| // Copyright 2015 The etcd 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 fileutil implements utility functions related to files and paths. |
| package fileutil |
| |
| import ( |
| "fmt" |
| "io" |
| "io/ioutil" |
| "os" |
| "path/filepath" |
| "sort" |
| |
| "github.com/coreos/pkg/capnslog" |
| ) |
| |
| const ( |
| // PrivateFileMode grants owner to read/write a file. |
| PrivateFileMode = 0600 |
| ) |
| |
| var ( |
| plog = capnslog.NewPackageLogger("github.com/coreos/etcd", "pkg/fileutil") |
| ) |
| |
| // IsDirWriteable checks if dir is writable by writing and removing a file |
| // to dir. It returns nil if dir is writable. |
| func IsDirWriteable(dir string) error { |
| f := filepath.Join(dir, ".touch") |
| if err := ioutil.WriteFile(f, []byte(""), PrivateFileMode); err != nil { |
| return err |
| } |
| return os.Remove(f) |
| } |
| |
| // ReadDir returns the filenames in the given directory in sorted order. |
| func ReadDir(dirpath string) ([]string, error) { |
| dir, err := os.Open(dirpath) |
| if err != nil { |
| return nil, err |
| } |
| defer dir.Close() |
| names, err := dir.Readdirnames(-1) |
| if err != nil { |
| return nil, err |
| } |
| sort.Strings(names) |
| return names, nil |
| } |
| |
| // TouchDirAll is similar to os.MkdirAll. It creates directories with 0700 permission if any directory |
| // does not exists. TouchDirAll also ensures the given directory is writable. |
| func TouchDirAll(dir string) error { |
| // If path is already a directory, MkdirAll does nothing and returns nil, so, |
| // first check if dir exist with an expected permission mode. |
| if Exist(dir) { |
| err := CheckDirPermission(dir, PrivateDirMode) |
| if err != nil { |
| plog.Warningf("check file permission: %v", err) |
| } |
| } else { |
| err := os.MkdirAll(dir, PrivateDirMode) |
| if err != nil { |
| // if mkdirAll("a/text") and "text" is not |
| // a directory, this will return syscall.ENOTDIR |
| return err |
| } |
| } |
| |
| return IsDirWriteable(dir) |
| } |
| |
| // CreateDirAll is similar to TouchDirAll but returns error |
| // if the deepest directory was not empty. |
| func CreateDirAll(dir string) error { |
| err := TouchDirAll(dir) |
| if err == nil { |
| var ns []string |
| ns, err = ReadDir(dir) |
| if err != nil { |
| return err |
| } |
| if len(ns) != 0 { |
| err = fmt.Errorf("expected %q to be empty, got %q", dir, ns) |
| } |
| } |
| return err |
| } |
| |
| func Exist(name string) bool { |
| _, err := os.Stat(name) |
| return err == nil |
| } |
| |
| // ZeroToEnd zeros a file starting from SEEK_CUR to its SEEK_END. May temporarily |
| // shorten the length of the file. |
| func ZeroToEnd(f *os.File) error { |
| // TODO: support FALLOC_FL_ZERO_RANGE |
| off, err := f.Seek(0, io.SeekCurrent) |
| if err != nil { |
| return err |
| } |
| lenf, lerr := f.Seek(0, io.SeekEnd) |
| if lerr != nil { |
| return lerr |
| } |
| if err = f.Truncate(off); err != nil { |
| return err |
| } |
| // make sure blocks remain allocated |
| if err = Preallocate(f, lenf, true); err != nil { |
| return err |
| } |
| _, err = f.Seek(off, io.SeekStart) |
| return err |
| } |
| |
| // CheckDirPermission checks permission on an existing dir. |
| // Returns error if dir is empty or exist with a different permission than specified. |
| func CheckDirPermission(dir string, perm os.FileMode) error { |
| if !Exist(dir) { |
| return fmt.Errorf("directory %q empty, cannot check permission.", dir) |
| } |
| //check the existing permission on the directory |
| dirInfo, err := os.Stat(dir) |
| if err != nil { |
| return err |
| } |
| dirMode := dirInfo.Mode().Perm() |
| if dirMode != perm { |
| err = fmt.Errorf("directory %q exist, but the permission is %q. The recommended permission is %q to prevent possible unprivileged access to the data.", dir, dirInfo.Mode(), os.FileMode(PrivateDirMode)) |
| return err |
| } |
| return nil |
| } |