Merge branch 'ab/pack-stdin-packs-fix' into seen

Input validation of "git pack-objects --stdin-packs" has been
corrected.

cf. <YND3h2l10PlnSNGJ@nand.local>

* ab/pack-stdin-packs-fix:
  pack-objects: fix segfault in --stdin-packs option
  pack-objects tests: cover blindspots in stdin handling

builtin/pack-objects.c

@@ -3310,6 +3310,16 @@ static void read_packs_list_from_stdin(void)
 			item->util = p;
 	}
 
+	/*
+	 * Arguments we got on stdin may not even be packs. Check that
+	 * to avoid segfaulting later on in e.g. pack_mtime_cmp().
+	 */
+	for_each_string_list_item(item, &include_packs) {
+		struct packed_git *p = item->util;
+		if (!p)
+			die(_("could not find pack '%s'"), item->string);
+	}
+
 	/*
 	 * First handle all of the excluded packs, marking them as kept in-core
 	 * so that later calls to add_object_entry() discards any objects that

t/t5300-pack-object.sh

@@ -34,6 +34,109 @@ test_expect_success 'setup' '
 	} >expect
 '
 
+test_expect_success 'setup pack-object <stdin' '
+	git init pack-object-stdin &&
+	test_commit -C pack-object-stdin one &&
+	test_commit -C pack-object-stdin two
+
+'
+
+test_expect_success 'pack-object <stdin parsing: basic [|--revs]' '
+	cat >in <<-EOF &&
+	$(git -C pack-object-stdin rev-parse one)
+	EOF
+
+	git -C pack-object-stdin pack-objects basic-stdin <in &&
+	idx=$(echo pack-object-stdin/basic-stdin-*.idx) &&
+	git show-index <"$idx" >actual &&
+	test_line_count = 1 actual &&
+
+	git -C pack-object-stdin pack-objects --revs basic-stdin-revs <in &&
+	idx=$(echo pack-object-stdin/basic-stdin-revs-*.idx) &&
+	git show-index <"$idx" >actual &&
+	test_line_count = 3 actual
+'
+
+test_expect_success 'pack-object <stdin parsing: [|--revs] bad line' '
+	cat >in <<-EOF &&
+	$(git -C pack-object-stdin rev-parse one)
+	garbage
+	$(git -C pack-object-stdin rev-parse two)
+	EOF
+
+	sed "s/^> //g" >err.expect <<-EOF &&
+	fatal: expected object ID, got garbage:
+	>  garbage
+
+	EOF
+	test_must_fail git -C pack-object-stdin pack-objects bad-line-stdin <in 2>err.actual &&
+	test_cmp err.expect err.actual &&
+
+	cat >err.expect <<-EOF &&
+	fatal: bad revision '"'"'garbage'"'"'
+	EOF
+	test_must_fail git -C pack-object-stdin pack-objects --revs bad-line-stdin-revs <in 2>err.actual &&
+	test_cmp err.expect err.actual
+'
+
+test_expect_success 'pack-object <stdin parsing: [|--revs] empty line' '
+	cat >in <<-EOF &&
+	$(git -C pack-object-stdin rev-parse one)
+
+	$(git -C pack-object-stdin rev-parse two)
+	EOF
+
+	sed -e "s/^> //g" -e "s/Z$//g" >err.expect <<-EOF &&
+	fatal: expected object ID, got garbage:
+	>  Z
+
+	EOF
+	test_must_fail git -C pack-object-stdin pack-objects empty-line-stdin <in 2>err.actual &&
+	test_cmp err.expect err.actual &&
+
+	git -C pack-object-stdin pack-objects --revs empty-line-stdin-revs <in &&
+	idx=$(echo pack-object-stdin/empty-line-stdin-revs-*.idx) &&
+	git show-index <"$idx" >actual &&
+	test_line_count = 3 actual
+'
+
+test_expect_success 'pack-object <stdin parsing: [|--revs] with --stdin' '
+	cat >in <<-EOF &&
+	$(git -C pack-object-stdin rev-parse one)
+	$(git -C pack-object-stdin rev-parse two)
+	EOF
+
+	# There is the "--stdin-packs is incompatible with --revs"
+	# test below, but we should make sure that the revision.c
+	# --stdin is not picked up
+	cat >err.expect <<-EOF &&
+	fatal: disallowed abbreviated or ambiguous option '"'"'stdin'"'"'
+	EOF
+	test_must_fail git -C pack-object-stdin pack-objects stdin-with-stdin-option --stdin <in 2>err.actual &&
+	test_cmp err.expect err.actual &&
+
+	test_must_fail git -C pack-object-stdin pack-objects --stdin --revs stdin-with-stdin-option-revs 2>err.actual <in &&
+	test_cmp err.expect err.actual
+'
+
+test_expect_success 'pack-object <stdin parsing: --stdin-packs handles garbage' '
+	cat >in <<-EOF &&
+	$(git -C pack-object-stdin rev-parse one)
+	$(git -C pack-object-stdin rev-parse two)
+	EOF
+
+	# We actually just report the first bad line in strcmp()
+	# order, it just so happens that we get the same result under
+	# SHA-1 and SHA-256 here. It does not really matter that we
+	# report the first bad item in this obscure case, so this
+	# oddity of the test is OK.
+	cat >err.expect <<-EOF &&
+	fatal: could not find pack '"'"'$(git -C pack-object-stdin rev-parse two)'"'"'
+	EOF
+	test_must_fail git -C pack-object-stdin pack-objects stdin-with-stdin-option --stdin-packs <in 2>err.actual &&
+	test_cmp err.expect err.actual
+'
+
 # usage: check_deltas <stderr_from_pack_objects> <cmp_op> <nr_deltas>
 # e.g.: check_deltas stderr -gt 0
 check_deltas() {