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authorPaolo Bonzini <pbonzini@redhat.com>2013-03-27 17:36:32 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2013-04-17 11:44:22 +0200
commite9d8fbf53a33983c81d67d18e1baa914eb16cdea (patch)
treed3a693927858d6d63fba49ae77795ba37cc9507b /savevm.c
parent83f75c26e8e791311900d0e2a4cc9379abedb85c (diff)
downloadqemu-arm-e9d8fbf53a33983c81d67d18e1baa914eb16cdea.tar.gz
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: Juan Quintela <quintela@redhat.com> Reviewed-by: Orit Wassermann <owasserm@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'savevm.c')
-rw-r--r--savevm.c101
1 files changed, 90 insertions, 11 deletions
diff --git a/savevm.c b/savevm.c
index ffabbff12c..31dcce975e 100644
--- a/savevm.c
+++ b/savevm.c
@@ -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 = {