src/suffix.c

   1 /* This file is part of GNU tar.
   2    Copyright 2007, 2009, 2013-2014, 2016-2017 Free Software Foundation,
   3    Inc.
   4
   5    Written by Sergey Poznyakoff.
   6
   7    GNU tar is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by the
   9    Free Software Foundation; either version 3, or (at your option) any later
  10    version.
  11
  12    GNU tar is distributed in the hope that it will be useful, but
  13    WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  15    Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License along
  18    with GNU tar.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include <system.h>
  21 #include "common.h"
  22
  23 struct compression_suffix
  24 {
  25   const char *suffix;
  26   size_t length;
  27   const char *program;
  28 };
  29
  30 static struct compression_suffix compression_suffixes[] = {
  31 #define __CAT2__(a,b) a ## b
  32 #define S(s,p) #s, sizeof (#s) - 1, __CAT2__(p,_PROGRAM)
  33   { "tar", 3, NULL },
  34   { S(gz,   GZIP) },
  35   { S(tgz,  GZIP) },
  36   { S(taz,  GZIP) },
  37   { S(Z,    COMPRESS) },
  38   { S(taZ,  COMPRESS) },
  39   { S(bz2,  BZIP2) },
  40   { S(tbz,  BZIP2) },
  41   { S(tbz2, BZIP2) },
  42   { S(tz2,  BZIP2) },
  43   { S(lz,   LZIP) },
  44   { S(lzma, LZMA) },
  45   { S(tlz,  LZMA) },
  46   { S(lzo,  LZOP) },
  47   { S(xz,   XZ) },
  48   { S(txz,  XZ) }, /* Slackware */
  49   { S(zst,  ZSTD) },
  50   { S(tzst, ZSTD) },
  51   { NULL }
  52 #undef S
  53 #undef __CAT2__
  54 };
  55
  56 static struct compression_suffix const *
  57 find_compression_suffix (const char *name, size_t *ret_len)
  58 {
  59   char *suf = strrchr (name, '.');
  60
  61   if (suf)
  62     {
  63       size_t len;
  64       struct compression_suffix *p;
  65
  66       suf++;
  67       len = strlen (suf);
  68
  69       for (p = compression_suffixes; p->suffix; p++)
  70         {
  71           if (p->length == len && memcmp (p->suffix, suf, len) == 0)
  72             {
  73               if (ret_len)
  74                 *ret_len = strlen (name) - len - 1;
  75               return p;
  76             }
  77         }
  78     }
  79   return NULL;
  80 }
  81
  82 static const char *
  83 find_compression_program (const char *name, const char *defprog)
  84 {
  85   struct compression_suffix const *p = find_compression_suffix (name, NULL);
  86   if (p)
  87     return p->program;
  88   return defprog;
  89 }
  90
  91 void
  92 set_compression_program_by_suffix (const char *name, const char *defprog)
  93 {
  94   const char *program = find_compression_program (name, defprog);
  95   if (program)
  96     use_compress_program_option = program;
  97 }
  98
  99 char *
 100 strip_compression_suffix (const char *name)
 101 {
 102   char *s = NULL;
 103   size_t len;
 104   struct compression_suffix const *p = find_compression_suffix (name, &len);
 105
 106   if (p)
 107     {
 108       /* Strip an additional ".tar" suffix, but only if the just-stripped
 109          "outer" suffix did not begin with "t".  */
 110       if (len > 4 && strncmp (name + len - 4, ".tar", 4) == 0
 111           && p->suffix[0] != 't')
 112         len -= 4;
 113       if (len == 0)
 114         return NULL;
 115       s = xmalloc (len + 1);
 116       memcpy (s, name, len);
 117       s[len] = 0;
 118     }
 119   return s;
 120 }