src/suffix.c

   1 /* This file is part of GNU tar.
   2    Copyright 2007-2024 Free Software Foundation, Inc.
   3
   4    Written by Sergey Poznyakoff.
   5
   6    GNU tar is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by the
   8    Free Software Foundation; either version 3, or (at your option) any later
   9    version.
  10
  11    GNU tar is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  14    Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License along
  17    with GNU tar.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <system.h>
  20 #include "common.h"
  21
  22 struct compression_suffix
  23 {
  24   const char *suffix;
  25   size_t length;
  26   const char *program;
  27 };
  28
  29 static struct compression_suffix compression_suffixes[] = {
  30 #define __CAT2__(a,b) a ## b
  31 #define S(s,p) #s, sizeof (#s) - 1, __CAT2__(p,_PROGRAM)
  32   { "tar", 3, NULL },
  33   { S(gz,   GZIP) },
  34   { S(z,    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(tzo,  LZOP) },
  48   { S(xz,   XZ) },
  49   { S(txz,  XZ) }, /* Slackware */
  50   { S(zst,  ZSTD) },
  51   { S(tzst, ZSTD) },
  52   { NULL }
  53 #undef S
  54 #undef __CAT2__
  55 };
  56
  57 /* Extract the suffix from archive file NAME, and return a pointer to
  58    compression_suffix associated with it or NULL if none is found.
  59    No matter what is the return value, if RET_LEN is not NULL, store
  60    there the length of NAME with that suffix stripped, or 0 if NAME has
  61    no suffix. */
  62 static struct compression_suffix const *
  63 find_compression_suffix (const char *name, size_t *ret_len)
  64 {
  65   char *suf = strrchr (name, '.');
  66
  67   if (suf && suf[1] != 0 && suf[1] != '/')
  68     {
  69       size_t len;
  70       struct compression_suffix *p;
  71
  72       suf++;
  73       len = strlen (suf);
  74       if (ret_len)
  75         *ret_len = strlen (name) - len - 1;
  76
  77       for (p = compression_suffixes; p->suffix; p++)
  78         {
  79           if (p->length == len && memcmp (p->suffix, suf, len) == 0)
  80             {
  81               return p;
  82             }
  83         }
  84     }
  85   else if (ret_len)
  86     *ret_len = 0;
  87   return NULL;
  88 }
  89
  90 /* Select compression program using the suffix of the archive file NAME.
  91    Use DEFPROG, if there is no suffix, or if no program is associated with
  92    the suffix.  In the latter case, if VERBOSE is true, issue a warning.
  93  */
  94 void
  95 set_compression_program_by_suffix (const char *name, const char *defprog,
  96                                    bool verbose)
  97 {
  98   size_t len;
  99   struct compression_suffix const *p = find_compression_suffix (name, &len);
 100   if (p)
 101     use_compress_program_option = p->program;
 102   else
 103     {
 104       use_compress_program_option = defprog;
 105       if (len > 0 && verbose)
 106         WARN ((0, 0,
 107                _("no compression program is defined for suffix '%s';"
 108                  " assuming %s"),
 109                name + len,
 110                defprog ? defprog : "uncompressed archive"));
 111     }
 112 }
 113
 114 char *
 115 strip_compression_suffix (const char *name)
 116 {
 117   char *s = NULL;
 118   size_t len;
 119   struct compression_suffix const *p = find_compression_suffix (name, &len);
 120
 121   if (p)
 122     {
 123       /* Strip an additional ".tar" suffix, but only if the just-stripped
 124          "outer" suffix did not begin with "t".  */
 125       if (len > 4 && strncmp (name + len - 4, ".tar", 4) == 0
 126           && p->suffix[0] != 't')
 127         len -= 4;
 128       if (len == 0)
 129         return NULL;
 130       s = xmalloc (len + 1);
 131       memcpy (s, name, len);
 132       s[len] = 0;
 133     }
 134   return s;
 135 }