Add nogo check annotations to GitHub.

When nogo checks are violated, they will automatically posted
as annotations on the specific GitHub commit. This allows us
to ensure analysis & style rules and have them called out.

PiperOrigin-RevId: 334447285

1 files changed, 192 insertions, 0 deletions

diff --git a/tools/github/reviver/reviver.go b/tools/github/reviver/reviver.go
new file mode 100644
index 000000000..2af7f0d59
--- /dev/null
+++ b/tools/github/reviver/reviver.go
@@ -0,0 +1,192 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package reviver scans the code looking for TODOs and pass them to registered
+// Buggers to ensure TODOs point to active issues.
+package reviver
+
+import (
+	"bufio"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sync"
+)
+
+// regexTodo matches a TODO or FIXME comment.
+var regexTodo = regexp.MustCompile(`(\/\/|#)\s*(TODO|FIXME)\(([a-zA-Z0-9.\/]+)\):\s*(.+)`)
+
+// Bugger interface is called for every TODO found in the code. If it can handle
+// the TODO, it must return true. If it returns false, the next Bugger is
+// called. If no Bugger handles the TODO, it's dropped on the floor.
+type Bugger interface {
+	Activate(todo *Todo) (bool, error)
+}
+
+// Location saves the location where the TODO was found.
+type Location struct {
+	Comment string
+	File    string
+	Line    uint
+}
+
+// Todo represents a unique TODO. There can be several TODOs pointing to the
+// same issue in the code. They are all grouped together.
+type Todo struct {
+	Issue     string
+	Locations []Location
+}
+
+// Reviver scans the given paths for TODOs and calls Buggers to handle them.
+type Reviver struct {
+	paths   []string
+	buggers []Bugger
+
+	mu    sync.Mutex
+	todos map[string]*Todo
+	errs  []error
+}
+
+// New create a new Reviver.
+func New(paths []string, buggers []Bugger) *Reviver {
+	return &Reviver{
+		paths:   paths,
+		buggers: buggers,
+		todos:   map[string]*Todo{},
+	}
+}
+
+// Run runs. It returns all errors found during processing, it doesn't stop
+// on errors.
+func (r *Reviver) Run() []error {
+	// Process each directory in parallel.
+	wg := sync.WaitGroup{}
+	for _, path := range r.paths {
+		wg.Add(1)
+		go func(path string) {
+			defer wg.Done()
+			r.processPath(path, &wg)
+		}(path)
+	}
+
+	wg.Wait()
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	fmt.Printf("Processing %d TODOs (%d errors)...\n", len(r.todos), len(r.errs))
+	dropped := 0
+	for _, todo := range r.todos {
+		ok, err := r.processTodo(todo)
+		if err != nil {
+			r.errs = append(r.errs, err)
+		}
+		if !ok {
+			dropped++
+		}
+	}
+	fmt.Printf("Processed %d TODOs, %d were skipped (%d errors)\n", len(r.todos)-dropped, dropped, len(r.errs))
+
+	return r.errs
+}
+
+func (r *Reviver) processPath(path string, wg *sync.WaitGroup) {
+	fmt.Printf("Processing dir %q\n", path)
+	fis, err := ioutil.ReadDir(path)
+	if err != nil {
+		r.addErr(fmt.Errorf("error processing dir %q: %v", path, err))
+		return
+	}
+
+	for _, fi := range fis {
+		childPath := filepath.Join(path, fi.Name())
+		switch {
+		case fi.Mode().IsDir():
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				r.processPath(childPath, wg)
+			}()
+
+		case fi.Mode().IsRegular():
+			file, err := os.Open(childPath)
+			if err != nil {
+				r.addErr(err)
+				continue
+			}
+
+			scanner := bufio.NewScanner(file)
+			lineno := uint(0)
+			for scanner.Scan() {
+				lineno++
+				line := scanner.Text()
+				if todo := r.processLine(line, childPath, lineno); todo != nil {
+					r.addTodo(todo)
+				}
+			}
+		}
+	}
+}
+
+func (r *Reviver) processLine(line, path string, lineno uint) *Todo {
+	matches := regexTodo.FindStringSubmatch(line)
+	if matches == nil {
+		return nil
+	}
+	if len(matches) != 5 {
+		panic(fmt.Sprintf("regex returned wrong matches for %q: %v", line, matches))
+	}
+	return &Todo{
+		Issue: matches[3],
+		Locations: []Location{
+			{
+				File:    path,
+				Line:    lineno,
+				Comment: matches[4],
+			},
+		},
+	}
+}
+
+func (r *Reviver) addTodo(newTodo *Todo) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if todo := r.todos[newTodo.Issue]; todo == nil {
+		r.todos[newTodo.Issue] = newTodo
+	} else {
+		todo.Locations = append(todo.Locations, newTodo.Locations...)
+	}
+}
+
+func (r *Reviver) addErr(err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.errs = append(r.errs, err)
+}
+
+func (r *Reviver) processTodo(todo *Todo) (bool, error) {
+	for _, bugger := range r.buggers {
+		ok, err := bugger.Activate(todo)
+		if err != nil {
+			return false, err
+		}
+		if ok {
+			return true, nil
+		}
+	}
+	return false, nil
+}