check-attr: Add --stdin option

This allows multiple paths to be specified on stdin.

Signed-off-by: Dmitry Potapov <dpotapov@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Documentation/git-check-attr.txt

@@ -9,6 +9,7 @@ git-check-attr - Display gitattributes information.
 SYNOPSIS
 --------
 'git check-attr' attr... [--] pathname...
+'git check-attr' --stdin [-z] attr... < <list-of-paths
 
 DESCRIPTION
 -----------
@@ -17,6 +18,13 @@ For every pathname, this command will list if each attr is 'unspecified',
 
 OPTIONS
 -------
+--stdin::
+	Read file names from stdin instead of from the command-line.
+
+-z::
+	Only meaningful with `--stdin`; paths are separated with
+	NUL character instead of LF.
+
 \--::
 	Interpret all preceding arguments as attributes, and all following
 	arguments as path names. If not supplied, only the first argument will

builtin-check-attr.c

@@ -2,9 +2,23 @@
 #include "cache.h"
 #include "attr.h"
 #include "quote.h"
+#include "parse-options.h"
 
-static const char check_attr_usage[] =
-"git check-attr attr... [--] pathname...";
+static int stdin_paths;
+static const char * const check_attr_usage[] = {
+"git check-attr attr... [--] pathname...",
+"git check-attr --stdin attr... < <list-of-paths>",
+NULL
+};
+
+static int null_term_line;
+
+static const struct option check_attr_options[] = {
+	OPT_BOOLEAN(0 , "stdin", &stdin_paths, "read file names from stdin"),
+	OPT_BOOLEAN('z', NULL, &null_term_line,
+		"input paths are terminated by a null character"),
+	OPT_END()
+};
 
 static void check_attr(int cnt, struct git_attr_check *check,
 	const char** name, const char *file)
@@ -27,17 +41,45 @@ static void check_attr(int cnt, struct git_attr_check *check,
 	}
 }
 
+static void check_attr_stdin_paths(int cnt, struct git_attr_check *check,
+	const char** name)
+{
+	struct strbuf buf, nbuf;
+	int line_termination = null_term_line ? 0 : '\n';
+
+	strbuf_init(&buf, 0);
+	strbuf_init(&nbuf, 0);
+	while (strbuf_getline(&buf, stdin, line_termination) != EOF) {
+		if (line_termination && buf.buf[0] == '"') {
+			strbuf_reset(&nbuf);
+			if (unquote_c_style(&nbuf, buf.buf, NULL))
+				die("line is badly quoted");
+			strbuf_swap(&buf, &nbuf);
+		}
+		check_attr(cnt, check, name, buf.buf);
+		maybe_flush_or_die(stdout, "attribute to stdout");
+	}
+	strbuf_release(&buf);
+	strbuf_release(&nbuf);
+}
+
 int cmd_check_attr(int argc, const char **argv, const char *prefix)
 {
 	struct git_attr_check *check;
 	int cnt, i, doubledash;
+	const char *errstr = NULL;
+
+	argc = parse_options(argc, argv, check_attr_options, check_attr_usage,
+		PARSE_OPT_KEEP_DASHDASH);
+	if (!argc)
+		usage_with_options(check_attr_usage, check_attr_options);
 
 	if (read_cache() < 0) {
 		die("invalid cache");
 	}
 
 	doubledash = -1;
-	for (i = 1; doubledash < 0 && i < argc; i++) {
+	for (i = 0; doubledash < 0 && i < argc; i++) {
 		if (!strcmp(argv[i], "--"))
 			doubledash = i;
 	}
@@ -45,26 +87,37 @@ int cmd_check_attr(int argc, const char **argv, const char *prefix)
 	/* If there is no double dash, we handle only one attribute */
 	if (doubledash < 0) {
 		cnt = 1;
-		doubledash = 1;
+		doubledash = 0;
 	} else
-		cnt = doubledash - 1;
+		cnt = doubledash;
 	doubledash++;
 
-	if (cnt <= 0 || argc < doubledash)
-		usage(check_attr_usage);
+	if (cnt <= 0)
+		errstr = "No attribute specified";
+	else if (stdin_paths && doubledash < argc)
+		errstr = "Can't specify files with --stdin";
+	if (errstr) {
+		error (errstr);
+		usage_with_options(check_attr_usage, check_attr_options);
+	}
+
 	check = xcalloc(cnt, sizeof(*check));
 	for (i = 0; i < cnt; i++) {
 		const char *name;
 		struct git_attr *a;
-		name = argv[i + 1];
+		name = argv[i];
 		a = git_attr(name, strlen(name));
 		if (!a)
 			return error("%s: not a valid attribute name", name);
 		check[i].attr = a;
 	}
 
+	if (stdin_paths)
+		check_attr_stdin_paths(cnt, check, argv);
+	else {
 		for (i = doubledash; i < argc; i++)
-		check_attr(cnt, check, argv+1, argv[i]);
+			check_attr(cnt, check, argv, argv[i]);
 		maybe_flush_or_die(stdout, "attribute to stdout");
+	}
 	return 0;
 }

t/t0003-attributes.sh

@@ -47,6 +47,23 @@ test_expect_success 'attribute test' '
 
 '
 
+test_expect_success 'attribute test: read paths from stdin' '
+
+	cat <<EOF > expect
+f: test: f
+a/f: test: f
+a/c/f: test: f
+a/g: test: a/g
+a/b/g: test: a/b/g
+b/g: test: unspecified
+a/b/h: test: a/b/h
+a/b/d/g: test: a/b/d/*
+EOF
+
+	sed -e "s/:.*//" < expect | git check-attr --stdin test > actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'root subdir attribute test' '
 
 	attr_check a/i a/i &&