Use pread/pwrite instead of lseek + read/write in preparation of using the qemu block API.
Signed-off-by: Christoph Hellwig <h...@lst.de> Index: qemu/block/cow.c =================================================================== --- qemu.orig/block/cow.c 2010-05-04 19:11:24.897004616 +0200 +++ qemu/block/cow.c 2010-05-04 19:12:29.010255070 +0200 @@ -78,7 +78,7 @@ static int cow_open(BlockDriverState *bs } s->fd = fd; /* see if it is a cow image */ - if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) { + if (pread(fd, &cow_header, sizeof(cow_header), 0) != sizeof(cow_header)) { goto fail; } @@ -159,8 +159,8 @@ static int cow_read(BlockDriverState *bs while (nb_sectors > 0) { if (is_changed(s->cow_bitmap, sector_num, nb_sectors, &n)) { - lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET); - ret = read(s->fd, buf, n * 512); + ret = pread(s->fd, buf, n * 512, + s->cow_sectors_offset + sector_num * 512); if (ret != n * 512) return -1; } else { @@ -186,8 +186,8 @@ static int cow_write(BlockDriverState *b BDRVCowState *s = bs->opaque; int ret, i; - lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET); - ret = write(s->fd, buf, nb_sectors * 512); + ret = pwrite(s->fd, buf, nb_sectors * 512, + s->cow_sectors_offset + sector_num * 512); if (ret != nb_sectors * 512) return -1; for (i = 0; i < nb_sectors; i++)