From: Mark Geisert <mark@maxrnd.com>
To: Corinna Vinschen via Cygwin-developers <cygwin-developers@cygwin.com>
Subject: Re: Extending domain of O_TMPFILE?
Date: Fri, 5 Feb 2021 23:56:57 -0800 (PST) [thread overview]
Message-ID: <Pine.BSF.4.63.2102052340320.49485@m0.truegem.net> (raw)
In-Reply-To: <20210205112650.GO4251@calimero.vinschen.de>
On Fri, 5 Feb 2021, Corinna Vinschen via Cygwin-developers wrote:
> On Feb 5 02:31, Mark Geisert wrote:
>> Hi folks,
>> I've been following up on a response I made to a Cygwin user in
>> https://cygwin.com/pipermail/cygwin/2021-January/247306.html .
>> I've figured out that Cygwin's implementation of the open() flag O_TMPFILE
>> follows Linux in that one can't specify the name of a file when using this
>> flag. User supplies only the path, and Cygwin chooses an obscure file name
>> for you.
>>
>> That means the OP's suggested improvement of applying O_TMPFILE semantics to
>> files created by tmpfile() won't work.
>
> I don't understand the problem. tmpfile(3) does not take filenames, it
> creates its own filenames. Thus, just adding O_TMPFILE in _tmpfile_r's
> and _tmpfile64's calls to open() on systems supporting this flag and not
> calling _remove_r subsequently would already do the trick.
That's what I thought too. But the open() fails and strace reveals ENOENT
is being generated at syscalls.cc:1516. The unix_path arg to open() needs
to indicate a directory, but _tmpfile_r is currently passing in a filename
path generated by _tmpnam_r.
So that's what led me to contemplate extending the domain of O_TMPFILE
such that one could proactively name the temporary file. But it's
probably more sane to just have _tmpfile_r skip the generation of a file
name and instead pass in a directory name to open(), either from
environment variable TMPDIR or the libc #define P_tmpdir.
Does this sound OK?
Thanks,
..mark
next prev parent reply other threads:[~2021-02-06 7:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-05 10:31 Mark Geisert
2021-02-05 11:26 ` Corinna Vinschen
2021-02-06 7:56 ` Mark Geisert [this message]
2021-02-08 10:34 ` Corinna Vinschen
2021-02-09 10:15 ` Mark Geisert
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