gitea/modules/context/panic.go
zeripath ca00ca8ee4 Provide better panic handling (#5902)
This PR gitea'ises the macaron.Recovery() handler meaning that in
the event of panic we get proper gitea 500 pages and the stacktrace
is logged with the gitea logger.

Signed-off-by: Andrew Thornton <art27@cantab.net>
2019-01-30 17:00:00 -05:00

113 lines
3.4 KiB
Go

// Copyright 2013 Martini Authors
// Copyright 2014 The Macaron Authors
// Copyright 2019 The Gitea 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 context
import (
"bytes"
"fmt"
"io/ioutil"
"runtime"
macaron "gopkg.in/macaron.v1"
)
// Recovery returns a middleware that recovers from any panics and writes a 500 and a log if so.
// Although similar to macaron.Recovery() the main difference is that this error will be created
// with the gitea 500 page.
func Recovery() macaron.Handler {
return func(ctx *Context) {
defer func() {
if err := recover(); err != nil {
combinedErr := fmt.Errorf("%s\n%s", err, string(stack(3)))
ctx.ServerError("PANIC:", combinedErr)
}
}()
ctx.Next()
}
}
var (
unknown = []byte("???")
)
// Although we could just use debug.Stack(), this routine will return the source code
// skip the provided number of frames - i.e. allowing us to ignore this function call
// and the preceding function call.
// If the problem is a lack of memory of course all this is not going to work...
func stack(skip int) []byte {
buf := new(bytes.Buffer)
// Store the last file we opened as its probable that the preceding stack frame
// will be in the same file
var lines [][]byte
var lastFilename string
for i := skip; ; i++ { // Skip over frames
programCounter, filename, lineNumber, ok := runtime.Caller(i)
// If we can't retrieve the information break - basically we're into go internals at this point.
if !ok {
break
}
// Print equivalent of debug.Stack()
fmt.Fprintf(buf, "%s:%d (0x%x)\n", filename, lineNumber, programCounter)
// Now try to print the offending line
if filename != lastFilename {
data, err := ioutil.ReadFile(filename)
if err != nil {
// can't read this sourcefile
// likely we don't have the sourcecode available
continue
}
lines = bytes.Split(data, []byte{'\n'})
lastFilename = filename
}
fmt.Fprintf(buf, "\t%s: %s\n", functionName(programCounter), source(lines, lineNumber))
}
return buf.Bytes()
}
// functionName converts the provided programCounter into a function name
func functionName(programCounter uintptr) []byte {
function := runtime.FuncForPC(programCounter)
if function == nil {
return unknown
}
name := []byte(function.Name())
// Because we provide the filename we can drop the preceding package name.
if lastslash := bytes.LastIndex(name, []byte("/")); lastslash >= 0 {
name = name[lastslash+1:]
}
// And the current package name.
if period := bytes.Index(name, []byte(".")); period >= 0 {
name = name[period+1:]
}
// And we should just replace the interpunct with a dot
name = bytes.Replace(name, []byte("ยท"), []byte("."), -1)
return name
}
// source returns a space-trimmed slice of the n'th line.
func source(lines [][]byte, n int) []byte {
n-- // in stack trace, lines are 1-indexed but our array is 0-indexed
if n < 0 || n >= len(lines) {
return unknown
}
return bytes.TrimSpace(lines[n])
}