test-pkt-line: add option parser for unpack-sideband

We can use the test helper program "test-tool pkt-line" to test pkt-line
related functions. E.g.:

 * Use "test-tool pkt-line send-split-sideband" to generate sideband
   messages.

 * Pipe these generated sideband messages to command "test-tool pkt-line
   unpack-sideband" to test packet_reader_read() function.

In order to make a complete test of the packet_reader_read() function,
add option parser for command "test-tool pkt-line unpack-sideband".

 * To remove newlines in sideband messages, we can use:

        $ test-tool pkt-line unpack-sideband --chomp-newline

 * To preserve newlines in sideband messages, we can use:

        $ test-tool pkt-line unpack-sideband --no-chomp-newline

 * To parse sideband messages using "demultiplex_sideband()" inside the
   function "packet_reader_read()", we can use:

        $ test-tool pkt-line unpack-sideband --reader-use-sideband

We also add new example sideband packets in send_split_sideband() and
add several new test cases in t0070. Among these test cases, we pipe
output of the "send-split-sideband" subcommand to the "unpack-sideband"
subcommand. We found two issues:

 1. The two splitted sideband messages "Hello," and " world!\n" should
    be concatenated together. But when we turn on use_sideband field of
    reader to parse sideband messages, the first part of the splitted
    message ("Hello,") is lost.

 2. The newline characters in sideband 2 (progress info) and sideband 3
    (error message) should be preserved, but they are both trimmed.

Will fix the above two issues in subsequent commits.

Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/helper/test-pkt-line.c

@@ -2,6 +2,7 @@
 #include "test-tool.h"
 #include "pkt-line.h"
 #include "write-or-die.h"
+#include "parse-options.h"
 
 static void pack_line(const char *line)
 {
@@ -64,12 +65,33 @@ static void unpack(void)
 	}
 }
 
-static void unpack_sideband(void)
+static void unpack_sideband(int argc, const char **argv)
 {
 	struct packet_reader reader;
-	packet_reader_init(&reader, 0, NULL, 0,
-			   PACKET_READ_GENTLE_ON_EOF |
-			   PACKET_READ_CHOMP_NEWLINE);
+	int options = PACKET_READ_GENTLE_ON_EOF;
+	int chomp_newline = 1;
+	int reader_use_sideband = 0;
+	const char *const unpack_sideband_usage[] = {
+		"test_tool unpack_sideband [options...]", NULL
+	};
+	struct option cmd_options[] = {
+		OPT_BOOL(0, "reader-use-sideband", &reader_use_sideband,
+			 "set use_sideband bit for packet reader (Default: off)"),
+		OPT_BOOL(0, "chomp-newline", &chomp_newline,
+			 "chomp newline in packet (Default: on)"),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, "", cmd_options, unpack_sideband_usage,
+			     0);
+	if (argc > 0)
+		usage_msg_opt(_("too many arguments"), unpack_sideband_usage,
+			      cmd_options);
+
+	if (chomp_newline)
+		options |= PACKET_READ_CHOMP_NEWLINE;
+	packet_reader_init(&reader, 0, NULL, 0, options);
+	reader.use_sideband = reader_use_sideband;
 
 	while (packet_reader_read(&reader) != PACKET_READ_EOF) {
 		int band;
@@ -79,6 +101,17 @@ static void unpack_sideband(void)
 		case PACKET_READ_EOF:
 			break;
 		case PACKET_READ_NORMAL:
+			/*
+			 * When the "use_sideband" field of the reader is turned
+			 * on, sideband packets other than the payload have been
+			 * parsed and consumed in packet_reader_read(), and only
+			 * the payload arrives here.
+			 */
+			if (reader.use_sideband) {
+				write_or_die(1, reader.line, reader.pktlen - 1);
+				break;
+			}
+
 			band = reader.line[0] & 0xff;
 			if (band < 1 || band > 2)
 				continue; /* skip non-sideband packets */
@@ -97,15 +130,31 @@ static void unpack_sideband(void)
 
 static int send_split_sideband(void)
 {
+	const char *foo = "Foo.\n";
+	const char *bar = "Bar.\n";
 	const char *part1 = "Hello,";
 	const char *primary = "\001primary: regular output\n";
 	const char *part2 = " world!\n";
 
+	/* Each sideband message has a trailing newline character. */
+	send_sideband(1, 2, foo, strlen(foo), LARGE_PACKET_MAX);
+	send_sideband(1, 2, bar, strlen(bar), LARGE_PACKET_MAX);
+
+	/*
+	 * One sideband message is divided into part1 and part2
+	 * by the primary message.
+	 */
 	send_sideband(1, 2, part1, strlen(part1), LARGE_PACKET_MAX);
 	packet_write(1, primary, strlen(primary));
 	send_sideband(1, 2, part2, strlen(part2), LARGE_PACKET_MAX);
 	packet_response_end(1);
 
+	/*
+	 * We use unpack_sideband() to consume packets. A flush packet
+	 * is required to end parsing.
+	 */
+	packet_flush(1);
+
 	return 0;
 }
 
@@ -126,7 +175,7 @@ int cmd__pkt_line(int argc, const char **argv)
 	else if (!strcmp(argv[1], "unpack"))
 		unpack();
 	else if (!strcmp(argv[1], "unpack-sideband"))
-		unpack_sideband();
+		unpack_sideband(argc - 1, argv + 1);
 	else if (!strcmp(argv[1], "send-split-sideband"))
 		send_split_sideband();
 	else if (!strcmp(argv[1], "receive-sideband"))

t/t0070-fundamental.sh

@@ -53,4 +53,62 @@ test_expect_success 'missing sideband designator is reported' '
 	test_i18ngrep "missing sideband" err
 '
 
+test_expect_success 'unpack-sideband: --no-chomp-newline' '
+	test_when_finished "rm -f expect-out expect-err" &&
+	test-tool pkt-line send-split-sideband >split-sideband &&
+	test-tool pkt-line unpack-sideband \
+		--no-chomp-newline <split-sideband >out 2>err &&
+	cat >expect-out <<-EOF &&
+		primary: regular output
+	EOF
+	cat >expect-err <<-EOF &&
+		Foo.
+		Bar.
+		Hello, world!
+	EOF
+	test_cmp expect-out out &&
+	test_cmp expect-err err
+'
+
+test_expect_success 'unpack-sideband: --chomp-newline (default)' '
+	test_when_finished "rm -f expect-out expect-err" &&
+	test-tool pkt-line send-split-sideband >split-sideband &&
+	test-tool pkt-line unpack-sideband \
+		--chomp-newline <split-sideband >out 2>err &&
+	printf "primary: regular output" >expect-out &&
+	printf "Foo.Bar.Hello, world!" >expect-err &&
+	test_cmp expect-out out &&
+	test_cmp expect-err err
+'
+
+test_expect_failure 'unpack-sideband: packet_reader_read() consumes sideband, no chomp payload' '
+	test_when_finished "rm -f expect-out expect-err" &&
+	test-tool pkt-line send-split-sideband >split-sideband &&
+	test-tool pkt-line unpack-sideband \
+		--reader-use-sideband \
+		--no-chomp-newline <split-sideband >out 2>err &&
+	cat >expect-out <<-EOF &&
+		primary: regular output
+	EOF
+	printf "remote: Foo.        \n"           >expect-err &&
+	printf "remote: Bar.        \n"          >>expect-err &&
+	printf "remote: Hello, world!        \n" >>expect-err &&
+	test_cmp expect-out out &&
+	test_cmp expect-err err
+'
+
+test_expect_failure 'unpack-sideband: packet_reader_read() consumes sideband, chomp payload' '
+	test_when_finished "rm -f expect-out expect-err" &&
+	test-tool pkt-line send-split-sideband >split-sideband &&
+	test-tool pkt-line unpack-sideband \
+		--reader-use-sideband \
+		--chomp-newline <split-sideband >out 2>err &&
+	printf "primary: regular output" >expect-out &&
+	printf "remote: Foo.        \n"           >expect-err &&
+	printf "remote: Bar.        \n"          >>expect-err &&
+	printf "remote: Hello, world!        \n" >>expect-err &&
+	test_cmp expect-out out &&
+	test_cmp expect-err err
+'
+
 test_done