common/percent.c

   1 /* percent.c - Percent escaping
   2  *      Copyright (C) 2008 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <stdlib.h>
  22 #include <errno.h>
  23 #include <ctype.h>
  24
  25 #include "util.h"
  26
  27
  28 /* Create a newly alloced string from STRING with all spaces and
  29    control characters converted to plus signs or %xx sequences.  The
  30    function returns the new string or NULL in case of a malloc
  31    failure.
  32
  33    Note that we also escape the quote character to work around a bug
  34    in the mingw32 runtime which does not correcty handle command line
  35    quoting.  We correctly double the quote mark when calling a program
  36    (i.e. gpg-protect-tool), but the pre-main code does not notice the
  37    double quote as an escaped quote.  We do this also on POSIX systems
  38    for consistency.  */
  39 char *
  40 percent_plus_escape (const char *string)
  41 {
  42   char *buffer, *p;
  43   const char *s;
  44   size_t length;
  45
  46   for (length=1, s=string; *s; s++)
  47     {
  48       if (*s == '+' || *s == '\"' || *s == '%'
  49           || *(const unsigned char *)s < 0x20)
  50         length += 3;
  51       else
  52         length++;
  53     }
  54
  55   buffer = p = xtrymalloc (length);
  56   if (!buffer)
  57     return NULL;
  58
  59   for (s=string; *s; s++)
  60     {
  61       if (*s == '+' || *s == '\"' || *s == '%'
  62           || *(const unsigned char *)s < 0x20)
  63         {
  64           snprintf (p, 4, "%%%02X", *(unsigned char *)s);
  65           p += 3;
  66         }
  67       else if (*s == ' ')
  68         *p++ = '+';
  69       else
  70         *p++ = *s;
  71     }
  72   *p = 0;
  73
  74   return buffer;
  75
  76 }