[PATCH 4/4] rev-list: support NUL-delimited --missing option

[Justin Tobler <jltobler@xxxxxxxxx>]

The `--missing={print,print-info}` option for git-rev-list(1) prints
missing objects found while performing the revision walk. Add support
for printing missing objects in a NUL-delimited format when the `-z`
option is enabled.

        $ git rev-list -z --missing=print-info <rev>
        <oid> NUL NUL
        ?<oid> [NUL <token>=<value>]... NUL NUL

In this mode, values containing special characters or spaces are printed
as-is without being escaped or quoted.

Signed-off-by: Justin Tobler <jltobler@xxxxxxxxx>
---
 Documentation/rev-list-options.adoc | 10 +++++++++-
 builtin/rev-list.c                  | 27 +++++++++++++++++++-------
 t/t6022-rev-list-missing.sh         | 30 +++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 8 deletions(-)

diff --git a/Documentation/rev-list-options.adoc b/Documentation/rev-list-options.adoc
index d21016d657..48648b7507 100644
--- a/Documentation/rev-list-options.adoc
+++ b/Documentation/rev-list-options.adoc
@@ -378,7 +378,15 @@ containing newline characters:
 <OID> [NUL <object-name>] NUL NUL
 -----------------------------------------------------------------------
 +
-This option is only compatible with `--objects`.
+When the `--missing` option is provided, missing objects are printed in the
+following form where value is printed as-is without any token specific
+encoding:
++
+-----------------------------------------------------------------------
+?<OID> [NUL <token>=<value>]... NUL NUL
+-----------------------------------------------------------------------
++
+This option is only compatible with `--objects` and `--missing`.
 endif::git-rev-list[]
 
 History Simplification
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index 86b3ce5806..5bbc4a787e 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -145,25 +145,38 @@ static void print_missing_object(struct missing_objects_map_entry *entry,
 				 int print_missing_info)
 {
 	struct strbuf sb = STRBUF_INIT;
+	char info_sep = ' ';
+
+	if (nul_delim)
+		info_sep = '\0';
+
+	printf("?%s", oid_to_hex(&entry->entry.oid));
 
 	if (!print_missing_info) {
-		printf("?%s\n", oid_to_hex(&entry->entry.oid));
+		print_object_term(nul_delim);
 		return;
 	}
 
 	if (entry->path && *entry->path) {
 		struct strbuf path = STRBUF_INIT;
 
-		strbuf_addstr(&sb, " path=");
-		quote_path(entry->path, NULL, &path, QUOTE_PATH_QUOTE_SP);
-		strbuf_addbuf(&sb, &path);
+		strbuf_addf(&sb, "%cpath=", info_sep);
+
+		if (nul_delim) {
+			strbuf_addstr(&sb, entry->path);
+		} else {
+			quote_path(entry->path, NULL, &path, QUOTE_PATH_QUOTE_SP);
+			strbuf_addbuf(&sb, &path);
+		}
 
 		strbuf_release(&path);
 	}
 	if (entry->type)
-		strbuf_addf(&sb, " type=%s", type_name(entry->type));
+		strbuf_addf(&sb, "%ctype=%s", info_sep, type_name(entry->type));
+
+	fwrite(sb.buf, sizeof(char), sb.len, stdout);
+	print_object_term(nul_delim);
 
-	printf("?%s%s\n", oid_to_hex(&entry->entry.oid), sb.buf);
 	strbuf_release(&sb);
 }
 
@@ -782,7 +795,7 @@ int cmd_rev_list(int argc,
 	if (nul_delim) {
 		if (revs.graph || revs.verbose_header || show_disk_usage ||
 		    info.show_timestamp || info.header_prefix || bisect_list ||
-		    use_bitmap_index || revs.edge_hint || arg_missing_action)
+		    use_bitmap_index || revs.edge_hint)
 			die(_("-z option used with unsupported option"));
 	}
 
diff --git a/t/t6022-rev-list-missing.sh b/t/t6022-rev-list-missing.sh
index 3e2790d4c8..3ae25e4cfb 100755
--- a/t/t6022-rev-list-missing.sh
+++ b/t/t6022-rev-list-missing.sh
@@ -198,4 +198,34 @@ do
 	'
 done
 
+test_expect_success "-z nul-delimited --missing" '
+	test_when_finished rm -rf repo &&
+
+	git init repo &&
+	(
+		cd repo &&
+		git commit --allow-empty -m first &&
+
+		path="foo bar" &&
+		echo foobar >"$path" &&
+		git add -A &&
+		git commit -m second &&
+
+		oid=$(git rev-parse "HEAD:$path") &&
+		type="$(git cat-file -t $oid)" &&
+
+		obj_path=".git/objects/$(test_oid_to_path $oid)" &&
+
+		git rev-list -z --objects --no-object-names \
+			HEAD ^"$oid" >expect &&
+		printf "?%s\0path=%s\0type=%s\0\0" "$oid" "$path" "$type" >>expect &&
+
+		mv "$obj_path" "$obj_path.hidden" &&
+		git rev-list -z --objects --no-object-names \
+			--missing=print-info HEAD >actual &&
+
+		test_cmp expect actual
+	)
+'
+
 test_done
-- 
2.49.0.rc2