/********************************************************************\
 * escape.c : escape SQL reserved characters                        *
 * Copyright (C) 2001 Linas Vepstas <linas@linas.org>               *
 *                                                                  *
 * 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 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, contact:                        *
 *                                                                  *
 * Free Software Foundation           Voice:  +1-617-542-5942       *
 * 59 Temple Place - Suite 330        Fax:    +1-617-542-2652       *
 * Boston, MA  02111-1307,  USA       gnu@gnu.org                   *
\********************************************************************/

/*
 * FILE:
 * esacpe.c
 *
 * FUNCTION:
 * Escapes the ' and \ characters in a string
 */

#define _GNU_SOURCE
#include <glib.h>
#include <string.h>

#include "gnc-engine-util.h"
#include "escape.h"

static short module = MOD_BACKEND; 

/* ================================================ */

struct _escape {
   /* pointer to memory used for escaping arguments */
   char * escape;
   size_t esc_buflen;
};

/* ================================================ */
/* escape single-quote marks and backslashes so that the 
 * database SQL parser doesn't puke on the query string 
 */

const char *
sqlEscapeString (sqlEscape *b, const char *str)
{
   const char *p, *src_head;
   char *dst_tail;
   size_t len, slen;

   if (!b || !str) return NULL;

   /* if a string is escaped twice, just return the first */
   if (b->escape == str)
     return str;

   /* if nothing to escape, just return */
   len = strlen (str);
   slen = strcspn (str, "\\\'");
   if (len == slen) return str;

   /* count to see how much space we'll need */
   p = str + slen + 1;
   while (*p)
   {
      len ++;
      p += 1 + strcspn (p, "\\\'");
   }

   /* get more space, if needed */
   if (len >= b->esc_buflen)
   {
      b->escape = g_realloc(b->escape, len+100);
      b->esc_buflen = len+100;
   }

   /* copy and escape */
   src_head = (char *) str;
   dst_tail = b->escape;
   p = src_head + strcspn (src_head, "\\\'");
   while (*p)
   {
      size_t cp_len = p - src_head;

      strncpy (dst_tail, src_head, cp_len);
      dst_tail += cp_len;
      *dst_tail = '\\';
      dst_tail ++;
      *dst_tail = *p;
      dst_tail ++;

      src_head = p+1;
      p = src_head + strcspn (src_head, "\\\'");
   }
   if (p != src_head)
   {
      size_t cp_len = p - src_head;

      strncpy (dst_tail, src_head, cp_len);
      dst_tail += cp_len;
   }
   *dst_tail = 0;

   return b->escape;
}

/* ================================================ */

#define INITIAL_BUFSZ 2000

sqlEscape *
sqlEscape_new (void)
{
   sqlEscape *b = g_new (sqlEscape, 1);

   b->escape = g_malloc (INITIAL_BUFSZ);
   b->esc_buflen = INITIAL_BUFSZ;
   return (b);
}

/* ================================================ */

void
sqlEscape_destroy (sqlEscape *b)
{
    ENTER(" ");
   if (!b) { LEAVE("b is (null)"); return; }
   g_free (b->escape);     b->escape = NULL;
   g_free (b);
   LEAVE(" ");
}

/* ================ END OF FILE ==================== */