From 2885d0e6132147550c0b2aa5d427fb4afd94969b Mon Sep 17 00:00:00 2001
From: Al Hoang <3811822-hoanga@users.noreply.gitlab.com>
Date: Fri, 18 Mar 2022 23:21:37 -0500
Subject: [PATCH] add plan9 support

---
 process_plan9.go      | 123 ++++++++++++++++++++++++++++++++++++++++++
 process_plan9_test.go |  11 ++++
 2 files changed, 134 insertions(+)
 create mode 100644 process_plan9.go
 create mode 100644 process_plan9_test.go

diff --git a/process_plan9.go b/process_plan9.go
new file mode 100644
index 0000000..5b33ac4
--- /dev/null
+++ b/process_plan9.go
@@ -0,0 +1,123 @@
+// +build plan9
+
+package ps
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// Plan9Process is an implementation of Process that contains Plan9-specific
+// fields and information.
+type Plan9Process struct {
+	pid    int
+	ppid   int
+	binary string
+}
+
+func (p *Plan9Process) Pid() int {
+	return p.pid
+}
+
+func (p *Plan9Process) PPid() int {
+	return p.ppid
+}
+
+func (p *Plan9Process) Executable() string {
+	return p.binary
+}
+
+func (p *Plan9Process) Refresh() error {
+	statusPath := fmt.Sprintf("/proc/%d/status", p.pid)
+	statusDataBytes, err := ioutil.ReadFile(statusPath)
+	if err != nil {
+		return err
+	}
+
+	// Parse out name of binary
+	data := string(statusDataBytes)
+	binStart := 0
+	binEnd := strings.IndexRune(data[binStart:], ' ')
+	p.binary = data[binStart : binStart+binEnd]
+
+	// Parse out ppid
+	ppidPath := fmt.Sprintf("/proc/%d/ppid", p.pid)
+	ppidBytes, err := ioutil.ReadFile(ppidPath)
+	if err != nil {
+		return err
+	}
+	ppidStr := strings.TrimSpace(string(ppidBytes))
+
+	ppid, err := strconv.ParseInt(ppidStr, 10, 0)
+	if err != nil {
+		return err
+	}
+	p.ppid = int(ppid)
+
+	return err
+}
+
+func findProcess(pid int) (Process, error) {
+	dir := fmt.Sprintf("/proc/%d", pid)
+	_, err := os.Stat(dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+
+		return nil, err
+	}
+
+	return newPlan9Process(pid)
+}
+
+func processes() ([]Process, error) {
+	d, err := os.Open("/proc")
+	if err != nil {
+		return nil, err
+	}
+	defer d.Close()
+
+	results := make([]Process, 0, 50)
+	for {
+		names, err := d.Readdirnames(10)
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		for _, name := range names {
+			// We only care if the name starts with a numeric
+			if name[0] < '0' || name[0] > '9' {
+				continue
+			}
+
+			// From this point forward, any errors we just ignore, because
+			// it might simply be that the process doesn't exist anymore.
+			pid, err := strconv.ParseInt(name, 10, 0)
+			if err != nil {
+				continue
+			}
+
+			p, err := newPlan9Process(int(pid))
+			if err != nil {
+				continue
+			}
+
+			results = append(results, p)
+		}
+	}
+
+	return results, nil
+}
+
+func newPlan9Process(pid int) (*Plan9Process, error) {
+	p := &Plan9Process{pid: pid}
+	return p, p.Refresh()
+}
diff --git a/process_plan9_test.go b/process_plan9_test.go
new file mode 100644
index 0000000..0974717
--- /dev/null
+++ b/process_plan9_test.go
@@ -0,0 +1,11 @@
+// +build plan9
+
+package ps
+
+import (
+	"testing"
+)
+
+func TestPlan9Process_impl(t *testing.T) {
+	var _ Process = new(Plan9Process)
+}