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From: Marc Balmer <marc@msys.ch>
Date: Thu, 7 Oct 2004 07:20:45 +0200
To: Dan Nelson <dnelson@allantgroup.com>
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cc: freebsd-hackers@freebsd.org
Subject: Re: syslog() reentrant when compiling with -pthread?
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Am 06.10.2004 um 16:48 schrieb Dan Nelson:

> The only unsafe part is openlog(), so set that up before you start any
> threads and you'll be okay.  Once the log fd is opened, the syslog()
> call looks to be thread-safe.  Everything in there is done with local
> variables and atomic writes.

At least on OpenBSD I can use "%m" in the syslog() format string.  This 
results in a call to strerror(), which is not thread safe, AFAIK.  This 
probably is true for FreeBSD as well, so we have the following three 
conditions for thread safe syslog():

1) openlog() must be called before any threads that use syslog() are 
started.
2) The first argument to openlog() must not be NULL.
3) The "%m" Format String must not be used in syslog() calls.

Any comments?

- Marc