From 482ca3af6d842055fe735f0db994896fca1e7505 Mon Sep 17 00:00:00 2001
From: Nick Kirsch <nick@kirsch.org>
Date: Thu, 4 Jan 2018 11:30:39 -0800
Subject: [PATCH 1/3] Parses the tgid field, which is the thread group id (aka
 user-space process id) on Linux. Returns error on other platforms.

---
 process/process.go          |  2 ++
 process/process_fallback.go |  3 +++
 process/process_linux.go    | 16 ++++++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/process/process.go b/process/process.go
index df5da2e..0e089bb 100644
--- a/process/process.go
+++ b/process/process.go
@@ -30,6 +30,8 @@ type Process struct {
 
 	lastCPUTimes *cpu.TimesStat
 	lastCPUTime  time.Time
+
+	tgid int32
 }
 
 type OpenFilesStat struct {
diff --git a/process/process_fallback.go b/process/process_fallback.go
index 12bd3a6..e8f545b 100644
--- a/process/process_fallback.go
+++ b/process/process_fallback.go
@@ -41,6 +41,9 @@ func (p *Process) Ppid() (int32, error) {
 func (p *Process) Name() (string, error) {
 	return "", common.ErrNotImplementedError
 }
+func (p *Process) Tgid() (int32, error) {
+	return 0, common.ErrNotImplementedError
+}
 func (p *Process) Exe() (string, error) {
 	return "", common.ErrNotImplementedError
 }
diff --git a/process/process_linux.go b/process/process_linux.go
index 9db1997..4b1ace1 100644
--- a/process/process_linux.go
+++ b/process/process_linux.go
@@ -100,6 +100,16 @@ func (p *Process) Name() (string, error) {
 	return p.name, nil
 }
 
+// Tgid returns tgid, a Linux-synonym for user-space Pid
+func (p *Process) Tgid() (int32, error) {
+	if p.tgid == 0 {
+		if err := p.fillFromStatus(); err != nil {
+			return 0, err
+		}
+	}
+	return p.tgid, nil
+}
+
 // Exe returns executable path of the process.
 func (p *Process) Exe() (string, error) {
 	return p.fillFromExe()
@@ -820,6 +830,12 @@ func (p *Process) fillFromStatus() error {
 				return err
 			}
 			p.parent = int32(pval)
+		case "Tgid":
+			pval, err := strconv.ParseInt(value, 10, 32)
+			if err != nil {
+				return err
+			}
+			p.tgid = int32(pval)
 		case "Uid":
 			p.uids = make([]int32, 0, 4)
 			for _, i := range strings.Split(value, "\t") {

From 6c35887d024f4257ed09809d3bab3f2fc50fe14f Mon Sep 17 00:00:00 2001
From: Nick Kirsch <nick@kirsch.org>
Date: Thu, 4 Jan 2018 11:51:49 -0800
Subject: [PATCH 2/3] Add ErrNotImplementedError to Darwin, FreeBSD, and
 OpenBSD.

---
 process/process_darwin.go  | 3 +++
 process/process_freebsd.go | 3 +++
 process/process_openbsd.go | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/process/process_darwin.go b/process/process_darwin.go
index cc289d2..2ed7a0b 100644
--- a/process/process_darwin.go
+++ b/process/process_darwin.go
@@ -83,6 +83,9 @@ func (p *Process) Name() (string, error) {
 
 	return common.IntToString(k.Proc.P_comm[:]), nil
 }
+func (p *Process) Tgid() (int32, error) {
+	return 0, common.ErrNotImplementedError
+}
 func (p *Process) Exe() (string, error) {
 	lsof_bin, err := exec.LookPath("lsof")
 	if err != nil {
diff --git a/process/process_freebsd.go b/process/process_freebsd.go
index 9d75717..4db021d 100644
--- a/process/process_freebsd.go
+++ b/process/process_freebsd.go
@@ -50,6 +50,9 @@ func (p *Process) Name() (string, error) {
 
 	return common.IntToString(k.Comm[:]), nil
 }
+func (p *Process) Tgid() (int32, error) {
+	return 0, common.ErrNotImplementedError
+}
 func (p *Process) Exe() (string, error) {
 	return "", common.ErrNotImplementedError
 }
diff --git a/process/process_openbsd.go b/process/process_openbsd.go
index aca4ffa..088abef 100644
--- a/process/process_openbsd.go
+++ b/process/process_openbsd.go
@@ -53,6 +53,9 @@ func (p *Process) Name() (string, error) {
 
 	return common.IntToString(k.Comm[:]), nil
 }
+func (p *Process) Tgid() (int32, error) {
+	return 0, common.ErrNotImplementedError
+}
 func (p *Process) Exe() (string, error) {
 	return "", common.ErrNotImplementedError
 }

From fb24c70d366b88caa381823e8e7e387784fcda8b Mon Sep 17 00:00:00 2001
From: Nick Kirsch <nick@kirsch.org>
Date: Fri, 5 Jan 2018 11:37:36 -0800
Subject: [PATCH 3/3] Add ErrNotImplementedError for Tgid support.

---
 process/process_windows.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/process/process_windows.go b/process/process_windows.go
index 3ce840b..14d466e 100644
--- a/process/process_windows.go
+++ b/process/process_windows.go
@@ -154,6 +154,10 @@ func (p *Process) Name() (string, error) {
 	return name, nil
 }
 
+func (p *Process) Tgid() (int32, error) {
+	return 0, common.ErrNotImplementedError
+}
+
 func (p *Process) Exe() (string, error) {
 	dst, err := GetWin32Proc(p.Pid)
 	if err != nil {