LXR qemu/util/qemu-coroutine-io.c

   1/*
   2 * Coroutine-aware I/O functions
   3 *
   4 * Copyright (C) 2009-2010 Nippon Telegraph and Telephone Corporation.
   5 * Copyright (c) 2011, Red Hat, Inc.
   6 *
   7 * Permission is hereby granted, free of charge, to any person obtaining a copy
   8 * of this software and associated documentation files (the "Software"), to deal
   9 * in the Software without restriction, including without limitation the rights
  10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 * copies of the Software, and to permit persons to whom the Software is
  12 * furnished to do so, subject to the following conditions:
  13 *
  14 * The above copyright notice and this permission notice shall be included in
  15 * all copies or substantial portions of the Software.
  16 *
  17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23 * THE SOFTWARE.
  24 */
  25#include "qemu/osdep.h"
  26#include "qemu-common.h"
  27#include "qemu/sockets.h"
  28#include "qemu/coroutine.h"
  29#include "qemu/iov.h"
  30#include "qemu/main-loop.h"
  31
  32ssize_t coroutine_fn
  33qemu_co_sendv_recvv(int sockfd, struct iovec *iov, unsigned iov_cnt,
  34                    size_t offset, size_t bytes, bool do_send)
  35{
  36    size_t done = 0;
  37    ssize_t ret;
  38    while (done < bytes) {
  39        ret = iov_send_recv(sockfd, iov, iov_cnt,
  40                            offset + done, bytes - done, do_send);
  41        if (ret > 0) {
  42            done += ret;
  43        } else if (ret < 0) {
  44            if (errno == EAGAIN || errno == EWOULDBLOCK) {
  45                qemu_coroutine_yield();
  46            } else if (done == 0) {
  47                return -errno;
  48            } else {
  49                break;
  50            }
  51        } else if (ret == 0 && !do_send) {
  52            /* write (send) should never return 0.
  53             * read (recv) returns 0 for end-of-file (-data).
  54             * In both cases there's little point retrying,
  55             * but we do for write anyway, just in case */
  56            break;
  57        }
  58    }
  59    return done;
  60}
  61
  62ssize_t coroutine_fn
  63qemu_co_send_recv(int sockfd, void *buf, size_t bytes, bool do_send)
  64{
  65    struct iovec iov = { .iov_base = buf, .iov_len = bytes };
  66    return qemu_co_sendv_recvv(sockfd, &iov, 1, 0, bytes, do_send);
  67}
  68
  69typedef struct {
  70    AioContext *ctx;
  71    Coroutine *co;
  72    int fd;
  73} FDYieldUntilData;
  74
  75static void fd_coroutine_enter(void *opaque)
  76{
  77    FDYieldUntilData *data = opaque;
  78    aio_set_fd_handler(data->ctx, data->fd, false, NULL, NULL, NULL, NULL);
  79    qemu_coroutine_enter(data->co);
  80}
  81
  82void coroutine_fn yield_until_fd_readable(int fd)
  83{
  84    FDYieldUntilData data;
  85
  86    assert(qemu_in_coroutine());
  87    data.ctx = qemu_get_current_aio_context();
  88    data.co = qemu_coroutine_self();
  89    data.fd = fd;
  90    aio_set_fd_handler(
  91        data.ctx, fd, false, fd_coroutine_enter, NULL, NULL, &data);
  92    qemu_coroutine_yield();
  93}
  94