package server import ( "bytes" "fmt" "io/ioutil" "net/http" "net/http/httputil" "runtime" "github.com/gin-gonic/gin" ) var ( dunno = []byte("???") centerDot = []byte("·") dot = []byte(".") slash = []byte("/") ) // Recovery returns a middleware that recovers from any panics and writes a 500 if there was one. func Recovery() gin.HandlerFunc { return func(c *gin.Context) { defer func() { if err := recover(); err != nil { stack := stack(3) req, _ := httputil.DumpRequest(c.Request, false) log.Debugf("http: %s (%s)\n%s", err, string(req), stack) c.AbortWithStatus(http.StatusInternalServerError) } }() c.Next() } } // stack returns a nicely formatted stack frame, skipping skip frames. func stack(skip int) []byte { buf := new(bytes.Buffer) // the returned data // As we loop, we open files and read them. These variables record the currently // loaded file. var lines [][]byte var lastFile string for i := skip; ; i++ { // Skip the expected number of frames pc, file, line, ok := runtime.Caller(i) if !ok { break } // Print this much at least. If we can't find the source, it won't show. fmt.Fprintf(buf, "%s:%d (0x%x)\n", file, line, pc) if file != lastFile { data, err := ioutil.ReadFile(file) if err != nil { continue } lines = bytes.Split(data, []byte{'\n'}) lastFile = file } fmt.Fprintf(buf, "\t%s: %s\n", function(pc), source(lines, line)) } return buf.Bytes() } // 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 dunno } return bytes.TrimSpace(lines[n]) } // function returns, if possible, the name of the function containing the PC. func function(pc uintptr) []byte { fn := runtime.FuncForPC(pc) if fn == nil { return dunno } name := []byte(fn.Name()) // 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 // Also the package path might contains dot (e.g. code.google.com/...), // so first eliminate the path prefix if lastslash := bytes.LastIndex(name, slash); lastslash >= 0 { name = name[lastslash+1:] } if period := bytes.Index(name, dot); period >= 0 { name = name[period+1:] } name = bytes.Replace(name, centerDot, dot, -1) return name }