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recovery.go
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recovery.go
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package jin
import (
"bytes"
"fmt"
"net/http"
"os"
"runtime"
)
// Recovery returns a middleware handler that recovers from any panics and
// writes a 500 status code to the response if there was one. While in
// development mode (EnvTypeDev), Recovery will also output the panic as HTML.
func Recovery() HandlerFunc {
const html = `<html>
<head><title>PANIC: %[1]s</title>
<meta charset="utf-8" />
<style type="text/css">
html, body {
font-family: "Roboto", sans-serif;
color: #333333;
background-color: #ea5343;
margin: 0px;
}
h1 {
color: #d04526;
background-color: #ffffff;
padding: 20px;
border-bottom: 1px dashed #2b3848;
}
pre {
margin: 20px;
padding: 20px;
border: 2px solid #2b3848;
background-color: #ffffff;
white-space: pre-wrap; /* css-3 */
white-space: -moz-pre-wrap; /* Mozilla, since 1999 */
white-space: -pre-wrap; /* Opera 4-6 */
white-space: -o-pre-wrap; /* Opera 7 */
word-wrap: break-word; /* Internet Explorer 5.5+ */
}
</style>
</head><body>
<h1>PANIC</h1>
<pre style="font-weight: bold;">%[1]s</pre>
<pre>%[2]s</pre>
</body>
</html>`
var (
dunno = []byte("???")
centerDot = []byte("·")
dot = []byte(".")
slash = []byte("/")
)
// source returns a space-trimmed slice of the n'th line.
source := func(lines [][]byte, n int) []byte {
n-- // In a 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.
function := func(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.ReplaceAll(name, centerDot, dot)
return name
}
// stack returns a nicely formated stack frame, skipping skip frames
stack := func(skip int) []byte {
buf := new(bytes.Buffer)
// 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 := os.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()
}
return func(c *Context) {
defer func() {
if err := recover(); err != nil {
stack := stack(3)
// Lookup the current ResponseWriter
w := c.Writer
// Respond with panic message only in development mode
var body []byte
if Mode() == DebugMode {
w.Header().Set("Content-Type", "text/html")
body = []byte(fmt.Sprintf(html, err, stack))
} else {
w.Header().Set("Content-Type", "text/plain")
body = []byte(http.StatusText(http.StatusInternalServerError))
}
w.WriteHeader(http.StatusInternalServerError)
_, _ = w.Write(body)
}
}()
c.Next()
}
}