contrib/diffutils/lib/prepargs.c

   1 /* Parse arguments from a string and prepend them to an argv.
   2
   3    Copyright (C) 1999-2002, 2006, 2009-2013 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation, either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert <eggert@twinsun.com>.  */
  19
  20 #include <config.h>
  21
  22 #include "prepargs.h"
  23 #include <string.h>
  24 #include <sys/types.h>
  25 #include <xalloc.h>
  26
  27 #include <ctype.h>
  28
  29 /* IN_CTYPE_DOMAIN (C) is nonzero if the unsigned char C can safely be given
  30    as an argument to <ctype.h> macros like "isspace".  */
  31 #ifdef STDC_HEADERS
  32 # define IN_CTYPE_DOMAIN(c) 1
  33 #else
  34 # define IN_CTYPE_DOMAIN(c) ((c) <= 0177)
  35 #endif
  36
  37 #define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
  38
  39 /* Find the white-space-separated options specified by OPTIONS, and
  40    using BUF to store copies of these options, set ARGV[0], ARGV[1],
  41    etc. to the option copies.  Return the number N of options found.
  42    Do not set ARGV[N].  If ARGV is zero, do not store ARGV[0] etc.
  43    Backslash can be used to escape whitespace (and backslashes).  */
  44 static int
  45 prepend_args (char const *options, char *buf, char **argv)
  46 {
  47   char const *o = options;
  48   char *b = buf;
  49   int n = 0;
  50
  51   for (;;)
  52     {
  53       while (ISSPACE ((unsigned char) *o))
  54         o++;
  55       if (!*o)
  56         return n;
  57       if (argv)
  58         argv[n] = b;
  59       n++;
  60
  61       do
  62         if ((*b++ = *o++) == '\\' && *o)
  63           b[-1] = *o++;
  64       while (*o && ! ISSPACE ((unsigned char) *o));
  65
  66       *b++ = '\0';
  67     }
  68 }
  69
  70 /* Prepend the whitespace-separated options in OPTIONS to the argument
  71    vector of a main program with argument count *PARGC and argument
  72    vector *PARGV.  */
  73 void
  74 prepend_default_options (char const *options, int *pargc, char ***pargv)
  75 {
  76   if (options)
  77     {
  78       char *buf = xmalloc (strlen (options) + 1);
  79       int prepended = prepend_args (options, buf, (char **) 0);
  80       int argc = *pargc;
  81       char * const *argv = *pargv;
  82       char **pp = xmalloc ((prepended + argc + 1) * sizeof *pp);
  83       *pargc = prepended + argc;
  84       *pargv = pp;
  85       *pp++ = *argv++;
  86       pp += prepend_args (options, buf, pp);
  87       while ((*pp++ = *argv++))
  88         continue;
  89     }
  90 }