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buffer.c
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/*
* Copyright (c) 2002-2007 Niels Provos <[email protected]>
* Copyright (c) 2007-2010 Niels Provos and Nick Mathewson
*
* 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.
*/
#include "event-config.h"
#ifdef WIN32
#include <winsock2.h>
#include <windows.h>
#include <io.h>
#endif
#ifdef _EVENT_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 _EVENT_HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef _EVENT_HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef _EVENT_HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif
#ifdef _EVENT_HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef _EVENT_HAVE_SYS_MMAN_H
#include <sys/mman.h>
#endif
#ifdef _EVENT_HAVE_SYS_SENDFILE_H
#include <sys/sendfile.h>
#endif
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _EVENT_HAVE_STDARG_H
#include <stdarg.h>
#endif
#ifdef _EVENT_HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "event2/event.h"
#include "event2/buffer.h"
#include "event2/buffer_compat.h"
#include "event2/bufferevent.h"
#include "event2/bufferevent_compat.h"
#include "event2/bufferevent_struct.h"
#include "event2/thread.h"
#include "event-config.h"
#include "log-internal.h"
#include "mm-internal.h"
#include "util-internal.h"
#include "evthread-internal.h"
#include "evbuffer-internal.h"
#include "bufferevent-internal.h"
/* some systems do not have MAP_FAILED */
#ifndef MAP_FAILED
#define MAP_FAILED ((void *)-1)
#endif
/* send file support */
#if defined(_EVENT_HAVE_SYS_SENDFILE_H) && defined(_EVENT_HAVE_SENDFILE) && defined(__linux__)
#define USE_SENDFILE 1
#define SENDFILE_IS_LINUX 1
#elif defined(_EVENT_HAVE_SENDFILE) && defined(__FreeBSD__)
#define USE_SENDFILE 1
#define SENDFILE_IS_FREEBSD 1
#elif defined(_EVENT_HAVE_SENDFILE) && defined(__APPLE__)
#define USE_SENDFILE 1
#define SENDFILE_IS_MACOSX 1
#elif defined(_EVENT_HAVE_SENDFILE) && defined(__sun__) && defined(__svr4__)
#define USE_SENDFILE 1
#define SENDFILE_IS_SOLARIS 1
#endif
#ifdef USE_SENDFILE
static int use_sendfile = 1;
#endif
#ifdef _EVENT_HAVE_MMAP
static int use_mmap = 1;
#endif
/* Mask of user-selectable callback flags. */
#define EVBUFFER_CB_USER_FLAGS 0xffff
/* Mask of all internal-use-only flags. */
#define EVBUFFER_CB_INTERNAL_FLAGS 0xffff0000
/* Flag set if the callback is using the cb_obsolete function pointer */
#define EVBUFFER_CB_OBSOLETE 0x00040000
/* evbuffer_chain support */
#define CHAIN_SPACE_PTR(ch) ((ch)->buffer + (ch)->misalign + (ch)->off)
#define CHAIN_SPACE_LEN(ch) ((ch)->flags & EVBUFFER_IMMUTABLE ? \
0 : (ch)->buffer_len - ((ch)->misalign + (ch)->off))
#define CHAIN_PINNED(ch) (((ch)->flags & EVBUFFER_MEM_PINNED_ANY) != 0)
#define CHAIN_PINNED_R(ch) (((ch)->flags & EVBUFFER_MEM_PINNED_R) != 0)
static void evbuffer_chain_align(struct evbuffer_chain *chain);
static void evbuffer_deferred_callback(struct deferred_cb *cb, void *arg);
static int evbuffer_ptr_memcmp(const struct evbuffer *buf,
const struct evbuffer_ptr *pos, const char *mem, size_t len);
static struct evbuffer_chain *
evbuffer_chain_new(size_t size)
{
struct evbuffer_chain *chain;
size_t to_alloc;
size += EVBUFFER_CHAIN_SIZE;
/* get the next largest memory that can hold the buffer */
to_alloc = MIN_BUFFER_SIZE;
while (to_alloc < size)
to_alloc <<= 1;
/* we get everything in one chunk */
if ((chain = mm_malloc(to_alloc)) == NULL)
return (NULL);
memset(chain, 0, EVBUFFER_CHAIN_SIZE);
chain->buffer_len = to_alloc - EVBUFFER_CHAIN_SIZE;
/* this way we can manipulate the buffer to different addresses,
* which is required for mmap for example.
*/
chain->buffer = EVBUFFER_CHAIN_EXTRA(u_char, chain);
return (chain);
}
static inline void
evbuffer_chain_free(struct evbuffer_chain *chain)
{
if (CHAIN_PINNED(chain)) {
chain->flags |= EVBUFFER_DANGLING;
return;
}
if (chain->flags & (EVBUFFER_MMAP|EVBUFFER_SENDFILE|
EVBUFFER_REFERENCE)) {
if (chain->flags & EVBUFFER_REFERENCE) {
struct evbuffer_chain_reference *info =
EVBUFFER_CHAIN_EXTRA(
struct evbuffer_chain_reference,
chain);
if (info->cleanupfn)
(*info->cleanupfn)(chain->buffer,
chain->buffer_len,
info->extra);
}
#ifdef _EVENT_HAVE_MMAP
if (chain->flags & EVBUFFER_MMAP) {
struct evbuffer_chain_fd *info =
EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_fd,
chain);
if (munmap(chain->buffer, chain->buffer_len) == -1)
event_warn("%s: munmap failed", __func__);
if (close(info->fd) == -1)
event_warn("%s: close(%d) failed",
__func__, info->fd);
}
#endif
#ifdef USE_SENDFILE
if (chain->flags & EVBUFFER_SENDFILE) {
struct evbuffer_chain_fd *info =
EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_fd,
chain);
if (close(info->fd) == -1)
event_warn("%s: close(%d) failed",
__func__, info->fd);
}
#endif
}
mm_free(chain);
}
static inline void
evbuffer_chain_insert(struct evbuffer *buf, struct evbuffer_chain *chain)
{
ASSERT_EVBUFFER_LOCKED(buf);
if (buf->first == NULL) {
buf->first = buf->last = chain;
buf->previous_to_last = NULL;
} else {
/* the last chain is empty so we can just drop it */
if (buf->last->off == 0 && !CHAIN_PINNED(buf->last)) {
evbuffer_chain_free(buf->last);
buf->previous_to_last->next = chain;
buf->last = chain;
} else {
buf->previous_to_last = buf->last;
buf->last->next = chain;
buf->last = chain;
}
}
buf->total_len += chain->off;
}
void
_evbuffer_chain_pin(struct evbuffer_chain *chain, unsigned flag)
{
EVUTIL_ASSERT((chain->flags & flag) == 0);
chain->flags |= flag;
}
void
_evbuffer_chain_unpin(struct evbuffer_chain *chain, unsigned flag)
{
EVUTIL_ASSERT((chain->flags & flag) != 0);
chain->flags &= ~flag;
if (chain->flags & EVBUFFER_DANGLING)
evbuffer_chain_free(chain);
}
struct evbuffer *
evbuffer_new(void)
{
struct evbuffer *buffer;
buffer = mm_calloc(1, sizeof(struct evbuffer));
if (buffer == NULL)
return (NULL);
TAILQ_INIT(&buffer->callbacks);
buffer->refcnt = 1;
return (buffer);
}
void
_evbuffer_incref(struct evbuffer *buf)
{
EVBUFFER_LOCK(buf);
++buf->refcnt;
EVBUFFER_UNLOCK(buf);
}
void
_evbuffer_incref_and_lock(struct evbuffer *buf)
{
EVBUFFER_LOCK(buf);
++buf->refcnt;
}
int
evbuffer_defer_callbacks(struct evbuffer *buffer, struct event_base *base)
{
EVBUFFER_LOCK(buffer);
buffer->cb_queue = event_base_get_deferred_cb_queue(base);
buffer->deferred_cbs = 1;
event_deferred_cb_init(&buffer->deferred,
evbuffer_deferred_callback, buffer);
EVBUFFER_UNLOCK(buffer);
return 0;
}
int
evbuffer_enable_locking(struct evbuffer *buf, void *lock)
{
#ifdef _EVENT_DISABLE_THREAD_SUPPORT
return -1;
#else
if (buf->lock)
return -1;
if (!lock) {
EVTHREAD_ALLOC_LOCK(lock, EVTHREAD_LOCKTYPE_RECURSIVE);
if (!lock)
return -1;
buf->lock = lock;
buf->own_lock = 1;
} else {
buf->lock = lock;
buf->own_lock = 0;
}
return 0;
#endif
}
void
evbuffer_set_parent(struct evbuffer *buf, struct bufferevent *bev)
{
EVBUFFER_LOCK(buf);
buf->parent = bev;
EVBUFFER_UNLOCK(buf);
}
static void
evbuffer_run_callbacks(struct evbuffer *buffer, int running_deferred)
{
struct evbuffer_cb_entry *cbent, *next;
struct evbuffer_cb_info info;
size_t new_size;
ev_uint32_t mask, masked_val;
int clear = 1;
if (running_deferred) {
mask = EVBUFFER_CB_NODEFER|EVBUFFER_CB_ENABLED;
masked_val = EVBUFFER_CB_ENABLED;
} else if (buffer->deferred_cbs) {
mask = EVBUFFER_CB_NODEFER|EVBUFFER_CB_ENABLED;
masked_val = EVBUFFER_CB_NODEFER|EVBUFFER_CB_ENABLED;
/* Don't zero-out n_add/n_del, since the deferred callbacks
will want to see them. */
clear = 0;
} else {
mask = EVBUFFER_CB_ENABLED;
masked_val = EVBUFFER_CB_ENABLED;
}
ASSERT_EVBUFFER_LOCKED(buffer);
if (TAILQ_EMPTY(&buffer->callbacks)) {
buffer->n_add_for_cb = buffer->n_del_for_cb = 0;
return;
}
if (buffer->n_add_for_cb == 0 && buffer->n_del_for_cb == 0)
return;
new_size = buffer->total_len;
info.orig_size = new_size + buffer->n_del_for_cb - buffer->n_add_for_cb;
info.n_added = buffer->n_add_for_cb;
info.n_deleted = buffer->n_del_for_cb;
if (clear) {
buffer->n_add_for_cb = 0;
buffer->n_del_for_cb = 0;
}
for (cbent = TAILQ_FIRST(&buffer->callbacks);
cbent != TAILQ_END(&buffer->callbacks);
cbent = next) {
/* Get the 'next' pointer now in case this callback decides
* to remove itself or something. */
next = TAILQ_NEXT(cbent, next);
if ((cbent->flags & mask) != masked_val)
continue;
if ((cbent->flags & EVBUFFER_CB_OBSOLETE))
cbent->cb.cb_obsolete(buffer,
info.orig_size, new_size, cbent->cbarg);
else
cbent->cb.cb_func(buffer, &info, cbent->cbarg);
}
}
static inline void
evbuffer_invoke_callbacks(struct evbuffer *buffer)
{
if (buffer->deferred_cbs) {
if (buffer->deferred.queued)
return;
_evbuffer_incref_and_lock(buffer);
if (buffer->parent)
bufferevent_incref(buffer->parent);
EVBUFFER_UNLOCK(buffer);
event_deferred_cb_schedule(buffer->cb_queue, &buffer->deferred);
}
evbuffer_run_callbacks(buffer, 0);
}
static void
evbuffer_deferred_callback(struct deferred_cb *cb, void *arg)
{
struct bufferevent *parent = NULL;
struct evbuffer *buffer = arg;
/* XXXX It would be better to run these callbacks without holding the
* lock */
EVBUFFER_LOCK(buffer);
parent = buffer->parent;
evbuffer_run_callbacks(buffer, 1);
_evbuffer_decref_and_unlock(buffer);
if (parent)
bufferevent_decref(parent);
}
static void
evbuffer_remove_all_callbacks(struct evbuffer *buffer)
{
struct evbuffer_cb_entry *cbent;
while ((cbent = TAILQ_FIRST(&buffer->callbacks))) {
TAILQ_REMOVE(&buffer->callbacks, cbent, next);
mm_free(cbent);
}
}
void
_evbuffer_decref_and_unlock(struct evbuffer *buffer)
{
struct evbuffer_chain *chain, *next;
ASSERT_EVBUFFER_LOCKED(buffer);
if (--buffer->refcnt > 0) {
EVBUFFER_UNLOCK(buffer);
return;
}
for (chain = buffer->first; chain != NULL; chain = next) {
next = chain->next;
evbuffer_chain_free(chain);
}
evbuffer_remove_all_callbacks(buffer);
if (buffer->deferred_cbs)
event_deferred_cb_cancel(buffer->cb_queue, &buffer->deferred);
EVBUFFER_UNLOCK(buffer);
if (buffer->own_lock)
EVTHREAD_FREE_LOCK(buffer->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
mm_free(buffer);
}
void
evbuffer_free(struct evbuffer *buffer)
{
EVBUFFER_LOCK(buffer);
_evbuffer_decref_and_unlock(buffer);
}
void
evbuffer_lock(struct evbuffer *buf)
{
EVBUFFER_LOCK(buf);
}
void
evbuffer_unlock(struct evbuffer *buf)
{
EVBUFFER_UNLOCK(buf);
}
size_t
evbuffer_get_length(const struct evbuffer *buffer)
{
size_t result;
EVBUFFER_LOCK(buffer);
result = (buffer->total_len);
EVBUFFER_UNLOCK(buffer);
return result;
}
size_t
evbuffer_get_contiguous_space(const struct evbuffer *buf)
{
struct evbuffer_chain *chain;
size_t result;
EVBUFFER_LOCK(buf);
chain = buf->first;
result = (chain != NULL ? chain->off : 0);
EVBUFFER_UNLOCK(buf);
return result;
}
int
evbuffer_reserve_space(struct evbuffer *buf, ev_ssize_t size,
struct evbuffer_iovec *vec, int n_vecs)
{
struct evbuffer_chain *chain;
int n = -1;
EVBUFFER_LOCK(buf);
if (buf->freeze_end)
goto done;
if (n_vecs < 1)
goto done;
if (n_vecs == 1) {
if (evbuffer_expand(buf, size) == -1)
goto done;
chain = buf->last;
vec[0].iov_base = CHAIN_SPACE_PTR(chain);
vec[0].iov_len = CHAIN_SPACE_LEN(chain);
n = 1;
} else {
if (_evbuffer_expand_fast(buf, size)<0)
goto done;
n = _evbuffer_read_setup_vecs(buf, size, vec, &chain, 0);
}
done:
EVBUFFER_UNLOCK(buf);
return n;
}
int
evbuffer_commit_space(struct evbuffer *buf,
struct evbuffer_iovec *vec, int n_vecs)
{
struct evbuffer_chain *last, *prev;
int result = -1;
size_t added;
EVBUFFER_LOCK(buf);
prev = buf->previous_to_last;
last = buf->last;
if (buf->freeze_end)
goto done;
if (n_vecs < 1 || n_vecs > 2)
goto done;
if (n_vecs == 2) {
if (!prev || !last ||
vec[0].iov_base != CHAIN_SPACE_PTR(prev) ||
vec[1].iov_base != CHAIN_SPACE_PTR(last) ||
vec[0].iov_len > CHAIN_SPACE_LEN(prev) ||
vec[1].iov_len > CHAIN_SPACE_LEN(last))
goto done;
prev->off += vec[0].iov_len;
last->off += vec[1].iov_len;
added = vec[0].iov_len + vec[1].iov_len;
} else {
/* n_vecs == 1 */
struct evbuffer_chain *chain;
if (prev && vec[0].iov_base == CHAIN_SPACE_PTR(prev))
chain = prev;
else if (last && vec[0].iov_base == CHAIN_SPACE_PTR(last))
chain = last;
else
goto done;
if (vec[0].iov_len > CHAIN_SPACE_LEN(chain))
goto done;
chain->off += vec[0].iov_len;
added = vec[0].iov_len;
}
buf->total_len += added;
buf->n_add_for_cb += added;
result = 0;
evbuffer_invoke_callbacks(buf);
done:
EVBUFFER_UNLOCK(buf);
return result;
}
#define ZERO_CHAIN(dst) do { \
ASSERT_EVBUFFER_LOCKED(dst); \
(dst)->first = NULL; \
(dst)->last = NULL; \
(dst)->previous_to_last = NULL; \
(dst)->total_len = 0; \
} while (0)
#define COPY_CHAIN(dst, src) do { \
ASSERT_EVBUFFER_LOCKED(dst); \
ASSERT_EVBUFFER_LOCKED(src); \
(dst)->first = (src)->first; \
(dst)->previous_to_last = (src)->previous_to_last; \
(dst)->last = (src)->last; \
(dst)->total_len = (src)->total_len; \
} while (0)
#define APPEND_CHAIN(dst, src) do { \
ASSERT_EVBUFFER_LOCKED(dst); \
ASSERT_EVBUFFER_LOCKED(src); \
(dst)->last->next = (src)->first; \
(dst)->previous_to_last = (src)->previous_to_last ? \
(src)->previous_to_last : (dst)->last; \
(dst)->last = (src)->last; \
(dst)->total_len += (src)->total_len; \
} while (0)
#define PREPEND_CHAIN(dst, src) do { \
ASSERT_EVBUFFER_LOCKED(dst); \
ASSERT_EVBUFFER_LOCKED(src); \
(src)->last->next = (dst)->first; \
(dst)->first = (src)->first; \
(dst)->total_len += (src)->total_len; \
if ((dst)->previous_to_last == NULL) \
(dst)->previous_to_last = (src)->last; \
} while (0)
int
evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
{
size_t in_total_len, out_total_len;
int result = 0;
EVBUFFER_LOCK2(inbuf, outbuf);
in_total_len = inbuf->total_len;
out_total_len = outbuf->total_len;
if (in_total_len == 0 || outbuf == inbuf)
goto done;
if (outbuf->freeze_end || inbuf->freeze_start) {
result = -1;
goto done;
}
if (out_total_len == 0) {
COPY_CHAIN(outbuf, inbuf);
} else {
APPEND_CHAIN(outbuf, inbuf);
}
/* remove everything from inbuf */
ZERO_CHAIN(inbuf);
inbuf->n_del_for_cb += in_total_len;
outbuf->n_add_for_cb += in_total_len;
evbuffer_invoke_callbacks(inbuf);
evbuffer_invoke_callbacks(outbuf);
done:
EVBUFFER_UNLOCK2(inbuf, outbuf);
return result;
}
int
evbuffer_prepend_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
{
size_t in_total_len, out_total_len;
int result = 0;
EVBUFFER_LOCK2(inbuf, outbuf);
in_total_len = inbuf->total_len;
out_total_len = outbuf->total_len;
if (!in_total_len || inbuf == outbuf)
goto done;
if (outbuf->freeze_start || inbuf->freeze_start) {
result = -1;
goto done;
}
if (out_total_len == 0) {
COPY_CHAIN(outbuf, inbuf);
} else {
PREPEND_CHAIN(outbuf, inbuf);
}
/* remove everything from inbuf */
ZERO_CHAIN(inbuf);
inbuf->n_del_for_cb += in_total_len;
outbuf->n_add_for_cb += in_total_len;
evbuffer_invoke_callbacks(inbuf);
evbuffer_invoke_callbacks(outbuf);
done:
EVBUFFER_UNLOCK2(inbuf, outbuf);
return result;
}
int
evbuffer_drain(struct evbuffer *buf, size_t len)
{
struct evbuffer_chain *chain, *next;
size_t old_len;
int result = 0;
EVBUFFER_LOCK(buf);
old_len = buf->total_len;
if (old_len == 0)
goto done;
if (buf->freeze_start) {
result = -1;
goto done;
}
if (len >= old_len && !(buf->last && CHAIN_PINNED_R(buf->last))) {
len = old_len;
for (chain = buf->first; chain != NULL; chain = next) {
next = chain->next;
evbuffer_chain_free(chain);
}
ZERO_CHAIN(buf);
} else {
if (len >= old_len)
len = old_len;
buf->total_len -= len;
for (chain = buf->first; len >= chain->off; chain = next) {
next = chain->next;
len -= chain->off;
if (len == 0 && CHAIN_PINNED_R(chain))
break;
evbuffer_chain_free(chain);
}
buf->first = chain;
if (buf->first == buf->last)
buf->previous_to_last = NULL;
chain->misalign += len;
chain->off -= len;
}
buf->n_del_for_cb += len;
/* Tell someone about changes in this buffer */
evbuffer_invoke_callbacks(buf);
done:
EVBUFFER_UNLOCK(buf);
return result;
}
/* Reads data from an event buffer and drains the bytes read */
int
evbuffer_remove(struct evbuffer *buf, void *data_out, size_t datlen)
{
/*XXX fails badly on sendfile case. */
struct evbuffer_chain *chain, *tmp;
char *data = data_out;
size_t nread;
int result = 0;
EVBUFFER_LOCK(buf);
chain = buf->first;
if (datlen >= buf->total_len)
datlen = buf->total_len;
if (datlen == 0)
goto done;
if (buf->freeze_start) {
result = -1;
goto done;
}
nread = datlen;
while (datlen && datlen >= chain->off) {
memcpy(data, chain->buffer + chain->misalign, chain->off);
data += chain->off;
datlen -= chain->off;
tmp = chain;
chain = chain->next;
evbuffer_chain_free(tmp);
}
buf->first = chain;
if (chain == NULL)
buf->last = NULL;
if (buf->first == buf->last)
buf->previous_to_last = NULL;
if (datlen) {
memcpy(data, chain->buffer + chain->misalign, datlen);
chain->misalign += datlen;
chain->off -= datlen;
}
buf->total_len -= nread;
buf->n_del_for_cb += nread;
if (nread)
evbuffer_invoke_callbacks(buf);
result = nread;
done:
EVBUFFER_UNLOCK(buf);
return result;
}
/* reads data from the src buffer to the dst buffer, avoids memcpy as
* possible. */
int
evbuffer_remove_buffer(struct evbuffer *src, struct evbuffer *dst,
size_t datlen)
{
/*XXX We should have an option to force this to be zero-copy.*/
/*XXX can fail badly on sendfile case. */
struct evbuffer_chain *chain, *previous, *previous_to_previous = NULL;
size_t nread = 0;
int result;
EVBUFFER_LOCK2(src, dst);
chain = previous = src->first;
if (datlen == 0 || dst == src) {
result = 0;
goto done;
}
if (dst->freeze_end || src->freeze_start) {
result = -1;
goto done;
}
/* short-cut if there is no more data buffered */
if (datlen >= src->total_len) {
datlen = src->total_len;
evbuffer_add_buffer(dst, src);
result = datlen;
goto done;
}
/* removes chains if possible */
while (chain->off <= datlen) {
nread += chain->off;
datlen -= chain->off;
previous_to_previous = previous;
previous = chain;
chain = chain->next;
}
if (nread) {
/* we can remove the chain */
if (dst->first == NULL) {
dst->first = src->first;
} else {
dst->last->next = src->first;
}
dst->previous_to_last = previous_to_previous;
dst->last = previous;
previous->next = NULL;
src->first = chain;
if (src->first == src->last)
src->previous_to_last = NULL;
dst->total_len += nread;
dst->n_add_for_cb += nread;
}
/* we know that there is more data in the src buffer than
* we want to read, so we manually drain the chain */
evbuffer_add(dst, chain->buffer + chain->misalign, datlen);
chain->misalign += datlen;
chain->off -= datlen;
nread += datlen;
src->total_len -= nread;
src->n_del_for_cb += nread;
if (nread) {
evbuffer_invoke_callbacks(dst);
evbuffer_invoke_callbacks(src);
}
result = nread;
done:
EVBUFFER_UNLOCK2(src, dst);
return result;
}
unsigned char *
evbuffer_pullup(struct evbuffer *buf, ev_ssize_t size)
{
struct evbuffer_chain *chain, *next, *tmp;
unsigned char *buffer, *result = NULL;
ev_ssize_t remaining;
EVBUFFER_LOCK(buf);
chain = buf->first;
if (size < 0)
size = buf->total_len;
/* if size > buf->total_len, we cannot guarantee to the user that she
* is going to have a long enough buffer afterwards; so we return
* NULL */
if (size == 0 || (size_t)size > buf->total_len)
goto done;
/* No need to pull up anything; the first size bytes are
* already here. */
if (chain->off >= (size_t)size) {
result = chain->buffer + chain->misalign;
goto done;
}
/* Make sure that none of the chains we need to copy from is pinned. */
remaining = size - chain->off;
EVUTIL_ASSERT(remaining >= 0);
for (tmp=chain->next; tmp; tmp=tmp->next) {
if (CHAIN_PINNED(tmp))
goto done;
if (tmp->off >= (size_t)remaining)
break;
remaining -= tmp->off;
}
if (CHAIN_PINNED(chain)) {
size_t old_off = chain->off;
if (CHAIN_SPACE_LEN(chain) < size - chain->off) {
/* not enough room at end of chunk. */
goto done;
}
buffer = CHAIN_SPACE_PTR(chain);
tmp = chain;
tmp->off = size;
size -= old_off;
chain = chain->next;
} else if (chain->buffer_len - chain->misalign >= (size_t)size) {
/* already have enough space in the first chain */
size_t old_off = chain->off;
buffer = chain->buffer + chain->misalign + chain->off;
tmp = chain;
tmp->off = size;
size -= old_off;
chain = chain->next;
} else {
if ((tmp = evbuffer_chain_new(size)) == NULL) {
event_warn("%s: out of memory", __func__);
goto done;
}
buffer = tmp->buffer;
tmp->off = size;
buf->first = tmp;
}
/* TODO(niels): deal with buffers that point to NULL like sendfile */
/* Copy and free every chunk that will be entirely pulled into tmp */
for (; chain != NULL && (size_t)size >= chain->off; chain = next) {
next = chain->next;
memcpy(buffer, chain->buffer + chain->misalign, chain->off);
size -= chain->off;
buffer += chain->off;
evbuffer_chain_free(chain);
}
if (chain != NULL) {
memcpy(buffer, chain->buffer + chain->misalign, size);
chain->misalign += size;
chain->off -= size;
if (chain == buf->last)
buf->previous_to_last = tmp;
} else {
buf->last = tmp;
/* the last is already the first, so we have no previous */
buf->previous_to_last = NULL;
}
tmp->next = chain;
result = (tmp->buffer + tmp->misalign);
done:
EVBUFFER_UNLOCK(buf);