Refactor template render (#36438)

routers/common/errpage.go

@@ -4,8 +4,11 @@
 package common
 
 import (
+	"bytes"
 	"fmt"
+	"io"
 	"net/http"
+	"strings"
 
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/httpcache"
@@ -19,6 +22,36 @@ import (
 
 const tplStatus500 templates.TplName = "status/500"
 
+func renderServerErrorPage(w http.ResponseWriter, req *http.Request, respCode int, tmpl templates.TplName, ctxData map[string]any, plainMsg string) {
+	acceptsHTML := false
+	for _, part := range req.Header["Accept"] {
+		if strings.Contains(part, "text/html") {
+			acceptsHTML = true
+			break
+		}
+	}
+
+	httpcache.SetCacheControlInHeader(w.Header(), &httpcache.CacheControlOptions{NoTransform: true})
+	w.Header().Set(`X-Frame-Options`, setting.CORSConfig.XFrameOptions)
+
+	tmplCtx := context.NewTemplateContext(req.Context(), req)
+	tmplCtx["Locale"] = middleware.Locale(w, req)
+
+	w.WriteHeader(respCode)
+
+	outBuf := &bytes.Buffer{}
+	if acceptsHTML {
+		err := templates.PageRenderer().HTML(outBuf, respCode, tmpl, ctxData, tmplCtx)
+		if err != nil {
+			_, _ = w.Write([]byte("Internal server error but failed to render error page template, please collect error logs and report to Gitea issue tracker"))
+			return
+		}
+	} else {
+		outBuf.WriteString(plainMsg)
+	}
+	_, _ = io.Copy(w, outBuf)
+}
+
 // RenderPanicErrorPage renders a 500 page, and it never panics
 func RenderPanicErrorPage(w http.ResponseWriter, req *http.Request, err any) {
 	combinedErr := fmt.Sprintf("%v\n%s", err, log.Stack(2))
@@ -32,24 +65,14 @@ func RenderPanicErrorPage(w http.ResponseWriter, req *http.Request, err any) {
 
 	routing.UpdatePanicError(req.Context(), err)
 
-	httpcache.SetCacheControlInHeader(w.Header(), &httpcache.CacheControlOptions{NoTransform: true})
-	w.Header().Set(`X-Frame-Options`, setting.CORSConfig.XFrameOptions)
-
-	tmplCtx := context.NewTemplateContext(req.Context(), req)
-	tmplCtx["Locale"] = middleware.Locale(w, req)
+	plainMsg := "Internal Server Error"
 	ctxData := middleware.GetContextData(req.Context())
-
 	// This recovery handler could be called without Gitea's web context, so we shouldn't touch that context too much.
 	// Otherwise, the 500-page may cause new panics, eg: cache.GetContextWithData, it makes the developer&users couldn't find the original panic.
 	user, _ := ctxData[middleware.ContextDataKeySignedUser].(*user_model.User)
 	if !setting.IsProd || (user != nil && user.IsAdmin) {
-		ctxData["ErrorMsg"] = "PANIC: " + combinedErr
-	}
-
-	err = templates.HTMLRenderer().HTML(w, http.StatusInternalServerError, tplStatus500, ctxData, tmplCtx)
-	if err != nil {
-		log.Error("Error occurs again when rendering error page: %v", err)
-		w.WriteHeader(http.StatusInternalServerError)
-		_, _ = w.Write([]byte("Internal server error, please collect error logs and report to Gitea issue tracker"))
+		plainMsg = "PANIC: " + combinedErr
+		ctxData["ErrorMsg"] = plainMsg
 	}
+	renderServerErrorPage(w, req, http.StatusInternalServerError, tplStatus500, ctxData, plainMsg)
 }