tarsnap/libarchive/archive_write_open_memory.c

/*-
 * Copyright (c) 2003-2007 Tim Kientzle
 * 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(S) ``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(S) 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 "archive_platform.h"
__FBSDID("$FreeBSD: src/lib/libarchive/archive_write_open_memory.c,v 1.3 2007/01/09 08:05:56 kientzle Exp $");

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

#include "archive.h"

/*
 * This is a little tricky.  I used to allow the
 * compression handling layer to fork the compressor,
 * which means this write function gets invoked in
 * a separate process.  That would, of course, make it impossible
 * to actually use the data stored into memory here.
 * Fortunately, none of the compressors fork today and
 * I'm reluctant to use that route in the future but, if
 * forking compressors ever do reappear, this will have
 * to get a lot more complicated.
 */

struct write_memory_data {
	size_t	used;
	size_t  size;
	size_t * client_size;
	unsigned char * buff;
};

static int	memory_write_close(struct archive *, void *);
static int	memory_write_open(struct archive *, void *);
static ssize_t	memory_write(struct archive *, void *, const void *buff, size_t);

/*
 * Client provides a pointer to a block of memory to receive
 * the data.  The 'size' param both tells us the size of the
 * client buffer and lets us tell the client the final size.
 */
int
archive_write_open_memory(struct archive *a, void *buff, size_t buffSize, size_t *used)
{
	struct write_memory_data *mine;

	mine = (struct write_memory_data *)malloc(sizeof(*mine));
	if (mine == NULL) {
		archive_set_error(a, ENOMEM, "No memory");
		return (ARCHIVE_FATAL);
	}
	memset(mine, 0, sizeof(*mine));
	mine->buff = buff;
	mine->size = buffSize;
	mine->client_size = used;
	return (archive_write_open(a, mine,
		    memory_write_open, memory_write, memory_write_close));
}

static int
memory_write_open(struct archive *a, void *client_data)
{
	struct write_memory_data *mine;
	mine = client_data;
	mine->used = 0;
	if (mine->client_size != NULL)
		*mine->client_size = mine->used;
	/* Disable padding if it hasn't been set explicitly. */
	if (-1 == archive_write_get_bytes_in_last_block(a))
		archive_write_set_bytes_in_last_block(a, 1);
	return (ARCHIVE_OK);
}

/*
 * Copy the data into the client buffer.
 * Note that we update mine->client_size on every write.
 * In particular, this means the client can follow exactly
 * how much has been written into their buffer at any time.
 */
static ssize_t
memory_write(struct archive *a, void *client_data, const void *buff, size_t length)
{
	struct write_memory_data *mine;
	mine = client_data;

	if (mine->used + length > mine->size) {
		archive_set_error(a, ENOMEM, "Buffer exhausted");
		return (ARCHIVE_FATAL);
	}
	memcpy(mine->buff + mine->used, buff, length);
	mine->used += length;
	if (mine->client_size != NULL)
		*mine->client_size = mine->used;
	return (length);
}

static int
memory_write_close(struct archive *a, void *client_data)
{
	struct write_memory_data *mine;
	(void)a; /* UNUSED */
	mine = client_data;
	free(mine);
	return (ARCHIVE_OK);
}