On Wed, Mar 23, 2011 at 9:04 AM, dennis jenkins
<dennis.jenkins.75@gmail.com> wrote:
> On Wed, Mar 23, 2011 at 5:08 AM, Adrian Schreyer <ams214@cam.ac.uk> wrote:
>>
>> you are right, it returns a char *.
>>
>> The prototype:
>>
>> char *function(bytea *b);
>>
>> The actual C++ function looks roughly like this
>>
>> extern "C"
>> char *function(bytea *b)
>> {
>> string ism;
>> [...]
>> return ism.c_str();
>> }
>>
>
>
> Don't do that. You are returning a pointer to an unallocated buffer
> (previously held by a local variable). c_str() is just a const
> pointer to a buffer held inside "ism". When ism goes out of scope,
> that buffer if freed.
>
> Either return "std::string", or strdup() the string and have the
> caller free that. (but use the postgresql alloc pool function to
> handle the strdup. I don't recall that function's name off the top of
> my head).
that would be pstrdup, and it's the way to go (you don't have to
pfree). who says C doesn't have garbage collection?
merlin