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