| /* |
| Copyright 2017 The Kubernetes 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 files |
| |
| import ( |
| "fmt" |
| "os" |
| "path/filepath" |
| |
| utilfs "k8s.io/kubernetes/pkg/util/filesystem" |
| ) |
| |
| const ( |
| defaultPerm = 0755 |
| tmptag = "tmp_" // additional prefix to prevent accidental collisions |
| ) |
| |
| // FileExists returns true if a regular file exists at `path`, false if `path` does not exist, otherwise an error |
| func FileExists(fs utilfs.Filesystem, path string) (bool, error) { |
| if info, err := fs.Stat(path); err == nil { |
| if info.Mode().IsRegular() { |
| return true, nil |
| } |
| return false, fmt.Errorf("expected regular file at %q, but mode is %q", path, info.Mode().String()) |
| } else if os.IsNotExist(err) { |
| return false, nil |
| } else { |
| return false, err |
| } |
| } |
| |
| // EnsureFile ensures that a regular file exists at `path`, and if it must create the file any |
| // necessary parent directories will also be created and the new file will be empty. |
| func EnsureFile(fs utilfs.Filesystem, path string) error { |
| // if file exists, don't change it, but do report any unexpected errors |
| if ok, err := FileExists(fs, path); ok || err != nil { |
| return err |
| } // Assert: file does not exist |
| |
| // create any necessary parents |
| err := fs.MkdirAll(filepath.Dir(path), defaultPerm) |
| if err != nil { |
| return err |
| } |
| |
| // create the file |
| file, err := fs.Create(path) |
| if err != nil { |
| return err |
| } |
| // close the file, since we don't intend to use it yet |
| return file.Close() |
| } |
| |
| // WriteTmpFile creates a temporary file at `path`, writes `data` into it, and fsyncs the file |
| // Expects the parent directory to exist. |
| func WriteTmpFile(fs utilfs.Filesystem, path string, data []byte) (tmpPath string, retErr error) { |
| dir := filepath.Dir(path) |
| prefix := tmptag + filepath.Base(path) |
| |
| // create the tmp file |
| tmpFile, err := fs.TempFile(dir, prefix) |
| if err != nil { |
| return "", err |
| } |
| defer func() { |
| // close the file, return the close error only if there haven't been any other errors |
| if err := tmpFile.Close(); retErr == nil { |
| retErr = err |
| } |
| // if there was an error writing, syncing, or closing, delete the temporary file and return the error |
| if retErr != nil { |
| if err := fs.Remove(tmpPath); err != nil { |
| retErr = fmt.Errorf("attempted to remove temporary file %q after error %v, but failed due to error: %v", tmpPath, retErr, err) |
| } |
| tmpPath = "" |
| } |
| }() |
| |
| // Name() will be an absolute path when using utilfs.DefaultFS, because ioutil.TempFile passes |
| // an absolute path to os.Open, and we ensure similar behavior in utilfs.FakeFS for testing. |
| tmpPath = tmpFile.Name() |
| |
| // write data |
| if _, err := tmpFile.Write(data); err != nil { |
| return tmpPath, err |
| } |
| // sync file, to ensure it's written in case a hard reset happens |
| return tmpPath, tmpFile.Sync() |
| } |
| |
| // ReplaceFile replaces the contents of the file at `path` with `data` by writing to a tmp file in the same |
| // dir as `path` and renaming the tmp file over `path`. The file does not have to exist to use ReplaceFile, |
| // but the parent directory must exist. |
| // Note ReplaceFile calls fsync. |
| func ReplaceFile(fs utilfs.Filesystem, path string, data []byte) error { |
| // write data to a temporary file |
| tmpPath, err := WriteTmpFile(fs, path, data) |
| if err != nil { |
| return err |
| } |
| // rename over existing file |
| return fs.Rename(tmpPath, path) |
| } |
| |
| // DirExists returns true if a directory exists at `path`, false if `path` does not exist, otherwise an error |
| func DirExists(fs utilfs.Filesystem, path string) (bool, error) { |
| if info, err := fs.Stat(path); err == nil { |
| if info.IsDir() { |
| return true, nil |
| } |
| return false, fmt.Errorf("expected dir at %q, but mode is %q", path, info.Mode().String()) |
| } else if os.IsNotExist(err) { |
| return false, nil |
| } else { |
| return false, err |
| } |
| } |
| |
| // EnsureDir ensures that a directory exists at `path`, and if it must create the directory any |
| // necessary parent directories will also be created and the new directory will be empty. |
| func EnsureDir(fs utilfs.Filesystem, path string) error { |
| // if dir exists, don't change it, but do report any unexpected errors |
| if ok, err := DirExists(fs, path); ok || err != nil { |
| return err |
| } // Assert: dir does not exist |
| |
| // create the dir |
| return fs.MkdirAll(path, defaultPerm) |
| } |
| |
| // WriteTempDir creates a temporary dir at `path`, writes `files` into it, and fsyncs all the files |
| // The keys of `files` represent file names. These names must not: |
| // - be empty |
| // - be a path that contains more than the base name of a file (e.g. foo/bar is invalid, as is /bar) |
| // - match `.` or `..` exactly |
| // - be longer than 255 characters |
| // The above validation rules are based on atomic_writer.go, though in this case are more restrictive |
| // because we only allow a flat hierarchy. |
| func WriteTempDir(fs utilfs.Filesystem, path string, files map[string]string) (tmpPath string, retErr error) { |
| // validate the filename keys; for now we only allow a flat keyset |
| for name := range files { |
| // invalidate empty names |
| if name == "" { |
| return "", fmt.Errorf("invalid file key: must not be empty: %q", name) |
| } |
| // invalidate: foo/bar and /bar |
| if name != filepath.Base(name) { |
| return "", fmt.Errorf("invalid file key %q, only base names are allowed", name) |
| } |
| // invalidate `.` and `..` |
| if name == "." || name == ".." { |
| return "", fmt.Errorf("invalid file key, may not be '.' or '..'") |
| } |
| // invalidate length > 255 characters |
| if len(name) > 255 { |
| return "", fmt.Errorf("invalid file key %q, must be less than 255 characters", name) |
| } |
| } |
| |
| // write the temp directory in parent dir and return path to the tmp directory |
| dir := filepath.Dir(path) |
| prefix := tmptag + filepath.Base(path) |
| |
| // create the tmp dir |
| var err error |
| tmpPath, err = fs.TempDir(dir, prefix) |
| if err != nil { |
| return "", err |
| } |
| // be sure to clean up if there was an error |
| defer func() { |
| if retErr != nil { |
| if err := fs.RemoveAll(tmpPath); err != nil { |
| retErr = fmt.Errorf("attempted to remove temporary directory %q after error %v, but failed due to error: %v", tmpPath, retErr, err) |
| } |
| } |
| }() |
| // write data |
| for name, data := range files { |
| // create the file |
| file, err := fs.Create(filepath.Join(tmpPath, name)) |
| if err != nil { |
| return tmpPath, err |
| } |
| // be sure to close the file when we're done |
| defer func() { |
| // close the file when we're done, don't overwrite primary retErr if close fails |
| if err := file.Close(); retErr == nil { |
| retErr = err |
| } |
| }() |
| // write the file |
| if _, err := file.Write([]byte(data)); err != nil { |
| return tmpPath, err |
| } |
| // sync the file, to ensure it's written in case a hard reset happens |
| if err := file.Sync(); err != nil { |
| return tmpPath, err |
| } |
| } |
| return tmpPath, nil |
| } |
| |
| // ReplaceDir replaces the contents of the dir at `path` with `files` by writing to a tmp dir in the same |
| // dir as `path` and renaming the tmp dir over `path`. The dir does not have to exist to use ReplaceDir. |
| func ReplaceDir(fs utilfs.Filesystem, path string, files map[string]string) error { |
| // write data to a temporary directory |
| tmpPath, err := WriteTempDir(fs, path, files) |
| if err != nil { |
| return err |
| } |
| // rename over target directory |
| return fs.Rename(tmpPath, path) |
| } |