)); n=$((n % 256)) 18printf'\%o'$(($n )); 19} 20 21# Print the big-endian 4-byte binary representation of $1 22uint32_binary () { 23printf"$(uint32_octal "$1")" 24} 25 26# Print a pack header, version 2, for a pack with $1 objects 27pack_header () { 28printf'PACK'&& 29printf'\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 () { 40case"$1"in 41# empty blob 42 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391) 43case"$2"in 44'') 45printf'\060\170\234\003\0\0\0\0\1' 46return 47;; 48esac 49;; 50 51# blob containing "\7\76" 52 e68fe8129b546b101aee9510c5328e7f21ca1d18) 53case"$2"in 54'') 55printf'\062\170\234\143\267\3\0\0\116\0\106' 56return 57;; 58esac 59;; 60esac 61 62echo>&2"BUG: don't know how to print$1${2:+ (from $2)}" 63return1 64} 65 66# Compute and append pack trailer to "$1" 67pack_trailer () { 68test-sha1 -b<"$1">trailer.tmp && 69cat trailer.tmp >>"$1"&& 70rm-f trailer.tmp 71} 72 73# Remove any existing packs to make sure that 74# whatever we index next will be the pack that we 75# actually use. 76clear_packs () { 77rm-f .git/objects/pack/* 78}