From patchwork Wed Dec 2 11:36:35 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [01/12] vmstate: Avoid seeking From: Juan Quintela X-Patchwork-Id: 39994 Message-Id: <356d13f1e7112c6daa693a0d937b74adc7de8f93.1259753146.git.quintela@redhat.com> To: qemu-devel@nongnu.org Cc: Jan Kiszka Date: Wed, 2 Dec 2009 12:36:35 +0100 From: Jan Kiszka 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 Signed-off-by: Juan Quintela --- savevm.c | 20 +++++++++++++++++--- 1 files changed, 17 insertions(+), 3 deletions(-) diff --git a/savevm.c b/savevm.c index 18c2e54..833bf3c 100644 --- a/savevm.c +++ b/savevm.c @@ -959,13 +959,27 @@ const VMStateInfo vmstate_info_buffer = { 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 = {