Re: [boost] [test] PATCH: putenv usage incorrect

From: Martin Wille (mw8329_at_[hidden])
Date: 2005-04-26 12:51:25

Caleb Epstein wrote:
> On 4/26/05, Martin Wille wrote:
> 

[...]

>>setenv() is a very recent addition to POSIX, IIRC. Older Unix versions
>>might not support it.
> 
> 
> OK, would you know of a better way to determine which "type" of putenv
> is available instead?  E.g. is it the one that takes a const char* and
> copies, or the one that takes a char* and inserts it into the
> environment in-place.  Using the wrong semantic will lead to either
> memory leak (bad) or undefined behavior (worse).

I once wrote my own version of putenv() in order to avoid the memory 
leak problem. I'm afraid this is a nasty problem, because POSIX putenv() 
doesn't copy but doesn't assume ownership, either. setenv() might leak 
for that reason, too.

You can check for the platforms you know to support setenv by using the 
various macros they supply (messy, I know). Every *BSD I know of and 
Linux do. setenv() was added to POSIX in IEEE Std 1003.1-2001, if I 
understand correctly. So setting _POSIX_C_SOURCE before #including any 
POSIX header and checking for _POSIX_VERSION >= 200112L should catch all 
POSIX implementations that added setenv() recently.

[...]

>>Your patch doesn't check the value returned by setenv() or putenv().
> 
> 
> Nor did the original.  I'm just trying to get this code working in
> order to clear up some of the test failures.

Well, I don't know the context of the code. I can't say whether it is ok 
to ignore the result here. I just wanted to state what I've seen.

Regards,
m