src/suffix.c

   1 /* This file is part of GNU tar.
   2    Copyright 2007-2022 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(tgz,  GZIP) },
  35   { S(taz,  GZIP) },
  36   { S(Z,    COMPRESS) },
  37   { S(taZ,  COMPRESS) },
  38   { S(bz2,  BZIP2) },
  39   { S(tbz,  BZIP2) },
  40   { S(tbz2, BZIP2) },
  41   { S(tz2,  BZIP2) },
  42   { S(lz,   LZIP) },
  43   { S(lzma, LZMA) },
  44   { S(tlz,  LZMA) },
  45   { S(lzo,  LZOP) },
  46   { S(xz,   XZ) },
  47   { S(txz,  XZ) }, /* Slackware */
  48   { S(zst,  ZSTD) },
  49   { S(tzst, ZSTD) },
  50   { NULL }
  51 #undef S
  52 #undef __CAT2__
  53 };
  54
  55 static struct compression_suffix const *
  56 find_compression_suffix (const char *name, size_t *ret_len)
  57 {
  58   char *suf = strrchr (name, '.');
  59
  60   if (suf)
  61     {
  62       size_t len;
  63       struct compression_suffix *p;
  64
  65       suf++;
  66       len = strlen (suf);
  67
  68       for (p = compression_suffixes; p->suffix; p++)
  69         {
  70           if (p->length == len && memcmp (p->suffix, suf, len) == 0)
  71             {
  72               if (ret_len)
  73                 *ret_len = strlen (name) - len - 1;
  74               return p;
  75             }
  76         }
  77     }
  78   return NULL;
  79 }
  80
  81 static const char *
  82 find_compression_program (const char *name, const char *defprog)
  83 {
  84   struct compression_suffix const *p = find_compression_suffix (name, NULL);
  85   if (p)
  86     return p->program;
  87   return defprog;
  88 }
  89
  90 void
  91 set_compression_program_by_suffix (const char *name, const char *defprog)
  92 {
  93   const char *program = find_compression_program (name, defprog);
  94   if (program)
  95     use_compress_program_option = program;
  96 }
  97
  98 char *
  99 strip_compression_suffix (const char *name)
 100 {
 101   char *s = NULL;
 102   size_t len;
 103   struct compression_suffix const *p = find_compression_suffix (name, &len);
 104
 105   if (p)
 106     {
 107       /* Strip an additional ".tar" suffix, but only if the just-stripped
 108          "outer" suffix did not begin with "t".  */
 109       if (len > 4 && strncmp (name + len - 4, ".tar", 4) == 0
 110           && p->suffix[0] != 't')
 111         len -= 4;
 112       if (len == 0)
 113         return NULL;
 114       s = xmalloc (len + 1);
 115       memcpy (s, name, len);
 116       s[len] = 0;
 117     }
 118   return s;
 119 }