Added --ppid command line option that includes the parent process identifier.

Also included small refactoring in PSScanner module to allow for parameter to be passed.

internal/psscanner/psscanner.go

@@ -2,15 +2,21 @@ package psscanner
 
 import (
 	"fmt"
+	"io/ioutil"
 	"strconv"
+	"strings"
 )
 
-type PSScanner struct{}
+type PSScanner struct {
+	enablePpid bool
+	eventCh    chan<- PSEvent
+}
 
 type PSEvent struct {
-	UID int
-	PID int
-	CMD string
+	UID  int
+	PID  int
+	PPID int
+	CMD  string
 }
 
 func (evt PSEvent) String() string {
@@ -19,23 +25,101 @@ func (evt PSEvent) String() string {
 		uid = "???"
 	}
 
-	return fmt.Sprintf("UID=%-4s PID=%-6d | %s", uid, evt.PID, evt.CMD)
+	if evt.PPID == -1 {
+		return fmt.Sprintf("UID=%-4s PID=%-6d | %s", uid, evt.PID, evt.CMD)
+	}
+
+	return fmt.Sprintf(
+		"UID=%-4s PID=%-6d PPID=%-6d | %s", uid, evt.PID, evt.PPID, evt.CMD)
 }
 
-func NewPSScanner() *PSScanner {
-	return &PSScanner{}
+func NewPSScanner(ppid bool) *PSScanner {
+	return &PSScanner{
+		enablePpid: ppid,
+		eventCh:    nil,
+	}
 }
 
 func (p *PSScanner) Run(triggerCh chan struct{}) (chan PSEvent, chan error) {
 	eventCh := make(chan PSEvent, 100)
+	p.eventCh = eventCh
 	errCh := make(chan error)
 	pl := make(procList)
 
 	go func() {
 		for {
 			<-triggerCh
-			pl.refresh(eventCh)
+			pl.refresh(p)
 		}
 	}()
 	return eventCh, errCh
 }
+
+func (p *PSScanner) processNewPid(pid int) {
+	// quickly load data into memory before processing it, with preferance for cmd
+	cmdLine, errCmdLine := cmdLineReader(pid)
+	status, errStatus := procStatusReader(pid)
+
+	cmd := "???" // process probably terminated
+	if errCmdLine == nil {
+		for i := 0; i < len(cmdLine); i++ {
+			if cmdLine[i] == 0 {
+				cmdLine[i] = 32
+			}
+		}
+		cmd = string(cmdLine)
+	}
+
+	uid, ppid := -1, -1
+	if errStatus == nil {
+		uid, ppid, errStatus = p.parseProcessStatus(status)
+		if errStatus != nil {
+			uid = -1
+			ppid = -1
+		}
+	}
+
+	p.eventCh <- PSEvent{UID: uid, PID: pid, PPID: ppid, CMD: cmd}
+}
+
+func (p *PSScanner) parseProcessStatus(status []byte) (int, int, error) {
+	lines := strings.Split(string(status), "\n")
+	if len(lines) < 9 {
+		return -1, -1, fmt.Errorf("no uid information")
+	}
+
+	uidL := strings.Split(lines[8], "\t")
+	if len(uidL) < 2 {
+		return -1, -1, fmt.Errorf("uid line read incomplete")
+	}
+
+	uid, err := strconv.Atoi(uidL[1])
+	if err != nil {
+		return -1, -1, fmt.Errorf("converting %s to int: %v", uidL[1], err)
+	}
+
+	ppid := -1
+	if p.enablePpid {
+		ppidL := strings.Split(lines[6], "\t")
+		if len(ppidL) < 2 {
+			return -1, -1, fmt.Errorf("ppid line read incomplete")
+		}
+
+		ppid, err = strconv.Atoi(ppidL[1])
+		if err != nil {
+			return -1, -1, fmt.Errorf("converting %s to int: %v", ppidL[1], err)
+		}
+	}
+
+	return uid, ppid, nil
+}
+
+var procStatusReader = func(pid int) ([]byte, error) {
+	statPath := fmt.Sprintf("/proc/%d/status", pid)
+	return ioutil.ReadFile(statPath)
+}
+
+var cmdLineReader = func(pid int) ([]byte, error) {
+	cmdPath := fmt.Sprintf("/proc/%d/cmdline", pid)
+	return ioutil.ReadFile(cmdPath)
+}