diff options
| -rw-r--r-- | fileutil/fileutil.go | 15 | ||||
| -rw-r--r-- | fileutil/fileutil_test.go | 80 |
2 files changed, 93 insertions, 2 deletions
diff --git a/fileutil/fileutil.go b/fileutil/fileutil.go index 34e2562fa..a019a14ea 100644 --- a/fileutil/fileutil.go +++ b/fileutil/fileutil.go @@ -59,14 +59,25 @@ func WriteTempFile(data []byte) (string, error) { // ProcessTempDir creates a new temp dir in where and returns its path and an unique index. // It also cleans up old, unused temp dirs after dead processes. func ProcessTempDir(where string) (string, int, error) { - for i := 0; i < 1e4; i++ { + lk := filepath.Join(where, "instance-lock") + lkf, err := syscall.Open(lk, syscall.O_RDWR|syscall.O_CREAT, 0600) + if err != nil { + return "", 0, err + } + defer syscall.Close(lkf) + if err := syscall.Flock(lkf, syscall.LOCK_EX); err != nil { + return "", 0, err + } + defer syscall.Flock(lkf, syscall.LOCK_UN) + + for i := 0; i < 1e3; i++ { path := filepath.Join(where, fmt.Sprintf("instance-%v", i)) pidfile := filepath.Join(path, ".pid") err := os.Mkdir(path, 0700) if os.IsExist(err) { // Try to clean up. data, err := ioutil.ReadFile(pidfile) - if err == nil { + if err == nil && len(data) > 0 { pid, err := strconv.Atoi(string(data)) if err == nil && pid > 1 { if err := syscall.Kill(pid, 0); err == syscall.ESRCH { diff --git a/fileutil/fileutil_test.go b/fileutil/fileutil_test.go new file mode 100644 index 000000000..1084cc98d --- /dev/null +++ b/fileutil/fileutil_test.go @@ -0,0 +1,80 @@ +// Copyright 2015 syzkaller project authors. All rights reserved. +// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file. + +package fileutil + +import ( + "bytes" + "io/ioutil" + "os" + "strconv" + "sync" + "testing" + "path/filepath" +) + +func TestProcessTempDir(t *testing.T) { + for try := 0; try < 10; try++ { + func() { + tmp, err := ioutil.TempDir("", "syz") + if err != nil { + t.Fatalf("failed to create a temp dir: %v", err) + } + defer os.RemoveAll(tmp) + const P = 16 + // Pre-create half of the instances with stale pid. + var dirs []string + for i := 0; i < P/2; i++ { + dir, idx, err := ProcessTempDir(tmp) + if err != nil { + t.Fatalf("failed to create process temp dir") + } + if idx != i { + t.Fatalf("unexpected index: want %v, got %v", i, idx) + } + dirs = append(dirs, dir) + } + for _, dir := range dirs { + if err := ioutil.WriteFile(filepath.Join(dir, ".pid"), []byte(strconv.Itoa(999999999)), 0600); err != nil { + t.Fatalf("failed to write pid file: %v", err) + } + } + // Now request a bunch of instances concurrently. + done := make(chan bool) + indices := make(map[int]bool) + var mu sync.Mutex + for p := 0; p < P; p++ { + go func() { + defer func() { + done <- true + }() + dir, idx, err := ProcessTempDir(tmp) + if err != nil { + t.Fatalf("failed to create process temp dir") + } + mu.Lock() + present := indices[idx] + indices[idx] = true + mu.Unlock() + if present { + t.Fatalf("duplicate index %v", idx) + } + data := []byte(strconv.Itoa(idx)) + if err := ioutil.WriteFile(filepath.Join(dir, "data"), data, 0600); err != nil { + t.Fatalf("failed to write data file: %v", err) + } + data1, err := ioutil.ReadFile(filepath.Join(dir, "data")) + if err != nil { + t.Fatalf("failed to read data file: %v", err) + } + if bytes.Compare(data, data1) != 0 { + t.Fatalf("corrupted data file") + } + }() + } + for p := 0; p < P; p++ { + <-done + } + }() + } +} |