Dogcows Code - chaz/tar/blob - lib/prepargs.c

   1 /* Parse arguments from a string and prepend them to an argv.
   2    Copyright 1999-2001, 2007, 2013-2014 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Paul Eggert <eggert@twinsun.com>.  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22 #include "prepargs.h"
  23 #include <sys/types.h>
  24 #include <xalloc.h>
  25
  26 #if HAVE_STRING_H
  27 # include <string.h>
  28 #endif
  29
  30 #include <ctype.h>
  31
  32 /* Find the white-space-separated options specified by OPTIONS, and
  33    using BUF to store copies of these options, set ARGV[0], ARGV[1],
  34    etc. to the option copies.  Return the number N of options found.
  35    Do not set ARGV[N].  If ARGV is null, do not store ARGV[0]
  36    etc.  Backslash can be used to escape whitespace (and backslashes).  */
  37 static int
  38 prepend_args (char const *options, char *buf, char **argv)
  39 {
  40   char const *o = options;
  41   char *b = buf;
  42   int n = 0;
  43
  44   for (;;)
  45     {
  46       while (isspace ((unsigned char) *o))
  47         o++;
  48       if (!*o)
  49         return n;
  50       if (argv)
  51         argv[n] = b;
  52       n++;
  53
  54       do
  55         if ((*b++ = *o++) == '\\' && *o)
  56           b[-1] = *o++;
  57       while (*o && ! isspace ((unsigned char) *o));
  58
  59       *b++ = '\0';
  60     }
  61 }
  62
  63 /* Prepend the whitespace-separated options in OPTIONS to the argument
  64    vector of a main program with argument count *PARGC and argument
  65    vector *PARGV.  */
  66 void
  67 prepend_default_options (char const *options, int *pargc, char ***pargv)
  68 {
  69   if (options)
  70     {
  71       char *buf = xmalloc (strlen (options) + 1);
  72       int prepended = prepend_args (options, buf, (char **) 0);
  73       int argc = *pargc;
  74       char * const *argv = *pargv;
  75       char **pp = (char **) xmalloc ((prepended + argc + 1) * sizeof *pp);
  76       *pargc = prepended + argc;
  77       *pargv = pp;
  78       *pp++ = *argv++;
  79       pp += prepend_args (options, buf, pp);
  80       while ((*pp++ = *argv++))
  81         continue;
  82     }
  83 }