source: vendor/patch/2.5.9/quotesys.c

/* Shell command argument quoting.
   Copyright (C) 1994, 1995, 1997 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 2, 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; see the file COPYING.
   If not, write to the Free Software Foundation,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by Paul Eggert <eggert@twinsun.com> */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#include <sys/types.h>
#include <quotesys.h>

/* Place into QUOTED a quoted version of ARG suitable for `system'.
   Return the length of the resulting string (which is not null-terminated).
   If QUOTED is null, return the length without any side effects.  */

size_t
quote_system_arg (quoted, arg)
     char *quoted;
     char const *arg;
{
  char const *a;
  size_t len = 0;

  /* Scan ARG, copying it to QUOTED if QUOTED is not null,
     looking for shell metacharacters.  */

  for (a = arg; ; a++)
    {
      char c = *a;
      switch (c)
        {
        case 0:
          /* ARG has no shell metacharacters.  */
          return len;

        case '=':
          if (*arg == '-')
            break;
          /* Fall through.  */
        case '\t': case '\n': case ' ':
        case '!': case '"': case '#': case '$': case '%': case '&': case '\'':
        case '(': case ')': case '*': case ';':
        case '<': case '>': case '?': case '[': case '\\':
        case '^': case '`': case '|': case '~':
          {
            /* ARG has a shell metacharacter.
               Start over, quoting it this time.  */

            len = 0;
            c = *arg++;

            /* If ARG is an option, quote just its argument.
               This is not necessary, but it looks nicer.  */
            if (c == '-'  &&  arg < a)
              {
                c = *arg++;

                if (quoted)
                  {
                    quoted[len] = '-';
                    quoted[len + 1] = c;
                  }
                len += 2;

                if (c == '-')
                  while (arg < a)
                    {
                      c = *arg++;
                      if (quoted)
                        quoted[len] = c;
                      len++;
                      if (c == '=')
                        break;
                    }
                c = *arg++;
              }

            if (quoted)
              quoted[len] = '\'';
            len++;

            for (;  c;  c = *arg++)
              {
                if (c == '\'')
                  {
                    if (quoted)
                      {
                        quoted[len] = '\'';
                        quoted[len + 1] = '\\';
                        quoted[len + 2] = '\'';
                      }
                    len += 3;
                  }
                if (quoted)
                  quoted[len] = c;
                len++;
              }

            if (quoted)
              quoted[len] = '\'';
            return len + 1;
          }
        }

      if (quoted)
        quoted[len] = c;
      len++;
    }
}