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-rw-r--r--dos/INSTALL.txt (renamed from dos/README)13
-rw-r--r--dos/README.txt123
2 files changed, 125 insertions, 11 deletions
diff --git a/dos/README b/dos/INSTALL.txt
index 9456ea1f..26dc611c 100644
--- a/dos/README
+++ b/dos/INSTALL.txt
@@ -1,6 +1,6 @@
-XZ Utils on DOS
-===============
+Building XZ Utils for DOS
+=========================
Introduction
@@ -77,12 +77,3 @@ Building
are not built. Having e.g. xzdec.exe doesn't save much space compared
to xz.exe, because the DJGPP runtime makes the .exe quite big anyway.
-
-Bugs
-
- xz doesn't necessarily work in Dosbox. It should work in DOSEMU.
-
- Pressing Ctrl-c or Ctrl-Break won't remove the incomplete target file
- when running under Windows XP Command Prompt (something goes wrong
- with SIGINT handling). It works correctly under Windows 95/98/98SE/ME.
-
diff --git a/dos/README.txt b/dos/README.txt
new file mode 100644
index 00000000..0e8f6c08
--- /dev/null
+++ b/dos/README.txt
@@ -0,0 +1,123 @@
+
+XZ Utils on DOS
+===============
+
+DOS-specific filename handling
+
+ xz detects at runtime if long filename (LFN) support is
+ available and will use it by default. It can be disabled by
+ setting an environment variable:
+
+ set lfn=n
+
+ When xz is in LFN mode, it behaves pretty much the same as it
+ does on other operating systems. Examples:
+
+ xz foo.tar -> foo.tar.xz
+ xz -d foo.tar.xz -> foo.tar
+
+ xz -F lzma foo.tar -> foo.tar.lzma
+ xz -d foo.tar.lzma -> foo.tar
+
+ When LFN support isn't available or it is disabled with LFN=n
+ environment setting, xz works in short filename (SFN) mode. This
+ affects filename suffix handling when compressing.
+
+ When compressing to the .xz format in SFN mode:
+
+ - Files without an extension get .xz just like on LFN systems.
+
+ - *.tar files become *.txz (shorthand for *.tar.xz). *.txz
+ is recognized by xz on all supported operating systems.
+ (Try to avoid confusing this with gzipped .txt files.)
+
+ - Files with 1-3 character extension have their extension modified
+ so that the last character is a dash ("-"). If the extension
+ is already three characters, the last character is lost. The
+ resulting *.?- or *.??- filename is recognized in LFN mode, but
+ it isn't recognized by xz on other operating systems.
+
+ Examples:
+
+ xz foo -> foo.xz | xz -d foo.xz -> foo
+ xz foo.tar -> foo.txz | xz -d foo.txz -> foo.tar
+ xz foo.c -> foo.c- | xz -d foo.c- -> foo.c
+ xz read.me -> read.me- | xz -d read.me- -> read.me
+ xz foo.txt -> foo.tx- | xz -d foo.tx- -> foo.tx !
+
+ Note that in the last example above, the third character of the
+ filename extension is lost.
+
+ When compressing to the legacy .lzma format in SFN mode:
+
+ - *.tar files become *.tlz (shorthand for *.tar.lzma). *.tlz
+ is recognized by xz on all supported operating systems.
+
+ - Other files become *.lzm. The original filename extension
+ is lost. *.lzm is recognized also in LFN mode, but it is not
+ recognized by xz on other operating systems.
+
+ Examples:
+
+ xz -F lzma foo -> foo.lzm | xz -d foo.lzm -> foo
+ xz -F lzma foo.tar -> foo.tlz | xz -d foo.tlz -> foo.tar
+ xz -F lzma foo.c -> foo.lzm | xz -d foo.lzm -> foo !
+ xz -F lzma read.me -> read.lzm | xz -d read.lzm -> read !
+ xz -F lzma foo.txt -> foo.lzm | xz -d foo.lzm -> foo !
+
+ When compressing with a custom suffix (-S .SUF, --suffix=.SUF) to
+ any file format:
+
+ - If the suffix begins with a dot, the filename extension is
+ replaced with the new suffix. The original extension is lost.
+
+ - If the suffix doesn't begin with a dot and the filename has no
+ extension and the filename given on the command line doesn't
+ have a dot at the end, the custom suffix is appended just like
+ on LFN systems.
+
+ - If the suffix doesn't begin with a dot and the filename has
+ an extension (or an extension-less filename is given with a dot
+ at the end), the last 1-3 characters of the filename extension
+ may get overwritten to fit the given custom suffix.
+
+ Examples:
+
+ xz -S x foo -> foox | xz -dS x foox -> foo
+ xz -S x foo. -> foo.x | xz -dS x foo.x -> foo
+ xz -S .x foo -> foo.x | xz -dS .x foo.x -> foo
+ xz -S .x foo. -> foo.x | xz -dS .x foo.x -> foo
+ xz -S x.y foo -> foox.y | xz -dS x.y foox.y -> foo
+ xz -S .a foo.c -> foo.a | xz -dS .a foo.a -> foo !
+ xz -S a foo.c -> foo.ca | xz -dS a foo.ca -> foo.c
+ xz -S ab foo.c -> foo.cab | xz -dS ab foo.cab -> foo.c
+ xz -S ab read.me -> read.mab | xz -dS ab read.mab -> read.m !
+ xz -S ab foo.txt -> foo.tab | xz -dS ab foo.tab -> foo.t !
+ xz -S abc foo.txt -> foo.abc | xz -dS abc foo.abc -> foo !
+
+ When decompressing, the suffix handling in SFN mode is the same as
+ in LFN mode. The DOS-specific filenames *.lzm, *.?-, and *.??- are
+ recognized also in LFN mode.
+
+ xz handles certain uncommon situations safely:
+
+ - If the generated output filename refers to the same file as
+ the input file, xz detects this and refuses to compress or
+ decompress the input file even if --force is used. This can
+ happen when giving an overlong filename in SFN mode. E.g.
+ "xz -S x foo.texinfo" would try to write to foo.tex which on
+ SFN system is the same file as foo.texinfo.
+
+ - If the generated output filename is a special file like "con"
+ or "prn", xz detects this and refuses to compress or decompress
+ the input file even if --force is used.
+
+
+Bugs
+
+ xz doesn't necessarily work in Dosbox. It should work in DOSEMU.
+
+ Pressing Ctrl-c or Ctrl-Break won't remove the incomplete target file
+ when running under Windows XP Command Prompt (something goes wrong
+ with SIGINT handling). It works correctly under Windows 95/98/98SE/ME.
+