1 files changed, 90 insertions, 0 deletions
diff --git a/common/herrors/errors.go b/common/herrors/errors.go
new file mode 100644
index 000000000..fded30b1a
--- /dev/null
+++ b/common/herrors/errors.go
@@ -0,0 +1,90 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package herrors contains common Hugo errors and error related utilities.
+package herrors
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"runtime"
+	"runtime/debug"
+	"strconv"
+
+	_errors "github.com/pkg/errors"
+)
+
+// As defined in https://godoc.org/github.com/pkg/errors
+type causer interface {
+	Cause() error
+}
+
+type stackTracer interface {
+	StackTrace() _errors.StackTrace
+}
+
+// PrintStackTraceFromErr prints the error's stack trace to stdoud.
+func PrintStackTraceFromErr(err error) {
+	FprintStackTraceFromErr(os.Stdout, err)
+}
+
+// FprintStackTraceFromErr prints the error's stack trace to w.
+func FprintStackTraceFromErr(w io.Writer, err error) {
+	if err, ok := err.(stackTracer); ok {
+		for _, f := range err.StackTrace() {
+			fmt.Fprintf(w, "%+s:%d\n", f, f)
+		}
+	}
+}
+
+// PrintStackTrace prints the current stacktrace to w.
+func PrintStackTrace(w io.Writer) {
+	buf := make([]byte, 1<<16)
+	runtime.Stack(buf, true)
+	fmt.Fprintf(w, "%s", buf)
+}
+
+// ErrorSender is a, typically, non-blocking error handler.
+type ErrorSender interface {
+	SendError(err error)
+}
+
+// Recover is a helper function that can be used to capture panics.
+// Put this at the top of a method/function that crashes in a template:
+//     defer herrors.Recover()
+func Recover(args ...interface{}) {
+	if r := recover(); r != nil {
+		fmt.Println("ERR:", r)
+		args = append(args, "stacktrace from panic: \n"+string(debug.Stack()), "\n")
+		fmt.Println(args...)
+	}
+}
+
+// Get the current goroutine id. Used only for debugging.
+func GetGID() uint64 {
+	b := make([]byte, 64)
+	b = b[:runtime.Stack(b, false)]
+	b = bytes.TrimPrefix(b, []byte("goroutine "))
+	b = b[:bytes.IndexByte(b, ' ')]
+	n, _ := strconv.ParseUint(string(b), 10, 64)
+	return n
+}
+
+// ErrFeatureNotAvailable denotes that a feature is unavailable.
+//
+// We will, at least to begin with, make some Hugo features (SCSS with libsass) optional,
+// and this error is used to signal those situations.
+var ErrFeatureNotAvailable = errors.New("this feature is not available in your current Hugo version, see https://goo.gl/YMrWcn for more information")