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Re: [Qemu-block] [Qemu-devel] [PATCH v2] file-posix: specify expected fi
From: |
Eric Blake |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v2] file-posix: specify expected filetypes |
Date: |
Tue, 16 Jan 2018 14:35:36 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 01/15/2018 04:50 PM, John Snow wrote:
> 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 <address@hidden>
> ---
>
> @@ -556,10 +557,30 @@ static int raw_open_common(BlockDriverState *bs, QDict
> *options,
> error_setg_errno(errp, errno, "Could not stat file");
> goto fail;
> }
> - if (S_ISREG(st.st_mode)) {
> - s->discard_zeroes = true;
> - s->has_fallocate = true;
> +
> + if (!device) {
> + if (S_ISBLK(st.st_mode)) {
> + warn_report("Opening a block device as file using 'file'"
> + "driver is deprecated");
Do we have a proper deprecation documentation in place, and a time frame
for when we'd start rejecting this rather than permitting it with the
warning?
> + } else if (S_ISCHR(st.st_mode)) {
> + warn_report("Opening a character device as file using the 'file'"
> + "driver is deprecated");
> + } else if (!S_ISREG(st.st_mode)) {
> + error_setg(errp, "A regular file was expected by the 'file'
> driver,"
> + "but something else was given");
This makes sense.
> @@ -589,7 +610,6 @@ static int raw_open_common(BlockDriverState *bs, QDict
> *options,
> s->needs_alignment = true;
> }
> #endif
> -
> #ifdef CONFIG_XFS
> if (platform_test_xfs_fd(s->fd)) {
Spurious whitespace change.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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