From f55fdad268aeaa476ebc95ba170d9c7e267b1bdb Mon Sep 17 00:00:00 2001
From: Martin Kobetic <mkobetic@gmail.com>
Date: Tue, 2 Apr 2019 09:52:40 -0400
Subject: [PATCH] Use CallersFames to build StackFrames (required for go 1.12)

---
 errors/error.go           | 12 ++++++---
 errors/stackframe.go      | 21 +++++++--------
 errors/stackframe_test.go | 55 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 15 deletions(-)
 create mode 100644 errors/stackframe_test.go

diff --git a/errors/error.go b/errors/error.go
index be7b7c89..82a36080 100644
--- a/errors/error.go
+++ b/errors/error.go
@@ -105,10 +105,14 @@ func (err *Error) Stack() []byte {
 // stack.
 func (err *Error) StackFrames() []StackFrame {
 	if err.frames == nil {
-		err.frames = make([]StackFrame, len(err.stack))
-
-		for i, pc := range err.stack {
-			err.frames[i] = NewStackFrame(pc)
+		err.frames = make([]StackFrame, 0, len(err.stack))
+		callers := runtime.CallersFrames(err.stack)
+		for {
+			frame, more := callers.Next()
+			err.frames = append(err.frames, NewStackFrame(frame))
+			if !more {
+				break
+			}
 		}
 	}
 
diff --git a/errors/stackframe.go b/errors/stackframe.go
index 4edadbc5..1221e26e 100644
--- a/errors/stackframe.go
+++ b/errors/stackframe.go
@@ -16,30 +16,29 @@ type StackFrame struct {
 	Name           string
 	Package        string
 	ProgramCounter uintptr
+	rFunc          *runtime.Func
 }
 
-// NewStackFrame popoulates a stack frame object from the program counter.
-func NewStackFrame(pc uintptr) (frame StackFrame) {
+// NewStackFrame popoulates a stack frame object from runtime frame.
+func NewStackFrame(f runtime.Frame) (frame StackFrame) {
 
-	frame = StackFrame{ProgramCounter: pc}
+	frame = StackFrame{
+		ProgramCounter: f.PC,
+		rFunc:          f.Func,
+		File:           f.File,
+		LineNumber:     f.Line,
+	}
 	if frame.Func() == nil {
 		return
 	}
 	frame.Package, frame.Name = packageAndName(frame.Func())
-
-	// pc -1 because the program counters we use are usually return addresses,
-	// and we want to show the line that corresponds to the function call
-	frame.File, frame.LineNumber = frame.Func().FileLine(pc - 1)
 	return
 
 }
 
 // Func returns the function that this stackframe corresponds to
 func (frame *StackFrame) Func() *runtime.Func {
-	if frame.ProgramCounter == 0 {
-		return nil
-	}
-	return runtime.FuncForPC(frame.ProgramCounter)
+	return frame.rFunc
 }
 
 // String returns the stackframe formatted in the same way as go does
diff --git a/errors/stackframe_test.go b/errors/stackframe_test.go
new file mode 100644
index 00000000..893fbdf3
--- /dev/null
+++ b/errors/stackframe_test.go
@@ -0,0 +1,55 @@
+package errors
+
+import (
+	"runtime"
+	"testing"
+
+	"github.com/pkg/errors"
+)
+
+func Test_StackFrames(t *testing.T) {
+	err := boom(5)
+	stack := getStack(err)
+	frames := getFrames(stack)
+	// for _, frame := range frames {
+	// 	fmt.Printf("%s:%d\n\t%s\n", frame.File, frame.Line, frame.Function)
+	// }
+
+	err2 := &Error{Err: err, stack: stack}
+	// fmt.Println(string(err2.Stack()))
+	frames2 := err2.StackFrames()
+	if name, name2 := frames[0].Function, frames2[0].Func().Name(); name != name2 {
+		t.Errorf("top frames don't match\n%s\n%s", name, name2)
+	}
+}
+
+func boom(depth int) error {
+	if depth > 0 {
+		return boom(depth - 1)
+	}
+	return errors.New("boom")
+}
+
+func getStack(err error) []uintptr {
+	type withStackTrace interface {
+		StackTrace() errors.StackTrace
+	}
+	frames := err.(withStackTrace).StackTrace()
+	stack := make([]uintptr, len(frames))
+	for i, f := range frames {
+		stack[i] = uintptr(f)
+	}
+	return stack
+}
+
+func getFrames(stack []uintptr) (frames []runtime.Frame) {
+	callers := runtime.CallersFrames(stack)
+	for {
+		frame, more := callers.Next()
+		frames = append(frames, frame)
+		if !more {
+			break
+		}
+	}
+	return frames
+}