preadv is going to be needed when 'fixed-ram'-enabled stream are to be
restored. Add a minimal implementation of preadv for file channels and
expose it via the generic io_preadv interface.
Signed-off-by: Nikolay Borisov <nbori...@suse.com>
---
io/channel-file.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/io/channel-file.c b/io/channel-file.c
index e213a0fd7cd2..d2f4706b7f6d 100644
--- a/io/channel-file.c
+++ b/io/channel-file.c
@@ -145,6 +145,32 @@ static ssize_t qio_channel_file_writev(QIOChannel *ioc,
return ret;
}
+static ssize_t qio_channel_file_preadv(QIOChannel *ioc,
+ const struct iovec *iov,
+ size_t niov,
+ off_t offset,
+ Error **errp)
+{
+ QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+ ssize_t ret;
+
+ retry:
+ ret = preadv(fioc->fd, iov, niov, offset);
+ if (ret < 0) {
+ if (errno == EAGAIN) {
+ return QIO_CHANNEL_ERR_BLOCK;
+ }
+ if (errno == EINTR) {
+ goto retry;
+ }
+
+ error_setg_errno(errp, errno, "Unable to read from file");
+ return -1;
+ }
+
+ return ret;
+}
+
static ssize_t qio_channel_file_pwritev(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
@@ -252,6 +278,7 @@ static void qio_channel_file_class_init(ObjectClass *klass,
ioc_klass->io_readv = qio_channel_file_readv;
ioc_klass->io_set_blocking = qio_channel_file_set_blocking;
ioc_klass->io_pwritev = qio_channel_file_pwritev;
+ ioc_klass->io_preadv = qio_channel_file_preadv;
ioc_klass->io_seek = qio_channel_file_seek;
ioc_klass->io_close = qio_channel_file_close;
ioc_klass->io_create_watch = qio_channel_file_create_watch;
--
2.34.1
