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 ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
 101                                   int64_t pos)
 102 {
 103     QEMUFileSocket *s = opaque;
 104     ssize_t len, offset;
 105     ssize_t size = iov_size(iov, iovcnt);
 106     ssize_t total = 0;
 107
 108     assert(iovcnt > 0);
 109     offset = 0;
 110     while (size > 0) {
 111         /* Find the next start position; skip all full-sized vector elements  */
 112         while (offset >= iov[0].iov_len) {
 113             offset -= iov[0].iov_len;
 114             iov++, iovcnt--;
 115         }
 116
 117         /* skip `offset' bytes from the (now) first element, undo it on exit */
 118         assert(iovcnt > 0);
 119         iov[0].iov_base += offset;
 120         iov[0].iov_len -= offset;
 121
 122         do {
 123             len = writev(s->fd, iov, iovcnt);
 124         } while (len == -1 && errno == EINTR);
 125         if (len == -1) {
 126             return -errno;
 127         }
 128
 129         /* Undo the changes above */
 130         iov[0].iov_base -= offset;
 131         iov[0].iov_len += offset;
 132
 133         /* Prepare for the next iteration */
 134         offset += len;
 135         total += len;
 136         size -= len;
 137     }
 138
 139     return total;
 140 }
 141
 142 static ssize_t unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
 143                               size_t size)
 144 {
 145     QEMUFileSocket *s = opaque;
 146     ssize_t len;
 147
 148     for (;;) {
 149         len = read(s->fd, buf, size);
 150         if (len != -1) {
 151             break;
 152         }
 153         if (errno == EAGAIN) {
 154             yield_until_fd_readable(s->fd);
 155         } else if (errno != EINTR) {
 156             break;
 157         }
 158     }
 159
 160     if (len == -1) {
 161         len = -errno;
 162     }
 163     return len;
 164 }
 165
 166 static int unix_close(void *opaque)
 167 {
 168     QEMUFileSocket *s = opaque;
 169     close(s->fd);
 170     g_free(s);
 171     return 0;
 172 }
 173
 174 static const QEMUFileOps unix_read_ops = {
 175     .get_fd =     socket_get_fd,
 176     .get_buffer = unix_get_buffer,
 177     .close =      unix_close
 178 };
 179
 180 static const QEMUFileOps unix_write_ops = {
 181     .get_fd =     socket_get_fd,
 182     .writev_buffer = unix_writev_buffer,
 183     .close =      unix_close
 184 };
 185
 186 QEMUFile *qemu_fdopen(int fd, const char *mode)
 187 {
 188     QEMUFileSocket *s;
 189
 190     if (mode == NULL ||
 191         (mode[0] != 'r' && mode[0] != 'w') ||
 192         mode[1] != 'b' || mode[2] != 0) {
 193         fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
 194         return NULL;
 195     }
 196
 197     s = g_new0(QEMUFileSocket, 1);
 198     s->fd = fd;
 199
 200     if (mode[0] == 'r') {
 201         s->file = qemu_fopen_ops(s, &unix_read_ops);
 202     } else {
 203         s->file = qemu_fopen_ops(s, &unix_write_ops);
 204     }
 205     return s->file;
 206 }
 207
 208 static const QEMUFileOps socket_read_ops = {
 209     .get_fd     = socket_get_fd,
 210     .get_buffer = socket_get_buffer,
 211     .close      = socket_close,
 212     .shut_down  = socket_shutdown
 213
 214 };
 215
 216 static const QEMUFileOps socket_write_ops = {
 217     .get_fd        = socket_get_fd,
 218     .writev_buffer = socket_writev_buffer,
 219     .close         = socket_close,
 220     .shut_down     = socket_shutdown
 221 };
 222
 223 QEMUFile *qemu_fopen_socket(int fd, const char *mode)
 224 {
 225     QEMUFileSocket *s;
 226
 227     if (qemu_file_mode_is_not_valid(mode)) {
 228         return NULL;
 229     }
 230
 231     s = g_new0(QEMUFileSocket, 1);
 232     s->fd = fd;
 233     if (mode[0] == 'w') {
 234         qemu_set_block(s->fd);
 235         s->file = qemu_fopen_ops(s, &socket_write_ops);
 236     } else {
 237         s->file = qemu_fopen_ops(s, &socket_read_ops);
 238     }
 239     return s->file;
 240 }