Report a coding issue that possibly leaks memory due to unclosed resources

[guodongli-google]

Is this a bug report or feature request?

• Bug Report

Deviation from expected behavior:

At https://github.com/rook/rook/blob/master/pkg/daemon/discover/discover.go#L156

rook/pkg/daemon/discover/discover.go

Line 156 in 078f648

stdout, err := cmd.StdoutPipe()

Pipe stdout is opened and then used in the scanner, however stdout is not closed after the usage, and cmd.Wait() is not called.

	cmd := exec.Command("stdbuf", "-oL", "udevadm", "monitor", "-u", "-k", "-s", "block")
	stdout, err := cmd.StdoutPipe()
	err = cmd.Start()
	scanner := bufio.NewScanner(stdout)

According to https://pkg.go.dev/os/exec#Cmd.StdoutPipe, cmd.Wait() will closed the pipe, but it is not invoked here.

stdout needs to be closed explicitly by invoking the closer, as demonstrated in:

rook/tests/framework/utils/exec_utils.go

Line 70 in 078f648

defer stdOut.Close()

Expected behavior:
While this may not be a real issue depending on the underlying logic and the concrete resource and memory consumption, it is cleaner and safer to explicitly close the pipe after the usage:

	cmd := exec.Command("stdbuf", "-oL", "udevadm", "monitor", "-u", "-k", "-s", "block")
	stdout, err := cmd.StdoutPipe()
	defer stdOut.Close()

and/or terminate the cmd in the end by calling

	err = cmd.Wait()
	...

Found by static analyzer "DeepGo"