git-commit-vandalism/t/lib-pack.sh
brian m. carlson db12505c2c t/lib-pack: support SHA-256
Update the support routines for generating packs to support both SHA-1
and SHA-256.  Compute the trailing pack checksum and its length
correctly depending on the algorithm, and look up the object names based
on the algorithm as well.  Ensure we initialize the algorithm facts so
that our callers need not do so.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-07 11:07:29 -08:00

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# Support routines for hand-crafting weird or malicious packs.
#
# You can make a complete pack like:
#
# pack_header 2 >foo.pack &&
# pack_obj e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 >>foo.pack &&
# pack_obj e68fe8129b546b101aee9510c5328e7f21ca1d18 >>foo.pack &&
# pack_trailer foo.pack
# Print the big-endian 4-byte octal representation of $1
uint32_octal () {
n=$1
printf '\\%o' $(($n / 16777216)); n=$((n % 16777216))
printf '\\%o' $(($n / 65536)); n=$((n % 65536))
printf '\\%o' $(($n / 256)); n=$((n % 256))
printf '\\%o' $(($n ));
}
# Print the big-endian 4-byte binary representation of $1
uint32_binary () {
printf "$(uint32_octal "$1")"
}
# Print a pack header, version 2, for a pack with $1 objects
pack_header () {
printf 'PACK' &&
printf '\0\0\0\2' &&
uint32_binary "$1"
}
# Print the pack data for object $1, as a delta against object $2 (or as a full
# object if $2 is missing or empty). The output is suitable for including
# directly in the packfile, and represents the entirety of the object entry.
# Doing this on the fly (especially picking your deltas) is quite tricky, so we
# have hardcoded some well-known objects. See the case statements below for the
# complete list.
pack_obj () {
test_oid_init
case "$1" in
# empty blob
$EMPTY_BLOB)
case "$2" in
'')
printf '\060\170\234\003\0\0\0\0\1'
return
;;
esac
;;
# blob containing "\7\76"
$(test_oid packlib_7_76))
case "$2" in
'')
printf '\062\170\234\143\267\3\0\0\116\0\106'
return
;;
01d7713666f4de822776c7622c10f1b07de280dc)
printf '\165\1\327\161\66\146\364\336\202\47\166' &&
printf '\307\142\54\20\361\260\175\342\200\334\170' &&
printf '\234\143\142\142\142\267\003\0\0\151\0\114'
return
;;
37c8e2c15bb22b912e59b43fd51a4f7e9465ed0b5084c5a1411d991cbe630683)
printf '\165\67\310\342\301\133\262\53\221\56\131' &&
printf '\264\77\325\32\117\176\224\145\355\13\120' &&
printf '\204\305\241\101\35\231\34\276\143\6\203\170' &&
printf '\234\143\142\142\142\267\003\0\0\151\0\114'
return
;;
esac
;;
# blob containing "\7\0"
$(test_oid packlib_7_0))
case "$2" in
'')
printf '\062\170\234\143\147\0\0\0\20\0\10'
return
;;
e68fe8129b546b101aee9510c5328e7f21ca1d18)
printf '\165\346\217\350\22\233\124\153\20\32\356' &&
printf '\225\20\305\62\216\177\41\312\35\30\170\234' &&
printf '\143\142\142\142\147\0\0\0\53\0\16'
return
;;
5d8e6fc40f2dab00e6983a48523fe57e621f46434cb58dbd4422fba03380d886)
printf '\165\135\216\157\304\17\55\253\0\346\230\72' &&
printf '\110\122\77\345\176\142\37\106\103\114\265' &&
printf '\215\275\104\42\373\240\63\200\330\206\170\234' &&
printf '\143\142\142\142\147\0\0\0\53\0\16'
return
;;
esac
;;
esac
# If it's not a delta, we can convince pack-objects to generate a pack
# with just our entry, and then strip off the header (12 bytes) and
# trailer (20 bytes).
if test -z "$2"
then
echo "$1" | git pack-objects --stdout >pack_obj.tmp &&
size=$(wc -c <pack_obj.tmp) &&
dd if=pack_obj.tmp bs=1 count=$((size - $(test_oid rawsz) - 12)) skip=12 &&
rm -f pack_obj.tmp
return
fi
echo >&2 "BUG: don't know how to print $1${2:+ (from $2)}"
return 1
}
# Compute and append pack trailer to "$1"
pack_trailer () {
test_oid_init &&
test-tool $(test_oid algo) -b <"$1" >trailer.tmp &&
cat trailer.tmp >>"$1" &&
rm -f trailer.tmp
}
# Remove any existing packs to make sure that
# whatever we index next will be the pack that we
# actually use.
clear_packs () {
rm -f .git/objects/pack/*
}
test_oid_cache <<-EOF
packlib_7_0 sha1:01d7713666f4de822776c7622c10f1b07de280dc
packlib_7_0 sha256:37c8e2c15bb22b912e59b43fd51a4f7e9465ed0b5084c5a1411d991cbe630683
packlib_7_76 sha1:e68fe8129b546b101aee9510c5328e7f21ca1d18
packlib_7_76 sha256:5d8e6fc40f2dab00e6983a48523fe57e621f46434cb58dbd4422fba03380d886
EOF