Disable the memory usage limiter by default.

For several people, the limiter causes bigger problems that
it solves, so it is better to have it disabled by default.
Those who want to have a limiter by default need to enable
it via the environment variable XZ_DEFAULTS.

Support for environment variable XZ_DEFAULTS was added. It is
parsed before XZ_OPT and technically identical with it. The
intended uses differ quite a bit though; see the man page.

The memory usage limit can now be set separately for
compression and decompression using --memlimit-compress and
--memlimit-decompress. To set both at once, -M or --memlimit
can be used. --memory was retained as a legacy alias for
--memlimit for backwards compatibility.

The semantics of --info-memory were changed in backwards
incompatible way. Compatibility wasn't meaningful due to
changes in the memory usage limiter functionality.

The memory usage limiter info is no longer shown at the
bottom of xz --long -help.

The memory usage limiter support for removed completely from xzdec.

xz's man page was updated to match the above changes. Various
unrelated fixes were also made to the man page.

1 files changed, 4 insertions, 41 deletions

diff --git a/src/xzdec/xzdec.1 b/src/xzdec/xzdec.1
index 3057c586..ed14a03c 100644
--- a/src/xzdec/xzdec.1
+++ b/src/xzdec/xzdec.1
@@ -4,7 +4,7 @@
 .\" This file has been put into the public domain.
 .\" You can do whatever you want with this file.
 .\"
-.TH XZDEC 1 "2010-03-07" "Tukaani" "XZ Utils"
+.TH XZDEC 1 "2010-08-07" "Tukaani" "XZ Utils"
 .SH NAME
 xzdec, lzmadec \- Small .xz and .lzma decompressors
 .SH SYNOPSIS
@@ -44,8 +44,10 @@ files.
 To reduce the size of the executable,
 .B xzdec
 doesn't support multithreading or localization, and doesn't read options from
+.B XZ_DEFAULTS
+and
 .B XZ_OPT
-environment variable.
+environment variables.
 .B xzdec
 doesn't support displaying intermediate progress information: sending
 .B SIGINFO
@@ -77,45 +79,6 @@ compatibility.
 .B xzdec
 always writes the decompressed data to standard output.
 .TP
-\fB\-M\fR \fIlimit\fR, \fB\-\-memory=\fIlimit
-Set the memory usage
-.IR limit .
-If this option is specified multiple times, the last one takes effect. The
-.I limit
-can be specified in multiple ways:
-.RS
-.IP \(bu 3
-The
-.I limit
-can be an absolute value in bytes. Using an integer suffix like
-.B MiB
-can be useful. Example:
-.B "\-\-memory=80MiB"
-.IP \(bu 3
-The
-.I limit
-can be specified as a percentage of physical RAM. Example:
-.B "\-\-memory=70%"
-.IP \(bu 3
-The
-.I limit
-can be reset back to its default value by setting it to
-.BR 0 .
-.IP \(bu 3
-The memory usage limiting can be effectively disabled by setting
-.I limit
-to
-.BR max .
-This isn't recommended. It's usually better to use, for example,
-.BR \-\-memory=90% .
-.RE
-.IP
-The current
-.I limit
-can be seen near the bottom of the output of the
-.B \-\-help
-option.
-.TP
 .BR \-q ", " \-\-quiet
 Specifying this once does nothing since
 .B xzdec