vmd read/write pfunctions

[Ted Unangst]

using pread and pwrite is a little shorter and half the syscalls.

Index: virtio.c
===================================================================
RCS file: /cvs/src/usr.sbin/vmd/virtio.c,v
retrieving revision 1.46
diff -u -p -r1.46 virtio.c
--- virtio.c    11 May 2017 07:31:20 -0000      1.46
+++ virtio.c    27 May 2017 23:20:23 -0000
@@ -335,14 +335,7 @@ vioblk_do_read(struct vioblk_dev *dev, o
                return (NULL);
        }
 
-       if (lseek(dev->fd, sector * VIRTIO_BLK_SECTOR_SIZE,
-           SEEK_SET) == -1) {
-               log_warn("seek error in vioblk read");
-               free(buf);
-               return (NULL);
-       }
-
-       if (read(dev->fd, buf, sz) != sz) {
+       if (pread(dev->fd, buf, sz, sector * VIRTIO_BLK_SECTOR_SIZE) != sz) {
                log_warn("vioblk read error");
                free(buf);
                return (NULL);
@@ -354,13 +347,7 @@ vioblk_do_read(struct vioblk_dev *dev, o
 static int
 vioblk_do_write(struct vioblk_dev *dev, off_t sector, char *buf, ssize_t sz)
 {
-       if (lseek(dev->fd, sector * VIRTIO_BLK_SECTOR_SIZE,
-           SEEK_SET) == -1) {
-               log_warn("seek error in vioblk write");
-               return (1);
-       }
-
-       if (write(dev->fd, buf, sz) != sz) {
+       if (pwrite(dev->fd, buf, sz, sector * VIRTIO_BLK_SECTOR_SIZE) != sz) {
                log_warn("vioblk write error");
                return (1);
        }