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kc3-lang/libevent/buffer_iocp.c

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  • Author : Nick Mathewson
    Date : 2012-02-29 15:07:32
    Hash : cb9da0bf
    Message : Fix all identifiers with names beginning with underscore. These are reserved in C. We'd been erroneously using them to indicate internal use. Instead, we now use a trailing underscore whenever we'd been using a leading underscore. This is an automatic conversion. The script that produced was made by running the following script over the output of git ls-tree -r --name-only HEAD | grep '\.[ch]$' | \ xargs ctags --c-kinds=defglmpstuvx -o - | grep '^_' | \ cut -f 1 | sort| uniq (GNU ctags was required.) ===== #!/usr/bin/perl -w -n use strict; BEGIN { print "#!/usr/bin/perl -w -i -p\n\n"; } chomp; next if (/^__func__/ or /^_FILE_OFFSET_BITS/ or /^_FORTIFY_SOURCE/ or /^_GNU_SOURCE/ or /^_WIN32/ or /^_DARWIN_UNLIMITED/ or /^_FILE_OFFSET_BITS/ or /^_LARGEFILE64_SOURCE/ or /^_LFS64_LARGEFILE/ or /^__cdecl/ or /^__attribute__/ or /^__func__/ or /^_SYS_TREE_H_/); my $ident = $_; my $better = $ident; $better =~ s/^_//; if ($ident !~ /EVENT_LOG_/) { $better = "${better}_"; } print "s/(?<![A-Za-z0-9_])$ident(?![A-Za-z0-9_])/$better/g;\n"; === And then running the script below that it generated over all === the .c and .h files again #!/usr/bin/perl -w -i -p s/(?<![A-Za-z0-9_])_ARC4_LOCK(?![A-Za-z0-9_])/ARC4_LOCK_/g; s/(?<![A-Za-z0-9_])_ARC4_UNLOCK(?![A-Za-z0-9_])/ARC4_UNLOCK_/g; s/(?<![A-Za-z0-9_])_bev_group_random_element(?![A-Za-z0-9_])/bev_group_random_element_/g; s/(?<![A-Za-z0-9_])_bev_group_refill_callback(?![A-Za-z0-9_])/bev_group_refill_callback_/g; s/(?<![A-Za-z0-9_])_bev_group_suspend_reading(?![A-Za-z0-9_])/bev_group_suspend_reading_/g; s/(?<![A-Za-z0-9_])_bev_group_suspend_writing(?![A-Za-z0-9_])/bev_group_suspend_writing_/g; s/(?<![A-Za-z0-9_])_bev_group_unsuspend_reading(?![A-Za-z0-9_])/bev_group_unsuspend_reading_/g; s/(?<![A-Za-z0-9_])_bev_group_unsuspend_writing(?![A-Za-z0-9_])/bev_group_unsuspend_writing_/g; s/(?<![A-Za-z0-9_])_bev_refill_callback(?![A-Za-z0-9_])/bev_refill_callback_/g; s/(?<![A-Za-z0-9_])_bufferevent_add_event(?![A-Za-z0-9_])/bufferevent_add_event_/g; s/(?<![A-Za-z0-9_])_bufferevent_cancel_all(?![A-Za-z0-9_])/bufferevent_cancel_all_/g; s/(?<![A-Za-z0-9_])_bufferevent_decref_and_unlock(?![A-Za-z0-9_])/bufferevent_decref_and_unlock_/g; s/(?<![A-Za-z0-9_])_bufferevent_decrement_read_buckets(?![A-Za-z0-9_])/bufferevent_decrement_read_buckets_/g; s/(?<![A-Za-z0-9_])_bufferevent_decrement_write_buckets(?![A-Za-z0-9_])/bufferevent_decrement_write_buckets_/g; s/(?<![A-Za-z0-9_])_bufferevent_del_generic_timeout_cbs(?![A-Za-z0-9_])/bufferevent_del_generic_timeout_cbs_/g; s/(?<![A-Za-z0-9_])_bufferevent_generic_adj_timeouts(?![A-Za-z0-9_])/bufferevent_generic_adj_timeouts_/g; s/(?<![A-Za-z0-9_])_bufferevent_get_read_max(?![A-Za-z0-9_])/bufferevent_get_read_max_/g; s/(?<![A-Za-z0-9_])_bufferevent_get_rlim_max(?![A-Za-z0-9_])/bufferevent_get_rlim_max_/g; s/(?<![A-Za-z0-9_])_bufferevent_get_write_max(?![A-Za-z0-9_])/bufferevent_get_write_max_/g; s/(?<![A-Za-z0-9_])_bufferevent_incref_and_lock(?![A-Za-z0-9_])/bufferevent_incref_and_lock_/g; s/(?<![A-Za-z0-9_])_bufferevent_init_generic_timeout_cbs(?![A-Za-z0-9_])/bufferevent_init_generic_timeout_cbs_/g; s/(?<![A-Za-z0-9_])_bufferevent_ratelim_init(?![A-Za-z0-9_])/bufferevent_ratelim_init_/g; s/(?<![A-Za-z0-9_])_bufferevent_run_eventcb(?![A-Za-z0-9_])/bufferevent_run_eventcb_/g; s/(?<![A-Za-z0-9_])_bufferevent_run_readcb(?![A-Za-z0-9_])/bufferevent_run_readcb_/g; s/(?<![A-Za-z0-9_])_bufferevent_run_writecb(?![A-Za-z0-9_])/bufferevent_run_writecb_/g; s/(?<![A-Za-z0-9_])_ev(?![A-Za-z0-9_])/ev_/g; s/(?<![A-Za-z0-9_])_evbuffer_chain_pin(?![A-Za-z0-9_])/evbuffer_chain_pin_/g; s/(?<![A-Za-z0-9_])_evbuffer_chain_unpin(?![A-Za-z0-9_])/evbuffer_chain_unpin_/g; s/(?<![A-Za-z0-9_])_evbuffer_decref_and_unlock(?![A-Za-z0-9_])/evbuffer_decref_and_unlock_/g; s/(?<![A-Za-z0-9_])_evbuffer_expand_fast(?![A-Za-z0-9_])/evbuffer_expand_fast_/g; s/(?<![A-Za-z0-9_])_evbuffer_incref(?![A-Za-z0-9_])/evbuffer_incref_/g; s/(?<![A-Za-z0-9_])_evbuffer_incref_and_lock(?![A-Za-z0-9_])/evbuffer_incref_and_lock_/g; s/(?<![A-Za-z0-9_])_EVBUFFER_IOVEC_IS_NATIVE(?![A-Za-z0-9_])/EVBUFFER_IOVEC_IS_NATIVE_/g; s/(?<![A-Za-z0-9_])_evbuffer_overlapped_get_fd(?![A-Za-z0-9_])/evbuffer_overlapped_get_fd_/g; s/(?<![A-Za-z0-9_])_evbuffer_overlapped_set_fd(?![A-Za-z0-9_])/evbuffer_overlapped_set_fd_/g; s/(?<![A-Za-z0-9_])_evbuffer_read_setup_vecs(?![A-Za-z0-9_])/evbuffer_read_setup_vecs_/g; s/(?<![A-Za-z0-9_])_evbuffer_validate(?![A-Za-z0-9_])/evbuffer_validate_/g; s/(?<![A-Za-z0-9_])_evdns_log(?![A-Za-z0-9_])/evdns_log_/g; s/(?<![A-Za-z0-9_])_evdns_nameserver_add_impl(?![A-Za-z0-9_])/evdns_nameserver_add_impl_/g; s/(?<![A-Za-z0-9_])_EVENT_CONFIG_H_(?![A-Za-z0-9_])/EVENT_CONFIG_H__/g; s/(?<![A-Za-z0-9_])_event_debug_assert_is_setup(?![A-Za-z0-9_])/event_debug_assert_is_setup_/g; s/(?<![A-Za-z0-9_])_event_debug_assert_not_added(?![A-Za-z0-9_])/event_debug_assert_not_added_/g; s/(?<![A-Za-z0-9_])_event_debug_get_logging_mask(?![A-Za-z0-9_])/event_debug_get_logging_mask_/g; s/(?<![A-Za-z0-9_])_event_debug_logging_mask(?![A-Za-z0-9_])/event_debug_logging_mask_/g; s/(?<![A-Za-z0-9_])_event_debug_map_lock(?![A-Za-z0-9_])/event_debug_map_lock_/g; s/(?<![A-Za-z0-9_])_event_debug_mode_on(?![A-Za-z0-9_])/event_debug_mode_on_/g; s/(?<![A-Za-z0-9_])_event_debug_note_add(?![A-Za-z0-9_])/event_debug_note_add_/g; s/(?<![A-Za-z0-9_])_event_debug_note_del(?![A-Za-z0-9_])/event_debug_note_del_/g; s/(?<![A-Za-z0-9_])_event_debug_note_setup(?![A-Za-z0-9_])/event_debug_note_setup_/g; s/(?<![A-Za-z0-9_])_event_debug_note_teardown(?![A-Za-z0-9_])/event_debug_note_teardown_/g; s/(?<![A-Za-z0-9_])_event_debugx(?![A-Za-z0-9_])/event_debugx_/g; s/(?<![A-Za-z0-9_])_EVENT_DEFINED_LISTENTRY(?![A-Za-z0-9_])/EVENT_DEFINED_LISTENTRY_/g; s/(?<![A-Za-z0-9_])_EVENT_DEFINED_TQENTRY(?![A-Za-z0-9_])/EVENT_DEFINED_TQENTRY_/g; s/(?<![A-Za-z0-9_])_EVENT_DEFINED_TQHEAD(?![A-Za-z0-9_])/EVENT_DEFINED_TQHEAD_/g; s/(?<![A-Za-z0-9_])_EVENT_DNS_USE_FTIME_FOR_ID(?![A-Za-z0-9_])/EVENT_DNS_USE_FTIME_FOR_ID_/g; s/(?<![A-Za-z0-9_])_EVENT_ERR_ABORT(?![A-Za-z0-9_])/EVENT_ERR_ABORT_/g; s/(?<![A-Za-z0-9_])_EVENT_EVCONFIG__PRIVATE_H(?![A-Za-z0-9_])/EVENT_EVCONFIG__PRIVATE_H_/g; s/(?<![A-Za-z0-9_])_event_iocp_port_unlock_and_free(?![A-Za-z0-9_])/event_iocp_port_unlock_and_free_/g; s/(?<![A-Za-z0-9_])_EVENT_LOG_DEBUG(?![A-Za-z0-9_])/EVENT_LOG_DEBUG/g; s/(?<![A-Za-z0-9_])_EVENT_LOG_ERR(?![A-Za-z0-9_])/EVENT_LOG_ERR/g; s/(?<![A-Za-z0-9_])_EVENT_LOG_MSG(?![A-Za-z0-9_])/EVENT_LOG_MSG/g; s/(?<![A-Za-z0-9_])_EVENT_LOG_WARN(?![A-Za-z0-9_])/EVENT_LOG_WARN/g; s/(?<![A-Za-z0-9_])_event_strlcpy(?![A-Za-z0-9_])/event_strlcpy_/g; s/(?<![A-Za-z0-9_])_EVHTTP_REQ_UNKNOWN(?![A-Za-z0-9_])/EVHTTP_REQ_UNKNOWN_/g; s/(?<![A-Za-z0-9_])_EVLOCK_SORTLOCKS(?![A-Za-z0-9_])/EVLOCK_SORTLOCKS_/g; s/(?<![A-Za-z0-9_])_evrpc_hooks(?![A-Za-z0-9_])/evrpc_hooks_/g; s/(?<![A-Za-z0-9_])_evsig_restore_handler(?![A-Za-z0-9_])/evsig_restore_handler_/g; s/(?<![A-Za-z0-9_])_evsig_set_handler(?![A-Za-z0-9_])/evsig_set_handler_/g; s/(?<![A-Za-z0-9_])_evthread_cond_fns(?![A-Za-z0-9_])/evthread_cond_fns_/g; s/(?<![A-Za-z0-9_])_evthread_debug_get_real_lock(?![A-Za-z0-9_])/evthread_debug_get_real_lock_/g; s/(?<![A-Za-z0-9_])_evthread_id_fn(?![A-Za-z0-9_])/evthread_id_fn_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_cond_alloc(?![A-Za-z0-9_])/evthreadimpl_cond_alloc_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_cond_free(?![A-Za-z0-9_])/evthreadimpl_cond_free_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_cond_signal(?![A-Za-z0-9_])/evthreadimpl_cond_signal_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_cond_wait(?![A-Za-z0-9_])/evthreadimpl_cond_wait_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_get_id(?![A-Za-z0-9_])/evthreadimpl_get_id_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_is_lock_debugging_enabled(?![A-Za-z0-9_])/evthreadimpl_is_lock_debugging_enabled_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_lock_alloc(?![A-Za-z0-9_])/evthreadimpl_lock_alloc_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_lock_free(?![A-Za-z0-9_])/evthreadimpl_lock_free_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_locking_enabled(?![A-Za-z0-9_])/evthreadimpl_locking_enabled_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_lock_lock(?![A-Za-z0-9_])/evthreadimpl_lock_lock_/g; s/(?<![A-Za-z0-9_])_evthreadimpl_lock_unlock(?![A-Za-z0-9_])/evthreadimpl_lock_unlock_/g; s/(?<![A-Za-z0-9_])_evthread_is_debug_lock_held(?![A-Za-z0-9_])/evthread_is_debug_lock_held_/g; s/(?<![A-Za-z0-9_])_evthread_lock_debugging_enabled(?![A-Za-z0-9_])/evthread_lock_debugging_enabled_/g; s/(?<![A-Za-z0-9_])_evthread_lock_fns(?![A-Za-z0-9_])/evthread_lock_fns_/g; s/(?<![A-Za-z0-9_])_EVUTIL_NIL_CONDITION(?![A-Za-z0-9_])/EVUTIL_NIL_CONDITION_/g; s/(?<![A-Za-z0-9_])_EVUTIL_NIL_STMT(?![A-Za-z0-9_])/EVUTIL_NIL_STMT_/g; s/(?<![A-Za-z0-9_])_evutil_weakrand(?![A-Za-z0-9_])/evutil_weakrand_/g; s/(?<![A-Za-z0-9_])_http_close_detection(?![A-Za-z0-9_])/http_close_detection_/g; s/(?<![A-Za-z0-9_])_http_connection_test(?![A-Za-z0-9_])/http_connection_test_/g; s/(?<![A-Za-z0-9_])_http_incomplete_test(?![A-Za-z0-9_])/http_incomplete_test_/g; s/(?<![A-Za-z0-9_])_http_stream_in_test(?![A-Za-z0-9_])/http_stream_in_test_/g; s/(?<![A-Za-z0-9_])_internal(?![A-Za-z0-9_])/internal_/g; s/(?<![A-Za-z0-9_])_mm_free_fn(?![A-Za-z0-9_])/mm_free_fn_/g; s/(?<![A-Za-z0-9_])_mm_malloc_fn(?![A-Za-z0-9_])/mm_malloc_fn_/g; s/(?<![A-Za-z0-9_])_mm_realloc_fn(?![A-Za-z0-9_])/mm_realloc_fn_/g; s/(?<![A-Za-z0-9_])_original_cond_fns(?![A-Za-z0-9_])/original_cond_fns_/g; s/(?<![A-Za-z0-9_])_original_lock_fns(?![A-Za-z0-9_])/original_lock_fns_/g; s/(?<![A-Za-z0-9_])_rpc_hook_ctx(?![A-Za-z0-9_])/rpc_hook_ctx_/g; 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  • buffer_iocp.c
  • /*
     * Copyright (c) 2009-2012 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.
     */
    
    /**
       @file buffer_iocp.c
    
       This module implements overlapped read and write functions for evbuffer
       objects on Windows.
    */
    #include "event2/event-config.h"
    #include "evconfig-private.h"
    
    #include "event2/buffer.h"
    #include "event2/buffer_compat.h"
    #include "event2/util.h"
    #include "event2/thread.h"
    #include "util-internal.h"
    #include "evthread-internal.h"
    #include "evbuffer-internal.h"
    #include "iocp-internal.h"
    #include "mm-internal.h"
    
    #include <winsock2.h>
    #include <windows.h>
    #include <stdio.h>
    
    #define MAX_WSABUFS 16
    
    /** An evbuffer that can handle overlapped IO. */
    struct evbuffer_overlapped {
    	struct evbuffer buffer;
    	/** The socket that we're doing overlapped IO on. */
    	evutil_socket_t fd;
    
    	/** pending I/O type */
    	unsigned read_in_progress : 1;
    	unsigned write_in_progress : 1;
    
    	/** The first pinned chain in the buffer. */
    	struct evbuffer_chain *first_pinned;
    
    	/** How many chains are pinned; how many of the fields in buffers
    	 * are we using. */
    	int n_buffers;
    	WSABUF buffers[MAX_WSABUFS];
    };
    
    /** Given an evbuffer, return the correponding evbuffer structure, or NULL if
     * the evbuffer isn't overlapped. */
    static inline struct evbuffer_overlapped *
    upcast_evbuffer(struct evbuffer *buf)
    {
    	if (!buf || !buf->is_overlapped)
    		return NULL;
    	return EVUTIL_UPCAST(buf, struct evbuffer_overlapped, buffer);
    }
    
    /** Unpin all the chains noted as pinned in 'eo'. */
    static void
    pin_release(struct evbuffer_overlapped *eo, unsigned flag)
    {
    	int i;
    	struct evbuffer_chain *next, *chain = eo->first_pinned;
    
    	for (i = 0; i < eo->n_buffers; ++i) {
    		EVUTIL_ASSERT(chain);
    		next = chain->next;
    		evbuffer_chain_unpin_(chain, flag);
    		chain = next;
    	}
    }
    
    void
    evbuffer_commit_read(struct evbuffer *evbuf, ev_ssize_t nBytes)
    {
    	struct evbuffer_overlapped *buf = upcast_evbuffer(evbuf);
    	struct evbuffer_chain **chainp;
    	size_t remaining, len;
    	unsigned i;
    
    	EVBUFFER_LOCK(evbuf);
    	EVUTIL_ASSERT(buf->read_in_progress && !buf->write_in_progress);
    	EVUTIL_ASSERT(nBytes >= 0); /* XXXX Can this be false? */
    
    	evbuffer_unfreeze(evbuf, 0);
    
    	chainp = evbuf->last_with_datap;
    	if (!((*chainp)->flags & EVBUFFER_MEM_PINNED_R))
    		chainp = &(*chainp)->next;
    	remaining = nBytes;
    	for (i = 0; remaining > 0 && i < (unsigned)buf->n_buffers; ++i) {
    		EVUTIL_ASSERT(*chainp);
    		len = buf->buffers[i].len;
    		if (remaining < len)
    			len = remaining;
    		(*chainp)->off += len;
    		evbuf->last_with_datap = chainp;
    		remaining -= len;
    		chainp = &(*chainp)->next;
    	}
    
    	pin_release(buf, EVBUFFER_MEM_PINNED_R);
    
    	buf->read_in_progress = 0;
    
    	evbuf->total_len += nBytes;
    	evbuf->n_add_for_cb += nBytes;
    
    	evbuffer_invoke_callbacks(evbuf);
    
    	evbuffer_decref_and_unlock_(evbuf);
    }
    
    void
    evbuffer_commit_write(struct evbuffer *evbuf, ev_ssize_t nBytes)
    {
    	struct evbuffer_overlapped *buf = upcast_evbuffer(evbuf);
    
    	EVBUFFER_LOCK(evbuf);
    	EVUTIL_ASSERT(buf->write_in_progress && !buf->read_in_progress);
    	evbuffer_unfreeze(evbuf, 1);
    	evbuffer_drain(evbuf, nBytes);
    	pin_release(buf,EVBUFFER_MEM_PINNED_W);
    	buf->write_in_progress = 0;
    	evbuffer_decref_and_unlock_(evbuf);
    }
    
    struct evbuffer *
    evbuffer_overlapped_new(evutil_socket_t fd)
    {
    	struct evbuffer_overlapped *evo;
    
    	evo = mm_calloc(1, sizeof(struct evbuffer_overlapped));
    	if (!evo)
    		return NULL;
    
    	LIST_INIT(&evo->buffer.callbacks);
    	evo->buffer.refcnt = 1;
    	evo->buffer.last_with_datap = &evo->buffer.first;
    
    	evo->buffer.is_overlapped = 1;
    	evo->fd = fd;
    
    	return &evo->buffer;
    }
    
    int
    evbuffer_launch_write(struct evbuffer *buf, ev_ssize_t at_most,
    		struct event_overlapped *ol)
    {
    	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
    	int r = -1;
    	int i;
    	struct evbuffer_chain *chain;
    	DWORD bytesSent;
    
    	if (!buf) {
    		/* No buffer, or it isn't overlapped */
    		return -1;
    	}
    
    	EVBUFFER_LOCK(buf);
    	EVUTIL_ASSERT(!buf_o->read_in_progress);
    	if (buf->freeze_start || buf_o->write_in_progress)
    		goto done;
    	if (!buf->total_len) {
    		/* Nothing to write */
    		r = 0;
    		goto done;
    	} else if (at_most < 0 || (size_t)at_most > buf->total_len) {
    		at_most = buf->total_len;
    	}
    	evbuffer_freeze(buf, 1);
    
    	buf_o->first_pinned = NULL;
    	buf_o->n_buffers = 0;
    	memset(buf_o->buffers, 0, sizeof(buf_o->buffers));
    
    	chain = buf_o->first_pinned = buf->first;
    
    	for (i=0; i < MAX_WSABUFS && chain; ++i, chain=chain->next) {
    		WSABUF *b = &buf_o->buffers[i];
    		b->buf = (char*)( chain->buffer + chain->misalign );
    		evbuffer_chain_pin_(chain, EVBUFFER_MEM_PINNED_W);
    
    		if ((size_t)at_most > chain->off) {
    			/* XXXX Cast is safe for now, since win32 has no
    			   mmaped chains.  But later, we need to have this
    			   add more WSAbufs if chain->off is greater than
    			   ULONG_MAX */
    			b->len = (unsigned long)chain->off;
    			at_most -= chain->off;
    		} else {
    			b->len = (unsigned long)at_most;
    			++i;
    			break;
    		}
    	}
    
    	buf_o->n_buffers = i;
    	evbuffer_incref_(buf);
    	if (WSASend(buf_o->fd, buf_o->buffers, i, &bytesSent, 0,
    		&ol->overlapped, NULL)) {
    		int error = WSAGetLastError();
    		if (error != WSA_IO_PENDING) {
    			/* An actual error. */
    			pin_release(buf_o, EVBUFFER_MEM_PINNED_W);
    			evbuffer_unfreeze(buf, 1);
    			evbuffer_free(buf); /* decref */
    			goto done;
    		}
    	}
    
    	buf_o->write_in_progress = 1;
    	r = 0;
    done:
    	EVBUFFER_UNLOCK(buf);
    	return r;
    }
    
    int
    evbuffer_launch_read(struct evbuffer *buf, size_t at_most,
    		struct event_overlapped *ol)
    {
    	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
    	int r = -1, i;
    	int nvecs;
    	int npin=0;
    	struct evbuffer_chain *chain=NULL, **chainp;
    	DWORD bytesRead;
    	DWORD flags = 0;
    	struct evbuffer_iovec vecs[MAX_WSABUFS];
    
    	if (!buf_o)
    		return -1;
    	EVBUFFER_LOCK(buf);
    	EVUTIL_ASSERT(!buf_o->write_in_progress);
    	if (buf->freeze_end || buf_o->read_in_progress)
    		goto done;
    
    	buf_o->first_pinned = NULL;
    	buf_o->n_buffers = 0;
    	memset(buf_o->buffers, 0, sizeof(buf_o->buffers));
    
    	if (evbuffer_expand_fast_(buf, at_most, MAX_WSABUFS) == -1)
    		goto done;
    	evbuffer_freeze(buf, 0);
    
    	nvecs = evbuffer_read_setup_vecs_(buf, at_most,
    	    vecs, MAX_WSABUFS, &chainp, 1);
    	for (i=0;i<nvecs;++i) {
    		WSABUF_FROM_EVBUFFER_IOV(
    			&buf_o->buffers[i],
    			&vecs[i]);
    	}
    
    	buf_o->n_buffers = nvecs;
    	buf_o->first_pinned = chain = *chainp;
    
    	npin=0;
    	for ( ; chain; chain = chain->next) {
    		evbuffer_chain_pin_(chain, EVBUFFER_MEM_PINNED_R);
    		++npin;
    	}
    	EVUTIL_ASSERT(npin == nvecs);
    
    	evbuffer_incref_(buf);
    	if (WSARecv(buf_o->fd, buf_o->buffers, nvecs, &bytesRead, &flags,
    		    &ol->overlapped, NULL)) {
    		int error = WSAGetLastError();
    		if (error != WSA_IO_PENDING) {
    			/* An actual error. */
    			pin_release(buf_o, EVBUFFER_MEM_PINNED_R);
    			evbuffer_unfreeze(buf, 0);
    			evbuffer_free(buf); /* decref */
    			goto done;
    		}
    	}
    
    	buf_o->read_in_progress = 1;
    	r = 0;
    done:
    	EVBUFFER_UNLOCK(buf);
    	return r;
    }
    
    evutil_socket_t
    evbuffer_overlapped_get_fd_(struct evbuffer *buf)
    {
    	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
    	return buf_o ? buf_o->fd : -1;
    }
    
    void
    evbuffer_overlapped_set_fd_(struct evbuffer *buf, evutil_socket_t fd)
    {
    	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
    	EVBUFFER_LOCK(buf);
    	/* XXX is this right?, should it cancel current I/O operations? */
    	if (buf_o)
    		buf_o->fd = fd;
    	EVBUFFER_UNLOCK(buf);
    }