mirror of
https://github.com/cuberite/libevent.git
synced 2025-08-04 01:36:23 -04:00
IOCP-related evbuffer fixes.
- Prevent evbuffer_{add,prepend}_buffer from moving read-pinned chains.
- Fix evbuffer_drain to handle read-pinned chains better.
- Raise the limit on WSABUFs from two to MAX_WSABUFS for overlapped reads.
This commit is contained in:
Christopher Davis
parent
42090072c1
commit
03afa209de
120
buffer.c
120
buffer.c
@ -575,7 +575,8 @@ evbuffer_reserve_space(struct evbuffer *buf, ev_ssize_t size,
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} else {
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if (_evbuffer_expand_fast(buf, size, n_vecs)<0)
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goto done;
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n = _evbuffer_read_setup_vecs(buf, size, vec, n_vecs, &chainp, 0);
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n = _evbuffer_read_setup_vecs(buf, size, vec, n_vecs,
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&chainp, 0);
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}
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done:
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@ -670,6 +671,12 @@ done:
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return result;
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}
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static inline int
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HAS_PINNED_R(struct evbuffer *buf)
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{
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return (buf->last && CHAIN_PINNED_R(buf->last));
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}
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static inline void
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ZERO_CHAIN(struct evbuffer *dst)
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{
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@ -680,6 +687,71 @@ ZERO_CHAIN(struct evbuffer *dst)
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dst->total_len = 0;
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}
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/* Prepares the contents of src to be moved to another buffer by removing
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* read-pinned chains. The first pinned chain is saved in first, and the
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* last in last. If src has no read-pinned chains, first and last are set
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* to NULL. */
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static int
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PRESERVE_PINNED(struct evbuffer *src, struct evbuffer_chain **first,
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struct evbuffer_chain **last)
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{
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struct evbuffer_chain *chain, **pinned;
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ASSERT_EVBUFFER_LOCKED(src);
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if (!HAS_PINNED_R(src)) {
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*first = *last = NULL;
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return 0;
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}
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pinned = src->last_with_datap;
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if (!CHAIN_PINNED_R(*pinned))
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pinned = &(*pinned)->next;
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EVUTIL_ASSERT(CHAIN_PINNED_R(*pinned));
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chain = *first = *pinned;
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*last = src->last;
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/* If there's data in the first pinned chain, we need to allocate
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* a new chain and copy the data over. */
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if (chain->off) {
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struct evbuffer_chain *tmp;
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EVUTIL_ASSERT(pinned == src->last_with_datap);
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tmp = evbuffer_chain_new(chain->off);
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if (!tmp)
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return -1;
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memcpy(tmp->buffer, chain->buffer + chain->misalign,
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chain->off);
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tmp->off = chain->off;
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*src->last_with_datap = tmp;
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src->last = tmp;
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chain->misalign += chain->off;
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chain->off = 0;
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} else {
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src->last = *src->last_with_datap;
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*pinned = NULL;
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}
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return 0;
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}
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static inline void
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RESTORE_PINNED(struct evbuffer *src, struct evbuffer_chain *pinned,
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struct evbuffer_chain *last)
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{
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ASSERT_EVBUFFER_LOCKED(src);
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if (!pinned) {
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ZERO_CHAIN(src);
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return;
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}
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src->first = pinned;
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src->last = last;
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src->last_with_datap = &src->first;
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src->total_len = 0;
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}
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static inline void
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COPY_CHAIN(struct evbuffer *dst, struct evbuffer *src)
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{
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@ -729,6 +801,7 @@ PREPEND_CHAIN(struct evbuffer *dst, struct evbuffer *src)
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int
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evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
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{
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struct evbuffer_chain *pinned, *last;
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size_t in_total_len, out_total_len;
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int result = 0;
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@ -744,6 +817,11 @@ evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
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goto done;
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}
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if (PRESERVE_PINNED(inbuf, &pinned, &last) < 0) {
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result = -1;
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goto done;
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}
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if (out_total_len == 0) {
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/* There might be an empty chain at the start of outbuf; free
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* it. */
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@ -753,8 +831,8 @@ evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
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APPEND_CHAIN(outbuf, inbuf);
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}
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/* remove everything from inbuf */
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ZERO_CHAIN(inbuf);
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RESTORE_PINNED(inbuf, pinned, last);
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inbuf->n_del_for_cb += in_total_len;
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outbuf->n_add_for_cb += in_total_len;
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@ -769,6 +847,7 @@ done:
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int
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evbuffer_prepend_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
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{
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struct evbuffer_chain *pinned, *last;
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size_t in_total_len, out_total_len;
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int result = 0;
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@ -785,6 +864,11 @@ evbuffer_prepend_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
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goto done;
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}
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if (PRESERVE_PINNED(inbuf, &pinned, &last) < 0) {
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result = -1;
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goto done;
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}
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if (out_total_len == 0) {
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/* There might be an empty chain at the start of outbuf; free
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* it. */
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@ -794,8 +878,8 @@ evbuffer_prepend_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf)
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PREPEND_CHAIN(outbuf, inbuf);
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}
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/* remove everything from inbuf */
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ZERO_CHAIN(inbuf);
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RESTORE_PINNED(inbuf, pinned, last);
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inbuf->n_del_for_cb += in_total_len;
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outbuf->n_add_for_cb += in_total_len;
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@ -810,7 +894,7 @@ int
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evbuffer_drain(struct evbuffer *buf, size_t len)
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{
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struct evbuffer_chain *chain, *next;
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size_t old_len;
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size_t remaining, old_len;
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int result = 0;
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EVBUFFER_LOCK(buf);
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@ -824,12 +908,10 @@ evbuffer_drain(struct evbuffer *buf, size_t len)
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goto done;
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}
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if (len >= old_len && !(buf->last && CHAIN_PINNED_R(buf->last))) {
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if (len >= old_len && !HAS_PINNED_R(buf)) {
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len = old_len;
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for (chain = buf->first; chain != NULL; chain = next) {
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next = chain->next;
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evbuffer_chain_free(chain);
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}
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@ -839,10 +921,12 @@ evbuffer_drain(struct evbuffer *buf, size_t len)
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len = old_len;
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buf->total_len -= len;
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for (chain = buf->first; len >= chain->off; chain = next) {
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remaining = len;
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for (chain = buf->first;
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remaining >= chain->off;
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chain = next) {
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next = chain->next;
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len -= chain->off;
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remaining -= chain->off;
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if (chain == *buf->last_with_datap) {
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buf->last_with_datap = &buf->first;
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@ -850,14 +934,20 @@ evbuffer_drain(struct evbuffer *buf, size_t len)
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if (&chain->next == buf->last_with_datap)
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buf->last_with_datap = &buf->first;
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if (len == 0 && CHAIN_PINNED_R(chain))
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if (CHAIN_PINNED_R(chain)) {
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EVUTIL_ASSERT(remaining == 0);
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chain->misalign += chain->off;
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chain->off = 0;
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break;
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} else
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evbuffer_chain_free(chain);
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}
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buf->first = chain;
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chain->misalign += len;
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chain->off -= len;
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if (chain) {
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chain->misalign += remaining;
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chain->off -= remaining;
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}
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}
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buf->n_del_for_cb += len;
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@ -82,12 +82,13 @@ static void
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pin_release(struct evbuffer_overlapped *eo, unsigned flag)
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{
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int i;
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struct evbuffer_chain *chain = eo->first_pinned;
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struct evbuffer_chain *next, *chain = eo->first_pinned;
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for (i = 0; i < eo->n_buffers; ++i) {
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EVUTIL_ASSERT(chain);
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next = chain->next;
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_evbuffer_chain_unpin(chain, flag);
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chain = chain->next;
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chain = next;
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}
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}
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@ -95,8 +96,9 @@ void
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evbuffer_commit_read(struct evbuffer *evbuf, ev_ssize_t nBytes)
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{
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struct evbuffer_overlapped *buf = upcast_evbuffer(evbuf);
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struct evbuffer_iovec iov[2];
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int n_vec;
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struct evbuffer_chain **chainp;
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size_t remaining, len;
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unsigned i;
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EVBUFFER_LOCK(evbuf);
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EVUTIL_ASSERT(buf->read_in_progress && !buf->write_in_progress);
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@ -104,24 +106,27 @@ evbuffer_commit_read(struct evbuffer *evbuf, ev_ssize_t nBytes)
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evbuffer_unfreeze(evbuf, 0);
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iov[0].iov_base = buf->buffers[0].buf;
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if ((size_t)nBytes <= buf->buffers[0].len) {
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iov[0].iov_len = nBytes;
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n_vec = 1;
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} else {
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iov[0].iov_len = buf->buffers[0].len;
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iov[1].iov_base = buf->buffers[1].buf;
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iov[1].iov_len = nBytes - iov[0].iov_len;
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n_vec = 2;
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chainp = evbuf->last_with_datap;
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if (!((*chainp)->flags & EVBUFFER_MEM_PINNED_R))
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chainp = &(*chainp)->next;
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remaining = nBytes;
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for (i = 0; remaining > 0 && i < buf->n_buffers; ++i) {
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EVUTIL_ASSERT(*chainp);
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len = buf->buffers[i].len;
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if (remaining < len)
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len = remaining;
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(*chainp)->off += len;
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evbuf->last_with_datap = chainp;
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remaining -= len;
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chainp = &(*chainp)->next;
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}
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if (evbuffer_commit_space(evbuf, iov, n_vec) < 0)
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EVUTIL_ASSERT(0); /* XXXX fail nicer. */
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pin_release(buf, EVBUFFER_MEM_PINNED_R);
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buf->read_in_progress = 0;
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evbuf->total_len += nBytes;
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_evbuffer_decref_and_unlock(evbuf);
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}
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@ -184,7 +189,7 @@ evbuffer_launch_write(struct evbuffer *buf, ev_ssize_t at_most,
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}
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evbuffer_freeze(buf, 1);
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buf_o->first_pinned = 0;
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buf_o->first_pinned = NULL;
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buf_o->n_buffers = 0;
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memset(buf_o->buffers, 0, sizeof(buf_o->buffers));
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@ -246,19 +251,16 @@ evbuffer_launch_read(struct evbuffer *buf, size_t at_most,
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if (buf->freeze_end || buf_o->read_in_progress)
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goto done;
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buf_o->first_pinned = 0;
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buf_o->first_pinned = NULL;
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buf_o->n_buffers = 0;
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memset(buf_o->buffers, 0, sizeof(buf_o->buffers));
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if (_evbuffer_expand_fast(buf, at_most, 2) == -1)
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if (_evbuffer_expand_fast(buf, at_most, MAX_WSABUFS) == -1)
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goto done;
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evbuffer_freeze(buf, 0);
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/* XXX This and evbuffer_read_setup_vecs() should say MAX_WSABUFS,
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* not "2". But commit_read() above can't handle more than two
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* buffers yet. */
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nvecs = _evbuffer_read_setup_vecs(buf, at_most,
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vecs, 2, &chainp, 1);
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vecs, MAX_WSABUFS, &chainp, 1);
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for (i=0;i<nvecs;++i) {
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WSABUF_FROM_EVBUFFER_IOV(
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&buf_o->buffers[i],
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@ -267,6 +269,7 @@ evbuffer_launch_read(struct evbuffer *buf, size_t at_most,
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buf_o->n_buffers = nvecs;
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buf_o->first_pinned = chain = *chainp;
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npin=0;
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for ( ; chain; chain = chain->next) {
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_evbuffer_chain_pin(chain, EVBUFFER_MEM_PINNED_R);
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@ -256,7 +256,8 @@ int _evbuffer_expand_fast(struct evbuffer *, size_t, int);
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* Returns the number of vecs used.
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*/
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int _evbuffer_read_setup_vecs(struct evbuffer *buf, ev_ssize_t howmuch,
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struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp, int exact);
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struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp,
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int exact);
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/* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */
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#define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \
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