psContext: store TTYs to allow concurrent accesses

Signed-off-by: Valentin Rothberg <[email protected]>

internal/dev/tty.go

@@ -31,20 +31,17 @@ type TTY struct {
 	Path string
 }
 
-// cache TTYs to avoid redundant lookups
-var devices *[]TTY
-
 // FindTTY return the corresponding TTY to the ttyNr or nil of non could be
 // found.
-func FindTTY(ttyNr uint64) (*TTY, error) {
+func FindTTY(ttyNr uint64, devices *[]TTY) (*TTY, error) {
 	// (man 5 proc) The minor device number is contained in the combination
 	// of bits 31 to 20 and 7 to 0; the major device number is in bits 15
 	// to 8.
 	maj := (ttyNr >> 8) & 0xFF
 	min := (ttyNr & 0xFF) | ((ttyNr >> 20) & 0xFFF)
 
 	if devices == nil {
-		devs, err := getTTYs()
+		devs, err := TTYs()
 		if err != nil {
 			return nil, err
 		}
@@ -70,8 +67,8 @@ func minDevNum(rdev uint64) uint64 {
 	return (rdev & 0xff) | ((rdev >> 12) & 0xfff00)
 }
 
-// getTTYs parses /dev for tty and pts devices.
-func getTTYs() (*[]TTY, error) {
+// TTYs parses /dev for tty and pts devices.
+func TTYs() (*[]TTY, error) {
 	devDir, err := os.Open("/dev/")
 	if err != nil {
 		return nil, err

internal/dev/tty_test.go

@@ -22,7 +22,7 @@ import (
 
 func TestGetTTYs(t *testing.T) {
 	// no thorough test but it makes sure things are working
-	devs, err := getTTYs()
+	devs, err := TTYs()
 	assert.Nil(t, err)
 	assert.NotNil(t, devs)
 }

psgo.go

@@ -48,6 +48,8 @@ type psContext struct {
 	containersProcesses []*process.Process
 	// Processes on the host.  Used to map those to the ones running in the container.
 	hostProcesses []*process.Process
+	// tty and pty devices.
+	ttys *[]dev.TTY
 }
 
 // processFunc is used to map a given aixFormatDescriptor to a corresponding
@@ -287,7 +289,10 @@ func JoinNamespaceAndProcessInfo(pid string, descriptors []string) ([][]string,
 	// of the specified descriptors requires host data
 	for _, d := range aixDescriptors {
 		if d.onHost {
-			ctx.hostProcesses, _ = hostProcesses(pid)
+			ctx.hostProcesses, err = hostProcesses(pid)
+			if err != nil {
+				return nil, err
+			}
 			break
 		}
 	}
@@ -607,7 +612,7 @@ func processTTY(p *process.Process, ctx *psContext) (string, error) {
 		return "", nil
 	}
 
-	tty, err := dev.FindTTY(ttyNr)
+	tty, err := dev.FindTTY(ttyNr, ctx.ttys)
 	if err != nil {
 		return "", nil
 	}