(rs#470) Localize github.com/pkg/errors

Signed-off-by: Bhargav Ravuri <vaguecoder0to.n@gmail.com>

internal/errors/errors.go

@@ -0,0 +1,27 @@
+package errors
+
+// New returns an error with the supplied message.
+// New also records the stack trace at the point it was called.
+func New(message string) error {
+	return &fundamental{
+		msg:   message,
+		Stack: callers(),
+	}
+}
+
+// Wrap returns an error annotating err with a stack trace
+// at the point Wrap is called, and the supplied message.
+// If err is nil, Wrap returns nil.
+func Wrap(err error, message string) error {
+	if err == nil {
+		return nil
+	}
+	err = &withMessage{
+		cause: err,
+		msg:   message,
+	}
+	return &withStack{
+		err,
+		callers(),
+	}
+}

internal/errors/errors_test.go

@@ -0,0 +1,57 @@
+package errors_test
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"testing"
+
+	internalErrors "github.com/rs/zerolog/internal/errors"
+)
+
+func TestNew(t *testing.T) {
+	tests := []struct {
+		err  string
+		want error
+	}{
+		{"", fmt.Errorf("")},
+		{"foo", fmt.Errorf("foo")},
+		{"foo", internalErrors.New("foo")},
+		{"string with format specifiers: %v", errors.New("string with format specifiers: %v")},
+	}
+
+	for _, tt := range tests {
+		got := internalErrors.New(tt.err)
+		if got.Error() != tt.want.Error() {
+			t.Errorf("New.Error(): got: %q, want %q", got, tt.want)
+		}
+	}
+}
+
+func TestWrapNil(t *testing.T) {
+	got := internalErrors.Wrap(nil, "no error")
+	if got != nil {
+		t.Errorf("Wrap(nil, \"no error\"): got %#v, expected nil", got)
+	}
+}
+
+func TestWrap(t *testing.T) {
+	tests := []struct {
+		err     error
+		message string
+		want    string
+	}{
+		{io.EOF, "read error", "read error: EOF"},
+		{internalErrors.Wrap(io.EOF, "read error"), "client error", "client error: read error: EOF"},
+	}
+
+	for _, tt := range tests {
+		var got string
+		if tt.err != nil {
+			got = internalErrors.Wrap(tt.err, tt.message).Error()
+		}
+		if got != tt.want {
+			t.Errorf("Wrap(%v, %q): got: %v, want %v", tt.err, tt.message, got, tt.want)
+		}
+	}
+}

internal/errors/stack.go

@@ -0,0 +1,146 @@
+package errors
+
+import (
+	"fmt"
+	"io"
+	"path"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+// Stack represents a stack of program counters.
+type Stack []uintptr
+
+// StackTrace prints the stack trace of program.
+func (s *Stack) StackTrace() StackTrace {
+	f := make([]Frame, len(*s))
+	for i := 0; i < len(f); i++ {
+		f[i] = Frame((*s)[i])
+	}
+	return f
+}
+
+// fundamental is an error that has a message and a stack, but no caller.
+type fundamental struct {
+	msg string
+	*Stack
+}
+
+// Error prints the error message string
+func (f *fundamental) Error() string {
+	return f.msg
+}
+
+// withStack is error with caller stack
+type withStack struct {
+	error
+	*Stack
+}
+
+// withMessage is error with added message
+type withMessage struct {
+	cause error
+	msg   string
+}
+
+// Error prints the error message string with cause
+func (w *withMessage) Error() string {
+	return w.msg + ": " + w.cause.Error()
+}
+
+// Frame represents a program counter inside a stack frame.
+// For historical reasons if Frame is interpreted as a uintptr
+// its value represents the program counter + 1.
+type Frame uintptr
+
+// pc returns the program counter for this frame;
+// multiple frames may have the same PC value.
+func (f Frame) pc() uintptr {
+	return uintptr(f) - 1
+}
+
+// file returns the full path to the file that contains the
+// function for this Frame's pc.
+func (f Frame) file() string {
+	fn := runtime.FuncForPC(f.pc())
+	if fn == nil {
+		return "unknown"
+	}
+	file, _ := fn.FileLine(f.pc())
+	return file
+}
+
+// line returns the line number of source code of the
+// function for this Frame's pc.
+func (f Frame) line() int {
+	fn := runtime.FuncForPC(f.pc())
+	if fn == nil {
+		return 0
+	}
+	_, line := fn.FileLine(f.pc())
+	return line
+}
+
+// name returns the name of this function, if known.
+func (f Frame) name() string {
+	fn := runtime.FuncForPC(f.pc())
+	if fn == nil {
+		return "unknown"
+	}
+	return fn.Name()
+}
+
+// Format formats the frame according to the fmt.Formatter interface.
+//
+//    %s    source file
+//    %d    source line
+//    %n    function name
+//    %v    equivalent to %s:%d
+//
+// Format accepts flags that alter the printing of some verbs, as follows:
+//
+//    %+s   function name and path of source file relative to the compile time
+//          GOPATH separated by \n\t (<funcname>\n\t<path>)
+//    %+v   equivalent to %+s:%d
+func (f Frame) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 's':
+		switch {
+		case s.Flag('+'):
+			_, _ = io.WriteString(s, f.name())
+			_, _ = io.WriteString(s, "\n\t")
+			_, _ = io.WriteString(s, f.file())
+		default:
+			_, _ = io.WriteString(s, path.Base(f.file()))
+		}
+	case 'd':
+		_, _ = io.WriteString(s, strconv.Itoa(f.line()))
+	case 'n':
+		_, _ = io.WriteString(s, funcName(f.name()))
+	case 'v':
+		f.Format(s, 's')
+		_, _ = io.WriteString(s, ":")
+		f.Format(s, 'd')
+	}
+}
+
+// StackTrace is stack of Frames from innermost (newest) to outermost (oldest).
+type StackTrace []Frame
+
+// callers gives caller function's stack
+func callers() *Stack {
+	const depth = 32
+	var pcs [depth]uintptr
+	n := runtime.Callers(3, pcs[:])
+	var st Stack = pcs[0:n]
+	return &st
+}
+
+// funcName removes the path prefix component of a function's name reported by func.Name().
+func funcName(name string) string {
+	i := strings.LastIndex(name, "/")
+	name = name[i+1:]
+	i = strings.Index(name, ".")
+	return name[i+1:]
+}