nbd/common.c

   1 /*
   2  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   3  *
   4  *  Network Block Device Common Code
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; under version 2 of the License.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "nbd-internal.h"
  20
  21 ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
  22 {
  23     size_t offset = 0;
  24     int err;
  25
  26     if (qemu_in_coroutine()) {
  27         if (do_read) {
  28             return qemu_co_recv(fd, buffer, size);
  29         } else {
  30             return qemu_co_send(fd, buffer, size);
  31         }
  32     }
  33
  34     while (offset < size) {
  35         ssize_t len;
  36
  37         if (do_read) {
  38             len = qemu_recv(fd, buffer + offset, size - offset, 0);
  39         } else {
  40             len = send(fd, buffer + offset, size - offset, 0);
  41         }
  42
  43         if (len < 0) {
  44             err = socket_error();
  45
  46             /* recoverable error */
  47             if (err == EINTR || (offset > 0 && (err == EAGAIN || err == EWOULDBLOCK))) {
  48                 continue;
  49             }
  50
  51             /* unrecoverable error */
  52             return -err;
  53         }
  54
  55         /* eof */
  56         if (len == 0) {
  57             break;
  58         }
  59
  60         offset += len;
  61     }
  62
  63     return offset;
  64 }