Return to fparseln.c CVS log

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modify the previous fix so that no pointless realloc()s are done in
the case of multiple empty continuation lines, and comment the code
to make the logics obvious
fix an unrelated comment

/*	$NetBSD: fparseln.c,v 1.7 2007/03/08 19:57:53 drochner 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: fparseln.c,v 1.7 2007/03/08 19:57:53 drochner 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 0;

	/* 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 continuation char */
				cnt = 1;
			}
		}

		if (s == 0) {
			/*
			 * nothing to add, skip realloc except in case
			 * we need a minimal buf to return an empty line
			 */
			if (cnt || 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 */