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-common.h"
  26 #include "qemu/sockets.h"
  27 #include "block/coroutine.h"
  28 #include "qemu/iov.h"
  29 #include "qemu/main-loop.h"
  30
  31 ssize_t coroutine_fn
  32 qemu_co_sendv_recvv(int sockfd, struct iovec *iov, unsigned iov_cnt,
  33                     size_t offset, size_t bytes, bool do_send)
  34 {
  35     size_t done = 0;
  36     ssize_t ret;
  37     int err;
  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             err = socket_error();
  45             if (err == EAGAIN || err == EWOULDBLOCK) {
  46                 qemu_coroutine_yield();
  47             } else if (done == 0) {
  48                 return -1;
  49             } else {
  50                 break;
  51             }
  52         } else if (ret == 0 && !do_send) {
  53             /* write (send) should never return 0.
  54              * read (recv) returns 0 for end-of-file (-data).
  55              * In both cases there's little point retrying,
  56              * but we do for write anyway, just in case */
  57             break;
  58         }
  59     }
  60     return done;
  61 }
  62
  63 ssize_t coroutine_fn
  64 qemu_co_send_recv(int sockfd, void *buf, size_t bytes, bool do_send)
  65 {
  66     struct iovec iov = { .iov_base = buf, .iov_len = bytes };
  67     return qemu_co_sendv_recvv(sockfd, &iov, 1, 0, bytes, do_send);
  68 }
  69
  70 typedef struct {
  71     Coroutine *co;
  72     int fd;
  73 } FDYieldUntilData;
  74
  75 static void fd_coroutine_enter(void *opaque)
  76 {
  77     FDYieldUntilData *data = opaque;
  78     qemu_set_fd_handler(data->fd, NULL, NULL, NULL);
  79     qemu_coroutine_enter(data->co, NULL);
  80 }
  81
  82 void coroutine_fn yield_until_fd_readable(int fd)
  83 {
  84     FDYieldUntilData data;
  85
  86     assert(qemu_in_coroutine());
  87     data.co = qemu_coroutine_self();
  88     data.fd = fd;
  89     qemu_set_fd_handler(fd, fd_coroutine_enter, NULL, &data);
  90     qemu_coroutine_yield();
  91 }