xref: /freebsd/contrib/diff/lib/prepargs.c (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1 /* Parse arguments from a string and prepend them to an argv.
2 
3    Copyright (C) 1999, 2000, 2001, 2002 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 2, or (at your option)
8    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, write to the Free Software
17    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
18    02111-1307, USA.  */
19 
20 /* Written by Paul Eggert <eggert@twinsun.com>.  */
21 
22 #ifdef HAVE_CONFIG_H
23 # include <config.h>
24 #endif
25 #include "prepargs.h"
26 #include <string.h>
27 #include <sys/types.h>
28 #include <xalloc.h>
29 
30 #include <ctype.h>
31 
32 /* IN_CTYPE_DOMAIN (C) is nonzero if the unsigned char C can safely be given
33    as an argument to <ctype.h> macros like "isspace".  */
34 #ifdef STDC_HEADERS
35 # define IN_CTYPE_DOMAIN(c) 1
36 #else
37 # define IN_CTYPE_DOMAIN(c) ((c) <= 0177)
38 #endif
39 
40 #define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
41 
42 /* Find the white-space-separated options specified by OPTIONS, and
43    using BUF to store copies of these options, set ARGV[0], ARGV[1],
44    etc. to the option copies.  Return the number N of options found.
45    Do not set ARGV[N].  If ARGV is zero, do not store ARGV[0] etc.
46    Backslash can be used to escape whitespace (and backslashes).  */
47 static int
48 prepend_args (char const *options, char *buf, char **argv)
49 {
50   char const *o = options;
51   char *b = buf;
52   int n = 0;
53 
54   for (;;)
55     {
56       while (ISSPACE ((unsigned char) *o))
57 	o++;
58       if (!*o)
59 	return n;
60       if (argv)
61 	argv[n] = b;
62       n++;
63 
64       do
65 	if ((*b++ = *o++) == '\\' && *o)
66 	  b[-1] = *o++;
67       while (*o && ! ISSPACE ((unsigned char) *o));
68 
69       *b++ = '\0';
70     }
71 }
72 
73 /* Prepend the whitespace-separated options in OPTIONS to the argument
74    vector of a main program with argument count *PARGC and argument
75    vector *PARGV.  */
76 void
77 prepend_default_options (char const *options, int *pargc, char ***pargv)
78 {
79   if (options)
80     {
81       char *buf = xmalloc (strlen (options) + 1);
82       int prepended = prepend_args (options, buf, (char **) 0);
83       int argc = *pargc;
84       char * const *argv = *pargv;
85       char **pp = (char **) xmalloc ((prepended + argc + 1) * sizeof *pp);
86       *pargc = prepended + argc;
87       *pargv = pp;
88       *pp++ = *argv++;
89       pp += prepend_args (options, buf, pp);
90       while ((*pp++ = *argv++))
91 	continue;
92     }
93 }
94