Dear Corinna,
Thank you for the rapid answer.
> The pthread_key_create function checks the incoming pthread_key_t pointer
> for being a valid object already and,if so, bails out with EBUSY.
The POSIX specification of this function [1] mentions that some value shall
be stored in *KEY but does not mention any meaning of *KEY upon entry to
the function. Therefore it's an output parameter, not an input-output parameter.
An implementation of the function can look at the value upon entry, and
decide to emit a message to a log file or something like that, but it should
not affect the function's return value.
Besides, code like this:
pthread_key_create (pthread_key_t *key, void (*destructor) (void *))
{
if (pthread_key::is_good_object (key))
return EBUSY;
...
}
misunderstands the ::is_good_object function: It tests for a pointer that
points to a certain magic number. But there can also be other occurrences
of the value 0xdf0df047 in memory; if you find a pointer to this magic
number, it's likely but not guaranteed(!) that the value is a pthread_key_t
in use. I could easily construct a test case by filling large blocks of memory
with the word 0xdf0df047. This affects also the functions
pthread_attr_init
pthread_condattr_init
pthread_rwlockattr_init
pthread_mutexattr_init
Bruno
[1] http://www.opengroup.org/susv3/functions/pthread_key_create.html
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