I don't think there's a legitimate reason to open directories as if they were files. This prevents QEMU from opening and attempting to probe a directory inode, which can break in exciting ways. One of those ways is lseek on ext4/xfs, which will return 0x7fffffffffffffff as the file size instead of EISDIR. This can coax QEMU into responding with a confusing "file too big" instead of "Hey, that's not a file".
See: https://bugs.launchpad.net/qemu/+bug/1739304/ Signed-off-by: John Snow <js...@redhat.com> --- block/file-posix.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/block/file-posix.c b/block/file-posix.c index 36ee89e940..bd29bdada6 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -589,6 +589,11 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, s->needs_alignment = true; } #endif + if (S_ISDIR(st.st_mode)) { + ret = -EISDIR; + error_setg_errno(errp, errno, "Cannot open directory as file"); + goto fail; + } #ifdef CONFIG_XFS if (platform_test_xfs_fd(s->fd)) { -- 2.14.3
