1 files changed, 91 insertions, 0 deletions
diff --git a/lib/prepargs.c b/lib/prepargs.c
new file mode 100644
index 0000000..f4a2f12
--- /dev/null
+++ b/lib/prepargs.c
@@ -0,0 +1,91 @@
+/* Parse arguments from a string and prepend them to an argv.
+
+   Copyright (C) 1999-2002, 2006, 2009-2013, 2015-2016 Free Software
+   Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert <eggert@twinsun.com>.  */
+
+#include <config.h>
+
+#include "prepargs.h"
+#include <string.h>
+#include <sys/types.h>
+#include <xalloc.h>
+
+#include <ctype.h>
+
+/* IN_CTYPE_DOMAIN (C) is nonzero if the unsigned char C can safely be given
+   as an argument to <ctype.h> macros like "isspace".  */
+#ifdef STDC_HEADERS
+# define IN_CTYPE_DOMAIN(c) 1
+#else
+# define IN_CTYPE_DOMAIN(c) ((c) <= 0177)
+#endif
+
+#define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
+
+/* Find the white-space-separated options specified by OPTIONS, and
+   using BUF to store copies of these options, set ARGV[0], ARGV[1],
+   etc. to the option copies.  Return the number N of options found.
+   Do not set ARGV[N].  If ARGV is zero, do not store ARGV[0] etc.
+   Backslash can be used to escape whitespace (and backslashes).  */
+static int
+prepend_args (char const *options, char *buf, char **argv)
+{
+  char const *o = options;
+  char *b = buf;
+  int n = 0;
+
+  for (;;)
+    {
+      while (ISSPACE ((unsigned char) *o))
+	o++;
+      if (!*o)
+	return n;
+      if (argv)
+	argv[n] = b;
+      n++;
+
+      do
+	if ((*b++ = *o++) == '\\' && *o)
+	  b[-1] = *o++;
+      while (*o && ! ISSPACE ((unsigned char) *o));
+
+      *b++ = '\0';
+    }
+}
+
+/* Prepend the whitespace-separated options in OPTIONS to the argument
+   vector of a main program with argument count *PARGC and argument
+   vector *PARGV.  */
+void
+prepend_default_options (char const *options, int *pargc, char ***pargv)
+{
+  if (options)
+    {
+      char *buf = xmalloc (strlen (options) + 1);
+      int prepended = prepend_args (options, buf, (char **) 0);
+      int argc = *pargc;
+      char * const *argv = *pargv;
+      char **pp = xmalloc ((prepended + argc + 1) * sizeof *pp);
+      *pargc = prepended + argc;
+      *pargv = pp;
+      *pp++ = *argv++;
+      pp += prepend_args (options, buf, pp);
+      while ((*pp++ = *argv++))
+	continue;
+    }
+}