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, 13 insertions, 10 deletions

diff --git a/src/xz/hardware.h b/src/xz/hardware.h
index b2cf34cb..bed952b0 100644
--- a/src/xz/hardware.h
+++ b/src/xz/hardware.h
@@ -23,13 +23,16 @@ extern void hardware_threadlimit_set(uint32_t threadlimit);
 extern uint32_t hardware_threadlimit_get(void);
 
 
-/// Set custom memory usage limit. This is used for both encoding and
-/// decoding. Zero indicates resetting the limit back to defaults.
-extern void hardware_memlimit_set(uint64_t memlimit);
-
-/// Set custom memory usage limit as a percentage of installed RAM.
-/// The percentage must be in the range [1, 100].
-extern void hardware_memlimit_set_percentage(uint32_t percentage);
-
-/// Get the current memory usage limit.
-extern uint64_t hardware_memlimit_get(void);
+/// Set the memory usage limit. There are separate limits for compression
+/// and decompression (the latter includes also --list), one or both can
+/// be set with a single call to this function. Zero indicates resetting
+/// the limit back to the defaults. The limit can also be set as a percentage
+/// of installed RAM; the percentage must be in the range [1, 100].
+extern void hardware_memlimit_set(uint64_t new_memlimit,
+		bool set_compress, bool set_decompress, bool is_percentage);
+
+/// Get the current memory usage limit for compression or decompression.
+extern uint64_t hardware_memlimit_get(enum operation_mode mode);
+
+/// Display the amount of RAM and memory usage limits and exit.
+extern void hardware_memlimit_show(void) lzma_attribute((noreturn));