Fix: stream fd leaks on error

Fix: stream fd leaks on error

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

This eliminates memory and fd leaks on error.

Change-Id: I447129ab1672ce4fc6cf3c0baf18dbf27bfcfaf8
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>