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