Re: Is this C style function well written and thread safe?

From:

=?ISO-8859-1?Q?Erik_Wikstr=F6m?= <Erik-wikstrom@telia.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 12 Sep 2007 17:40:37 GMT

Message-ID:

<pwVFi.8544$ZA.4322@newsb.telia.net>

On 2007-09-12 17:10, jeff_j_dunlap@yahoo.com wrote:

Dear C++ Users:

I alwasy use std::string and avoid char buffers but last night I
wanted to see if I could make a C style function that would be thread
safe.

The easiest way to make things thread safe is to avoid shared data, for
functions this usually means static variables, or parameters passed as
pointers.

For me, it was a good learning experience since my C/C++ knowledge is
limited but I do understand threading issues due to prior Delphi
experience.

In the following function, pleas assume that the Date object is well
written. What I really want to know is if my char buff is being
handled safely.

It is safe if you trust the user, which more or less means that it is
unsafe. The problem with a pointer to a buffer is that it contains no
information about the size of the buffer, which means that you have to
trust the user to supply a large enough buffer. To solve this versions
like snprintf() and strncpy() were created, but once again you have to
trust the user, this time to not lie about the buffer size.

--
Erik Wikstr?m