On Fri, Mar 30, 2007 at 09:31:34AM +1000, Russell Coker wrote:
> Package: libc6
> Version: 2.3.6.ds1-13
> Severity: normal
>
> Below is part of the strace output from running "ldconfig" with no
> parameters. As you can see the O_SYNC parameter is not used for the open()
> system call and the fsync() system call is not used to sync the file to disk
> before closing it.
>
> This means that if the system has a power failure immediately after a rename
> the file /etc/ld.so.cache may have corrupt contents. I have seen this happen
> on a real system (it's not a theoretical bug).
>
> unlink("/etc/ld.so.cache~") = -1 ENOENT (No such file or directory)
> open("/etc/ld.so.cache~", O_WRONLY|O_CREAT|O_TRUNC|O_NOFOLLOW, 0644) = 3
> write(3, "ld.so-1.7.0\0\376\2\0\0\3\0\0\0\310L\0\0\322L\0\0\3\0\0"..., 9208) = 9208
> write(3, "", 0) = 0
> write(3, "glibc-ld.so.cache1.11\3\0\0m\213\0\0\0\0\0\0"..., 19656) = 19656
> write(3, "libz.so.1\0/usr/lib/libz.so.1\0lib"..., 35693) = 35693
> close(3) = 0
> chmod("/etc/ld.so.cache~", 0644) = 0
> rename("/etc/ld.so.cache~", "/etc/ld.so.cache") = 0
Given that it uses a temporary file, a fsync should be enough IMHO.
O_SYNC looks like an overkill.
--
·O· Pierre Habouzit
··O madcoder@debian.org
OOO http://www.madism.org
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