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fparseln.c

/*    $OpenBSD: fparseln.c,v 1.5 2004/05/28 07:03:47 deraadt Exp $      */
/*    $NetBSD: fparseln.c,v 1.7 1999/07/02 15:49:12 simonb Exp $  */

/*
 * Copyright (c) 2009 Thorsten Glaser
 * Copyright (c) 1997 Christos Zoulas.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by Christos Zoulas.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#ifdef DEBIAN
#include "mbsdtree.h"
#else
#include "util.h"
#endif

__RCSID("$MirOS: src/lib/libutil/fparseln.c,v 1.2 2009/07/23 19:32:21 tg Exp $");

static int isescaped(const char *, const char *, int);

/* isescaped():
 *    Return true if the character in *p that belongs to a string
 *    that starts in *sp, is escaped by the escape character esc.
 */
static int
isescaped(const char *sp, const char *p, int esc)
{
      const char     *cp;
      size_t            ne;

      /* No escape character */
      if (esc == '\0')
            return 1;

      /* Count the number of escape characters that precede ours */
      for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
            continue;

      /* Return true if odd number of escape characters */
      return (ne & 1) != 0;
}


/* fparseln():
 *    Read a line from a file parsing continuations ending in \
 *    and eliminating trailing newlines, or comments starting with
 *    the comment char.
 */
char *
fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3],
    int flags)
{
      static const char dstr[3] = { '\\', '\\', '#' };
      char  *buf = NULL, *ptr, *cp, esc, con, nl, com;
      size_t      s, len = 0;
      int   cnt = 1;

      if (str == NULL)
            str = dstr;

      esc = str[0];
      con = str[1];
      com = str[2];

      /*
       * XXX: it would be cool to be able to specify the newline character,
       * but unfortunately, fgetln does not let us
       */
      nl  = '\n';

      while (cnt) {
            cnt = 0;

            if (lineno)
                  (*lineno)++;

            if ((ptr = fgetln(fp, &s)) == NULL)
                  break;

            if (s && com) {         /* Check and eliminate comments */
                  for (cp = ptr; cp < ptr + s; cp++)
                        if (*cp == com && !isescaped(ptr, cp, esc)) {
                              s = cp - ptr;
                              cnt = s == 0 && buf == NULL;
                              break;
                        }
            }

            if (s && nl) {          /* Check and eliminate newlines */
                  cp = &ptr[s - 1];

                  if (*cp == nl)
                        s--;  /* forget newline */
            }

            if (s && con) {         /* Check and eliminate continuations */
                  cp = &ptr[s - 1];

                  if (*cp == con && !isescaped(ptr, cp, esc)) {
                        s--;  /* forget escape */
                        cnt = 1;
                  }
            }

            if (s == 0 && buf != NULL)
                  continue;

            if ((cp = realloc(buf, len + s + 1)) == NULL) {
                  free(buf);
                  return NULL;
            }
            buf = cp;

            (void) memcpy(buf + len, ptr, s);
            len += s;
            buf[len] = '\0';
      }

      if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
          strchr(buf, esc) != NULL) {
            ptr = cp = buf;
            while (cp[0] != '\0') {
                  int skipesc;

                  while (cp[0] != '\0' && cp[0] != esc)
                        *ptr++ = *cp++;
                  if (cp[0] == '\0' || cp[1] == '\0')
                        break;

                  skipesc = 0;
                  if (cp[1] == com)
                        skipesc += (flags & FPARSELN_UNESCCOMM);
                  if (cp[1] == con)
                        skipesc += (flags & FPARSELN_UNESCCONT);
                  if (cp[1] == esc)
                        skipesc += (flags & FPARSELN_UNESCESC);
                  if (cp[1] != com && cp[1] != con && cp[1] != esc)
                        skipesc = (flags & FPARSELN_UNESCREST);

                  if (skipesc)
                        cp++;
                  else
                        *ptr++ = *cp++;
                  *ptr++ = *cp++;
            }
            *ptr = '\0';
            len = strlen(buf);
      }

      if (size)
            *size = len;
      return buf;
}

#ifdef TEST

int main(int, char **);

int
main(argc, argv)
      int argc;
      char **argv;
{
      char   *ptr;
      size_t      size, line;

      line = 0;
      while ((ptr = fparseln(stdin, &size, &line, NULL,
          FPARSELN_UNESCALL)) != NULL)
            printf("line %d (%d) |%s|\n", line, size, ptr);
      return 0;
}

/*

# This is a test
line 1
line 2 \
line 3 # Comment
line 4 \# Not comment \\\\

# And a comment \
line 5 \\\
line 6

*/

#endif /* TEST */

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