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Date: Mon, 25 Apr 2005 21:19:12 +0800
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Thread-Topic: Query regarding thread safety of few libc stdio functions
thread-index: AcVJmHm33y2izWcETyyNZsTSYWUJwAAABKhw
From: "Mayank Kumar" <mayank@microsoft.com>
To: <freebsd-current@freebsd.org>
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Subject: Query regarding thread safety of few libc stdio functions
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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 =3D __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