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Re: threads/79887: [patch] freopen() isn't thread-safe
The following reply was made to PR threads/79887; it has been noted by GNATS.
From: David Xu <davidxu@xxxxxxxxxxx>
To: Dmitrij Tejblum <tejblum@xxxxxxxxxxxxxx>
Cc: bug-followup@xxxxxxxxxxx
Subject: Re: threads/79887: [patch] freopen() isn't thread-safe
Date: Thu, 29 Dec 2005 14:23:39 +0800
Dmitrij Tejblum wrote:
>
> Well, this is C, not C++, so there cannot be strict difference between
> allowed and disallowed. But the _close field is not required by any
> standarts (funopen() too) and is not documented by manpages (I checked
> manpages with grep). And there does exist documented interface for
> setting _close: funopen(). Thus _close is internal.
>
>
>
Then why use the following code to close a file descriptor,
if (isopen)
(void) (*fp->_close)(fp->_cookie);
Why don't use _close(fp->_file)? this should be faster.
This implies that someone can replace fp->_close with another function
pointer,so that function must be called unconditionally. I think the
libc should have a document to clarify this problem. Also should we move
the PR to freebsd-standard@ list ?
