rev-list: support NUL-delimited --missing option

The `--missing={print,print-info}` option for git-rev-list(1) prints
missing objects found while performing the object walk in the form:

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

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 missing=yes NUL [<token>=<value> NUL]...

In this mode, values containing special characters or spaces are printed
as-is without being escaped or quoted. Instead of prefixing the missing
OID with '?', a separate `missing=yes` token/value pair is appended.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/rev-list-options.adoc

@@ -380,10 +380,11 @@ and thus is used to signal the start of a new object record. Examples:
 <OID> NUL
 <OID> NUL path=<path> NUL
 <OID> NUL boundary=yes NUL
+<OID> NUL missing=yes NUL [<token>=<value> NUL]...
 -----------------------------------------------------------------------
 +
-This mode is only compatible with the `--objects` and `--boundary` output
-options.
+This mode is only compatible with the `--objects`, `--boundary`, and
+`--missing` output options.
 endif::git-rev-list[]
 
 History Simplification

builtin/rev-list.c

@@ -136,24 +136,37 @@ static void print_missing_object(struct missing_objects_map_entry *entry,
 {
 	struct strbuf sb = STRBUF_INIT;
 
+	if (line_term)
+		printf("?%s", oid_to_hex(&entry->entry.oid));
+	else
+		printf("%s%cmissing=yes", oid_to_hex(&entry->entry.oid),
+		       info_term);
+
 	if (!print_missing_info) {
-		printf("?%s\n", oid_to_hex(&entry->entry.oid));
+		putchar(line_term);
 		return;
 	}
 
 	if (entry->path && *entry->path) {
+		strbuf_addf(&sb, "%cpath=", info_term);
+
+		if (line_term) {
 			struct strbuf path = STRBUF_INIT;
 
-		strbuf_addstr(&sb, " path=");
 			quote_path(entry->path, NULL, &path, QUOTE_PATH_QUOTE_SP);
 			strbuf_addbuf(&sb, &path);
 
 			strbuf_release(&path);
+		} else {
+			strbuf_addstr(&sb, entry->path);
+		}
 	}
 	if (entry->type)
-		strbuf_addf(&sb, " type=%s", type_name(entry->type));
+		strbuf_addf(&sb, "%ctype=%s", info_term, type_name(entry->type));
+
+	fwrite(sb.buf, sizeof(char), sb.len, stdout);
+	putchar(line_term);
 
-	printf("?%s%s\n", oid_to_hex(&entry->entry.oid), sb.buf);
 	strbuf_release(&sb);
 }
 
@@ -783,7 +796,7 @@ int cmd_rev_list(int argc,
 		if (revs.graph || revs.verbose_header || show_disk_usage ||
 		    info.show_timestamp || info.header_prefix || bisect_list ||
 		    use_bitmap_index || revs.edge_hint || revs.left_right ||
-		    revs.cherry_mark || arg_missing_action)
+		    revs.cherry_mark)
 			die(_("-z option used with unsupported option"));
 	}
 

t/t6022-rev-list-missing.sh

@@ -198,4 +198,35 @@ 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\0missing=yes\0path=%s\0type=%s\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