Update XZ Utils to 5.0.4 (third_party)

doc/faq.txt

 
 XZ Utils FAQ
 ============
 
 Q:  What do the letters XZ mean?
 
 A:  Nothing. They are just two letters, which come from the file format
     suffix .xz. The .xz suffix was selected, because it seemed to be
     pretty much unused. It has no deeper meaning.
 
 
 Q:  What are LZMA and LZMA2?
 
 A:  LZMA stands for Lempel-Ziv-Markov chain-Algorithm. It is the name
     of the compression algorithm designed by Igor Pavlov for 7-Zip.
     LZMA is based on LZ77 and range encoding.
 
     LZMA2 is an updated version of the original LZMA to fix a couple of
     practical issues. In context of XZ Utils, LZMA is called LZMA1 to
     emphasize that LZMA is not the same thing as LZMA2. LZMA2 is the
     primary compression algorithm in the .xz file format.
 
 
 Q:  There are many LZMA related projects. How does XZ Utils relate to them?
 
 A:  7-Zip and LZMA SDK are the original projects. LZMA SDK is roughly
     a subset of the 7-Zip source tree.
 
-    p7zip is 7-Zip's command line tools ported to POSIX-like systems.
+    p7zip is 7-Zip's command-line tools ported to POSIX-like systems.
 
     LZMA Utils provide a gzip-like lzma tool for POSIX-like systems.
     LZMA Utils are based on LZMA SDK. XZ Utils are the successor to
     LZMA Utils.
 
     There are several other projects using LZMA. Most are more or less
     based on LZMA SDK. See <http://7-zip.org/links.html>.
 
 
 Q:  Why is liblzma named liblzma if its primary file format is .xz?
     Shouldn't it be e.g. libxz?
 
 A:  When the designing of the .xz format began, the idea was to replace
     the .lzma format and use the same .lzma suffix. It would have been
     quite OK to reuse the suffix when there were very few .lzma files
-    around. However, the old .lzma format become popular before the
+    around. However, the old .lzma format became popular before the
     new format was finished. The new format was renamed to .xz but the
     name of liblzma wasn't changed.
 
 
 Q:  Do XZ Utils support the .7z format?
 
 A:  No. Use 7-Zip (Windows) or p7zip (POSIX-like systems) to handle .7z
     files.
 
 
@@ skipping 10 matching lines @@
 
 Q:  I have many .lzma files. Can I quickly convert them to the .xz format?
 
 A:  For now, no. Since XZ Utils supports the .lzma format, it's usually
     not too bad to keep the old files in the old format. If you want to
     do the conversion anyway, you need to decompress the .lzma files and
     then recompress to the .xz format.
 
     Technically, there is a way to make the conversion relatively fast
     (roughly twice the time that normal decompression takes). Writing
-    such a tool would take quite a bit time though, and would probably
+    such a tool would take quite a bit of time though, and would probably
     be useful to only a few people. If you really want such a conversion
     tool, contact Lasse Collin and offer some money.
 
 
 Q:  I have installed xz, but my tar doesn't recognize .tar.xz files.
     How can I extract .tar.xz files?
 
 A:  xz -dc foo.tar.xz | tar xf -
 
 
-Q:  Can I recover parts of a broken .xz file (e.g. corrupted CD-R)?
+Q:  Can I recover parts of a broken .xz file (e.g. a corrupted CD-R)?
 
 A:  It may be possible if the file consists of multiple blocks, which
     typically is not the case if the file was created in single-threaded
     mode. There is no recovery program yet.
 
 
 Q:  Is (some part of) XZ Utils patented?
 
 A:  Lasse Collin is not aware of any patents that could affect XZ Utils.
-    However, due to nature of software patents, it's not possible to
+    However, due to the nature of software patents, it's not possible to
     guarantee that XZ Utils isn't affected by any third party patent(s).
 
 
 Q:  Where can I find documentation about the file format and algorithms?
 
 A:  The .xz format is documented in xz-file-format.txt. It is a container
     format only, and doesn't include descriptions of any non-trivial
     filters.
 
     Documenting LZMA and LZMA2 is planned, but for now, there is no other
-    documentation that the source code. Before you begin, you should know
-    the basics of LZ77 and range coding algorithms. LZMA is based on LZ77,
+    documentation than the source code. Before you begin, you should know
+    the basics of LZ77 and range-coding algorithms. LZMA is based on LZ77,
     but LZMA is a lot more complex. Range coding is used to compress
     the final bitstream like Huffman coding is used in Deflate.
 
 
 Q:  I cannot find BCJ and BCJ2 filters. Don't they exist in liblzma?
 
 A:  BCJ filter is called "x86" in liblzma. BCJ2 is not included,
     because it requires using more than one encoded output stream.
     A streamable version of BCJ2-style filtering is planned.
 
@@ skipping 21 matching lines @@
 A:  See the documentation in XZ Embedded. In short, something like
     this is a good start:
 
         xz --check=crc32 --lzma2=preset=6e,dict=64KiB
 
     Or if a BCJ filter is needed too, e.g. if compressing
     a kernel image for PowerPC:
 
         xz --check=crc32 --powerpc --lzma2=preset=6e,dict=64KiB
 
-    Adjust dictionary size to get a good compromise between
+    Adjust the dictionary size to get a good compromise between
     compression ratio and decompressor memory usage. Note that
     in single-call decompression mode of XZ Embedded, a big
     dictionary doesn't increase memory usage.
 
 
 Q:  Will xz support threaded compression?
 
 A:  It is planned and has been taken into account when designing
     the .xz file format. Eventually there will probably be three types
     of threading, each method having its own advantages and disadvantages.
@@ skipping 15 matching lines @@
     Match finder parallelization is another threading method. It has
     been in 7-Zip for ages. It doesn't affect compression ratio or
     memory usage significantly. Among the three threading methods, only
     this is useful when compressing small files (files that are not
     significantly bigger than the dictionary). Unfortunately this method
     scales only to about two CPU cores.
 
     The third method is pigz-style threading (I use that name, because
     pigz <http://www.zlib.net/pigz/> uses that method). It doesn't
     affect compression ratio significantly and scales to many cores.
-    The memory usage scales linearly when threads are added. It isn't
-    significant with pigz, because Deflate uses only 32 KiB dictionary,
+    The memory usage scales linearly when threads are added. This isn't
+    significant with pigz, because Deflate uses only a 32 KiB dictionary,
     but with LZMA2 the memory usage will increase dramatically just like
-    with the independent blocks method. There is also a constant
+    with the independent-blocks method. There is also a constant
     computational overhead, which may make pigz-method a bit dull on
     dual-core compared to the parallel match finder method, but with more
     cores the overhead is not a big deal anymore.
 
     Combining the threading methods will be possible and also useful.
     E.g. combining match finder parallelization with pigz-style threading
     can cut the memory usage by 50 %.
 
     It is possible that the single-threaded method will be modified to
-    create files indentical to the pigz-style method. We'll see once
+    create files identical to the pigz-style method. We'll see once
     pigz-style threading has been implemented in liblzma.
 
 
 Q:  How do I build a program that needs liblzmadec (lzmadec.h)?
 
 A:  liblzmadec is part of LZMA Utils. XZ Utils has liblzma, but no
     liblzmadec. The code using liblzmadec should be ported to use
     liblzma instead. If you cannot or don't want to do that, download
     LZMA Utils from <http://tukaani.org/lzma/>.
 
 
 Q:  The default build of liblzma is too big. How can I make it smaller?
 
 A:  Give --enable-small to the configure script. Use also appropriate
     --enable or --disable options to include only those filter encoders
     and decoders and integrity checks that you actually need. Use
     CFLAGS=-Os (with GCC) or equivalent to tell your compiler to optimize
     for size. See INSTALL for information about configure options.
 
     If the result is still too big, take a look at XZ Embedded. It is
     a separate project, which provides a limited but significantly
     smaller XZ decoder implementation than XZ Utils. You can find it
     at <http://tukaani.org/xz/embedded.html>.