until stable: pin-dependency, update-vendor, update-bazel, lint-dep

vendor/github.com/go-errors/errors/stackframe.go

@@ -0,0 +1,102 @@
+package errors
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"runtime"
+	"strings"
+)
+
+// A StackFrame contains all necessary information about to generate a line
+// in a callstack.
+type StackFrame struct {
+	// The path to the file containing this ProgramCounter
+	File string
+	// The LineNumber in that file
+	LineNumber int
+	// The Name of the function that contains this ProgramCounter
+	Name string
+	// The Package that contains this function
+	Package string
+	// The underlying ProgramCounter
+	ProgramCounter uintptr
+}
+
+// NewStackFrame popoulates a stack frame object from the program counter.
+func NewStackFrame(pc uintptr) (frame StackFrame) {
+
+	frame = StackFrame{ProgramCounter: pc}
+	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 contained this frame.
+func (frame *StackFrame) Func() *runtime.Func {
+	if frame.ProgramCounter == 0 {
+		return nil
+	}
+	return runtime.FuncForPC(frame.ProgramCounter)
+}
+
+// String returns the stackframe formatted in the same way as go does
+// in runtime/debug.Stack()
+func (frame *StackFrame) String() string {
+	str := fmt.Sprintf("%s:%d (0x%x)\n", frame.File, frame.LineNumber, frame.ProgramCounter)
+
+	source, err := frame.SourceLine()
+	if err != nil {
+		return str
+	}
+
+	return str + fmt.Sprintf("\t%s: %s\n", frame.Name, source)
+}
+
+// SourceLine gets the line of code (from File and Line) of the original source if possible.
+func (frame *StackFrame) SourceLine() (string, error) {
+	data, err := ioutil.ReadFile(frame.File)
+
+	if err != nil {
+		return "", New(err)
+	}
+
+	lines := bytes.Split(data, []byte{'\n'})
+	if frame.LineNumber <= 0 || frame.LineNumber >= len(lines) {
+		return "???", nil
+	}
+	// -1 because line-numbers are 1 based, but our array is 0 based
+	return string(bytes.Trim(lines[frame.LineNumber-1], " \t")), nil
+}
+
+func packageAndName(fn *runtime.Func) (string, string) {
+	name := fn.Name()
+	pkg := ""
+
+	// The name includes the path name to the package, which is unnecessary
+	// since the file name is already included.  Plus, it has center dots.
+	// That is, we see
+	//  runtime/debug.*T·ptrmethod
+	// and want
+	//  *T.ptrmethod
+	// Since the package path might contains dots (e.g. code.google.com/...),
+	// we first remove the path prefix if there is one.
+	if lastslash := strings.LastIndex(name, "/"); lastslash >= 0 {
+		pkg += name[:lastslash] + "/"
+		name = name[lastslash+1:]
+	}
+	if period := strings.Index(name, "."); period >= 0 {
+		pkg += name[:period]
+		name = name[period+1:]
+	}
+
+	name = strings.Replace(name, "·", ".", -1)
+	return pkg, name
+}