Fix context usage (#33554)

Some old code use direct type-casting to get context, it causes
problems.

This PR fixes all legacy problems and use correct `ctx.Value` to get
low-level contexts.

Fix #33518

routers/install/install.go

@@ -64,7 +64,7 @@ func Contexter() func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
 			base := context.NewBaseContext(resp, req)
 			ctx := context.NewWebContext(base, rnd, session.GetSession(req))
-			ctx.SetContextValue(context.WebContextKey, ctx)
+			ctx.SetContextValue(context.WebContextKey, ctx) // FIXME: this should be removed because NewWebContext should already set it
 			ctx.Data.MergeFrom(middleware.CommonTemplateContextData())
 			ctx.Data.MergeFrom(reqctx.ContextData{
 				"Title":          ctx.Locale.Tr("install.install"),

routers/private/internal.go

@@ -88,7 +88,7 @@ func Routes() *web.Router {
 		// Fortunately, the LFS handlers are able to handle requests without a complete web context
 		common.AddOwnerRepoGitLFSRoutes(r, func(ctx *context.PrivateContext) {
 			webContext := &context.Context{Base: ctx.Base}
-			ctx.SetContextValue(context.WebContextKey, webContext)
+			ctx.SetContextValue(context.WebContextKey, webContext) // FIXME: this is not ideal but no other way at the moment
 		})
 	})
 

routers/web/web.go

@@ -1637,7 +1637,7 @@ func registerRoutes(m *web.Router) {
 	}
 
 	m.NotFound(func(w http.ResponseWriter, req *http.Request) {
-		ctx := context.GetWebContext(req)
+		ctx := context.GetWebContext(req.Context())
 		defer routing.RecordFuncInfo(ctx, routing.GetFuncInfo(ctx.NotFound, "WebNotFound"))()
 		ctx.NotFound("", nil)
 	})