/*-
* Copyright (c) 2009-2010 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Pawel Jakub Dawidek under sponsorship from
* the FreeBSD Foundation.
*
* 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 AUTHORS 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 AUTHORS 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>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <strings.h>
#include <unistd.h>
#include "ebuf.h"
#define EBUF_MAGIC 0xeb0f41c
struct ebuf {
/* Magic to assert the caller uses valid structure. */
int eb_magic;
/* Address where we did the allocation. */
unsigned char *eb_start;
/* Allocation end address. */
unsigned char *eb_end;
/* Start of real data. */
unsigned char *eb_used;
/* Size of real data. */
size_t eb_size;
};
static int ebuf_head_extend(struct ebuf *eb, size_t size);
static int ebuf_tail_extend(struct ebuf *eb, size_t size);
struct ebuf *
ebuf_alloc(size_t size)
{
struct ebuf *eb;
int rerrno;
eb = malloc(sizeof(*eb));
if (eb == NULL)
return (NULL);
size += PAGE_SIZE;
eb->eb_start = malloc(size);
if (eb->eb_start == NULL) {
rerrno = errno;
free(eb);
errno = rerrno;
return (NULL);
}
eb->eb_end = eb->eb_start + size;
/*
* We set start address for real data not at the first entry, because
* we want to be able to add data at the front.
*/
eb->eb_used = eb->eb_start + PAGE_SIZE / 4;
eb->eb_size = 0;
eb->eb_magic = EBUF_MAGIC;
return (eb);
}
void
ebuf_free(struct ebuf *eb)
{
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
eb->eb_magic = 0;
free(eb->eb_start);
free(eb);
}
int
ebuf_add_head(struct ebuf *eb, const void *data, size_t size)
{
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
if (size > (size_t)(eb->eb_used - eb->eb_start)) {
/*
* We can't add more entries at the front, so we have to extend
* our buffer.
*/
if (ebuf_head_extend(eb, size) < 0)
return (-1);
}
assert(size <= (size_t)(eb->eb_used - eb->eb_start));
eb->eb_size += size;
eb->eb_used -= size;
/*
* If data is NULL the caller just wants to reserve place.
*/
if (data != NULL)
bcopy(data, eb->eb_used, size);
return (0);
}
int
ebuf_add_tail(struct ebuf *eb, const void *data, size_t size)
{
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
if (size > (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))) {
/*
* We can't add more entries at the back, so we have to extend
* our buffer.
*/
if (ebuf_tail_extend(eb, size) < 0)
return (-1);
}
assert(size <= (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size)));
/*
* If data is NULL the caller just wants to reserve space.
*/
if (data != NULL)
bcopy(data, eb->eb_used + eb->eb_size, size);
eb->eb_size += size;
return (0);
}
void
ebuf_del_head(struct ebuf *eb, size_t size)
{
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
assert(size <= eb->eb_size);
eb->eb_used += size;
eb->eb_size -= size;
}
void
ebuf_del_tail(struct ebuf *eb, size_t size)
{
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
assert(size <= eb->eb_size);
eb->eb_size -= size;
}
/*
* Return pointer to the data and data size.
*/
void *
ebuf_data(struct ebuf *eb, size_t *sizep)
{
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
if (sizep != NULL)
*sizep = eb->eb_size;
return (eb->eb_size > 0 ? eb->eb_used : NULL);
}
/*
* Return data size.
*/
size_t
ebuf_size(struct ebuf *eb)
{
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
return (eb->eb_size);
}
/*
* Function adds size + (PAGE_SIZE / 4) bytes at the front of the buffer..
*/
static int
ebuf_head_extend(struct ebuf *eb, size_t size)
{
unsigned char *newstart, *newused;
size_t newsize;
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
newsize = eb->eb_end - eb->eb_start + (PAGE_SIZE / 4) + size;
newstart = malloc(newsize);
if (newstart == NULL)
return (-1);
newused =
newstart + (PAGE_SIZE / 4) + size + (eb->eb_used - eb->eb_start);
bcopy(eb->eb_used, newused, eb->eb_size);
eb->eb_start = newstart;
eb->eb_used = newused;
eb->eb_end = newstart + newsize;
return (0);
}
/*
* Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back.
*/
static int
ebuf_tail_extend(struct ebuf *eb, size_t size)
{
unsigned char *newstart;
size_t newsize;
assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
newsize = eb->eb_end - eb->eb_start + size + ((3 * PAGE_SIZE) / 4);
newstart = realloc(eb->eb_start, newsize);
if (newstart == NULL)
return (-1);
eb->eb_used = newstart + (eb->eb_used - eb->eb_start);
eb->eb_start = newstart;
eb->eb_end = newstart + newsize;
return (0);
}
