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>
This commit is contained in:
zeripath 2022-10-07 22:02:24 +01:00 committed by GitHub
parent 56aabf3e8d
commit 7d2545d183
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 225 additions and 1 deletions

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@ -33,6 +33,21 @@ func GetAsset(name string) ([]byte, error) {
return os.ReadFile(filepath.Join(setting.StaticRootPath, name)) return os.ReadFile(filepath.Join(setting.StaticRootPath, name))
} }
// GetAssetFilename returns the filename of the provided asset
func GetAssetFilename(name string) (string, error) {
filename := filepath.Join(setting.CustomPath, name)
_, err := os.Stat(filename)
if err != nil && !os.IsNotExist(err) {
return filename, err
} else if err == nil {
return filename, nil
}
filename = filepath.Join(setting.StaticRootPath, name)
_, err = os.Stat(filename)
return filename, err
}
// walkTemplateFiles calls a callback for each template asset // walkTemplateFiles calls a callback for each template asset
func walkTemplateFiles(callback func(path, name string, d fs.DirEntry, err error) error) error { func walkTemplateFiles(callback func(path, name string, d fs.DirEntry, err error) error) error {
if err := walkAssetDir(filepath.Join(setting.CustomPath, "templates"), true, callback); err != nil && !os.IsNotExist(err) { if err := walkAssetDir(filepath.Join(setting.CustomPath, "templates"), true, callback); err != nil && !os.IsNotExist(err) {

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@ -5,7 +5,12 @@
package templates package templates
import ( import (
"bytes"
"context" "context"
"fmt"
"regexp"
"strconv"
"strings"
"code.gitea.io/gitea/modules/log" "code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting" "code.gitea.io/gitea/modules/setting"
@ -14,7 +19,14 @@ import (
"github.com/unrolled/render" "github.com/unrolled/render"
) )
var rendererKey interface{} = "templatesHtmlRendereer" 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 // 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) { func HTMLRenderer(ctx context.Context) (context.Context, *render.Render) {
@ -32,6 +44,25 @@ func HTMLRenderer(ctx context.Context) (context.Context, *render.Render) {
} }
log.Log(1, log.DEBUG, "Creating "+rendererType+" HTML Renderer") 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{ renderer := render.New(render.Options{
Extensions: []string{".tmpl"}, Extensions: []string{".tmpl"},
Directory: "templates", Directory: "templates",
@ -42,6 +73,7 @@ func HTMLRenderer(ctx context.Context) (context.Context, *render.Render) {
IsDevelopment: false, IsDevelopment: false,
DisableHTTPErrorRendering: true, DisableHTTPErrorRendering: true,
}) })
compilingTemplates = false
if !setting.IsProd { if !setting.IsProd {
watcher.CreateWatcher(ctx, "HTML Templates", &watcher.CreateWatcherOpts{ watcher.CreateWatcher(ctx, "HTML Templates", &watcher.CreateWatcherOpts{
PathsCallback: walkTemplateFiles, PathsCallback: walkTemplateFiles,
@ -50,3 +82,168 @@ func HTMLRenderer(ctx context.Context) (context.Context, *render.Render) {
} }
return context.WithValue(ctx, rendererKey, renderer), renderer 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()
}

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@ -31,6 +31,18 @@ func GlobalModTime(filename string) time.Time {
return timeutil.GetExecutableModTime() return timeutil.GetExecutableModTime()
} }
// GetAssetFilename returns the filename of the provided asset
func GetAssetFilename(name string) (string, error) {
filename := filepath.Join(setting.CustomPath, name)
_, err := os.Stat(filename)
if err != nil && !os.IsNotExist(err) {
return name, err
} else if err == nil {
return filename, nil
}
return "(builtin) " + name, nil
}
// GetAsset get a special asset, only for chi // GetAsset get a special asset, only for chi
func GetAsset(name string) ([]byte, error) { func GetAsset(name string) ([]byte, error) {
bs, err := os.ReadFile(filepath.Join(setting.CustomPath, name)) bs, err := os.ReadFile(filepath.Join(setting.CustomPath, name))