Date: Wed, 13 Jan 1999 17:31:45 -0800 (PST) From: Mike Meyer <mwm@phone.net> To: "'freebsd-questions@FreeBSD.ORG'" <freebsd-questions@FreeBSD.ORG> Subject: Re: reentrant code Message-ID: <Pine.BSF.4.05.9901131724550.4281-100000@guru.phone.net> In-Reply-To: <Pine.BSF.4.05.9901132000290.356-100000@nyc-ny66-33.ix.netcom.com>
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Personally, I always thought I had a good grip on what re-entrant
meant and what "thread-safe" means. If I correctly understand those,
then thread-safe functions should all be reentrant (pretty much
required, isn't it?).
In which case:
On Wed, 13 Jan 1999, Spike Gronim wrote:
> According to _Advanced Programming in the Unix Environment_, a reentrant
> function must not call malloc(), free(), a function from the standard I/O
> library, or a function which uses a static data structure of which there
> is only one available to the process.
Malloc, free and the standard i/o library are in libc. From 'man pthread':
The current FreeBSD POSIX thread implementation is built in the library
libc_r which contains both thread-safe libc functions and the thread
functions. This library replaces libc for threaded applications.
So, by linking with libc_r instead of libc, you should be able to use
those routines in functions and have them remain reentrant. These may
well be overkill.
If that isn't the case, I'd be interested in knowing the technical
details of how a thread-safe routine can be non-reentrant.
Thanx,
<mike
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