forgejo/modules/templates/htmlrenderer.go
zeripath 7d2545d183
Add nicer error handling on template compile errors (#21350)
There are repeated issues reported whereby users are unable to interpret
the template errors. This PR adds some (somewhat complex) error handling
to the panic recovery for template renderering but hopefully makes the
interpretation of the error easier.

Reference #21344

Signed-off-by: Andrew Thornton <art27@cantab.net>
2022-10-07 22:02:24 +01:00

249 lines
7.1 KiB
Go

// Copyright 2022 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package templates
import (
"bytes"
"context"
"fmt"
"regexp"
"strconv"
"strings"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/watcher"
"github.com/unrolled/render"
)
var (
rendererKey interface{} = "templatesHtmlRenderer"
templateError = regexp.MustCompile(`^template: (.*):([0-9]+): (.*)`)
notDefinedError = regexp.MustCompile(`^template: (.*):([0-9]+): function "(.*)" not defined`)
unexpectedError = regexp.MustCompile(`^template: (.*):([0-9]+): unexpected "(.*)" in operand`)
expectedEndError = regexp.MustCompile(`^template: (.*):([0-9]+): expected end; found (.*)`)
)
// HTMLRenderer returns the current html renderer for the context or creates and stores one within the context for future use
func HTMLRenderer(ctx context.Context) (context.Context, *render.Render) {
rendererInterface := ctx.Value(rendererKey)
if rendererInterface != nil {
renderer, ok := rendererInterface.(*render.Render)
if ok {
return ctx, renderer
}
}
rendererType := "static"
if !setting.IsProd {
rendererType = "auto-reloading"
}
log.Log(1, log.DEBUG, "Creating "+rendererType+" HTML Renderer")
compilingTemplates := true
defer func() {
if !compilingTemplates {
return
}
panicked := recover()
if panicked == nil {
return
}
// OK try to handle the panic...
err, ok := panicked.(error)
if ok {
handlePanicError(err)
}
log.Fatal("PANIC: Unable to compile templates!\n%v\n\nStacktrace:\n%s", panicked, log.Stack(2))
}()
renderer := render.New(render.Options{
Extensions: []string{".tmpl"},
Directory: "templates",
Funcs: NewFuncMap(),
Asset: GetAsset,
AssetNames: GetTemplateAssetNames,
UseMutexLock: !setting.IsProd,
IsDevelopment: false,
DisableHTTPErrorRendering: true,
})
compilingTemplates = false
if !setting.IsProd {
watcher.CreateWatcher(ctx, "HTML Templates", &watcher.CreateWatcherOpts{
PathsCallback: walkTemplateFiles,
BetweenCallback: renderer.CompileTemplates,
})
}
return context.WithValue(ctx, rendererKey, renderer), renderer
}
func handlePanicError(err error) {
wrapFatal(handleNotDefinedPanicError(err))
wrapFatal(handleUnexpected(err))
wrapFatal(handleExpectedEnd(err))
wrapFatal(handleGenericTemplateError(err))
}
func wrapFatal(format string, args []interface{}) {
if format == "" {
return
}
log.FatalWithSkip(1, format, args...)
}
func handleGenericTemplateError(err error) (string, []interface{}) {
groups := templateError.FindStringSubmatch(err.Error())
if len(groups) != 4 {
return "", nil
}
templateName, lineNumberStr, message := groups[1], groups[2], groups[3]
filename, assetErr := GetAssetFilename("templates/" + templateName + ".tmpl")
if assetErr != nil {
return "", nil
}
lineNumber, _ := strconv.Atoi(lineNumberStr)
line := getLineFromAsset(templateName, lineNumber, "")
return "PANIC: Unable to compile templates!\n%s in template file %s at line %d:\n\n%s\nStacktrace:\n\n%s", []interface{}{message, filename, lineNumber, log.NewColoredValue(line, log.Reset), log.Stack(2)}
}
func handleNotDefinedPanicError(err error) (string, []interface{}) {
groups := notDefinedError.FindStringSubmatch(err.Error())
if len(groups) != 4 {
return "", nil
}
templateName, lineNumberStr, functionName := groups[1], groups[2], groups[3]
functionName, _ = strconv.Unquote(`"` + functionName + `"`)
filename, assetErr := GetAssetFilename("templates/" + templateName + ".tmpl")
if assetErr != nil {
return "", nil
}
lineNumber, _ := strconv.Atoi(lineNumberStr)
line := getLineFromAsset(templateName, lineNumber, functionName)
return "PANIC: Unable to compile templates!\nUndefined function %q in template file %s at line %d:\n\n%s", []interface{}{functionName, filename, lineNumber, log.NewColoredValue(line, log.Reset)}
}
func handleUnexpected(err error) (string, []interface{}) {
groups := unexpectedError.FindStringSubmatch(err.Error())
if len(groups) != 4 {
return "", nil
}
templateName, lineNumberStr, unexpected := groups[1], groups[2], groups[3]
unexpected, _ = strconv.Unquote(`"` + unexpected + `"`)
filename, assetErr := GetAssetFilename("templates/" + templateName + ".tmpl")
if assetErr != nil {
return "", nil
}
lineNumber, _ := strconv.Atoi(lineNumberStr)
line := getLineFromAsset(templateName, lineNumber, unexpected)
return "PANIC: Unable to compile templates!\nUnexpected %q in template file %s at line %d:\n\n%s", []interface{}{unexpected, filename, lineNumber, log.NewColoredValue(line, log.Reset)}
}
func handleExpectedEnd(err error) (string, []interface{}) {
groups := expectedEndError.FindStringSubmatch(err.Error())
if len(groups) != 4 {
return "", nil
}
templateName, lineNumberStr, unexpected := groups[1], groups[2], groups[3]
filename, assetErr := GetAssetFilename("templates/" + templateName + ".tmpl")
if assetErr != nil {
return "", nil
}
lineNumber, _ := strconv.Atoi(lineNumberStr)
line := getLineFromAsset(templateName, lineNumber, unexpected)
return "PANIC: Unable to compile templates!\nMissing end with unexpected %q in template file %s at line %d:\n\n%s", []interface{}{unexpected, filename, lineNumber, log.NewColoredValue(line, log.Reset)}
}
const dashSeparator = "----------------------------------------------------------------------\n"
func getLineFromAsset(templateName string, targetLineNum int, target string) string {
bs, err := GetAsset("templates/" + templateName + ".tmpl")
if err != nil {
return fmt.Sprintf("(unable to read template file: %v)", err)
}
sb := &strings.Builder{}
// Write the header
sb.WriteString(dashSeparator)
var lineBs []byte
// Iterate through the lines from the asset file to find the target line
for start, currentLineNum := 0, 1; currentLineNum <= targetLineNum && start < len(bs); currentLineNum++ {
// Find the next new line
end := bytes.IndexByte(bs[start:], '\n')
// adjust the end to be a direct pointer in to []byte
if end < 0 {
end = len(bs)
} else {
end += start
}
// set lineBs to the current line []byte
lineBs = bs[start:end]
// move start to after the current new line position
start = end + 1
// Write 2 preceding lines + the target line
if targetLineNum-currentLineNum < 3 {
_, _ = sb.Write(lineBs)
_ = sb.WriteByte('\n')
}
}
// If there is a provided target to look for in the line add a pointer to it
// e.g. ^^^^^^^
if target != "" {
idx := bytes.Index(lineBs, []byte(target))
if idx >= 0 {
// take the current line and replace preceding text with whitespace (except for tab)
for i := range lineBs[:idx] {
if lineBs[i] != '\t' {
lineBs[i] = ' '
}
}
// write the preceding "space"
_, _ = sb.Write(lineBs[:idx])
// Now write the ^^ pointer
_, _ = sb.WriteString(strings.Repeat("^", len(target)))
_ = sb.WriteByte('\n')
}
}
// Finally write the footer
sb.WriteString(dashSeparator)
return sb.String()
}