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/osdep.h"
  25 #include "qemu-common.h"
  26 #include "qemu/error-report.h"
  27 #include "qemu/iov.h"
  28 #include "qemu/sockets.h"
  29 #include "qemu/coroutine.h"
  30 #include "migration/qemu-file.h"
  31 #include "migration/qemu-file-internal.h"
  32
  33 typedef struct QEMUFileSocket {
  34     int fd;
  35     QEMUFile *file;
  36 } QEMUFileSocket;
  37
  38 static ssize_t socket_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
  39                                     int64_t pos)
  40 {
  41     QEMUFileSocket *s = opaque;
  42     ssize_t len;
  43     ssize_t size = iov_size(iov, iovcnt);
  44     ssize_t offset = 0;
  45     int     err;
  46
  47     while (size > 0) {
  48         len = iov_send(s->fd, iov, iovcnt, offset, size);
  49
  50         if (len > 0) {
  51             size -= len;
  52             offset += len;
  53         }
  54
  55         if (size > 0) {
  56             err = socket_error();
  57
  58             if (err != EAGAIN && err != EWOULDBLOCK) {
  59                 error_report("socket_writev_buffer: Got err=%d for (%zu/%zu)",
  60                              err, (size_t)size, (size_t)len);
  61                 /*
  62                  * If I've already sent some but only just got the error, I
  63                  * could return the amount validly sent so far and wait for the
  64                  * next call to report the error, but I'd rather flag the error
  65                  * immediately.
  66                  */
  67                 return -err;
  68             }
  69
  70             /* Emulate blocking */
  71             GPollFD pfd;
  72
  73             pfd.fd = s->fd;
  74             pfd.events = G_IO_OUT | G_IO_ERR;
  75             pfd.revents = 0;
  76             TFR(err = g_poll(&pfd, 1, -1 /* no timeout */));
  77             /* Errors other than EINTR intentionally ignored */
  78         }
  79      }
  80
  81     return offset;
  82 }
  83
  84 static int socket_get_fd(void *opaque)
  85 {
  86     QEMUFileSocket *s = opaque;
  87
  88     return s->fd;
  89 }
  90
  91 static ssize_t socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
  92                                  size_t size)
  93 {
  94     QEMUFileSocket *s = opaque;
  95     ssize_t len;
  96
  97     for (;;) {
  98         len = qemu_recv(s->fd, buf, size, 0);
  99         if (len != -1) {
 100             break;
 101         }
 102         if (socket_error() == EAGAIN) {
 103             yield_until_fd_readable(s->fd);
 104         } else if (socket_error() != EINTR) {
 105             break;
 106         }
 107     }
 108
 109     if (len == -1) {
 110         len = -socket_error();
 111     }
 112     return len;
 113 }
 114
 115 static int socket_close(void *opaque)
 116 {
 117     QEMUFileSocket *s = opaque;
 118     closesocket(s->fd);
 119     g_free(s);
 120     return 0;
 121 }
 122
 123 static int socket_shutdown(void *opaque, bool rd, bool wr)
 124 {
 125     QEMUFileSocket *s = opaque;
 126
 127     if (shutdown(s->fd, rd ? (wr ? SHUT_RDWR : SHUT_RD) : SHUT_WR)) {
 128         return -errno;
 129     } else {
 130         return 0;
 131     }
 132 }
 133
 134 static int socket_return_close(void *opaque)
 135 {
 136     QEMUFileSocket *s = opaque;
 137     /*
 138      * Note: We don't close the socket, that should be done by the forward
 139      * path.
 140      */
 141     g_free(s);
 142     return 0;
 143 }
 144
 145 static const QEMUFileOps socket_return_read_ops = {
 146     .get_fd          = socket_get_fd,
 147     .get_buffer      = socket_get_buffer,
 148     .close           = socket_return_close,
 149     .shut_down       = socket_shutdown,
 150 };
 151
 152 static const QEMUFileOps socket_return_write_ops = {
 153     .get_fd          = socket_get_fd,
 154     .writev_buffer   = socket_writev_buffer,
 155     .close           = socket_return_close,
 156     .shut_down       = socket_shutdown,
 157 };
 158
 159 /*
 160  * Give a QEMUFile* off the same socket but data in the opposite
 161  * direction.
 162  */
 163 static QEMUFile *socket_get_return_path(void *opaque)
 164 {
 165     QEMUFileSocket *forward = opaque;
 166     QEMUFileSocket *reverse;
 167
 168     if (qemu_file_get_error(forward->file)) {
 169         /* If the forward file is in error, don't try and open a return */
 170         return NULL;
 171     }
 172
 173     reverse = g_malloc0(sizeof(QEMUFileSocket));
 174     reverse->fd = forward->fd;
 175     /* I don't think there's a better way to tell which direction 'this' is */
 176     if (forward->file->ops->get_buffer != NULL) {
 177         /* being called from the read side, so we need to be able to write */
 178         return qemu_fopen_ops(reverse, &socket_return_write_ops);
 179     } else {
 180         return qemu_fopen_ops(reverse, &socket_return_read_ops);
 181     }
 182 }
 183
 184 static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
 185                                   int64_t pos)
 186 {
 187     QEMUFileSocket *s = opaque;
 188     ssize_t len, offset;
 189     ssize_t size = iov_size(iov, iovcnt);
 190     ssize_t total = 0;
 191
 192     assert(iovcnt > 0);
 193     offset = 0;
 194     while (size > 0) {
 195         /* Find the next start position; skip all full-sized vector elements  */
 196         while (offset >= iov[0].iov_len) {
 197             offset -= iov[0].iov_len;
 198             iov++, iovcnt--;
 199         }
 200
 201         /* skip `offset' bytes from the (now) first element, undo it on exit */
 202         assert(iovcnt > 0);
 203         iov[0].iov_base += offset;
 204         iov[0].iov_len -= offset;
 205
 206         do {
 207             len = writev(s->fd, iov, iovcnt);
 208         } while (len == -1 && errno == EINTR);
 209         if (len == -1) {
 210             return -errno;
 211         }
 212
 213         /* Undo the changes above */
 214         iov[0].iov_base -= offset;
 215         iov[0].iov_len += offset;
 216
 217         /* Prepare for the next iteration */
 218         offset += len;
 219         total += len;
 220         size -= len;
 221     }
 222
 223     return total;
 224 }
 225
 226 static ssize_t unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
 227                               size_t size)
 228 {
 229     QEMUFileSocket *s = opaque;
 230     ssize_t len;
 231
 232     for (;;) {
 233         len = read(s->fd, buf, size);
 234         if (len != -1) {
 235             break;
 236         }
 237         if (errno == EAGAIN) {
 238             yield_until_fd_readable(s->fd);
 239         } else if (errno != EINTR) {
 240             break;
 241         }
 242     }
 243
 244     if (len == -1) {
 245         len = -errno;
 246     }
 247     return len;
 248 }
 249
 250 static int unix_close(void *opaque)
 251 {
 252     QEMUFileSocket *s = opaque;
 253     close(s->fd);
 254     g_free(s);
 255     return 0;
 256 }
 257
 258 static const QEMUFileOps unix_read_ops = {
 259     .get_fd =     socket_get_fd,
 260     .get_buffer = unix_get_buffer,
 261     .close =      unix_close
 262 };
 263
 264 static const QEMUFileOps unix_write_ops = {
 265     .get_fd =     socket_get_fd,
 266     .writev_buffer = unix_writev_buffer,
 267     .close =      unix_close
 268 };
 269
 270 QEMUFile *qemu_fdopen(int fd, const char *mode)
 271 {
 272     QEMUFileSocket *s;
 273
 274     if (mode == NULL ||
 275         (mode[0] != 'r' && mode[0] != 'w') ||
 276         mode[1] != 'b' || mode[2] != 0) {
 277         fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
 278         return NULL;
 279     }
 280
 281     s = g_new0(QEMUFileSocket, 1);
 282     s->fd = fd;
 283
 284     if (mode[0] == 'r') {
 285         s->file = qemu_fopen_ops(s, &unix_read_ops);
 286     } else {
 287         s->file = qemu_fopen_ops(s, &unix_write_ops);
 288     }
 289     return s->file;
 290 }
 291
 292 static const QEMUFileOps socket_read_ops = {
 293     .get_fd          = socket_get_fd,
 294     .get_buffer      = socket_get_buffer,
 295     .close           = socket_close,
 296     .shut_down       = socket_shutdown,
 297     .get_return_path = socket_get_return_path
 298 };
 299
 300 static const QEMUFileOps socket_write_ops = {
 301     .get_fd          = socket_get_fd,
 302     .writev_buffer   = socket_writev_buffer,
 303     .close           = socket_close,
 304     .shut_down       = socket_shutdown,
 305     .get_return_path = socket_get_return_path
 306 };
 307
 308 QEMUFile *qemu_fopen_socket(int fd, const char *mode)
 309 {
 310     QEMUFileSocket *s;
 311
 312     if (qemu_file_mode_is_not_valid(mode)) {
 313         return NULL;
 314     }
 315
 316     s = g_new0(QEMUFileSocket, 1);
 317     s->fd = fd;
 318     if (mode[0] == 'w') {
 319         qemu_set_block(s->fd);
 320         s->file = qemu_fopen_ops(s, &socket_write_ops);
 321     } else {
 322         s->file = qemu_fopen_ops(s, &socket_read_ops);
 323     }
 324     return s->file;
 325 }