1 files changed, 110 insertions, 0 deletions
diff --git a/t/lib-pack.sh b/t/lib-pack.sh
new file mode 100644
index 0000000000..c4d907a450
--- /dev/null
+++ b/t/lib-pack.sh
@@ -0,0 +1,110 @@
+# 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 () {
+	case "$1" in
+	# empty blob
+	e69de29bb2d1d6434b8b29ae775ad8c2e48c5391)
+		case "$2" in
+		'')
+			printf '\060\170\234\003\0\0\0\0\1'
+			return
+			;;
+		esac
+		;;
+
+	# blob containing "\7\76"
+	e68fe8129b546b101aee9510c5328e7f21ca1d18)
+		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
+			;;
+		esac
+		;;
+
+	# blob containing "\7\0"
+	01d7713666f4de822776c7622c10f1b07de280dc)
+		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
+			;;
+		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 - 20 - 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-tool sha1 -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/*
+}