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