xref: /dragonfly/contrib/diffutils/lib/prepargs.c (revision 4d0c54c1)
1 /* Parse arguments from a string and prepend them to an argv.
2 
3    Copyright (C) 1999-2002, 2006, 2009-2011 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 }
91