vmstate: Avoid seeking
Seeking on vmstate save/load does not work if the underlying file is a
stream. We could try to make all QEMUFile* forward-seek-aware, but first
attempts in this direction indicated that it's saner to convert the few
qemu_fseek-on-vmstates users to plain reads/writes.
This fixes various subtle vmstate corruptions where unused fields were
involved.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/savevm.c b/savevm.c
index d6da050..55a2763 100644
--- a/savevm.c
+++ b/savevm.c
@@ -959,13 +959,27 @@
static int get_unused_buffer(QEMUFile *f, void *pv, size_t size)
{
- qemu_fseek(f, size, SEEK_CUR);
- return 0;
+ uint8_t buf[1024];
+ int block_len;
+
+ while (size > 0) {
+ block_len = MIN(sizeof(buf), size);
+ size -= block_len;
+ qemu_get_buffer(f, buf, block_len);
+ }
+ return 0;
}
static void put_unused_buffer(QEMUFile *f, void *pv, size_t size)
{
- qemu_fseek(f, size, SEEK_CUR);
+ static const uint8_t buf[1024];
+ int block_len;
+
+ while (size > 0) {
+ block_len = MIN(sizeof(buf), size);
+ size -= block_len;
+ qemu_put_buffer(f, buf, block_len);
+ }
}
const VMStateInfo vmstate_info_unused_buffer = {
