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

   1 /* Parse arguments from a string and prepend them to an argv.
   2    Copyright 1999, 2000 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 2, 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, write to the Free Software
  16    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  17    02111-1307, USA.  */
  18
  19 /* Written by Paul Eggert <eggert@twinsun.com>.  */
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24 #include "prepargs.h"
  25 #include <sys/types.h>
  26 #include <xalloc.h>
  27
  28 #include <ctype.h>
  29
  30 /* IN_CTYPE_DOMAIN (C) is nonzero if the unsigned char C can safely be given
  31    as an argument to <ctype.h> macros like "isspace".  */
  32 #ifdef STDC_HEADERS
  33 # define IN_CTYPE_DOMAIN(c) 1
  34 #else
  35 # define IN_CTYPE_DOMAIN(c) ((c) <= 0177)
  36 #endif
  37
  38 #define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
  39
  40 /* Find the white-space-separated options specified by OPTIONS, and
  41    using BUF to store copies of these options, set ARGV[0], ARGV[1],
  42    etc. to the option copies.  Return the number N of options found.
  43    Do not set ARGV[N].  If ARGV is null, do not store ARGV[0]
  44    etc.  Backslash can be used to escape whitespace (and backslashes).  */
  45 static int
  46 prepend_args (char const *options, char *buf, char **argv)
  47 {
  48   char const *o = options;
  49   char *b = buf;
  50   int n = 0;
  51
  52   for (;;)
  53     {
  54       while (ISSPACE ((unsigned char) *o))
  55         o++;
  56       if (!*o)
  57         return n;
  58       if (argv)
  59         argv[n] = b;
  60       n++;
  61
  62       do
  63         if ((*b++ = *o++) == '\\' && *o)
  64           b[-1] = *o++;
  65       while (*o && ! ISSPACE ((unsigned char) *o));
  66
  67       *b++ = '\0';
  68     }
  69 }
  70
  71 /* Prepend the whitespace-separated options in OPTIONS to the argument
  72    vector of a main program with argument count *PARGC and argument
  73    vector *PARGV.  */
  74 void
  75 prepend_default_options (char const *options, int *pargc, char ***pargv)
  76 {
  77   if (options)
  78     {
  79       char *buf = xmalloc (strlen (options) + 1);
  80       int prepended = prepend_args (options, buf, (char **) 0);
  81       int argc = *pargc;
  82       char * const *argv = *pargv;
  83       char **pp = (char **) xmalloc ((prepended + argc + 1) * sizeof *pp);
  84       *pargc = prepended + argc;
  85       *pargv = pp;
  86       *pp++ = *argv++;
  87       pp += prepend_args (options, buf, pp);
  88       while ((*pp++ = *argv++))
  89         continue;
  90     }
  91 }