Date: Thu, 29 Dec 2005 05:50:07 GMT From: Dmitrij Tejblum <tejblum@yandex-team.ru> To: freebsd-threads@FreeBSD.org Subject: Re: threads/79887: [patch] freopen() isn't thread-safe Message-ID: <200512290550.jBT5o7Cn072507@freefall.freebsd.org>
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The following reply was made to PR threads/79887; it has been noted by GNATS. From: Dmitrij Tejblum <tejblum@yandex-team.ru> To: David Xu <davidxu@freebsd.org> Cc: bug-followup@freebsd.org Subject: Re: threads/79887: [patch] freopen() isn't thread-safe Date: Thu, 29 Dec 2005 08:43:15 +0300 David Xu wrote: > Dmitrij Tejblum wrote: > >> >> David Xu wrote: >> >>> Indeed, this a bug, but the patch you provided breaks the samentic the >>> FILE structure was designed for, here you conditionally call >>> fp->_close(), this is incorrect, because the hook may be an external >>> function, it should always be called to notify external code. >> >> >> >> I only assume that >> 1) _file and _close fields are internal to stdio, i.e. only stdio >> code manipulate with them directly >> 2) If _file != -1, then the FILE is associated with the file >> descriptor, fp->_close == __sclose (because the only code that can >> set fp_close to something different is funopen, and it set _file to >> -1) and __sclose just close the _fp->_file >> If so, we know that dup2() will close the descriptor too, dup2() is >> required to do it. >> > I think we allow _close and others to be changed by user code unless > someone can clarify that this is not allowed now, otherwise your > assumption is false. 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.
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