From c731a8342476ccd3ac1b324cc34d69bfaf3114c5 Mon Sep 17 00:00:00 2001
From: Derek Parker <derek.parker@coreos.com>
Date: Tue, 6 Oct 2015 10:45:36 -0700
Subject: [PATCH] proc: Refactor ptrace calls on Darwin

---
 proc/proc.go          |  2 +-
 proc/ptrace_darwin.go | 29 +++++++++--------------------
 2 files changed, 10 insertions(+), 21 deletions(-)

diff --git a/proc/proc.go b/proc/proc.go
index b32b4d3a..260898de 100644
--- a/proc/proc.go
+++ b/proc/proc.go
@@ -673,7 +673,7 @@ func (dbp *Process) run(fn func() error) error {
 
 func (dbp *Process) handlePtraceFuncs() {
 	// We must ensure here that we are running on the same thread during
-	// the execution of dbg. This is due to the fact that ptrace(2) expects
+	// while invoking the ptrace(2) syscall. This is due to the fact that ptrace(2) expects
 	// all commands after PTRACE_ATTACH to come from the same thread.
 	runtime.LockOSThread()
 
diff --git a/proc/ptrace_darwin.go b/proc/ptrace_darwin.go
index 3c31451c..a6c3147d 100644
--- a/proc/ptrace_darwin.go
+++ b/proc/ptrace_darwin.go
@@ -1,31 +1,20 @@
 package proc
 
-import (
-	"syscall"
-
-	sys "golang.org/x/sys/unix"
-)
+import sys "golang.org/x/sys/unix"
 
 func PtraceDetach(tid, sig int) error {
-	_, _, err := sys.Syscall6(sys.SYS_PTRACE, sys.PT_DETACH, uintptr(tid), 1, uintptr(sig), 0, 0)
-	if err != syscall.Errno(0) {
-		return err
-	}
-	return nil
+	return ptrace(sys.PT_DETACH, tid, 1, uintptr(sig))
 }
 
 func PtraceCont(tid, sig int) error {
-	_, _, err := sys.Syscall6(sys.SYS_PTRACE, sys.PTRACE_CONT, uintptr(tid), 1, uintptr(sig), 0, 0)
-	if err != syscall.Errno(0) {
-		return err
-	}
-	return nil
+	return ptrace(sys.PTRACE_CONT, tid, 1, 0)
 }
 
 func PtraceSingleStep(tid int) error {
-	_, _, err := sys.Syscall6(sys.SYS_PTRACE, sys.PT_STEP, uintptr(tid), 1, 0, 0, 0)
-	if err != syscall.Errno(0) {
-		return err
-	}
-	return nil
+	return ptrace(sys.PT_STEP, tid, 1, 0)
+}
+
+func ptrace(request, pid int, addr uintptr, data uintptr) (err error) {
+	_, _, err = sys.Syscall6(sys.SYS_PTRACE, uintptr(request), uintptr(pid), uintptr(addr), uintptr(data), 0, 0)
+	return
 }