Return_Values

   x                  getpwnam returns a pointer to a valid passwd
                      structure, if a matching entry is found.
   NULL               getpwnam returns NULL if an error occurred
                      or a the specified entry was not found. errno
                      is set to indicate the error. The getpwnam
                      function may fail if:

                      o  EIO - An I/O error has occurred.

                      o  EINTR - A signal was intercepted during
                         getpwnam.

                      o  EMFILE - OPEN_MAX file descriptors are
                         currently open in the calling process.

                      o  ENFILE - The maximum allowable number of
                         files is currently open in the system.

   0                  When successful, getpwnam_r returns 0 and
                      stores a pointer to the updated passwd
                      structure at the location pointed to by
                      result.
   0                  When unsuccessful (on error or if the
                      requested entry is not found), getpwnam_r
                      returns 0 and stores a NULL pointer at the
                      location pointed to by result. The getpwnam_r
                      function may fail if:

                      o  ERANGE - Insufficient storage was supplied
                         through buffer and bufsize to contain the
                         data to be referenced by the resulting
                         passwd structure.