Make the default memory usage limit 40 % of RAM for both

compressing and decompressing. This should be OK now that
xz automatically scales down the compression settings if
they would exceed the memory usage limit (earlier, the limit
for compression was increased to 90 % because low limit broke
scripts that used "xz -9" on systems with low RAM).

Support spcifying the memory usage limit as a percentage
of RAM (e.g. --memory=50%).

Support --threads=0 to reset the thread limit to the default
value (number of available CPU cores). Use UINT32_MAX instead
of SIZE_MAX as the maximum in args.c. hardware.c was already
expecting uint32_t value.

Cleaned up the output of --help and --long-help.

1 files changed, 13 insertions, 15 deletions

diff --git a/src/xz/message.c b/src/xz/message.c
index 971305ba..9e1ee2f6 100644
--- a/src/xz/message.c
+++ b/src/xz/message.c
@@ -1072,7 +1072,8 @@ message_help(bool long_help)
 "  -e, --extreme       use more CPU time when encoding to increase compression\n"
 "                      ratio without increasing memory usage of the decoder"));
 
-	puts(_(
+	if (long_help)
+		puts(_(
 "  -M, --memory=NUM    use roughly NUM bytes of memory at maximum; 0 indicates\n"
 "                      the default setting, which depends on the operation mode\n"
 "                      and the amount of physical memory (RAM)"));
@@ -1085,9 +1086,9 @@ message_help(bool long_help)
 		|| defined(HAVE_ENCODER_LZMA2) || defined(HAVE_DECODER_LZMA2)
 		puts(_(
 "\n"
-"  --lzma1=[OPTS]      LZMA1 or LZMA2; OPTS is a comma-separated list of zero or\n"
-"  --lzma2=[OPTS]      more of the following options (valid values; default):\n"
-"                        preset=NUM reset options to preset number NUM (1-9)\n"
+"  --lzma1[=OPTS]      LZMA1 or LZMA2; OPTS is a comma-separated list of zero or\n"
+"  --lzma2[=OPTS]      more of the following options (valid values; default):\n"
+"                        preset=NUM reset options to preset number NUM (0-9)\n"
 "                        dict=NUM   dictionary size (4KiB - 1536MiB; 8MiB)\n"
 "                        lc=NUM     number of literal context bits (0-4; 3)\n"
 "                        lp=NUM     number of literal position bits (0-4; 0)\n"
@@ -1110,7 +1111,7 @@ message_help(bool long_help)
 #if defined(HAVE_ENCODER_DELTA) || defined(HAVE_DECODER_DELTA)
 		puts(_(
 "\n"
-"  --delta=[OPTS]      Delta filter; valid OPTS (valid values; default):\n"
+"  --delta[=OPTS]      Delta filter; valid OPTS (valid values; default):\n"
 "                        dist=NUM   distance between bytes being subtracted\n"
 "                                   from each other (1-256; 1)"));
 #endif
@@ -1118,7 +1119,7 @@ message_help(bool long_help)
 #if defined(HAVE_ENCODER_SUBBLOCK) || defined(HAVE_DECODER_SUBBLOCK)
 		puts(_(
 "\n"
-"  --subblock=[OPTS]   Subblock filter; valid OPTS (valid values; default):\n"
+"  --subblock[=OPTS]   Subblock filter; valid OPTS (valid values; default):\n"
 "                        size=NUM   number of bytes of data per subblock\n"
 "                                   (1 - 256Mi; 4Ki)\n"
 "                        rle=NUM    run-length encoder chunk size (0-256; 0)"));
@@ -1149,19 +1150,16 @@ message_help(bool long_help)
 
 	if (long_help) {
 		printf(_(
-"On this system and configuration, the tool will use at maximum of\n"
-"  * roughly %'" PRIu64 " MiB RAM for compression;\n"
-"  * roughly %'" PRIu64 " MiB RAM for decompression; and\n"),
-				hardware_memlimit_encoder() / (1024 * 1024),
-				hardware_memlimit_decoder() / (1024 * 1024));
-		printf(N_("  * one thread for (de)compression.\n\n",
-			"  * %'" PRIu32 " threads for (de)compression.\n\n",
-			hardware_threadlimit_get()),
-			hardware_threadlimit_get());
+"On this system and configuration, this program will use at maximum of roughly\n"
+"%'" PRIu64 " MiB RAM and "), hardware_memlimit_get() / (1024 * 1024));
+		printf(N_("one thread.\n\n", "%'" PRIu32 " threads.\n\n",
+				hardware_threadlimit_get()),
+				hardware_threadlimit_get());
 	}
 
 	printf(_("Report bugs to <%s> (in English or Finnish).\n"),
 			PACKAGE_BUGREPORT);
+	printf(_("XZ Utils home page: <http://tukaani.org/xz/>\n"));
 
 	my_exit(E_SUCCESS);
 }