Rewrite fuzzers to native Go harnesses (go-gitea#22313)

Author: AdamKorcz

tools/fuzz.go

@@ -0,0 +1,38 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"testing"
+
+	"code.gitea.io/gitea/modules/markup"
+	"code.gitea.io/gitea/modules/markup/markdown"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+var renderContext = markup.RenderContext{
+	Ctx:       context.Background(),
+	URLPrefix: "https://example.com/go-gitea/gitea",
+	Metas: map[string]string{
+		"user": "go-gitea",
+		"repo": "gitea",
+	},
+}
+
+func FuzzMarkdownRenderRaw(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		setting.AppURL = "http://localhost:3000/"
+		markdown.RenderRaw(&renderContext, bytes.NewReader(data), io.Discard)
+	})
+}
+
+func FuzzMarkupPostProcess(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		setting.AppURL = "http://localhost:3000/"
+		markup.PostProcess(&renderContext, bytes.NewReader(data), io.Discard)
+	})
+}