Date: Mon, 25 Apr 2005 21:33:02 +0800 From: David Xu <davidxu@freebsd.org> To: Mayank Kumar <mayank@microsoft.com> Cc: freebsd-current@freebsd.org Subject: Re: Query regarding thread safety of few libc stdio functions Message-ID: <426CF18E.5050203@freebsd.org> In-Reply-To: <3A5384BC2FBA4C488865F2275A036BFF027C1614@APS-MSG-01.southpacific.corp.microsoft.com>
index | next in thread | previous in thread | raw e-mail
Mayank Kumar wrote: >Hi All >Recently I have been looking at few freebsd libc functions and I found >That they were not thread safe. Can one of you please confirm. > >Following functions in freebsd libc are not thread safe:- >1: vsnprintf >2: vsprintf >3: vsscanf > theere are many more. > >Functions like vfprintf are written as follows:- >------------- >int ret; > > FLOCKFILE(fp); > ret = __vfprintf(fp, fmt0, ap); > FUNLOCKFILE(fp); > return (ret); >---------------- >Which ensures that they are thread safe. > >Why is the same case not followed for eg with vsnprintf or vsprintf >Vsnprintf calls directly __vfprintf which is not thread safe. Hence >How is there thready safey guranteed. Any help on this front >Would be helpful. > >Thanks and regards >Mayank > vsnprintf and vsprintf use a on stack FILE structure, no other threads can see the structure, it won't be shared with other threads, so lock is not needed. Cheers, David Xuhome | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?426CF18E.5050203>