migration/qemu-file-unix.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #include "qemu-common.h"
  25 #include "qemu/iov.h"
  26 #include "qemu/sockets.h"
  27 #include "block/coroutine.h"
  28 #include "migration/qemu-file.h"
  29 #include "migration/qemu-file-internal.h"
  30
  31 typedef struct QEMUFileSocket {
  32     int fd;
  33     QEMUFile *file;
  34 } QEMUFileSocket;
  35
  36 static ssize_t socket_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
  37                                     int64_t pos)
  38 {
  39     QEMUFileSocket *s = opaque;
  40     ssize_t len;
  41     ssize_t size = iov_size(iov, iovcnt);
  42
  43     len = iov_send(s->fd, iov, iovcnt, 0, size);
  44     if (len < size) {
  45         len = -socket_error();
  46     }
  47     return len;
  48 }
  49
  50 static int socket_get_fd(void *opaque)
  51 {
  52     QEMUFileSocket *s = opaque;
  53
  54     return s->fd;
  55 }
  56
  57 static int socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
  58 {
  59     QEMUFileSocket *s = opaque;
  60     ssize_t len;
  61
  62     for (;;) {
  63         len = qemu_recv(s->fd, buf, size, 0);
  64         if (len != -1) {
  65             break;
  66         }
  67         if (socket_error() == EAGAIN) {
  68             yield_until_fd_readable(s->fd);
  69         } else if (socket_error() != EINTR) {
  70             break;
  71         }
  72     }
  73
  74     if (len == -1) {
  75         len = -socket_error();
  76     }
  77     return len;
  78 }
  79
  80 static int socket_close(void *opaque)
  81 {
  82     QEMUFileSocket *s = opaque;
  83     closesocket(s->fd);
  84     g_free(s);
  85     return 0;
  86 }
  87
  88 static int socket_shutdown(void *opaque, bool rd, bool wr)
  89 {
  90     QEMUFileSocket *s = opaque;
  91
  92     if (shutdown(s->fd, rd ? (wr ? SHUT_RDWR : SHUT_RD) : SHUT_WR)) {
  93         return -errno;
  94     } else {
  95         return 0;
  96     }
  97 }
  98
  99 static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
 100                                   int64_t pos)
 101 {
 102     QEMUFileSocket *s = opaque;
 103     ssize_t len, offset;
 104     ssize_t size = iov_size(iov, iovcnt);
 105     ssize_t total = 0;
 106
 107     assert(iovcnt > 0);
 108     offset = 0;
 109     while (size > 0) {
 110         /* Find the next start position; skip all full-sized vector elements  */
 111         while (offset >= iov[0].iov_len) {
 112             offset -= iov[0].iov_len;
 113             iov++, iovcnt--;
 114         }
 115
 116         /* skip `offset' bytes from the (now) first element, undo it on exit */
 117         assert(iovcnt > 0);
 118         iov[0].iov_base += offset;
 119         iov[0].iov_len -= offset;
 120
 121         do {
 122             len = writev(s->fd, iov, iovcnt);
 123         } while (len == -1 && errno == EINTR);
 124         if (len == -1) {
 125             return -errno;
 126         }
 127
 128         /* Undo the changes above */
 129         iov[0].iov_base -= offset;
 130         iov[0].iov_len += offset;
 131
 132         /* Prepare for the next iteration */
 133         offset += len;
 134         total += len;
 135         size -= len;
 136     }
 137
 138     return total;
 139 }
 140
 141 static int unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
 142 {
 143     QEMUFileSocket *s = opaque;
 144     ssize_t len;
 145
 146     for (;;) {
 147         len = read(s->fd, buf, size);
 148         if (len != -1) {
 149             break;
 150         }
 151         if (errno == EAGAIN) {
 152             yield_until_fd_readable(s->fd);
 153         } else if (errno != EINTR) {
 154             break;
 155         }
 156     }
 157
 158     if (len == -1) {
 159         len = -errno;
 160     }
 161     return len;
 162 }
 163
 164 static int unix_close(void *opaque)
 165 {
 166     QEMUFileSocket *s = opaque;
 167     close(s->fd);
 168     g_free(s);
 169     return 0;
 170 }
 171
 172 static const QEMUFileOps unix_read_ops = {
 173     .get_fd =     socket_get_fd,
 174     .get_buffer = unix_get_buffer,
 175     .close =      unix_close
 176 };
 177
 178 static const QEMUFileOps unix_write_ops = {
 179     .get_fd =     socket_get_fd,
 180     .writev_buffer = unix_writev_buffer,
 181     .close =      unix_close
 182 };
 183
 184 QEMUFile *qemu_fdopen(int fd, const char *mode)
 185 {
 186     QEMUFileSocket *s;
 187
 188     if (mode == NULL ||
 189         (mode[0] != 'r' && mode[0] != 'w') ||
 190         mode[1] != 'b' || mode[2] != 0) {
 191         fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
 192         return NULL;
 193     }
 194
 195     s = g_malloc0(sizeof(QEMUFileSocket));
 196     s->fd = fd;
 197
 198     if (mode[0] == 'r') {
 199         s->file = qemu_fopen_ops(s, &unix_read_ops);
 200     } else {
 201         s->file = qemu_fopen_ops(s, &unix_write_ops);
 202     }
 203     return s->file;
 204 }
 205
 206 static const QEMUFileOps socket_read_ops = {
 207     .get_fd     = socket_get_fd,
 208     .get_buffer = socket_get_buffer,
 209     .close      = socket_close,
 210     .shut_down  = socket_shutdown
 211
 212 };
 213
 214 static const QEMUFileOps socket_write_ops = {
 215     .get_fd        = socket_get_fd,
 216     .writev_buffer = socket_writev_buffer,
 217     .close         = socket_close,
 218     .shut_down     = socket_shutdown
 219 };
 220
 221 QEMUFile *qemu_fopen_socket(int fd, const char *mode)
 222 {
 223     QEMUFileSocket *s;
 224
 225     if (qemu_file_mode_is_not_valid(mode)) {
 226         return NULL;
 227     }
 228
 229     s = g_malloc0(sizeof(QEMUFileSocket));
 230     s->fd = fd;
 231     if (mode[0] == 'w') {
 232         qemu_set_block(s->fd);
 233         s->file = qemu_fopen_ops(s, &socket_write_ops);
 234     } else {
 235         s->file = qemu_fopen_ops(s, &socket_read_ops);
 236     }
 237     return s->file;
 238 }