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 "qemu/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 ssize_t socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
  58                                  size_t size)
  59 {
  60     QEMUFileSocket *s = opaque;
  61     ssize_t len;
  62
  63     for (;;) {
  64         len = qemu_recv(s->fd, buf, size, 0);
  65         if (len != -1) {
  66             break;
  67         }
  68         if (socket_error() == EAGAIN) {
  69             yield_until_fd_readable(s->fd);
  70         } else if (socket_error() != EINTR) {
  71             break;
  72         }
  73     }
  74
  75     if (len == -1) {
  76         len = -socket_error();
  77     }
  78     return len;
  79 }
  80
  81 static int socket_close(void *opaque)
  82 {
  83     QEMUFileSocket *s = opaque;
  84     closesocket(s->fd);
  85     g_free(s);
  86     return 0;
  87 }
  88
  89 static int socket_shutdown(void *opaque, bool rd, bool wr)
  90 {
  91     QEMUFileSocket *s = opaque;
  92
  93     if (shutdown(s->fd, rd ? (wr ? SHUT_RDWR : SHUT_RD) : SHUT_WR)) {
  94         return -errno;
  95     } else {
  96         return 0;
  97     }
  98 }
  99
 100 static int socket_return_close(void *opaque)
 101 {
 102     QEMUFileSocket *s = opaque;
 103     /*
 104      * Note: We don't close the socket, that should be done by the forward
 105      * path.
 106      */
 107     g_free(s);
 108     return 0;
 109 }
 110
 111 static const QEMUFileOps socket_return_read_ops = {
 112     .get_fd          = socket_get_fd,
 113     .get_buffer      = socket_get_buffer,
 114     .close           = socket_return_close,
 115     .shut_down       = socket_shutdown,
 116 };
 117
 118 static const QEMUFileOps socket_return_write_ops = {
 119     .get_fd          = socket_get_fd,
 120     .writev_buffer   = socket_writev_buffer,
 121     .close           = socket_return_close,
 122     .shut_down       = socket_shutdown,
 123 };
 124
 125 /*
 126  * Give a QEMUFile* off the same socket but data in the opposite
 127  * direction.
 128  */
 129 static QEMUFile *socket_get_return_path(void *opaque)
 130 {
 131     QEMUFileSocket *forward = opaque;
 132     QEMUFileSocket *reverse;
 133
 134     if (qemu_file_get_error(forward->file)) {
 135         /* If the forward file is in error, don't try and open a return */
 136         return NULL;
 137     }
 138
 139     reverse = g_malloc0(sizeof(QEMUFileSocket));
 140     reverse->fd = forward->fd;
 141     /* I don't think there's a better way to tell which direction 'this' is */
 142     if (forward->file->ops->get_buffer != NULL) {
 143         /* being called from the read side, so we need to be able to write */
 144         return qemu_fopen_ops(reverse, &socket_return_write_ops);
 145     } else {
 146         return qemu_fopen_ops(reverse, &socket_return_read_ops);
 147     }
 148 }
 149
 150 static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
 151                                   int64_t pos)
 152 {
 153     QEMUFileSocket *s = opaque;
 154     ssize_t len, offset;
 155     ssize_t size = iov_size(iov, iovcnt);
 156     ssize_t total = 0;
 157
 158     assert(iovcnt > 0);
 159     offset = 0;
 160     while (size > 0) {
 161         /* Find the next start position; skip all full-sized vector elements  */
 162         while (offset >= iov[0].iov_len) {
 163             offset -= iov[0].iov_len;
 164             iov++, iovcnt--;
 165         }
 166
 167         /* skip `offset' bytes from the (now) first element, undo it on exit */
 168         assert(iovcnt > 0);
 169         iov[0].iov_base += offset;
 170         iov[0].iov_len -= offset;
 171
 172         do {
 173             len = writev(s->fd, iov, iovcnt);
 174         } while (len == -1 && errno == EINTR);
 175         if (len == -1) {
 176             return -errno;
 177         }
 178
 179         /* Undo the changes above */
 180         iov[0].iov_base -= offset;
 181         iov[0].iov_len += offset;
 182
 183         /* Prepare for the next iteration */
 184         offset += len;
 185         total += len;
 186         size -= len;
 187     }
 188
 189     return total;
 190 }
 191
 192 static ssize_t unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
 193                               size_t size)
 194 {
 195     QEMUFileSocket *s = opaque;
 196     ssize_t len;
 197
 198     for (;;) {
 199         len = read(s->fd, buf, size);
 200         if (len != -1) {
 201             break;
 202         }
 203         if (errno == EAGAIN) {
 204             yield_until_fd_readable(s->fd);
 205         } else if (errno != EINTR) {
 206             break;
 207         }
 208     }
 209
 210     if (len == -1) {
 211         len = -errno;
 212     }
 213     return len;
 214 }
 215
 216 static int unix_close(void *opaque)
 217 {
 218     QEMUFileSocket *s = opaque;
 219     close(s->fd);
 220     g_free(s);
 221     return 0;
 222 }
 223
 224 static const QEMUFileOps unix_read_ops = {
 225     .get_fd =     socket_get_fd,
 226     .get_buffer = unix_get_buffer,
 227     .close =      unix_close
 228 };
 229
 230 static const QEMUFileOps unix_write_ops = {
 231     .get_fd =     socket_get_fd,
 232     .writev_buffer = unix_writev_buffer,
 233     .close =      unix_close
 234 };
 235
 236 QEMUFile *qemu_fdopen(int fd, const char *mode)
 237 {
 238     QEMUFileSocket *s;
 239
 240     if (mode == NULL ||
 241         (mode[0] != 'r' && mode[0] != 'w') ||
 242         mode[1] != 'b' || mode[2] != 0) {
 243         fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
 244         return NULL;
 245     }
 246
 247     s = g_new0(QEMUFileSocket, 1);
 248     s->fd = fd;
 249
 250     if (mode[0] == 'r') {
 251         s->file = qemu_fopen_ops(s, &unix_read_ops);
 252     } else {
 253         s->file = qemu_fopen_ops(s, &unix_write_ops);
 254     }
 255     return s->file;
 256 }
 257
 258 static const QEMUFileOps socket_read_ops = {
 259     .get_fd          = socket_get_fd,
 260     .get_buffer      = socket_get_buffer,
 261     .close           = socket_close,
 262     .shut_down       = socket_shutdown,
 263     .get_return_path = socket_get_return_path
 264 };
 265
 266 static const QEMUFileOps socket_write_ops = {
 267     .get_fd          = socket_get_fd,
 268     .writev_buffer   = socket_writev_buffer,
 269     .close           = socket_close,
 270     .shut_down       = socket_shutdown,
 271     .get_return_path = socket_get_return_path
 272 };
 273
 274 QEMUFile *qemu_fopen_socket(int fd, const char *mode)
 275 {
 276     QEMUFileSocket *s;
 277
 278     if (qemu_file_mode_is_not_valid(mode)) {
 279         return NULL;
 280     }
 281
 282     s = g_new0(QEMUFileSocket, 1);
 283     s->fd = fd;
 284     if (mode[0] == 'w') {
 285         qemu_set_block(s->fd);
 286         s->file = qemu_fopen_ops(s, &socket_write_ops);
 287     } else {
 288         s->file = qemu_fopen_ops(s, &socket_read_ops);
 289     }
 290     return s->file;
 291 }