/*  $NetBSD: fparseln.c,v 1.5 2004/06/20 22:20:15 jmc Exp $ */

/*
 * 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  <LibConfig.h>
#include <sys/EfiCdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: fparseln.c,v 1.5 2004/06/20 22:20:15 jmc Exp $");
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"

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

#ifdef __weak_alias
__weak_alias(fparseln,_fparseln)
#endif

#if ! HAVE_FPARSELN

#ifndef HAVE_NBTOOL_CONFIG_H
#include "reentrant.h"
#include "local.h"
#else
#define FLOCKFILE(fp)
#define FUNLOCKFILE(fp)
#endif

#if defined(_REENTRANT) && !HAVE_NBTOOL_CONFIG_H
#define __fgetln(f, l) __fgetstr(f, l, '\n')
#else
#define __fgetln(f, l) fgetln(f, l)
#endif

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;

  _DIAGASSERT(sp != NULL);
  _DIAGASSERT(p != NULL);

  /* 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] = { '\\', '\\', '#' };

  size_t  s, len;
  char   *buf;
  char   *ptr, *cp;
  int cnt;
  char  esc, con, nl, com;

  _DIAGASSERT(fp != NULL);

  len = 0;
  buf = NULL;
  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';

  FLOCKFILE(fp);

  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) {
      FUNLOCKFILE(fp);
      free(buf);
      return NULL;
    }
    buf = cp;

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

  FUNLOCKFILE(fp);

  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(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 */
#endif  /* ! HAVE_FPARSELN */