RE: QzshSystem API ... almost there...

On Thu, 4 Sep 2003, Joel Cochran wrote:
> The only odd thing is that while the QzshSystem commands are working
> correctly, I always get the 'Path or Directory Not Found' error.  I'm
> getting it after the mkdir command also (as seen indebug).  But it still
> works...

You shouldn't use errno to determine if an error occurred.   Errno always
contains the last error that occurred.  So if you did this:

         rmdir('/foo/bar')       <--- this generates a "path not found"
         mkdir('/foo/bar':511)   <--- this is successful
         errno may still be set to "path not found"

Instead, you need to use the return values from the actual APIs to first
determine *IF* an error has occurred, and then query errno to see what
happened.

         if (rmdir('/foo/bar') < 0);
             msg = %str(strerror(errno));
             send_escape_msg(msg);
         endif;

         if (mkdir('/foo/bar': 511) < 0);
             msg = %str(strerror(errno));
             send_escape_msg(msg);
         endif;

See the difference?  I only check errno if an error has occurred.

With QzshSystem(), if it returns a -1, then the QzshSystem() API itself
failed, in that case you can check errno.

But, if you get a number higher than 0, that means that the command that
it ran failed.  This does not set errno, but rather returns the exit code
that the called program specified.   So, if you get higher than 0, you
don't want to check errno.

Hope that helps...