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   char suffix[sizeof "tbz2"];  /* "tbz2" is tied for longest.  */
  25   char program[max (max (max (sizeof GZIP_PROGRAM, sizeof COMPRESS_PROGRAM),
  26                          max (sizeof BZIP2_PROGRAM, sizeof LZIP_PROGRAM)),
  27                     max (max (sizeof LZMA_PROGRAM, sizeof LZOP_PROGRAM),
  28                          max (sizeof XZ_PROGRAM, sizeof ZSTD_PROGRAM)))];
  29 };
  30
  31 static struct compression_suffix const compression_suffixes[] = {
  32 #define __CAT2__(a,b) a ## b
  33 #define S(s, p) #s, __CAT2__(p,_PROGRAM)
  34   { "tar", "" },
  35   { S(gz,   GZIP) },
  36   { S(z,    GZIP) },
  37   { S(tgz,  GZIP) },
  38   { S(taz,  GZIP) },
  39   { S(Z,    COMPRESS) },
  40   { S(taZ,  COMPRESS) },
  41   { S(bz2,  BZIP2) },
  42   { S(tbz,  BZIP2) },
  43   { S(tbz2, BZIP2) },
  44   { S(tz2,  BZIP2) },
  45   { S(lz,   LZIP) },
  46   { S(lzma, LZMA) },
  47   { S(tlz,  LZMA) },
  48   { S(lzo,  LZOP) },
  49   { S(tzo,  LZOP) },
  50   { S(xz,   XZ) },
  51   { S(txz,  XZ) }, /* Slackware */
  52   { S(zst,  ZSTD) },
  53   { S(tzst, ZSTD) },
  54 #undef S
  55 #undef __CAT2__
  56 };
  57
  58 /* Extract the suffix from archive file NAME, and return a pointer to
  59    compression_suffix associated with it or NULL if none is found.
  60    No matter what is the return value, if RET_LEN is not NULL, store
  61    there the length of NAME with that suffix stripped, or 0 if NAME has
  62    no suffix. */
  63 static struct compression_suffix const *
  64 find_compression_suffix (char const *name, idx_t *ret_len)
  65 {
  66   char const *suf = strrchr (name, '.');
  67
  68   if (suf && suf[1] != 0 && suf[1] != '/')
  69     {
  70       if (ret_len)
  71         *ret_len = suf - name;
  72       suf++;
  73
  74       for (struct compression_suffix const *p = compression_suffixes;
  75            p < (compression_suffixes
  76                 + sizeof compression_suffixes / sizeof *compression_suffixes);
  77            p++)
  78         if (strcmp (p->suffix, suf) == 0)
  79           return p;
  80     }
  81   else if (ret_len)
  82     *ret_len = 0;
  83   return NULL;
  84 }
  85
  86 /* Select compression program using the suffix of the archive file NAME.
  87    Use DEFPROG, if there is no suffix, or if no program is associated with
  88    the suffix.  In the latter case, if VERBOSE is true, issue a warning.
  89  */
  90 void
  91 set_compression_program_by_suffix (const char *name, const char *defprog,
  92                                    bool verbose)
  93 {
  94   idx_t len;
  95   struct compression_suffix const *p = find_compression_suffix (name, &len);
  96   if (p)
  97     use_compress_program_option = p->program[0] ? p->program : NULL;
  98   else
  99     {
 100       use_compress_program_option = defprog;
 101       if (len > 0 && verbose)
 102         paxwarn (0,
 103                  _("no compression program is defined for suffix '%s';"
 104                    " assuming %s"),
 105                  name + len,
 106                  defprog ? defprog : "uncompressed archive");
 107     }
 108 }
 109
 110 char *
 111 strip_compression_suffix (const char *name)
 112 {
 113   char *s = NULL;
 114   idx_t len;
 115   struct compression_suffix const *p = find_compression_suffix (name, &len);
 116
 117   if (p)
 118     {
 119       /* Strip an additional ".tar" suffix, but only if the just-stripped
 120          "outer" suffix did not begin with "t".  */
 121       if (len > 4 && strncmp (name + len - 4, ".tar", 4) == 0
 122           && p->suffix[0] != 't')
 123         len -= 4;
 124       if (len == 0)
 125         return NULL;
 126       s = xmalloc (len + 1);
 127       memcpy (s, name, len);
 128       s[len] = 0;
 129     }
 130   return s;
 131 }