[Bug-tar] [PATCH] ZSTD compression support.

[Adam Borowski]

Its customary file extension is ".zst", while some tools use ".tzst" as a
shorthand for ".tar.zst".
---
Not sure what/if a short option would be appropriate.

 configure.ac |  1 +
 doc/tar.1    |  4 ++++
 doc/tar.texi | 12 ++++++++++--
 src/buffer.c |  5 ++++-
 src/suffix.c |  2 ++
 src/tar.c    | 12 +++++++++++-
 6 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/configure.ac b/configure.ac
index e89ed1d..42c892c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -250,6 +250,7 @@ TAR_COMPR_PROGRAM(lzip)
 TAR_COMPR_PROGRAM(lzma)
 TAR_COMPR_PROGRAM(lzop)
 TAR_COMPR_PROGRAM(xz)
+TAR_COMPR_PROGRAM(zstd)
 
 AC_MSG_CHECKING(for default archive format)
 
diff --git a/doc/tar.1 b/doc/tar.1
index f5c1fca..b140446 100644
--- a/doc/tar.1
+++ b/doc/tar.1
@@ -828,6 +828,10 @@ Filter the archive through
 \fB\-Z\fR, \fB\-\-compress\fR, \fB\-\-uncompress\fR
 Filter the archive through
 .BR compress (1).
+.TP
+\fB\-\-zstd\fR
+Filter the archive through
+.BR zstd (1).
 .SS Local file selection
 .TP
 \fB\-\-add\-file\fR=\fIFILE\fR
diff --git a/doc/tar.texi b/doc/tar.texi
index 64d1268..a5f66e0 100644
--- a/doc/tar.texi
+++ b/doc/tar.texi
@@ -3713,6 +3713,10 @@ only attributes from the user namespace.
 @itemx -J
 Use @command{xz} for compressing or decompressing the archives.  @xref{gzip}.
 
address@hidden
address@hidden --zstd
+Use @command{zstd} for compressing or decompressing the archives.  @xref{gzip}.
+
 @end table
 
 @node Short Option Summary
@@ -9569,6 +9573,7 @@ switch to @samp{posix}.
 @cindex lzma
 @cindex lzop
 @cindex compress
address@hidden zstd
 @GNUTAR{} is able to create and read compressed archives.  It supports
 a wide variety of compression programs, namely: @command{gzip},
 @command{bzip2}, @command{lzip}, @command{lzma}, @command{lzop},
@@ -9585,8 +9590,9 @@ create a @command{gzip} compressed archive, @option{-j}
 @option{--lzip} to create an @asis{lzip} compressed archive,
 @option{-J} (@option{--xz}) to create an @asis{XZ} archive,
 @option{--lzma} to create an @asis{LZMA} compressed
-archive, @option{--lzop} to create an @asis{LSOP} archive, and
address@hidden (@option{--compress}) to use @command{compress} program.
+archive, @option{--lzop} to create an @asis{LSOP} archive,
address@hidden (@option{--compress}) to use @command{compress} program,
+and @option{--zstd} to create a @asis{ZSTD} archive.
 For example:
 
 @smallexample
@@ -9779,6 +9785,8 @@ suffix.  The following suffixes are recognized:
 @item @samp{.tlz} @tab @command{lzma}
 @item @samp{.lzo} @tab @command{lzop}
 @item @samp{.xz} @tab @command{xz}
address@hidden @samp{.zst} @tab @command{zstd}
address@hidden @samp{.tzst} @tab @command{zstd}
 @end multitable
 
 @anchor{use-compress-program}
diff --git a/src/buffer.c b/src/buffer.c
index 6f96c2f..94d30c8 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -281,7 +281,8 @@ enum compress_type {
   ct_lzip,
   ct_lzma,
   ct_lzop,
-  ct_xz
+  ct_xz,
+  ct_zstd
 };
 
 static enum compress_type archive_compression_type = ct_none;
@@ -310,6 +311,7 @@ static struct zip_magic const magic[] = {
   { ct_lzma,     6, "\xFFLZMA" },
   { ct_lzop,     4, "\211LZO" },
   { ct_xz,       6, "\xFD" "7zXZ" },
+  { ct_zstd,     4, "\x28\xB5\x2F\xFD" },
 };
 
 #define NMAGIC (sizeof(magic)/sizeof(magic[0]))
@@ -325,6 +327,7 @@ static struct zip_program zip_program[] = {
   { ct_lzma,     XZ_PROGRAM,       "-J" },
   { ct_lzop,     LZOP_PROGRAM,     "--lzop" },
   { ct_xz,       XZ_PROGRAM,       "-J" },
+  { ct_zstd,     ZSTD_PROGRAM,     "--zstd" },
   { ct_none }
 };
 
diff --git a/src/suffix.c b/src/suffix.c
index 47027e7..66b5694 100644
--- a/src/suffix.c
+++ b/src/suffix.c
@@ -46,6 +46,8 @@ static struct compression_suffix compression_suffixes[] = {
   { S(lzo,  LZOP) },
   { S(xz,   XZ) },
   { S(txz,  XZ) }, /* Slackware */
+  { S(zst,  ZSTD) },
+  { S(tzst, ZSTD) },
   { NULL }
 #undef S
 #undef __CAT2__
diff --git a/src/tar.c b/src/tar.c
index 2a5f86e..a440590 100644
--- a/src/tar.c
+++ b/src/tar.c
@@ -348,7 +348,8 @@ enum
   WARNING_OPTION,
   XATTR_OPTION,
   XATTR_EXCLUDE,
-  XATTR_INCLUDE
+  XATTR_INCLUDE,
+  ZSTD_OPTION,
 };
 
 static char const doc[] = N_("\
@@ -682,6 +683,7 @@ static struct argp_option options[] = {
   {"lzma", LZMA_OPTION, 0, 0, NULL, GRID+1 },
   {"lzop", LZOP_OPTION, 0, 0, NULL, GRID+1 },
   {"xz", 'J', 0, 0, NULL, GRID+1 },
+  {"zstd", ZSTD_OPTION, 0, 0, NULL, GRID+1 },
 #undef GRID
 
 #define GRID 100
@@ -1129,6 +1131,10 @@ tar_help_filter (int key, const char *text, void *input)
       s = xasprintf (_("filter the archive through %s"), XZ_PROGRAM);
       break;
 
+    case ZSTD_OPTION:
+      s = xasprintf (_("filter the archive through %s"), ZSTD_PROGRAM);
+      break;
+
     case ARGP_KEY_HELP_EXTRA:
       {
        const char *tstr;
@@ -1652,6 +1658,10 @@ parse_opt (int key, char *arg, struct argp_state *state)
       set_use_compress_program_option (COMPRESS_PROGRAM, args->loc);
       break;
 
+    case ZSTD_OPTION:
+      set_use_compress_program_option (ZSTD_PROGRAM, args->loc);
+      break;
+
     case ATIME_PRESERVE_OPTION:
       atime_preserve_option =
        (arg
-- 
2.15.0