Commit e9d8fbf5 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

qemu-file: do not use stdio for qemu_fdopen



This uses system calls directly for Unix file descriptors, so that the
efficient writev_buffer can be used.  Pay attention to the possibility
of partial writes in writev.
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Reviewed-by: default avatarOrit Wassermann <owasserm@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 83f75c26
......@@ -356,9 +356,94 @@ static const QEMUFileOps stdio_file_write_ops = {
.close = stdio_fclose
};
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 int unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int 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)
{
QEMUFileStdio *s;
QEMUFileSocket *s;
if (mode == NULL ||
(mode[0] != 'r' && mode[0] != 'w') ||
......@@ -367,21 +452,15 @@ QEMUFile *qemu_fdopen(int fd, const char *mode)
return NULL;
}
s = g_malloc0(sizeof(QEMUFileStdio));
s->stdio_file = fdopen(fd, mode);
if (!s->stdio_file)
goto fail;
s = g_malloc0(sizeof(QEMUFileSocket));
s->fd = fd;
if(mode[0] == 'r') {
s->file = qemu_fopen_ops(s, &stdio_file_read_ops);
s->file = qemu_fopen_ops(s, &unix_read_ops);
} else {
s->file = qemu_fopen_ops(s, &stdio_file_write_ops);
s->file = qemu_fopen_ops(s, &unix_write_ops);
}
return s->file;
fail:
g_free(s);
return NULL;
}
static const QEMUFileOps socket_read_ops = {
......
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