Howdy,
I just came across the apr_procattr_child_{in,out,err}_set()
implementations for UNIX and got to wonder about the semantics of those
functions. Their doxygen comments are lacking a bit of preciseness.
What I understand is, that by using apr_procattr_io_set() it is defined,
which of stdin/stdout/stderr the child process inherits from its parents
and for which pipes are created. I also see what
apr_procattr_child_{in,out,err}_set() shall do, if I pass a pipe. But in
case one or both of the supplied file handles are NULL, the implementation
behaves a bit strange, IMHO.
If I want to direct my child process' stdout to a log file I have already
open, I would intuitively pass the pair (<log file>, NULL) to
apr_procattr_child_out_set(). What the implementation does in this case, is
to create a pipe and then replace the child part with my log file, but keep
the parent part.
Even stranger I find the behavior in case of passing a (NULL, NULL) pair. I
would expect the inheritence behavior from the parent process to be
restored, but instead a pipe is installed.
Personally I would consider it straight forward, if the functions would
always close the file handles that are there and set them to NULL and then
dup() the non-NULL arguments. A (NULL, non-NULL) argument pair doesn't seem
to make much sense, so it could be considered an error case.
Does that sound reasonable or do I miss something?
CU, Ingo
