diff mbox series

[07/11] migration: add qemu_get_buffer_at

Message ID 20221004123733.2745519-8-nborisov@suse.com
State New
Headers show
Series Add support for fixed ram offsets during migration | expand

Commit Message

Nikolay Borisov Oct. 4, 2022, 12:37 p.m. UTC 
Restoring a 'fixed-ram' enabled migration stream would require reading
from specific offsets in the file so add a helper to QEMUFile that uses
the newly introduced qio_channel_file_preadv.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 migration/qemu-file.c | 23 +++++++++++++++++++++++
 migration/qemu-file.h |  1 +
 2 files changed, 24 insertions(+)
diff mbox series

Patch

diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 07ba1125e83f..73fffbdb9b7e 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -564,6 +564,29 @@  void qemu_put_buffer_at(QEMUFile *f, const uint8_t *buf, size_t buflen, off_t po
     return;
 }
 
+
+size_t qemu_get_buffer_at(QEMUFile *f, const uint8_t *buf, size_t buflen, off_t pos)
+{
+    Error *err = NULL;
+    struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
+    ssize_t ret;
+
+    if (f->last_error) {
+        return 0;
+    }
+
+    ret = qio_channel_file_preadv(f->ioc, &iov, 1, pos, &err);
+    if (ret == -1) {
+	    goto error;
+    }
+
+    return (size_t)ret;
+
+ error:
+    qemu_file_set_error_obj(f, -EIO, err);
+    return 0;
+}
+
 void qemu_set_offset(QEMUFile *f, off_t off, int whence)
 {
     Error *err = NULL;
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index 33cfc07b81d1..ab10c3ad7e42 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -151,6 +151,7 @@  void qemu_file_set_blocking(QEMUFile *f, bool block);
 void qemu_set_offset(QEMUFile *f, off_t off, int whence);
 off_t qemu_get_offset(QEMUFile *f);
 void qemu_put_buffer_at(QEMUFile *f, const uint8_t *buf, size_t buflen, off_t pos);
+size_t qemu_get_buffer_at(QEMUFile *f, const uint8_t *buf, size_t buflen, off_t pos);
 
 void ram_control_before_iterate(QEMUFile *f, uint64_t flags);
 void ram_control_after_iterate(QEMUFile *f, uint64_t flags);