Add support for --info-memory and --robot to xz.

Currently --robot works only with --info-memory and
--version. --help and --long-help work too, but --robot
has no effect on them.

Thanks to Jonathan Nieder for the original patches.

src/xz/args.c

@@ -21,6 +21,7 @@
 bool opt_stdout = false;
 bool opt_force = false;
 bool opt_keep_original = false;
+bool opt_robot = false;
 
 // We don't modify or free() this, but we need to assign it in some
 // non-const pointers.
@@ -44,6 +45,8 @@ parse_real(args_info *args, int argc, char **argv)
 
 		OPT_FILES,
 		OPT_FILES0,
+		OPT_INFO_MEMORY,
+		OPT_ROBOT,
 	};
 
 	static const char short_opts[]
@@ -93,6 +96,8 @@ parse_real(args_info *args, int argc, char **argv)
 		{ "quiet",        no_argument,       NULL,  'q' },
 		{ "verbose",      no_argument,       NULL,  'v' },
 		{ "no-warn",      no_argument,       NULL,  'Q' },
+		{ "robot",        no_argument,       NULL,  OPT_ROBOT },
+		{ "info-memory",  no_argument,       NULL,  OPT_INFO_MEMORY },
 		{ "help",         no_argument,       NULL,  'h' },
 		{ "long-help",    no_argument,       NULL,  'H' },
 		{ "version",      no_argument,       NULL,  'V' },
@@ -169,6 +174,11 @@ parse_real(args_info *args, int argc, char **argv)
 			opt_force = true;
 			break;
 
+		// --info-memory
+		case OPT_INFO_MEMORY:
+			// This doesn't return.
+			message_memlimit();
+
 		// --help
 		case 'h':
 			// This doesn't return.
@@ -207,6 +217,11 @@ parse_real(args_info *args, int argc, char **argv)
 			message_verbosity_increase();
 			break;
 
+		// --robot
+		case OPT_ROBOT:
+			opt_robot = true;
+			break;
+
 		case 'z':
 			opt_mode = MODE_COMPRESS;
 			break;

src/xz/args.h

@@ -35,6 +35,7 @@ extern bool opt_stdout;
 extern bool opt_force;
 extern bool opt_keep_original;
 // extern bool opt_recursive;
+extern bool opt_robot;
 
 extern const char *stdin_filename;
 

src/xz/main.c

@@ -153,6 +153,13 @@ main(int argc, char **argv)
 	args_info args;
 	args_parse(&args, argc, argv);
 
+	if (opt_mode == MODE_LIST)
+		message_fatal("--list is not implemented yet.");
+
+	if (opt_robot)
+		message_fatal(_("Compression and decompression with --robot "
+			"are not supported yet."));
+
 	// Tell the message handling code how many input files there are if
 	// we know it. This way the progress indicator can show it.
 	if (args.files_name != NULL)
@@ -172,10 +179,6 @@ main(int argc, char **argv)
 		}
 	}
 
-	if (opt_mode == MODE_LIST) {
-		message_fatal("--list is not implemented yet.");
-	}
-
 	// Hook the signal handlers. We don't need these before we start
 	// the actual action, so this is done after parsing the command
 	// line arguments.

src/xz/message.c

@@ -1,7 +1,7 @@
 ///////////////////////////////////////////////////////////////////////////////
 //
 /// \file       message.c
-/// \brief      Printing messages to stderr
+/// \brief      Printing messages
 //
 //  Author:     Lasse Collin
 //
@@ -152,7 +152,7 @@ message_init(void)
 	if (progress_automatic) {
 		// stderr is a terminal. Check the COLUMNS environment
 		// variable to see if the terminal is wide enough. If COLUMNS
-		// doesn't exist or it has some unparseable value, we assume
+		// doesn't exist or it has some unparsable value, we assume
 		// that the terminal is wide enough.
 		const char *columns_str = getenv("COLUMNS");
 		if (columns_str != NULL) {
@@ -1012,13 +1012,33 @@ message_try_help(void)
 }
 
 
+extern void
+message_memlimit(void)
+{
+	if (opt_robot)
+		printf("%" PRIu64 "\n", hardware_memlimit_get());
+	else
+		printf(_("%s MiB (%s bytes)\n"),
+			uint64_to_str(hardware_memlimit_get() >> 20, 0),
+			uint64_to_str(hardware_memlimit_get(), 1));
+
+	tuklib_exit(E_SUCCESS, E_ERROR, verbosity != V_SILENT);
+}
+
+
 extern void
 message_version(void)
 {
 	// It is possible that liblzma version is different than the command
 	// line tool version, so print both.
+	if (opt_robot) {
+		printf("XZ_VERSION=%d\nLIBLZMA_VERSION=%d\n",
+				LZMA_VERSION, lzma_version_number());
+	} else {
 		printf("xz (" PACKAGE_NAME ") " LZMA_VERSION_STRING "\n");
 		printf("liblzma %s\n", lzma_version_string());
+	}
+
 	tuklib_exit(E_SUCCESS, E_ERROR, verbosity != V_SILENT);
 }
 
@@ -1137,22 +1157,25 @@ message_help(bool long_help)
 "  -q, --quiet         suppress warnings; specify twice to suppress errors too\n"
 "  -v, --verbose       be verbose; specify twice for even more verbose"));
 
-	if (long_help)
+	if (long_help) {
 		puts(_(
 "  -Q, --no-warn       make warnings not affect the exit status"));
-
-	if (long_help)
 		puts(_(
-"\n"
+"      --robot         use machine-parsable messages (useful for scripts)"));
+		puts("");
+		puts(_(
+"      --info-memory   display the memory usage limit and exit"));
+		puts(_(
 "  -h, --help          display the short help (lists only the basic options)\n"
-"  -H, --long-help     display this long help"));
+"  -H, --long-help     display this long help and exit"));
-	else
+	} else {
 		puts(_(
-"  -h, --help          display this short help\n"
+"  -h, --help          display this short help and exit\n"
 "  -H, --long-help     display the long help (lists also the advanced options)"));
+	}
 
 	puts(_(
-"  -V, --version       display the version number"));
+"  -V, --version       display the version number and exit"));
 
 	puts(_("\nWith no FILE, or when FILE is -, read standard input.\n"));
 

src/xz/message.h

@@ -96,6 +96,10 @@ extern void message_filters(
 extern void message_try_help(void);
 
 
+/// Print the memory usage limit and exit.
+extern void message_memlimit(void) lzma_attribute((noreturn));
+
+
 /// Prints the version number to stdout and exits with exit status SUCCESS.
 extern void message_version(void) lzma_attribute((noreturn));
 

src/xz/xz.1

@@ -5,7 +5,7 @@
 .\" This file has been put into the public domain.
 .\" You can do whatever you want with this file.
 .\"
-.TH XZ 1 "2009-11-14" "Tukaani" "XZ Utils"
+.TH XZ 1 "2009-11-16" "Tukaani" "XZ Utils"
 .SH NAME
 xz, unxz, xzcat, lzma, unlzma, lzcat \- Compress or decompress .xz and .lzma files
 .SH SYNOPSIS
@@ -219,8 +219,9 @@ but it is possible that a block later in the file will exceed the memory usage
 limit, and an error about too low memory usage limit gets displayed after some
 data has already been decompressed.
 .PP
-The absolute value of the active memory usage limit can be seen near
+The absolute value of the active memory usage limit can be seen with
-the bottom of the output of
+.B \-\-info-memory
+or near the bottom of the output of
 .BR \-\-long\-help .
 The default limit can be overriden with
 \fB\-\-memory=\fIlimit\fR.
@@ -1052,6 +1053,34 @@ and
 .B \-\-no\-warn
 have to be used to not display warnings and to not alter the exit status.
 .TP
+.B \-\-robot
+Print messages in a machine-parsable format. This is intended to ease
+writing frontends that want to use
+.B xz
+instead of liblzma, which may be the case with various scripts. The output
+with this option enabled is meant to be stable across
+.B xz
+releases. Currently
+.B \-\-robot
+is implemented only for
+.B \-\-info\-memory
+and
+.BR \-\-version ,
+but the idea is to make it usable for actual compression
+and decompression too.
+.TP
+.BR \-\-info-memory
+Display the current memory usage limit in human-readable format on
+a single line, and exit successfully. To see how much RAM
+.B xz
+thinks your system has, use
+.BR "\-\-memory=100% \-\-info\-memory" .
+To get machine-parsable output
+(memory usage limit as bytes without thousand separators), specify
+.B \-\-robot
+before
+.BR \-\-info-memory .
+.TP
 .BR \-h ", " \-\-help
 Display a help message describing the most commonly used options,
 and exit successfully.
@@ -1064,7 +1093,10 @@ and exit successfully
 .BR \-V ", " \-\-version
 Display the version number of
 .B xz
-and liblzma.
+and liblzma in human readable format. To get machine-parsable output, specify
+.B \-\-robot
+before
+.BR \-\-version .
 .SH "EXIT STATUS"
 .TP
 .B 0