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
  32 ssize_t coroutine_fn
  33 qemu_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
  62 ssize_t coroutine_fn
  63 qemu_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
  69 typedef struct {
  70     Coroutine *co;
  71     int fd;
  72 } FDYieldUntilData;
  73
  74 static void fd_coroutine_enter(void *opaque)
  75 {
  76     FDYieldUntilData *data = opaque;
  77     qemu_set_fd_handler(data->fd, NULL, NULL, NULL);
  78     qemu_coroutine_enter(data->co);
  79 }
  80
  81 void coroutine_fn yield_until_fd_readable(int fd)
  82 {
  83     FDYieldUntilData data;
  84
  85     assert(qemu_in_coroutine());
  86     data.co = qemu_coroutine_self();
  87     data.fd = fd;
  88     qemu_set_fd_handler(fd, fd_coroutine_enter, NULL, &data);
  89     qemu_coroutine_yield();
  90 }