add zcat symlink support, suggested by @wtarreau

added some test
also updated relevant doc

+ fixed a mistake in `lz4` symlink support :
  lz4 utility doesn't remove source files by default (like zstd, but unlike gzip).
  The symlink must behave the same.

Makefile

@@ -72,14 +72,18 @@ zstdmt:
 zlibwrapper:
 	$(MAKE) -C $(ZWRAPDIR) test
 
-.PHONY: check
+.PHONY: test
-check: shortest
+test:
-
-.PHONY: test shortest
-test shortest:
 	$(MAKE) -C $(PRGDIR) allVariants MOREFLAGS+="-g -DZSTD_DEBUG=1"
 	$(MAKE) -C $(TESTDIR) $@
 
+.PHONY: shortest
+shortest:
+	$(MAKE) -C $(TESTDIR) $@
+
+.PHONY: check
+check: shortest
+
 .PHONY: examples
 examples:
 	CPPFLAGS=-I../lib LDFLAGS=-L../lib $(MAKE) -C examples/ all

programs/README.md

@@ -11,44 +11,14 @@ There are however other Makefile targets that create different variations of CLI
 
 
 #### Compilation variables
-`zstd` scope can be altered by modifying the following compilation variables :
+`zstd` scope can be altered by modifying the following `make` variables :
 
 - __HAVE_THREAD__ : multithreading is automatically enabled when `pthread` is detected.
-  It's possible to disable multithread support, by setting HAVE_THREAD=0 .
+  It's possible to disable multithread support, by setting `HAVE_THREAD=0`.
-  Example : make zstd HAVE_THREAD=0
+  Example : `make zstd HAVE_THREAD=0`
-  It's also possible to force compilation with multithread support, using HAVE_THREAD=1.
+  It's also possible to force multithread support, using `HAVE_THREAD=1`.
-  In which case, linking stage will fail if `pthread` library cannot be found.
+  In which case, linking stage will fail if neither `pthread` nor `windows.h` library can be found.
-  This might be useful to prevent silent feature disabling.
+  This is useful to ensure this feature is not silently disabled.
-
-- __HAVE_ZLIB__ : `zstd` can compress and decompress files in `.gz` format.
-  This is ordered through command `--format=gzip`.
-  Alternatively, symlinks named `gzip` or `gunzip` will mimic intended behavior.
-  `.gz` support is automatically enabled when `zlib` library is detected at build time.
-  It's possible to disable `.gz` support, by setting HAVE_ZLIB=0.
-  Example : make zstd HAVE_ZLIB=0
-  It's also possible to force compilation with zlib support, using HAVE_ZLIB=1.
-  In which case, linking stage will fail if `zlib` library cannot be found.
-  This might be useful to prevent silent feature disabling.
-
-- __HAVE_LZMA__ : `zstd` can compress and decompress files in `.xz` and `.lzma` formats.
-  This is ordered through commands `--format=xz` and `--format=lzma` respectively.
-  Alternatively, symlinks named `xz`, `unxz`, `lzma`, or `unlzma` will mimic intended behavior.
-  `.xz` and `.lzma` support is automatically enabled when `lzma` library is detected at build time.
-  It's possible to disable `.xz` and `.lzma` support, by setting HAVE_LZMA=0 .
-  Example : make zstd HAVE_LZMA=0
-  It's also possible to force compilation with lzma support, using HAVE_LZMA=1.
-  In which case, linking stage will fail if `lzma` library cannot be found.
-  This might be useful to prevent silent feature disabling.
-
-- __HAVE_LZ4__ : `zstd` can compress and decompress files in `.lz4` formats.
-  This is ordered through commands `--format=lz4`.
-  Alternatively, symlinks named `lz4`, or `unlz4` will mimic intended behavior.
-  `.lz4` support is automatically enabled when `lz4` library is detected at build time.
-  It's possible to disable `.lz4` support, by setting HAVE_LZ4=0 .
-  Example : make zstd HAVE_LZ4=0
-  It's also possible to force compilation with lz4 support, using HAVE_LZ4=1.
-  In which case, linking stage will fail if `lz4` library cannot be found.
-  This might be useful to prevent silent feature disabling.
 
 - __ZSTD_LEGACY_SUPPORT__ : `zstd` can decompress files compressed by older versions of `zstd`.
   Starting v0.8.0, all versions of `zstd` produce frames compliant with the [specification](../doc/zstd_compression_format.md), and are therefore compatible.
@@ -61,11 +31,54 @@ There are however other Makefile targets that create different variations of CLI
   if `ZSTD_LEGACY_SUPPORT >= 8`, it's the same as `0`, since there is no legacy format after `7`.
   Note : `zstd` only supports decoding older formats, and cannot generate any legacy format.
 
+- __HAVE_ZLIB__ : `zstd` can compress and decompress files in `.gz` format.
+  This is ordered through command `--format=gzip`.
+  Alternatively, symlinks named `gzip` or `gunzip` will mimic intended behavior.
+  `.gz` support is automatically enabled when `zlib` library is detected at build time.
+  It's possible to disable `.gz` support, by setting `HAVE_ZLIB=0`.
+  Example : `make zstd HAVE_ZLIB=0`
+  It's also possible to force compilation with zlib support, `using HAVE_ZLIB=1`.
+  In which case, linking stage will fail if `zlib` library cannot be found.
+  This is useful to prevent silent feature disabling.
+
+- __HAVE_LZMA__ : `zstd` can compress and decompress files in `.xz` and `.lzma` formats.
+  This is ordered through commands `--format=xz` and `--format=lzma` respectively.
+  Alternatively, symlinks named `xz`, `unxz`, `lzma`, or `unlzma` will mimic intended behavior.
+  `.xz` and `.lzma` support is automatically enabled when `lzma` library is detected at build time.
+  It's possible to disable `.xz` and `.lzma` support, by setting `HAVE_LZMA=0` .
+  Example : `make zstd HAVE_LZMA=0`
+  It's also possible to force compilation with lzma support, using `HAVE_LZMA=1`.
+  In which case, linking stage will fail if `lzma` library cannot be found.
+  This is useful to prevent silent feature disabling.
+
+- __HAVE_LZ4__ : `zstd` can compress and decompress files in `.lz4` formats.
+  This is ordered through commands `--format=lz4`.
+  Alternatively, symlinks named `lz4`, or `unlz4` will mimic intended behavior.
+  `.lz4` support is automatically enabled when `lz4` library is detected at build time.
+  It's possible to disable `.lz4` support, by setting `HAVE_LZ4=0` .
+  Example : `make zstd HAVE_LZ4=0`
+  It's also possible to force compilation with lz4 support, using `HAVE_LZ4=1`.
+  In which case, linking stage will fail if `lz4` library cannot be found.
+  This is useful to prevent silent feature disabling.
+
 
 #### Aggregation of parameters
 CLI supports aggregation of parameters i.e. `-b1`, `-e18`, and `-i1` can be joined into `-b1e18i1`.
 
 
+#### Symlink shortcuts
+It's possible to invoke `zstd` through a symlink.
+When the name of the symlink has a specific value, it triggers an associated behavior.
+- `zstdmt` : compress using all cores available on local system.
+- `zcat` : will decompress and output target file using any of the supported formats. `gzcat` and `zstdcat` are also equivalent.
+- `gzip` : if zlib support is enabled, will mimic `gzip` by compressing file using `.gz` format, removing source file by default (use `--keep` to preserve). If zlib is not supported, triggers an error.
+- `xz` : if lzma support is enabled, will mimic `xz` by compressing file using `.xz` format, removing source file by default (use `--keep` to preserve). If xz is not supported, triggers an error.
+- `lzma` : if lzma support is enabled, will mimic `lzma` by compressing file using `.lzma` format, removing source file by default (use `--keep` to preserve). If lzma is not supported, triggers an error.
+- `lz4` : if lz4 support is enabled, will mimic `lz4` by compressing file using `.lz4` format. If lz4 is not supported, triggers an error.
+- `unzstd` and `unlz4` will decompress any of the supported format.
+- `ungz`, `unxz` and `unlzma` will do the same, and will also remove source file by default (use `--keep` to preserve).
+
+
 #### Dictionary builder in Command Line Interface
 Zstd offers a training mode, which can be used to tune the algorithm for a selected
 type of data, by providing it with a few samples. The result of the training is stored
@@ -202,8 +215,3 @@ The below table illustrates this on the [Silesia compression corpus].
 | `zstd -5 --long` | `3.319` | `51.7 MB/s` | `371.9 MB/s` |
 | `zstd -10` | `3.523`    | `16.4 MB/s`   | `489.2 MB/s`  |
 | `zstd -10 --long`| `3.566` | `16.2 MB/s` | `415.7 MB/s`  |
-
-
-
-
-

programs/zstdcli.c

@@ -54,6 +54,7 @@
 #define ZSTD_ZSTDMT "zstdmt"
 #define ZSTD_UNZSTD "unzstd"
 #define ZSTD_CAT "zstdcat"
+#define ZSTD_ZCAT "zcat"
 #define ZSTD_GZ "gzip"
 #define ZSTD_GUNZIP "gunzip"
 #define ZSTD_GZCAT "gzcat"
@@ -423,16 +424,17 @@ int main(int argCount, const char* argv[])
     /* preset behaviors */
     if (exeNameMatch(programName, ZSTD_ZSTDMT)) nbThreads=0;
     if (exeNameMatch(programName, ZSTD_UNZSTD)) operation=zom_decompress;
-    if (exeNameMatch(programName, ZSTD_CAT)) { operation=zom_decompress; forceStdout=1; FIO_overwriteMode(); outFileName=stdoutmark; g_displayLevel=1; }
+    if (exeNameMatch(programName, ZSTD_CAT)) { operation=zom_decompress; forceStdout=1; FIO_overwriteMode(); outFileName=stdoutmark; g_displayLevel=1; }   /* supports multiple formats */
+    if (exeNameMatch(programName, ZSTD_ZCAT)) { operation=zom_decompress; forceStdout=1; FIO_overwriteMode(); outFileName=stdoutmark; g_displayLevel=1; }  /* behave like zcat, also supports multiple formats */
     if (exeNameMatch(programName, ZSTD_GZ)) { suffix = GZ_EXTENSION; FIO_setCompressionType(FIO_gzipCompression); FIO_setRemoveSrcFile(1); }               /* behave like gzip */
-    if (exeNameMatch(programName, ZSTD_GUNZIP)) { operation=zom_decompress; FIO_setRemoveSrcFile(1); }                                          /* behave like gunzip */
+    if (exeNameMatch(programName, ZSTD_GUNZIP)) { operation=zom_decompress; FIO_setRemoveSrcFile(1); }                                                     /* behave like gunzip, also supports multiple formats */
-    if (exeNameMatch(programName, ZSTD_GZCAT)) { operation=zom_decompress; forceStdout=1; FIO_overwriteMode(); outFileName=stdoutmark; g_displayLevel=1; }  /* behave like gzcat */
+    if (exeNameMatch(programName, ZSTD_GZCAT)) { operation=zom_decompress; forceStdout=1; FIO_overwriteMode(); outFileName=stdoutmark; g_displayLevel=1; } /* behave like gzcat, also supports multiple formats */
     if (exeNameMatch(programName, ZSTD_LZMA)) { suffix = LZMA_EXTENSION; FIO_setCompressionType(FIO_lzmaCompression); FIO_setRemoveSrcFile(1); }           /* behave like lzma */
-    if (exeNameMatch(programName, ZSTD_UNLZMA)) { operation=zom_decompress; FIO_setCompressionType(FIO_lzmaCompression); FIO_setRemoveSrcFile(1); }    /* behave like unlzma */
+    if (exeNameMatch(programName, ZSTD_UNLZMA)) { operation=zom_decompress; FIO_setCompressionType(FIO_lzmaCompression); FIO_setRemoveSrcFile(1); }        /* behave like unlzma, also supports multiple formats */
     if (exeNameMatch(programName, ZSTD_XZ)) { suffix = XZ_EXTENSION; FIO_setCompressionType(FIO_xzCompression); FIO_setRemoveSrcFile(1); }                 /* behave like xz */
-    if (exeNameMatch(programName, ZSTD_UNXZ)) { operation=zom_decompress; FIO_setCompressionType(FIO_xzCompression); FIO_setRemoveSrcFile(1); }    /* behave like unxz */
+    if (exeNameMatch(programName, ZSTD_UNXZ)) { operation=zom_decompress; FIO_setCompressionType(FIO_xzCompression); FIO_setRemoveSrcFile(1); }            /* behave like unxz, also supports multiple formats */
-    if (exeNameMatch(programName, ZSTD_LZ4)) { suffix = LZ4_EXTENSION; FIO_setCompressionType(FIO_lz4Compression); FIO_setRemoveSrcFile(1); }    /* behave like xz */
+    if (exeNameMatch(programName, ZSTD_LZ4)) { suffix = LZ4_EXTENSION; FIO_setCompressionType(FIO_lz4Compression); }                                       /* behave like lz4 */
-    if (exeNameMatch(programName, ZSTD_UNLZ4)) { operation=zom_decompress; FIO_setCompressionType(FIO_lz4Compression); FIO_setRemoveSrcFile(1); }    /* behave like unxz */
+    if (exeNameMatch(programName, ZSTD_UNLZ4)) { operation=zom_decompress; FIO_setCompressionType(FIO_lz4Compression); }                                   /* behave like unlz4, also supports multiple formats */
     memset(&compressionParams, 0, sizeof(compressionParams));
 
     /* command switches */

tests/.gitignore

@@ -24,6 +24,8 @@ pool
 poolTests
 invalidDictionaries
 checkTag
+zcat
+zstdcat
 
 # Tmp test directory
 zstdtest
@@ -53,6 +55,7 @@ tmp*
 *.gz
 result
 out
+*.zstd
 
 # fuzzer
 afl

tests/playTests.sh

@@ -239,8 +239,18 @@ $ZSTD -c hello.tmp > hello.zstd --no-check
 $ZSTD -c world.tmp > world.zstd --no-check
 cat hello.zstd world.zstd > helloworld.zstd
 $ZSTD -dc helloworld.zstd > result.tmp
-cat result.tmp
 $DIFF helloworld.tmp result.tmp
+$ECHO "testing zstdcat symlink"
+ln -sf $ZSTD zstdcat
+./zstdcat helloworld.zstd > result.tmp
+$DIFF helloworld.tmp result.tmp
+rm zstdcat
+rm result.tmp
+$ECHO "testing zcat symlink"
+ln -sf $ZSTD zcat
+./zcat helloworld.zstd > result.tmp
+$DIFF helloworld.tmp result.tmp
+rm zcat
 rm ./*.tmp ./*.zstd
 $ECHO "frame concatenation tests completed"