migration/qemu-file-unix.c - qemu - Git at Google

 /*
  * QEMU System Emulator
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 #include "qemu/osdep.h"
 #include "qemu-common.h"
 #include "qemu/error-report.h"
 #include "qemu/iov.h"
 #include "qemu/sockets.h"
 #include "qemu/coroutine.h"
 #include "migration/qemu-file.h"
 #include "migration/qemu-file-internal.h"

 typedef struct QEMUFileSocket {
     int fd;
     QEMUFile *file;
 } QEMUFileSocket;

 static ssize_t socket_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
                                     int64_t pos)
 {
     QEMUFileSocket *s = opaque;
     ssize_t len;
     ssize_t size = iov_size(iov, iovcnt);
     ssize_t offset = 0;
     int     err;

     while (size > 0) {
         len = iov_send(s->fd, iov, iovcnt, offset, size);

         if (len > 0) {
             size -= len;
             offset += len;
         }

         if (size > 0) {
             err = socket_error();

             if (err != EAGAIN && err != EWOULDBLOCK) {
                 error_report("socket_writev_buffer: Got err=%d for (%zu/%zu)",
                              err, (size_t)size, (size_t)len);
                 /*
                  * If I've already sent some but only just got the error, I
                  * could return the amount validly sent so far and wait for the
                  * next call to report the error, but I'd rather flag the error
                  * immediately.
                  */
                 return -err;
             }

             /* Emulate blocking */
             GPollFD pfd;

             pfd.fd = s->fd;
             pfd.events = G_IO_OUT | G_IO_ERR;
             pfd.revents = 0;
             TFR(err = g_poll(&pfd, 1, -1 /* no timeout */));
             /* Errors other than EINTR intentionally ignored */
         }
      }

     return offset;
 }

 static int socket_get_fd(void *opaque)
 {
     QEMUFileSocket *s = opaque;

     return s->fd;
 }

 static ssize_t socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
                                  size_t size)
 {
     QEMUFileSocket *s = opaque;
     ssize_t len;

     for (;;) {
         len = qemu_recv(s->fd, buf, size, 0);
         if (len != -1) {
             break;
         }
         if (socket_error() == EAGAIN) {
             yield_until_fd_readable(s->fd);
         } else if (socket_error() != EINTR) {
             break;
         }
     }

     if (len == -1) {
         len = -socket_error();
     }
     return len;
 }

 static int socket_close(void *opaque)
 {
     QEMUFileSocket *s = opaque;
     closesocket(s->fd);
     g_free(s);
     return 0;
 }

 static int socket_shutdown(void *opaque, bool rd, bool wr)
 {
     QEMUFileSocket *s = opaque;

     if (shutdown(s->fd, rd ? (wr ? SHUT_RDWR : SHUT_RD) : SHUT_WR)) {
         return -errno;
     } else {
         return 0;
     }
 }

 static int socket_return_close(void *opaque)
 {
     QEMUFileSocket *s = opaque;
     /*
      * Note: We don't close the socket, that should be done by the forward
      * path.
      */
     g_free(s);
     return 0;
 }

 static const QEMUFileOps socket_return_read_ops = {
     .get_fd          = socket_get_fd,
     .get_buffer      = socket_get_buffer,
     .close           = socket_return_close,
     .shut_down       = socket_shutdown,
 };

 static const QEMUFileOps socket_return_write_ops = {
     .get_fd          = socket_get_fd,
     .writev_buffer   = socket_writev_buffer,
     .close           = socket_return_close,
     .shut_down       = socket_shutdown,
 };

 /*
  * Give a QEMUFile* off the same socket but data in the opposite
  * direction.
  */
 static QEMUFile *socket_get_return_path(void *opaque)
 {
     QEMUFileSocket *forward = opaque;
     QEMUFileSocket *reverse;

     if (qemu_file_get_error(forward->file)) {
         /* If the forward file is in error, don't try and open a return */
         return NULL;
     }

     reverse = g_malloc0(sizeof(QEMUFileSocket));
     reverse->fd = forward->fd;
     /* I don't think there's a better way to tell which direction 'this' is */
     if (forward->file->ops->get_buffer != NULL) {
         /* being called from the read side, so we need to be able to write */
         return qemu_fopen_ops(reverse, &socket_return_write_ops);
     } else {
         return qemu_fopen_ops(reverse, &socket_return_read_ops);
     }
 }

 static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
                                   int64_t pos)
 {
     QEMUFileSocket *s = opaque;
     ssize_t len, offset;
     ssize_t size = iov_size(iov, iovcnt);
     ssize_t total = 0;

     assert(iovcnt > 0);
     offset = 0;
     while (size > 0) {
         /* Find the next start position; skip all full-sized vector elements  */
         while (offset >= iov[0].iov_len) {
             offset -= iov[0].iov_len;
             iov++, iovcnt--;
         }

         /* skip `offset' bytes from the (now) first element, undo it on exit */
         assert(iovcnt > 0);
         iov[0].iov_base += offset;
         iov[0].iov_len -= offset;

         do {
             len = writev(s->fd, iov, iovcnt);
         } while (len == -1 && errno == EINTR);
         if (len == -1) {
             return -errno;
         }

         /* Undo the changes above */
         iov[0].iov_base -= offset;
         iov[0].iov_len += offset;

         /* Prepare for the next iteration */
         offset += len;
         total += len;
         size -= len;
     }

     return total;
 }

 static ssize_t unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
                               size_t size)
 {
     QEMUFileSocket *s = opaque;
     ssize_t len;

     for (;;) {
         len = read(s->fd, buf, size);
         if (len != -1) {
             break;
         }
         if (errno == EAGAIN) {
             yield_until_fd_readable(s->fd);
         } else if (errno != EINTR) {
             break;
         }
     }

     if (len == -1) {
         len = -errno;
     }
     return len;
 }

 static int unix_close(void *opaque)
 {
     QEMUFileSocket *s = opaque;
     close(s->fd);
     g_free(s);
     return 0;
 }

 static const QEMUFileOps unix_read_ops = {
     .get_fd =     socket_get_fd,
     .get_buffer = unix_get_buffer,
     .close =      unix_close
 };

 static const QEMUFileOps unix_write_ops = {
     .get_fd =     socket_get_fd,
     .writev_buffer = unix_writev_buffer,
     .close =      unix_close
 };

 QEMUFile *qemu_fdopen(int fd, const char *mode)
 {
     QEMUFileSocket *s;

     if (mode == NULL ||
         (mode[0] != 'r' && mode[0] != 'w') ||
         mode[1] != 'b' || mode[2] != 0) {
         fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
         return NULL;
     }

     s = g_new0(QEMUFileSocket, 1);
     s->fd = fd;

     if (mode[0] == 'r') {
         s->file = qemu_fopen_ops(s, &unix_read_ops);
     } else {
         s->file = qemu_fopen_ops(s, &unix_write_ops);
     }
     return s->file;
 }

 static const QEMUFileOps socket_read_ops = {
     .get_fd          = socket_get_fd,
     .get_buffer      = socket_get_buffer,
     .close           = socket_close,
     .shut_down       = socket_shutdown,
     .get_return_path = socket_get_return_path
 };

 static const QEMUFileOps socket_write_ops = {
     .get_fd          = socket_get_fd,
     .writev_buffer   = socket_writev_buffer,
     .close           = socket_close,
     .shut_down       = socket_shutdown,
     .get_return_path = socket_get_return_path
 };

 QEMUFile *qemu_fopen_socket(int fd, const char *mode)
 {
     QEMUFileSocket *s;

     if (qemu_file_mode_is_not_valid(mode)) {
         return NULL;
     }

     s = g_new0(QEMUFileSocket, 1);
     s->fd = fd;
     if (mode[0] == 'w') {
         qemu_set_block(s->fd);
         s->file = qemu_fopen_ops(s, &socket_write_ops);
     } else {
         s->file = qemu_fopen_ops(s, &socket_read_ops);
     }
     return s->file;
 }
	/*
	* QEMU System Emulator
	*
	* Copyright (c) 2003-2008 Fabrice Bellard
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/
	#include "qemu/osdep.h"
	#include "qemu-common.h"
	#include "qemu/error-report.h"
	#include "qemu/iov.h"
	#include "qemu/sockets.h"
	#include "qemu/coroutine.h"
	#include "migration/qemu-file.h"
	#include "migration/qemu-file-internal.h"

	typedef struct QEMUFileSocket {
	int fd;
	QEMUFile *file;
	} QEMUFileSocket;

	static ssize_t socket_writev_buffer(void opaque, struct iovec iov, int iovcnt,
	int64_t pos)
	{
	QEMUFileSocket *s = opaque;
	ssize_t len;
	ssize_t size = iov_size(iov, iovcnt);
	ssize_t offset = 0;
	int err;

	while (size > 0) {
	len = iov_send(s->fd, iov, iovcnt, offset, size);

	if (len > 0) {
	size -= len;
	offset += len;
	}

	if (size > 0) {
	err = socket_error();

	if (err != EAGAIN && err != EWOULDBLOCK) {
	error_report("socket_writev_buffer: Got err=%d for (%zu/%zu)",
	err, (size_t)size, (size_t)len);
	/*
	* If I've already sent some but only just got the error, I
	* could return the amount validly sent so far and wait for the
	* next call to report the error, but I'd rather flag the error
	* immediately.
	*/
	return -err;
	}

	/* Emulate blocking */
	GPollFD pfd;

	pfd.fd = s->fd;
	pfd.events = G_IO_OUT \| G_IO_ERR;
	pfd.revents = 0;
	TFR(err = g_poll(&pfd, 1, -1 /* no timeout */));
	/* Errors other than EINTR intentionally ignored */
	}
	}

	return offset;
	}

	static int socket_get_fd(void *opaque)
	{
	QEMUFileSocket *s = opaque;

	return s->fd;
	}

	static ssize_t socket_get_buffer(void opaque, uint8_t buf, int64_t pos,
	size_t size)
	{
	QEMUFileSocket *s = opaque;
	ssize_t len;

	for (;;) {
	len = qemu_recv(s->fd, buf, size, 0);
	if (len != -1) {
	break;
	}
	if (socket_error() == EAGAIN) {
	yield_until_fd_readable(s->fd);
	} else if (socket_error() != EINTR) {
	break;
	}
	}

	if (len == -1) {
	len = -socket_error();
	}
	return len;
	}

	static int socket_close(void *opaque)
	{
	QEMUFileSocket *s = opaque;
	closesocket(s->fd);
	g_free(s);
	return 0;
	}

	static int socket_shutdown(void *opaque, bool rd, bool wr)
	{
	QEMUFileSocket *s = opaque;

	if (shutdown(s->fd, rd ? (wr ? SHUT_RDWR : SHUT_RD) : SHUT_WR)) {
	return -errno;
	} else {
	return 0;
	}
	}

	static int socket_return_close(void *opaque)
	{
	QEMUFileSocket *s = opaque;
	/*
	* Note: We don't close the socket, that should be done by the forward
	* path.
	*/
	g_free(s);
	return 0;
	}

	static const QEMUFileOps socket_return_read_ops = {
	.get_fd = socket_get_fd,
	.get_buffer = socket_get_buffer,
	.close = socket_return_close,
	.shut_down = socket_shutdown,
	};

	static const QEMUFileOps socket_return_write_ops = {
	.get_fd = socket_get_fd,
	.writev_buffer = socket_writev_buffer,
	.close = socket_return_close,
	.shut_down = socket_shutdown,
	};

	/*
	* Give a QEMUFile* off the same socket but data in the opposite
	* direction.
	*/
	static QEMUFile socket_get_return_path(void opaque)
	{
	QEMUFileSocket *forward = opaque;
	QEMUFileSocket *reverse;

	if (qemu_file_get_error(forward->file)) {
	/* If the forward file is in error, don't try and open a return */
	return NULL;
	}

	reverse = g_malloc0(sizeof(QEMUFileSocket));
	reverse->fd = forward->fd;
	/* I don't think there's a better way to tell which direction 'this' is */
	if (forward->file->ops->get_buffer != NULL) {
	/* being called from the read side, so we need to be able to write */
	return qemu_fopen_ops(reverse, &socket_return_write_ops);
	} else {
	return qemu_fopen_ops(reverse, &socket_return_read_ops);
	}
	}

	static ssize_t unix_writev_buffer(void opaque, struct iovec iov, int iovcnt,
	int64_t pos)
	{
	QEMUFileSocket *s = opaque;
	ssize_t len, offset;
	ssize_t size = iov_size(iov, iovcnt);
	ssize_t total = 0;

	assert(iovcnt > 0);
	offset = 0;
	while (size > 0) {
	/* Find the next start position; skip all full-sized vector elements */
	while (offset >= iov[0].iov_len) {
	offset -= iov[0].iov_len;
	iov++, iovcnt--;
	}

	/* skip `offset' bytes from the (now) first element, undo it on exit */
	assert(iovcnt > 0);
	iov[0].iov_base += offset;
	iov[0].iov_len -= offset;

	do {
	len = writev(s->fd, iov, iovcnt);
	} while (len == -1 && errno == EINTR);
	if (len == -1) {
	return -errno;
	}

	/* Undo the changes above */
	iov[0].iov_base -= offset;
	iov[0].iov_len += offset;

	/* Prepare for the next iteration */
	offset += len;
	total += len;
	size -= len;
	}

	return total;
	}

	static ssize_t unix_get_buffer(void opaque, uint8_t buf, int64_t pos,
	size_t size)
	{
	QEMUFileSocket *s = opaque;
	ssize_t len;

	for (;;) {
	len = read(s->fd, buf, size);
	if (len != -1) {
	break;
	}
	if (errno == EAGAIN) {
	yield_until_fd_readable(s->fd);
	} else if (errno != EINTR) {
	break;
	}
	}

	if (len == -1) {
	len = -errno;
	}
	return len;
	}

	static int unix_close(void *opaque)
	{
	QEMUFileSocket *s = opaque;
	close(s->fd);
	g_free(s);
	return 0;
	}

	static const QEMUFileOps unix_read_ops = {
	.get_fd = socket_get_fd,
	.get_buffer = unix_get_buffer,
	.close = unix_close
	};

	static const QEMUFileOps unix_write_ops = {
	.get_fd = socket_get_fd,
	.writev_buffer = unix_writev_buffer,
	.close = unix_close
	};

	QEMUFile qemu_fdopen(int fd, const char mode)
	{
	QEMUFileSocket *s;

	if (mode == NULL \|\|
	(mode[0] != 'r' && mode[0] != 'w') \|\|
	mode[1] != 'b' \|\| mode[2] != 0) {
	fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
	return NULL;
	}

	s = g_new0(QEMUFileSocket, 1);
	s->fd = fd;

	if (mode[0] == 'r') {
	s->file = qemu_fopen_ops(s, &unix_read_ops);
	} else {
	s->file = qemu_fopen_ops(s, &unix_write_ops);
	}
	return s->file;
	}

	static const QEMUFileOps socket_read_ops = {
	.get_fd = socket_get_fd,
	.get_buffer = socket_get_buffer,
	.close = socket_close,
	.shut_down = socket_shutdown,
	.get_return_path = socket_get_return_path
	};

	static const QEMUFileOps socket_write_ops = {
	.get_fd = socket_get_fd,
	.writev_buffer = socket_writev_buffer,
	.close = socket_close,
	.shut_down = socket_shutdown,
	.get_return_path = socket_get_return_path
	};

	QEMUFile qemu_fopen_socket(int fd, const char mode)
	{
	QEMUFileSocket *s;

	if (qemu_file_mode_is_not_valid(mode)) {
	return NULL;
	}

	s = g_new0(QEMUFileSocket, 1);
	s->fd = fd;
	if (mode[0] == 'w') {
	qemu_set_block(s->fd);
	s->file = qemu_fopen_ops(s, &socket_write_ops);
	} else {
	s->file = qemu_fopen_ops(s, &socket_read_ops);
	}
	return s->file;
	}