On Feb 05, 2006, at 11:15, Phillip Susi wrote:
Jan Engelhardt wrote:
I would say we all forgot to RTFM. Because O_EXCL does nothing
*unless* O_CREAT is specified, which probably *is not* specified
in cdrecord or hal. There is no reason to have hal or cdrecord
create a device node - which you can't do with open() anyway.
I think you are misinterpreting the man page, because it isn't
worded very clearly. It should not even mention O_CREAT because it
has nothing to do with O_EXCL; it is just repeating the semantics
of O_CREAT ( if the file already exists, the call fails ) which
would of course, apply if you do use O_CREAT in conjunction with
any other flag including O_EXCL. It does not say that you must use
O_EXCL with O_CREAT. The rest of the description talks about using
lockfiles as an alternative to ensure exclusive access to the file
on NFS where O_EXCL is broken. The intent of O_EXCL is clearly to
provide the caller with exclusive access to the file.
You don't have this right either. The way open() works:
If you specify O_CREAT (and not O_EXCL), it will create the file if
it does not exist, and open the existing file otherwise.
If you specify O_EXCL (and not O_CREAT), it is implementation defined
what will happen (in the Linux case, this opens a block device for
exclusive access).
If you specify O_CREAT|O_EXCL, it will atomically create the file if
it does not exist, otherwise it will return the error -EEXIST.
Cheers,
Kyle Moffett
--
Q: Why do programmers confuse Halloween and Christmas?
A: Because OCT 31 == DEC 25.
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