third_party/libevent/buffer.c - platform/external/chromium - Git at Google

 /*
  * Copyright (c) 2002, 2003 Niels Provos <provos@citi.umich.edu>
  * 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. 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.
  */

 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

 #ifdef WIN32
 #include <winsock2.h>
 #include <windows.h>
 #endif

 #ifdef HAVE_VASPRINTF
 /* If we have vasprintf, we need to define this before we include stdio.h. */
 #define _GNU_SOURCE
 #endif

 #include <sys/types.h>

 #ifdef HAVE_SYS_TIME_H
 #include <sys/time.h>
 #endif

 #ifdef HAVE_SYS_IOCTL_H
 #include <sys/ioctl.h>
 #endif

 #include <assert.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #ifdef HAVE_STDARG_H
 #include <stdarg.h>
 #endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif

 #include "event.h"
 #include "config.h"
 #include "evutil.h"

 struct evbuffer *
 evbuffer_new(void)
 {
 	struct evbuffer *buffer;

 	buffer = calloc(1, sizeof(struct evbuffer));

 	return (buffer);
 }

 void
 evbuffer_free(struct evbuffer *buffer)
 {
 	if (buffer->orig_buffer != NULL)
 		free(buffer->orig_buffer);
 	free(buffer);
 }

 /*
  * This is a destructive add.  The data from one buffer moves into
  * the other buffer.
  */

 #define SWAP(x,y) do { \
 	(x)->buffer = (y)->buffer; \
 	(x)->orig_buffer = (y)->orig_buffer; \
 	(x)->misalign = (y)->misalign; \
 	(x)->totallen = (y)->totallen; \
 	(x)->off = (y)->off; \
 } while (0)

 int
 evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
 {
 	int res;

 	/* Short cut for better performance */
 	if (outbuf->off == 0) {
 		struct evbuffer tmp;
 		size_t oldoff = inbuf->off;

 		/* Swap them directly */
 		SWAP(&tmp, outbuf);
 		SWAP(outbuf, inbuf);
 		SWAP(inbuf, &tmp);

 		/*
 		 * Optimization comes with a price; we need to notify the
 		 * buffer if necessary of the changes. oldoff is the amount
 		 * of data that we transfered from inbuf to outbuf
 		 */
 		if (inbuf->off != oldoff && inbuf->cb != NULL)
 			(*inbuf->cb)(inbuf, oldoff, inbuf->off, inbuf->cbarg);
 		if (oldoff && outbuf->cb != NULL)
 			(*outbuf->cb)(outbuf, 0, oldoff, outbuf->cbarg);

 		return (0);
 	}

 	res = evbuffer_add(outbuf, inbuf->buffer, inbuf->off);
 	if (res == 0) {
 		/* We drain the input buffer on success */
 		evbuffer_drain(inbuf, inbuf->off);
 	}

 	return (res);
 }

 int
 evbuffer_add_vprintf(struct evbuffer *buf, const char *fmt, va_list ap)
 {
 	char *buffer;
 	size_t space;
 	size_t oldoff = buf->off;
 	int sz;
 	va_list aq;

 	/* make sure that at least some space is available */
 	evbuffer_expand(buf, 64);
 	for (;;) {
 		size_t used = buf->misalign + buf->off;
 		buffer = (char *)buf->buffer + buf->off;
 		assert(buf->totallen >= used);
 		space = buf->totallen - used;

 #ifndef va_copy
 #define	va_copy(dst, src)	memcpy(&(dst), &(src), sizeof(va_list))
 #endif
 		va_copy(aq, ap);

 		sz = evutil_vsnprintf(buffer, space, fmt, aq);

 		va_end(aq);

 		if (sz < 0)
 			return (-1);
 		if ((size_t)sz < space) {
 			buf->off += sz;
 			if (buf->cb != NULL)
 				(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
 			return (sz);
 		}
 		if (evbuffer_expand(buf, sz + 1) == -1)
 			return (-1);

 	}
 	/* NOTREACHED */
 }

 int
 evbuffer_add_printf(struct evbuffer *buf, const char *fmt, ...)
 {
 	int res = -1;
 	va_list ap;

 	va_start(ap, fmt);
 	res = evbuffer_add_vprintf(buf, fmt, ap);
 	va_end(ap);

 	return (res);
 }

 /* Reads data from an event buffer and drains the bytes read */

 int
 evbuffer_remove(struct evbuffer *buf, void *data, size_t datlen)
 {
 	size_t nread = datlen;
 	if (nread >= buf->off)
 		nread = buf->off;

 	memcpy(data, buf->buffer, nread);
 	evbuffer_drain(buf, nread);

 	return (nread);
 }

 /*
  * Reads a line terminated by either '\r\n', '\n\r' or '\r' or '\n'.
  * The returned buffer needs to be freed by the called.
  */

 char *
 evbuffer_readline(struct evbuffer *buffer)
 {
 	u_char *data = EVBUFFER_DATA(buffer);
 	size_t len = EVBUFFER_LENGTH(buffer);
 	char *line;
 	unsigned int i;

 	for (i = 0; i < len; i++) {
 		if (data[i] == '\r' || data[i] == '\n')
 			break;
 	}

 	if (i == len)
 		return (NULL);

 	if ((line = malloc(i + 1)) == NULL) {
 		fprintf(stderr, "%s: out of memory\n", __func__);
 		return (NULL);
 	}

 	memcpy(line, data, i);
 	line[i] = '\0';

 	/*
 	 * Some protocols terminate a line with '\r\n', so check for
 	 * that, too.
 	 */
 	if ( i < len - 1 ) {
 		char fch = data[i], sch = data[i+1];

 		/* Drain one more character if needed */
 		if ( (sch == '\r' || sch == '\n') && sch != fch )
 			i += 1;
 	}

 	evbuffer_drain(buffer, i + 1);

 	return (line);
 }

 /* Adds data to an event buffer */

 static void
 evbuffer_align(struct evbuffer *buf)
 {
 	memmove(buf->orig_buffer, buf->buffer, buf->off);
 	buf->buffer = buf->orig_buffer;
 	buf->misalign = 0;
 }

 /* Expands the available space in the event buffer to at least datlen */

 int
 evbuffer_expand(struct evbuffer *buf, size_t datlen)
 {
 	size_t need = buf->misalign + buf->off + datlen;

 	/* If we can fit all the data, then we don't have to do anything */
 	if (buf->totallen >= need)
 		return (0);

 	/*
 	 * If the misalignment fulfills our data needs, we just force an
 	 * alignment to happen.  Afterwards, we have enough space.
 	 */
 	if (buf->misalign >= datlen) {
 		evbuffer_align(buf);
 	} else {
 		void *newbuf;
 		size_t length = buf->totallen;

 		if (length < 256)
 			length = 256;
 		while (length < need)
 			length <<= 1;

 		if (buf->orig_buffer != buf->buffer)
 			evbuffer_align(buf);
 		if ((newbuf = realloc(buf->buffer, length)) == NULL)
 			return (-1);

 		buf->orig_buffer = buf->buffer = newbuf;
 		buf->totallen = length;
 	}

 	return (0);
 }

 int
 evbuffer_add(struct evbuffer *buf, const void *data, size_t datlen)
 {
 	size_t need = buf->misalign + buf->off + datlen;
 	size_t oldoff = buf->off;

 	if (buf->totallen < need) {
 		if (evbuffer_expand(buf, datlen) == -1)
 			return (-1);
 	}

 	memcpy(buf->buffer + buf->off, data, datlen);
 	buf->off += datlen;

 	if (datlen && buf->cb != NULL)
 		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);

 	return (0);
 }

 void
 evbuffer_drain(struct evbuffer *buf, size_t len)
 {
 	size_t oldoff = buf->off;

 	if (len >= buf->off) {
 		buf->off = 0;
 		buf->buffer = buf->orig_buffer;
 		buf->misalign = 0;
 		goto done;
 	}

 	buf->buffer += len;
 	buf->misalign += len;

 	buf->off -= len;

  done:
 	/* Tell someone about changes in this buffer */
 	if (buf->off != oldoff && buf->cb != NULL)
 		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);

 }

 /*
  * Reads data from a file descriptor into a buffer.
  */

 #define EVBUFFER_MAX_READ	4096

 int
 evbuffer_read(struct evbuffer *buf, int fd, int howmuch)
 {
 	u_char *p;
 	size_t oldoff = buf->off;
 	int n = EVBUFFER_MAX_READ;

 #if defined(FIONREAD)
 #ifdef WIN32
 	long lng = n;
 	if (ioctlsocket(fd, FIONREAD, &lng) == -1 || (n=lng) <= 0) {
 #else
 	if (ioctl(fd, FIONREAD, &n) == -1 || n <= 0) {
 #endif
 		n = EVBUFFER_MAX_READ;
 	} else if (n > EVBUFFER_MAX_READ && n > howmuch) {
 		/*
 		 * It's possible that a lot of data is available for
 		 * reading.  We do not want to exhaust resources
 		 * before the reader has a chance to do something
 		 * about it.  If the reader does not tell us how much
 		 * data we should read, we artifically limit it.
 		 */
 		if ((size_t)n > buf->totallen << 2)
 			n = buf->totallen << 2;
 		if (n < EVBUFFER_MAX_READ)
 			n = EVBUFFER_MAX_READ;
 	}
 #endif
 	if (howmuch < 0 || howmuch > n)
 		howmuch = n;

 	/* If we don't have FIONREAD, we might waste some space here */
 	if (evbuffer_expand(buf, howmuch) == -1)
 		return (-1);

 	/* We can append new data at this point */
 	p = buf->buffer + buf->off;

 #ifndef WIN32
 	n = read(fd, p, howmuch);
 #else
 	n = recv(fd, p, howmuch, 0);
 #endif
 	if (n == -1)
 		return (-1);
 	if (n == 0)
 		return (0);

 	buf->off += n;

 	/* Tell someone about changes in this buffer */
 	if (buf->off != oldoff && buf->cb != NULL)
 		(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);

 	return (n);
 }

 int
 evbuffer_write(struct evbuffer *buffer, int fd)
 {
 	int n;

 #ifndef WIN32
 	n = write(fd, buffer->buffer, buffer->off);
 #else
 	n = send(fd, buffer->buffer, buffer->off, 0);
 #endif
 	if (n == -1)
 		return (-1);
 	if (n == 0)
 		return (0);
 	evbuffer_drain(buffer, n);

 	return (n);
 }

 u_char *
 evbuffer_find(struct evbuffer *buffer, const u_char *what, size_t len)
 {
 	u_char *search = buffer->buffer, *end = search + buffer->off;
 	u_char *p;

 	while (search < end &&
 	    (p = memchr(search, *what, end - search)) != NULL) {
 		if (p + len > end)
 			break;
 		if (memcmp(p, what, len) == 0)
 			return (p);
 		search = p + 1;
 	}

 	return (NULL);
 }

 void evbuffer_setcb(struct evbuffer *buffer,
     void (*cb)(struct evbuffer *, size_t, size_t, void *),
     void *cbarg)
 {
 	buffer->cb = cb;
 	buffer->cbarg = cbarg;
 }
	/*
	* Copyright (c) 2002, 2003 Niels Provos <provos@citi.umich.edu>
	* 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. 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.
	*/

	#ifdef HAVE_CONFIG_H
	#include "config.h"
	#endif

	#ifdef WIN32
	#include <winsock2.h>
	#include <windows.h>
	#endif

	#ifdef HAVE_VASPRINTF
	/* If we have vasprintf, we need to define this before we include stdio.h. */
	#define _GNU_SOURCE
	#endif

	#include <sys/types.h>

	#ifdef HAVE_SYS_TIME_H
	#include <sys/time.h>
	#endif

	#ifdef HAVE_SYS_IOCTL_H
	#include <sys/ioctl.h>
	#endif

	#include <assert.h>
	#include <errno.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#ifdef HAVE_STDARG_H
	#include <stdarg.h>
	#endif
	#ifdef HAVE_UNISTD_H
	#include <unistd.h>
	#endif

	#include "event.h"
	#include "config.h"
	#include "evutil.h"

	struct evbuffer *
	evbuffer_new(void)
	{
	struct evbuffer *buffer;

	buffer = calloc(1, sizeof(struct evbuffer));

	return (buffer);
	}

	void
	evbuffer_free(struct evbuffer *buffer)
	{
	if (buffer->orig_buffer != NULL)
	free(buffer->orig_buffer);
	free(buffer);
	}

	/*
	* This is a destructive add. The data from one buffer moves into
	* the other buffer.
	*/

	#define SWAP(x,y) do { \
	(x)->buffer = (y)->buffer; \
	(x)->orig_buffer = (y)->orig_buffer; \
	(x)->misalign = (y)->misalign; \
	(x)->totallen = (y)->totallen; \
	(x)->off = (y)->off; \
	} while (0)

	int
	evbuffer_add_buffer(struct evbuffer outbuf, struct evbuffer inbuf)
	{
	int res;

	/* Short cut for better performance */
	if (outbuf->off == 0) {
	struct evbuffer tmp;
	size_t oldoff = inbuf->off;

	/* Swap them directly */
	SWAP(&tmp, outbuf);
	SWAP(outbuf, inbuf);
	SWAP(inbuf, &tmp);

	/*
	* Optimization comes with a price; we need to notify the
	* buffer if necessary of the changes. oldoff is the amount
	* of data that we transfered from inbuf to outbuf
	*/
	if (inbuf->off != oldoff && inbuf->cb != NULL)
	(*inbuf->cb)(inbuf, oldoff, inbuf->off, inbuf->cbarg);
	if (oldoff && outbuf->cb != NULL)
	(*outbuf->cb)(outbuf, 0, oldoff, outbuf->cbarg);

	return (0);
	}

	res = evbuffer_add(outbuf, inbuf->buffer, inbuf->off);
	if (res == 0) {
	/* We drain the input buffer on success */
	evbuffer_drain(inbuf, inbuf->off);
	}

	return (res);
	}

	int
	evbuffer_add_vprintf(struct evbuffer buf, const char fmt, va_list ap)
	{
	char *buffer;
	size_t space;
	size_t oldoff = buf->off;
	int sz;
	va_list aq;

	/* make sure that at least some space is available */
	evbuffer_expand(buf, 64);
	for (;;) {
	size_t used = buf->misalign + buf->off;
	buffer = (char *)buf->buffer + buf->off;
	assert(buf->totallen >= used);
	space = buf->totallen - used;

	#ifndef va_copy
	#define va_copy(dst, src) memcpy(&(dst), &(src), sizeof(va_list))
	#endif
	va_copy(aq, ap);

	sz = evutil_vsnprintf(buffer, space, fmt, aq);

	va_end(aq);

	if (sz < 0)
	return (-1);
	if ((size_t)sz < space) {
	buf->off += sz;
	if (buf->cb != NULL)
	(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);
	return (sz);
	}
	if (evbuffer_expand(buf, sz + 1) == -1)
	return (-1);

	}
	/* NOTREACHED */
	}

	int
	evbuffer_add_printf(struct evbuffer buf, const char fmt, ...)
	{
	int res = -1;
	va_list ap;

	va_start(ap, fmt);
	res = evbuffer_add_vprintf(buf, fmt, ap);
	va_end(ap);

	return (res);
	}

	/* Reads data from an event buffer and drains the bytes read */

	int
	evbuffer_remove(struct evbuffer buf, void data, size_t datlen)
	{
	size_t nread = datlen;
	if (nread >= buf->off)
	nread = buf->off;

	memcpy(data, buf->buffer, nread);
	evbuffer_drain(buf, nread);

	return (nread);
	}

	/*
	* Reads a line terminated by either '\r\n', '\n\r' or '\r' or '\n'.
	* The returned buffer needs to be freed by the called.
	*/

	char *
	evbuffer_readline(struct evbuffer *buffer)
	{
	u_char *data = EVBUFFER_DATA(buffer);
	size_t len = EVBUFFER_LENGTH(buffer);
	char *line;
	unsigned int i;

	for (i = 0; i < len; i++) {
	if (data[i] == '\r' \|\| data[i] == '\n')
	break;
	}

	if (i == len)
	return (NULL);

	if ((line = malloc(i + 1)) == NULL) {
	fprintf(stderr, "%s: out of memory\n", __func__);
	return (NULL);
	}

	memcpy(line, data, i);
	line[i] = '\0';

	/*
	* Some protocols terminate a line with '\r\n', so check for
	* that, too.
	*/
	if ( i < len - 1 ) {
	char fch = data[i], sch = data[i+1];

	/* Drain one more character if needed */
	if ( (sch == '\r' \|\| sch == '\n') && sch != fch )
	i += 1;
	}

	evbuffer_drain(buffer, i + 1);

	return (line);
	}

	/* Adds data to an event buffer */

	static void
	evbuffer_align(struct evbuffer *buf)
	{
	memmove(buf->orig_buffer, buf->buffer, buf->off);
	buf->buffer = buf->orig_buffer;
	buf->misalign = 0;
	}

	/* Expands the available space in the event buffer to at least datlen */

	int
	evbuffer_expand(struct evbuffer *buf, size_t datlen)
	{
	size_t need = buf->misalign + buf->off + datlen;

	/* If we can fit all the data, then we don't have to do anything */
	if (buf->totallen >= need)
	return (0);

	/*
	* If the misalignment fulfills our data needs, we just force an
	* alignment to happen. Afterwards, we have enough space.
	*/
	if (buf->misalign >= datlen) {
	evbuffer_align(buf);
	} else {
	void *newbuf;
	size_t length = buf->totallen;

	if (length < 256)
	length = 256;
	while (length < need)
	length <<= 1;

	if (buf->orig_buffer != buf->buffer)
	evbuffer_align(buf);
	if ((newbuf = realloc(buf->buffer, length)) == NULL)
	return (-1);

	buf->orig_buffer = buf->buffer = newbuf;
	buf->totallen = length;
	}

	return (0);
	}

	int
	evbuffer_add(struct evbuffer buf, const void data, size_t datlen)
	{
	size_t need = buf->misalign + buf->off + datlen;
	size_t oldoff = buf->off;

	if (buf->totallen < need) {
	if (evbuffer_expand(buf, datlen) == -1)
	return (-1);
	}

	memcpy(buf->buffer + buf->off, data, datlen);
	buf->off += datlen;

	if (datlen && buf->cb != NULL)
	(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);

	return (0);
	}

	void
	evbuffer_drain(struct evbuffer *buf, size_t len)
	{
	size_t oldoff = buf->off;

	if (len >= buf->off) {
	buf->off = 0;
	buf->buffer = buf->orig_buffer;
	buf->misalign = 0;
	goto done;
	}

	buf->buffer += len;
	buf->misalign += len;

	buf->off -= len;

	done:
	/* Tell someone about changes in this buffer */
	if (buf->off != oldoff && buf->cb != NULL)
	(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);

	}

	/*
	* Reads data from a file descriptor into a buffer.
	*/

	#define EVBUFFER_MAX_READ 4096

	int
	evbuffer_read(struct evbuffer *buf, int fd, int howmuch)
	{
	u_char *p;
	size_t oldoff = buf->off;
	int n = EVBUFFER_MAX_READ;

	#if defined(FIONREAD)
	#ifdef WIN32
	long lng = n;
	if (ioctlsocket(fd, FIONREAD, &lng) == -1 \|\| (n=lng) <= 0) {
	#else
	if (ioctl(fd, FIONREAD, &n) == -1 \|\| n <= 0) {
	#endif
	n = EVBUFFER_MAX_READ;
	} else if (n > EVBUFFER_MAX_READ && n > howmuch) {
	/*
	* It's possible that a lot of data is available for
	* reading. We do not want to exhaust resources
	* before the reader has a chance to do something
	* about it. If the reader does not tell us how much
	* data we should read, we artifically limit it.
	*/
	if ((size_t)n > buf->totallen << 2)
	n = buf->totallen << 2;
	if (n < EVBUFFER_MAX_READ)
	n = EVBUFFER_MAX_READ;
	}
	#endif
	if (howmuch < 0 \|\| howmuch > n)
	howmuch = n;

	/* If we don't have FIONREAD, we might waste some space here */
	if (evbuffer_expand(buf, howmuch) == -1)
	return (-1);

	/* We can append new data at this point */
	p = buf->buffer + buf->off;

	#ifndef WIN32
	n = read(fd, p, howmuch);
	#else
	n = recv(fd, p, howmuch, 0);
	#endif
	if (n == -1)
	return (-1);
	if (n == 0)
	return (0);

	buf->off += n;

	/* Tell someone about changes in this buffer */
	if (buf->off != oldoff && buf->cb != NULL)
	(*buf->cb)(buf, oldoff, buf->off, buf->cbarg);

	return (n);
	}

	int
	evbuffer_write(struct evbuffer *buffer, int fd)
	{
	int n;

	#ifndef WIN32
	n = write(fd, buffer->buffer, buffer->off);
	#else
	n = send(fd, buffer->buffer, buffer->off, 0);
	#endif
	if (n == -1)
	return (-1);
	if (n == 0)
	return (0);
	evbuffer_drain(buffer, n);

	return (n);
	}

	u_char *
	evbuffer_find(struct evbuffer buffer, const u_char what, size_t len)
	{
	u_char search = buffer->buffer, end = search + buffer->off;
	u_char *p;

	while (search < end &&
	(p = memchr(search, *what, end - search)) != NULL) {
	if (p + len > end)
	break;
	if (memcmp(p, what, len) == 0)
	return (p);
	search = p + 1;
	}

	return (NULL);
	}

	void evbuffer_setcb(struct evbuffer *buffer,
	void (cb)(struct evbuffer , size_t, size_t, void *),
	void *cbarg)
	{
	buffer->cb = cb;
	buffer->cbarg = cbarg;
	}