/*	$NetBSD: mmfile.c,v 1.3 2006/05/15 21:12:21 rillig Exp $	*/

/*-

 * Copyright (c) 1999 James Howard and Dag-Erling Codan Smrgrav

 * 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.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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>

#ifndef lint

__RCSID("$NetBSD: mmfile.c,v 1.3 2006/05/15 21:12:21 rillig Exp $");

#endif /* not lint */

#include "grep.h"

#define MAX_MAP_LEN (SIZE_T_MAX / 64)	/* ~70M is reasonable size */

/* Open the mmap file */

mmf_t *

mmopen(const char *fn, const char *mode)

{

	mmf_t *mmf;

	struct stat st;

	/* XXX ignore mode for now */

	mode = mode;

	mmf = (mmf_t *)grep_malloc(sizeof *mmf);	

	if ((mmf->fd = open(fn, O_RDONLY)) == -1)

		goto ouch1;

	if (fstat(mmf->fd, &st) == -1)

		goto ouch2;

	if (st.st_size > MAX_MAP_LEN)		/* too big to mmap */		

		goto ouch2;

	if ((st.st_mode & S_IFREG) == 0)	/* only mmap regular files */

		goto ouch2;

	mmf->len = (size_t)st.st_size;

	mmf->base = (char *)mmap(NULL, mmf->len, PROT_READ, MAP_PRIVATE, mmf->fd, 0);

	if (mmf->base == MAP_FAILED)

		goto ouch2;

	mmf->ptr = mmf->base;

	mmf->end = mmf->base + mmf->len;

	return mmf;

ouch2:

	close(mmf->fd);

ouch1:

	free(mmf);

	return (mmf_t*)NULL;

}

/* Clode the mmap file */

void

mmclose(mmf_t *mmf)

{

	munmap(mmf->base, mmf->len);

	close(mmf->fd);

	free(mmf);

}

/* Get a line of data from the mmaped file */

char *

mmfgetln(mmf_t *mmf, size_t *l)

{

	static char *p;

	if (mmf->ptr >= mmf->end)

		return NULL;

	for (p = mmf->ptr; mmf->ptr < mmf->end; ++mmf->ptr)

		if (*mmf->ptr == line_endchar)

			break;

	*l = mmf->ptr - p;

	++mmf->ptr;

	return p;

}

/* Rewind in mmaped file */

void

mmrewind(mmf_t *mmf)

{

	mmf->ptr = mmf->base;

}