asprintf() issue

[Michael Kerrisk (man-pages)]

On 05/13/2015 07:12 PM, Carlos O'Donell wrote:
> On 05/13/2015 12:14 PM, Joseph Myers wrote:
>> Does anyone know of implementations that do something other than leaving 
>> the value unchanged or setting it to NULL?  The external specifications in 
>> question are LSB and TR 24731-2:2010 (which defers to LSB), and they seem 
>> to be silent on this issue.
> 
> Windows lacks asprintf, Solaris lacks asprintf, HPUX lacks asprintf,
> so we have little guidance from these OSs.

Actually, it looks like Soalris does have it.
See http://docs.oracle.com/cd/E36784_01/html/E36874/asprintf-3c.html
which says:

    If sufficient space cannot be allocated, the asprintf() function 
    returns -1 and sets ret to be a NULL pointer.

> I know of no other implementations that do something other than leave the
> value unchanged or set to NULL.
> 
> My preference is that we set it to NULL. This will aid in debugging as any
> dereferences to NULL will immediately trap. Leaving the value unchanged
> could result in further manipulation of an invalid memory location and
> program corruption.
> 
> This is in line with what the BSDs do, and therefore aids in porting code
> between them.

And also in line with Solaris.

> So +1 to set it to NULL.

Not that I get to vote, but +1 to the +1 ;-).

Cheers,

Michael



-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/