t: add lib-loose.sh

This commit adds a shell library for writing raw loose objects into the
object database. Normally this is done with hash-object, but the
specific intent here is to allow broken objects that hash-object may not
support.

We'll convert several cases that use "hash-object --literally" to write
objects with invalid types. That works currently, but dropping this
dependency will allow us to remove that feature and simplify the
object-writing code.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/lib-loose.sh

@@ -0,0 +1,30 @@
+# Support routines for hand-crafting loose objects.
+
+# Write a loose object into the odb at $1, with object type $2 and contents
+# from stdin. Writes the oid to stdout. Example:
+#
+#   oid=$(echo foo | loose_obj .git/objects blob)
+#
+loose_obj () {
+	cat >tmp_loose.content &&
+	size=$(wc -c <tmp_loose.content) &&
+	{
+		# Do not quote $size here; we want the shell
+		# to strip whitespace that "wc" adds on some platforms.
+		printf "%s %s\0" "$2" $size &&
+		cat tmp_loose.content
+	} >tmp_loose.raw &&
+
+	oid=$(test-tool $test_hash_algo <tmp_loose.raw) &&
+	suffix=${oid#??} &&
+	prefix=${oid%$suffix} &&
+	dir=$1/$prefix &&
+	file=$dir/$suffix &&
+
+	test-tool zlib deflate <tmp_loose.raw >tmp_loose.zlib &&
+	mkdir -p "$dir" &&
+	mv tmp_loose.zlib "$file" &&
+
+	rm tmp_loose.raw tmp_loose.content &&
+	echo "$oid"
+}

t/t1006-cat-file.sh

@@ -3,6 +3,7 @@
 test_description='git cat-file'
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY/lib-loose.sh"
 
 test_cmdmode_usage () {
 	test_expect_code 129 "$@" 2>err &&
@@ -657,12 +658,12 @@ test_expect_success 'setup bogus data' '
 	bogus_short_type="bogus" &&
 	bogus_short_content="bogus" &&
 	bogus_short_size=$(strlen "$bogus_short_content") &&
-	bogus_short_oid=$(echo_without_newline "$bogus_short_content" | git hash-object -t $bogus_short_type --literally -w --stdin) &&
+	bogus_short_oid=$(echo_without_newline "$bogus_short_content" | loose_obj .git/objects $bogus_short_type) &&
 
 	bogus_long_type="abcdefghijklmnopqrstuvwxyz1234679" &&
 	bogus_long_content="bogus" &&
 	bogus_long_size=$(strlen "$bogus_long_content") &&
-	bogus_long_oid=$(echo_without_newline "$bogus_long_content" | git hash-object -t $bogus_long_type --literally -w --stdin)
+	bogus_long_oid=$(echo_without_newline "$bogus_long_content" | loose_obj .git/objects $bogus_long_type)
 '
 
 for arg1 in -s -t -p

t/t1450-fsck.sh

@@ -7,6 +7,7 @@ test_description='git fsck random collection of tests
 '
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY/lib-loose.sh"
 
 test_expect_success setup '
 	git config gc.auto 0 &&
@@ -973,7 +974,7 @@ test_expect_success 'fsck error and recovery on invalid object type' '
 	(
 		cd garbage-type &&
 
-		garbage_blob=$(git hash-object --stdin -w -t garbage --literally </dev/null) &&
+		garbage_blob=$(loose_obj objects garbage </dev/null) &&
 
 		test_must_fail git fsck 2>err &&
 		grep -e "^error" -e "^fatal" err >errors &&

t/t1512-rev-parse-disambiguation.sh

@@ -24,6 +24,7 @@ GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY/lib-loose.sh"
 
 test_cmp_failed_rev_parse () {
 	dir=$1
@@ -67,8 +68,8 @@ test_expect_success 'ambiguous loose bad object parsed as OBJ_BAD' '
 		cd blob.bad &&
 
 		# Both have the prefix "bad0"
-		echo xyzfaowcoh | git hash-object -t bad -w --stdin --literally &&
-		echo xyzhjpyvwl | git hash-object -t bad -w --stdin --literally
+		echo xyzfaowcoh | loose_obj objects bad &&
+		echo xyzhjpyvwl | loose_obj objects bad
 	) &&
 
 	test_cmp_failed_rev_parse blob.bad bad0 <<-\EOF