common/sexp-parse.h

   1 /* sexp-parse.h - S-Exp helper functions
   2  *      Copyright (C) 2002, 2003 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 2 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, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19  * USA.
  20  */
  21
  22 #ifndef SEXP_PARSE_H
  23 #define SEXP_PARSE_H
  24
  25 #include <gpg-error.h>
  26
  27 /* Return the length of the next S-Exp part and update the pointer to
  28    the first data byte.  0 is returned on error */
  29 static inline size_t
  30 snext (unsigned char const **buf)
  31 {
  32   const unsigned char *s;
  33   int n;
  34
  35   s = *buf;
  36   for (n=0; *s && *s != ':' && (*s >= '0' && *s <= '9'); s++)
  37     n = n*10 + (*s - '0');
  38   if (!n || *s != ':')
  39     return 0; /* we don't allow empty lengths */
  40   *buf = s+1;
  41   return n;
  42 }
  43
  44 /* Skip over the S-Expression BUF points to and update BUF to point to
  45    the chacter right behind.  DEPTH gives the initial number of open
  46    lists and may be passed as a positive number to skip over the
  47    remainder of an S-Expression if the current position is somewhere
  48    in an S-Expression.  The function may return an error code if it
  49    encounters an impossible conditions */
  50 static inline gpg_error_t
  51 sskip (unsigned char const **buf, int *depth)
  52 {
  53   const unsigned char *s = *buf;
  54   size_t n;
  55   int d = *depth;
  56
  57   while (d > 0)
  58     {
  59       if (*s == '(')
  60         {
  61           d++;
  62           s++;
  63         }
  64       else if (*s == ')')
  65         {
  66           d--;
  67           s++;
  68         }
  69       else
  70         {
  71           if (!d)
  72             return gpg_error (GPG_ERR_INV_SEXP);
  73           n = snext (&s);
  74           if (!n)
  75             return gpg_error (GPG_ERR_INV_SEXP);
  76           s += n;
  77         }
  78     }
  79   *buf = s;
  80   *depth = d;
  81   return 0;
  82 }
  83
  84
  85 /* Check whether the the string at the address BUF points to matches
  86    the token.  Return true on match and update BUF to point behind the
  87    token.  Return false and dont update tha buffer if it does not
  88    match. */
  89 static inline int
  90 smatch (unsigned char const **buf, size_t buflen, const char *token)
  91 {
  92   size_t toklen = strlen (token);
  93
  94   if (buflen != toklen || memcmp (*buf, token, toklen))
  95     return 0;
  96   *buf += toklen;
  97   return 1;
  98 }
  99
 100 #endif /*SEXP_PARSE_H*/