check-attr -z: a single -z should apply to both input and output

Unless a command has separate --nul-terminated-{input,output}
options, the --nul-terminated-records (-z) option should apply
to both input and output for consistency.  The caller knows that its
input paths may need to be protected for LF, and the program shows
these problematic paths to its output.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-check-attr.txt

@@ -31,8 +31,9 @@ OPTIONS
 	Read file names from stdin instead of from the command-line.
 
 -z::
-	Only meaningful with `--stdin`; paths are separated with a
-	NUL character instead of a linefeed character.
+	The output format is modified to be machine-parseable.
+	If `--stdin` is also given, input paths are separated
+	with a NUL character instead of a linefeed character.
 
 \--::
 	Interpret all preceding arguments as attributes and all following
@@ -48,6 +49,10 @@ OUTPUT
 The output is of the form:
 <path> COLON SP <attribute> COLON SP <info> LF
 
+unless `-z` is in effect, in which case NUL is used as delimiter:
+<path> NUL <attribute> NUL <info> NUL
+
+
 <path> is the path of a file being queried, <attribute> is an attribute
 being queried and <info> can be either:
 

builtin/check-attr.c

@@ -20,7 +20,7 @@ static const struct option check_attr_options[] = {
 	OPT_BOOLEAN(0,  "cached", &cached_attrs, N_("use .gitattributes only from the index")),
 	OPT_BOOLEAN(0 , "stdin", &stdin_paths, N_("read file names from stdin")),
 	OPT_BOOLEAN('z', NULL, &nul_term_line,
-		    N_("input paths are terminated by a NUL character")),
+		    N_("terminate input and output records by a NUL character")),
 	OPT_END()
 };
 
@@ -38,8 +38,16 @@ static void output_attr(int cnt, struct git_attr_check *check,
 		else if (ATTR_UNSET(value))
 			value = "unspecified";
 
-		quote_c_style(file, NULL, stdout, 0);
-		printf(": %s: %s\n", git_attr_name(check[j].attr), value);
+		if (nul_term_line) {
+			printf("%s%c" /* path */
+			       "%s%c" /* attrname */
+			       "%s%c" /* attrvalue */,
+			       file, 0, git_attr_name(check[j].attr), 0, value, 0);
+		} else {
+			quote_c_style(file, NULL, stdout, 0);
+			printf(": %s: %s\n", git_attr_name(check[j].attr), value);
+		}
+
 	}
 }