pax_global_header00006660000000000000000000000064141260176030014512gustar00rootroot0000000000000052 comment=0450d4d46d68d9e2184fe3a7cea9ec500b37a68a renameio-2.0.0/000077500000000000000000000000001412601760300133105ustar00rootroot00000000000000renameio-2.0.0/.github/000077500000000000000000000000001412601760300146505ustar00rootroot00000000000000renameio-2.0.0/.github/workflows/000077500000000000000000000000001412601760300167055ustar00rootroot00000000000000renameio-2.0.0/.github/workflows/main.yml000066400000000000000000000021371412601760300203570ustar00rootroot00000000000000name: Test on: pull_request: push: branches: - master tags: - v* jobs: test: strategy: matrix: go-version: - 1.16.x - 1.17.x os: - macos-latest - ubuntu-latest - windows-latest runs-on: ${{ matrix.os }} steps: - name: Set up Go uses: actions/setup-go@v1 with: go-version: ${{ matrix.go-version }} - name: Cache Go modules uses: actions/cache@v1 with: path: ~/go/pkg/mod key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }} restore-keys: | ${{ runner.os }}-go- - name: Checkout uses: actions/checkout@v2 - name: Linux test if: matrix.os == 'ubuntu-latest' run: | go test -c -race . sudo ./renameio.test -test.v - name: Non-Linux test if: matrix.os != 'ubuntu-latest' run: go test . lint: runs-on: ubuntu-latest steps: - name: Checkout uses: actions/checkout@v2 - name: Lint uses: golangci/golangci-lint-action@v2 with: version: v1.31 renameio-2.0.0/.golangci.yml000066400000000000000000000000651412601760300156750ustar00rootroot00000000000000linters: disable: - errcheck enable: - gofmt renameio-2.0.0/CONTRIBUTING.md000066400000000000000000000021151412601760300155400ustar00rootroot00000000000000# How to Contribute We'd love to accept your patches and contributions to this project. There are just a few small guidelines you need to follow. ## Contributor License Agreement Contributions to this project must be accompanied by a Contributor License Agreement. You (or your employer) retain the copyright to your contribution; this simply gives us permission to use and redistribute your contributions as part of the project. Head over to to see your current agreements on file or to sign a new one. You generally only need to submit a CLA once, so if you've already submitted one (even if it was for a different project), you probably don't need to do it again. ## Code reviews All submissions, including submissions by project members, require review. We use GitHub pull requests for this purpose. 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See the License for the specific language governing permissions and limitations under the License. renameio-2.0.0/README.md000066400000000000000000000066021412601760300145730ustar00rootroot00000000000000[![Build Status](https://github.com/google/renameio/workflows/Test/badge.svg)](https://github.com/google/renameio/actions?query=workflow%3ATest) [![PkgGoDev](https://pkg.go.dev/badge/github.com/google/renameio)](https://pkg.go.dev/github.com/google/renameio) [![Go Report Card](https://goreportcard.com/badge/github.com/google/renameio)](https://goreportcard.com/report/github.com/google/renameio) The `renameio` Go package provides a way to atomically create or replace a file or symbolic link. ## Atomicity vs durability `renameio` concerns itself *only* with atomicity, i.e. making sure applications never see unexpected file content (a half-written file, or a 0-byte file). As a practical example, consider https://manpages.debian.org/: if there is a power outage while the site is updating, we are okay with losing the manpages which were being rendered at the time of the power outage. They will be added in a later run of the software. We are not okay with having a manpage replaced by a 0-byte file under any circumstances, though. ## Advantages of this package There are other packages for atomically replacing files, and sometimes ad-hoc implementations can be found in programs. A naive approach to the problem is to create a temporary file followed by a call to `os.Rename()`. However, there are a number of subtleties which make the correct sequence of operations hard to identify: * The temporary file should be removed when an error occurs, but a remove must not be attempted if the rename succeeded, as a new file might have been created with the same name. This renders a throwaway `defer os.Remove(t.Name())` insufficient; state must be kept. * The temporary file must be created on the same file system (same mount point) for the rename to work, but the TMPDIR environment variable should still be respected, e.g. to direct temporary files into a separate directory outside of the webserver’s document root but on the same file system. * On POSIX operating systems, the [`fsync`](https://manpages.debian.org/stretch/manpages-dev/fsync.2) system call must be used to ensure that the `os.Rename()` call will not result in a 0-length file. This package attempts to get all of these details right, provides an intuitive, yet flexible API and caters to use-cases where high performance is required. ## Major changes in v2 With major version renameio/v2, `renameio.WriteFile` changes the way that permissions are handled. Before version 2, files were created with the permissions passed to the function, ignoring the [umask](https://en.wikipedia.org/wiki/Umask). From version 2 onwards, these permissions are further modified by process' umask (usually the user's preferred umask). If you were relying on the umask being ignored, add the `renameio.IgnoreUmask()` option to your `renameio.WriteFile` calls when upgrading to v2. ## Windows support It is [not possible to reliably write files atomically on Windows](https://github.com/golang/go/issues/22397#issuecomment-498856679), and [`chmod` is not reliably supported by the Go standard library on Windows](https://github.com/google/renameio/issues/17). As it is not possible to provide a correct implementation, this package does not export any functions on Windows. ## Disclaimer This is not an official Google product (experimental or otherwise), it is just code that happens to be owned by Google. This project is not affiliated with the Go project. renameio-2.0.0/doc.go000066400000000000000000000016101412601760300144020ustar00rootroot00000000000000// Copyright 2018 Google Inc. // // 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 renameio provides a way to atomically create or replace a file or // symbolic link. // // Caveat: this package requires the file system rename(2) implementation to be // atomic. Notably, this is not the case when using NFS with multiple clients: // https://stackoverflow.com/a/41396801 package renameio renameio-2.0.0/example_test.go000066400000000000000000000036651412601760300163430ustar00rootroot00000000000000// Copyright 2018 Google Inc. // // 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. //go:build !windows // +build !windows package renameio_test import ( "fmt" "log" "github.com/google/renameio/v2" ) func ExampleTempFile_justone() { persist := func(temperature float64) error { t, err := renameio.TempFile("", "/srv/www/metrics.txt") if err != nil { return err } defer t.Cleanup() if _, err := fmt.Fprintf(t, "temperature_degc %f\n", temperature); err != nil { return err } return t.CloseAtomicallyReplace() } // Thanks to the write package, a webserver exposing /srv/www never // serves an incomplete or missing file. if err := persist(31.2); err != nil { log.Fatal(err) } } func ExampleTempFile_many() { // Prepare for writing files to /srv/www, effectively caching calls to // TempDir which TempFile would otherwise need to make. dir := renameio.TempDir("/srv/www") persist := func(temperature float64) error { t, err := renameio.TempFile(dir, "/srv/www/metrics.txt") if err != nil { return err } defer t.Cleanup() if _, err := fmt.Fprintf(t, "temperature_degc %f\n", temperature); err != nil { return err } return t.CloseAtomicallyReplace() } // Imagine this was an endless loop, reading temperature sensor values. // Thanks to the write package, a webserver exposing /srv/www never // serves an incomplete or missing file. for { if err := persist(31.2); err != nil { log.Fatal(err) } } } renameio-2.0.0/go.mod000066400000000000000000000000561412601760300144170ustar00rootroot00000000000000module github.com/google/renameio/v2 go 1.13 renameio-2.0.0/maybe/000077500000000000000000000000001412601760300144055ustar00rootroot00000000000000renameio-2.0.0/maybe/doc.go000066400000000000000000000001621412601760300155000ustar00rootroot00000000000000// Package maybe provides a way to atomically create or replace a file, if // technically possible. package maybe renameio-2.0.0/maybe/maybe_unix.go000066400000000000000000000017151412601760300171000ustar00rootroot00000000000000//go:build !windows // +build !windows package maybe import ( "os" "github.com/google/renameio/v2" ) // WriteFile mirrors ioutil.WriteFile. On Linux it uses renameio.WriteFile to // create or replace an existing file with the same name atomically. On Windows // files cannot be written atomically, so this function falls back to // ioutil.WriteFile, which does not write the file atomically and ignores most // permission bits. See https://github.com/google/renameio/issues/1 and // https://github.com/golang/go/issues/22397#issuecomment-498856679 for // discussion. // // Prefer using renameio.WriteFile instead so that you get an error if atomic // replacement is not possible on the runtime platform. maybe.WriteFile is meant // as a convenience wrapper if you are okay with atomic replacement not being // supported by the runtime platform. func WriteFile(filename string, data []byte, perm os.FileMode) error { return renameio.WriteFile(filename, data, perm) } renameio-2.0.0/maybe/maybe_windows.go000066400000000000000000000016161412601760300176070ustar00rootroot00000000000000package maybe import ( "io/ioutil" "os" ) // WriteFile mirrors ioutil.WriteFile. On Linux it uses renameio.WriteFile to // create or replace an existing file with the same name atomically. On Windows // files cannot be written atomically, so this function falls back to // ioutil.WriteFile, which does not write the file atomically and ignores most // permission bits. See https://github.com/google/renameio/issues/1 and // https://github.com/golang/go/issues/22397#issuecomment-498856679 for // discussion. // // Prefer using renameio.WriteFile instead so that you get an error if atomic // replacement is not possible on the runtime platform. maybe.WriteFile is meant // as a convenience wrapper if you are okay with atomic replacement not being // supported by the runtime platform. func WriteFile(filename string, data []byte, perm os.FileMode) error { return ioutil.WriteFile(filename, data, perm) } renameio-2.0.0/option.go000066400000000000000000000046101412601760300151500ustar00rootroot00000000000000// Copyright 2021 Google Inc. // // 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. //go:build !windows // +build !windows package renameio import "os" // Option is the interface implemented by all configuration function return // values. type Option interface { apply(*config) } type optionFunc func(*config) func (fn optionFunc) apply(cfg *config) { fn(cfg) } // WithTempDir configures the directory to use for temporary, uncommitted // files. Suitable for using a cached directory from // TempDir(filepath.Base(path)). func WithTempDir(dir string) Option { return optionFunc(func(cfg *config) { cfg.dir = dir }) } // WithPermissions sets the permissions for the target file while respecting // the umask(2). Bits set in the umask are removed from the permissions given // unless IgnoreUmask is used. func WithPermissions(perm os.FileMode) Option { perm &= os.ModePerm return optionFunc(func(cfg *config) { cfg.createPerm = perm }) } // IgnoreUmask causes the permissions configured using WithPermissions to be // applied directly without applying the umask. func IgnoreUmask() Option { return optionFunc(func(cfg *config) { cfg.ignoreUmask = true }) } // WithStaticPermissions sets the permissions for the target file ignoring the // umask(2). This is equivalent to calling Chmod() on the file handle or using // WithPermissions in combination with IgnoreUmask. func WithStaticPermissions(perm os.FileMode) Option { perm &= os.ModePerm return optionFunc(func(cfg *config) { cfg.chmod = &perm }) } // WithExistingPermissions configures the file creation to try to use the // permissions from an already existing target file. If the target file doesn't // exist yet or is not a regular file the default permissions are used unless // overridden using WithPermissions or WithStaticPermissions. func WithExistingPermissions() Option { return optionFunc(func(c *config) { c.attemptPermCopy = true }) } renameio-2.0.0/symlink_test.go000066400000000000000000000024541412601760300163710ustar00rootroot00000000000000// Copyright 2018 Google Inc. // // 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. //go:build !windows // +build !windows package renameio import ( "bytes" "io/ioutil" "os" "path/filepath" "testing" ) func TestSymlink(t *testing.T) { d, err := ioutil.TempDir("", "tempdirtest") if err != nil { t.Fatal(err) } defer os.RemoveAll(d) want := []byte("Hello World") if err := ioutil.WriteFile(filepath.Join(d, "hello.txt"), want, 0644); err != nil { t.Fatal(err) } for i := 0; i < 2; i++ { if err := Symlink("hello.txt", filepath.Join(d, "hi.txt")); err != nil { t.Fatal(err) } got, err := ioutil.ReadFile(filepath.Join(d, "hi.txt")) if err != nil { t.Fatal(err) } if !bytes.Equal(got, want) { t.Fatalf("unexpected content: got %q, want %q", string(got), string(want)) } } } renameio-2.0.0/tempfile.go000066400000000000000000000204471412601760300154530ustar00rootroot00000000000000// Copyright 2018 Google Inc. // // 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. //go:build !windows // +build !windows package renameio import ( "io/ioutil" "math/rand" "os" "path/filepath" "strconv" ) // Default permissions for created files const defaultPerm os.FileMode = 0o600 // nextrandom is a function generating a random number. var nextrandom = rand.Int63 // openTempFile creates a randomly named file and returns an open handle. It is // similar to ioutil.TempFile except that the directory must be given, the file // permissions can be controlled and patterns in the name are not supported. // The name is always suffixed with a random number. func openTempFile(dir, name string, perm os.FileMode) (*os.File, error) { prefix := filepath.Join(dir, name) for attempt := 0; ; { // Generate a reasonably random name which is unlikely to already // exist. O_EXCL ensures that existing files generate an error. name := prefix + strconv.FormatInt(nextrandom(), 10) f, err := os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, perm) if !os.IsExist(err) { return f, err } if attempt++; attempt > 10000 { return nil, &os.PathError{ Op: "tempfile", Path: name, Err: os.ErrExist, } } } } // TempDir checks whether os.TempDir() can be used as a temporary directory for // later atomically replacing files within dest. If no (os.TempDir() resides on // a different mount point), dest is returned. // // Note that the returned value ceases to be valid once either os.TempDir() // changes (e.g. on Linux, once the TMPDIR environment variable changes) or the // file system is unmounted. func TempDir(dest string) string { return tempDir("", filepath.Join(dest, "renameio-TempDir")) } func tempDir(dir, dest string) string { if dir != "" { return dir // caller-specified directory always wins } // Chose the destination directory as temporary directory so that we // definitely can rename the file, for which both temporary and destination // file need to point to the same mount point. fallback := filepath.Dir(dest) // The user might have overridden the os.TempDir() return value by setting // the TMPDIR environment variable. tmpdir := os.TempDir() testsrc, err := ioutil.TempFile(tmpdir, "."+filepath.Base(dest)) if err != nil { return fallback } cleanup := true defer func() { if cleanup { os.Remove(testsrc.Name()) } }() testsrc.Close() testdest, err := ioutil.TempFile(filepath.Dir(dest), "."+filepath.Base(dest)) if err != nil { return fallback } defer os.Remove(testdest.Name()) testdest.Close() if err := os.Rename(testsrc.Name(), testdest.Name()); err != nil { return fallback } cleanup = false // testsrc no longer exists return tmpdir } // PendingFile is a pending temporary file, waiting to replace the destination // path in a call to CloseAtomicallyReplace. type PendingFile struct { *os.File path string done bool closed bool } // Cleanup is a no-op if CloseAtomicallyReplace succeeded, and otherwise closes // and removes the temporary file. // // This method is not safe for concurrent use by multiple goroutines. func (t *PendingFile) Cleanup() error { if t.done { return nil } // An error occurred. Close and remove the tempfile. Errors are returned for // reporting, there is nothing the caller can recover here. var closeErr error if !t.closed { closeErr = t.Close() } if err := os.Remove(t.Name()); err != nil { return err } t.done = true return closeErr } // CloseAtomicallyReplace closes the temporary file and atomically replaces // the destination file with it, i.e., a concurrent open(2) call will either // open the file previously located at the destination path (if any), or the // just written file, but the file will always be present. // // This method is not safe for concurrent use by multiple goroutines. func (t *PendingFile) CloseAtomicallyReplace() error { // Even on an ordered file system (e.g. ext4 with data=ordered) or file // systems with write barriers, we cannot skip the fsync(2) call as per // Theodore Ts'o (ext2/3/4 lead developer): // // > data=ordered only guarantees the avoidance of stale data (e.g., the previous // > contents of a data block showing up after a crash, where the previous data // > could be someone's love letters, medical records, etc.). Without the fsync(2) // > a zero-length file is a valid and possible outcome after the rename. if err := t.Sync(); err != nil { return err } t.closed = true if err := t.Close(); err != nil { return err } if err := os.Rename(t.Name(), t.path); err != nil { return err } t.done = true return nil } // TempFile creates a temporary file destined to atomically creating or // replacing the destination file at path. // // If dir is the empty string, TempDir(filepath.Base(path)) is used. If you are // going to write a large number of files to the same file system, store the // result of TempDir(filepath.Base(path)) and pass it instead of the empty // string. // // The file's permissions will be 0600. You can change these by explicitly // calling Chmod on the returned PendingFile. func TempFile(dir, path string) (*PendingFile, error) { return NewPendingFile(path, WithTempDir(dir), WithStaticPermissions(defaultPerm)) } type config struct { dir, path string createPerm os.FileMode attemptPermCopy bool ignoreUmask bool chmod *os.FileMode } // NewPendingFile creates a temporary file destined to atomically creating or // replacing the destination file at path. // // TempDir(filepath.Base(path)) is used to store the temporary file. If you are // going to write a large number of files to the same file system, use the // result of TempDir(filepath.Base(path)) with the WithTempDir option. // // The file's permissions will be (0600 & ^umask). Use WithPermissions, // IgnoreUmask, WithStaticPermissions and WithExistingPermissions to control // them. func NewPendingFile(path string, opts ...Option) (*PendingFile, error) { cfg := config{ path: path, createPerm: defaultPerm, } for _, o := range opts { o.apply(&cfg) } if cfg.ignoreUmask && cfg.chmod == nil { cfg.chmod = &cfg.createPerm } if cfg.attemptPermCopy { // Try to determine permissions from an existing file. if existing, err := os.Lstat(cfg.path); err == nil && existing.Mode().IsRegular() { perm := existing.Mode() & os.ModePerm cfg.chmod = &perm // Try to already create file with desired permissions; at worst // a chmod will be needed afterwards. cfg.createPerm = perm } else if err != nil && !os.IsNotExist(err) { return nil, err } } f, err := openTempFile(tempDir(cfg.dir, cfg.path), "."+filepath.Base(cfg.path), cfg.createPerm) if err != nil { return nil, err } if cfg.chmod != nil { if fi, err := f.Stat(); err != nil { return nil, err } else if fi.Mode()&os.ModePerm != *cfg.chmod { if err := f.Chmod(*cfg.chmod); err != nil { return nil, err } } } return &PendingFile{File: f, path: cfg.path}, nil } // Symlink wraps os.Symlink, replacing an existing symlink with the same name // atomically (os.Symlink fails when newname already exists, at least on Linux). func Symlink(oldname, newname string) error { // Fast path: if newname does not exist yet, we can skip the whole dance // below. if err := os.Symlink(oldname, newname); err == nil || !os.IsExist(err) { return err } // We need to use ioutil.TempDir, as we cannot overwrite a ioutil.TempFile, // and removing+symlinking creates a TOCTOU race. d, err := ioutil.TempDir(filepath.Dir(newname), "."+filepath.Base(newname)) if err != nil { return err } cleanup := true defer func() { if cleanup { os.RemoveAll(d) } }() symlink := filepath.Join(d, "tmp.symlink") if err := os.Symlink(oldname, symlink); err != nil { return err } if err := os.Rename(symlink, newname); err != nil { return err } cleanup = false return os.RemoveAll(d) } renameio-2.0.0/tempfile_linux_test.go000066400000000000000000000047171412601760300177330ustar00rootroot00000000000000// Copyright 2018 Google Inc. // // 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 renameio import ( "io/ioutil" "os" "path/filepath" "syscall" "testing" ) func TestTempDir(t *testing.T) { if tmpdir, ok := os.LookupEnv("TMPDIR"); ok { defer os.Setenv("TMPDIR", tmpdir) // restore } else { defer os.Unsetenv("TMPDIR") // restore } mount1, err := ioutil.TempDir("", "tempdirtest") if err != nil { t.Fatal(err) } defer os.RemoveAll(mount1) mount2, err := ioutil.TempDir("", "tempdirtest") if err != nil { t.Fatal(err) } defer os.RemoveAll(mount2) if err := syscall.Mount("tmpfs", mount1, "tmpfs", 0, ""); err != nil { t.Skipf("cannot mount tmpfs on %s: %v", mount1, err) } defer syscall.Unmount(mount1, 0) if err := syscall.Mount("tmpfs", mount2, "tmpfs", 0, ""); err != nil { t.Skipf("cannot mount tmpfs on %s: %v", mount2, err) } defer syscall.Unmount(mount2, 0) tests := []struct { name string dir string path string TMPDIR string want string }{ { name: "implicit TMPDIR", path: filepath.Join(os.TempDir(), "foo.txt"), want: os.TempDir(), }, { name: "explicit TMPDIR", path: filepath.Join(mount1, "foo.txt"), TMPDIR: mount1, want: mount1, }, { name: "explicit unsuitable TMPDIR", path: filepath.Join(mount1, "foo.txt"), TMPDIR: mount2, want: mount1, }, { name: "nonexistant TMPDIR", path: filepath.Join(mount1, "foo.txt"), TMPDIR: "/nonexistant", want: mount1, }, { name: "caller-specified", dir: "/overridden", path: filepath.Join(mount1, "foo.txt"), TMPDIR: "/nonexistant", want: "/overridden", }, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { if tt.TMPDIR == "" { os.Unsetenv("TMPDIR") } else { os.Setenv("TMPDIR", tt.TMPDIR) } if got := tempDir(tt.dir, tt.path); got != tt.want { t.Fatalf("tempDir(%q, %q): got %q, want %q", tt.dir, tt.path, got, tt.want) } }) } } renameio-2.0.0/tempfile_test.go000066400000000000000000000216031412601760300165050ustar00rootroot00000000000000// Copyright 2021 Google Inc. // // 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. //go:build !windows // +build !windows package renameio import ( "errors" "fmt" "io/ioutil" "os" "path/filepath" "syscall" "testing" ) func withUmask(t *testing.T, mask os.FileMode) { t.Helper() old := syscall.Umask(int(mask)) t.Cleanup(func() { syscall.Umask(old) }) } func withCustomRng(t *testing.T, fn func() int64) { t.Helper() orig := nextrandom t.Cleanup(func() { nextrandom = orig }) nextrandom = fn } func TestOpenTempFile(t *testing.T) { const count = 100 // Install a deterministic random generator var next int64 = 12345 withCustomRng(t, func() int64 { v := next next++ return v }) for _, umask := range []os.FileMode{0o000, 0o011, 0o007, 0o027, 0o077} { t.Run(fmt.Sprintf("0%o", umask), func(t *testing.T) { withUmask(t, umask) dir := t.TempDir() for i := 0; i < count; i++ { perm := [...]os.FileMode{0600, 0755, 0411}[i%3] maskedPerm := perm & ^umask got, err := openTempFile(dir, "test", perm) if err != nil { t.Errorf("openTempFile() failed: %v", err) } t.Cleanup(func() { if err := got.Close(); err != nil { t.Errorf("Close() failed: %v", err) } }) if fi, err := os.Stat(got.Name()); err != nil { t.Errorf("Stat(%q) failed: %v", got.Name(), err) } else if gotPerm := fi.Mode() & os.ModePerm; gotPerm != maskedPerm { t.Errorf("Got permissions 0%o, want 0%o", gotPerm, maskedPerm) } } if entries, err := ioutil.ReadDir(dir); err != nil { t.Errorf("ReadDir(%q) failed: %v", dir, err) } else if len(entries) < count { t.Errorf("Directory %q contains fewer than %d entries", dir, count) } }) } } func TestOpenTempFileConflict(t *testing.T) { withUmask(t, 0077) // https://xkcd.com/221/ withCustomRng(t, func() int64 { return 4 }) dir := t.TempDir() if first, err := openTempFile(dir, "test", 0644); err != nil { t.Errorf("openTempFile() failed: %v", err) } else { first.Close() } if _, err := openTempFile(dir, "test", 0644); !errors.Is(err, os.ErrExist) { t.Errorf("openTempFile() did not fail with ErrExist: %v", err) } } func TestPendingFileCreation(t *testing.T) { withUmask(t, 0077) pathExisting := filepath.Join(t.TempDir(), "existing.txt") pathExistingWithPerm := filepath.Join(t.TempDir(), "perm.txt") for path, content := range map[string]string{ pathExisting: "content", pathExistingWithPerm: "", } { if err := ioutil.WriteFile(path, []byte(content), 0644); err != nil { t.Errorf("WriteFile(%q) failed: %v", path, err) } } for _, tc := range []struct { name string path string umask os.FileMode useTempFile bool options []Option want string wantPerm os.FileMode }{ { name: "tempfile new file", path: filepath.Join(t.TempDir(), "new.txt"), useTempFile: true, want: "replaced:tempfile new file", wantPerm: 0o600, }, { name: "tempfile existing", path: pathExisting, useTempFile: true, want: "replaced:tempfile existing", wantPerm: 0o600, }, { name: "tempfile umask", path: filepath.Join(t.TempDir(), "masked"), useTempFile: true, umask: 0o377, want: "replaced:tempfile umask", wantPerm: 0o600, }, { name: "defaults", path: filepath.Join(t.TempDir(), "npf defaults"), want: "replaced:defaults", wantPerm: 0o600, }, { name: "fixed perm", path: filepath.Join(t.TempDir(), "npf new perm"), options: []Option{WithStaticPermissions(0o654)}, want: "replaced:fixed perm", wantPerm: 0o654, }, { name: "umask perm 0644", path: filepath.Join(t.TempDir(), "npf umask perm"), options: []Option{WithPermissions(0o777)}, umask: 0o012, want: "replaced:umask perm 0644", wantPerm: 0o765, }, { name: "setup with perm", path: pathExistingWithPerm, options: []Option{WithStaticPermissions(0o754)}, want: "replaced:setup with perm", wantPerm: 0o754, }, { name: "overwrite existing with perm", path: pathExistingWithPerm, options: []Option{WithExistingPermissions()}, want: "replaced:overwrite existing with perm", wantPerm: 0o754, }, { name: "use permissions from non-existing with unset", path: filepath.Join(t.TempDir(), "never before"), options: []Option{WithExistingPermissions()}, want: "replaced:use permissions from non-existing with unset", wantPerm: 0o600, }, { name: "use permissions from non-existing with mode", path: filepath.Join(t.TempDir(), "never before"), options: []Option{WithPermissions(0o633), WithExistingPermissions()}, umask: 0o012, want: "replaced:use permissions from non-existing with mode", wantPerm: 0o621, }, { name: "use permissions from non-existing with fixed", path: filepath.Join(t.TempDir(), "never before"), options: []Option{WithExistingPermissions(), WithStaticPermissions(0o612)}, want: "replaced:use permissions from non-existing with fixed", wantPerm: 0o612, }, { name: "custom tempdir", path: filepath.Join(t.TempDir(), "foo"), options: []Option{WithTempDir(t.TempDir()), WithStaticPermissions(0o612)}, umask: 0o012, want: "replaced:custom tempdir", wantPerm: 0o612, }, { name: "ignore umask", path: filepath.Join(t.TempDir(), "ignore umask"), options: []Option{IgnoreUmask(), WithPermissions(0o644)}, want: "replaced:ignore umask", wantPerm: 0o644, }, { name: "ignore umask with static permissions", path: filepath.Join(t.TempDir(), "ignore umask"), options: []Option{IgnoreUmask(), WithStaticPermissions(0o632), WithPermissions(0o765)}, want: "replaced:ignore umask with static permissions", wantPerm: 0o632, }, } { t.Run(tc.name, func(t *testing.T) { if tc.umask != 0 { withUmask(t, tc.umask) } var err error var pf *PendingFile if tc.useTempFile { pf, err = TempFile("", tc.path) if err != nil { t.Errorf("TempFile(%q) failed: %v", tc.path, err) } } else { pf, err = NewPendingFile(tc.path, tc.options...) if err != nil { t.Errorf("NewPendingFile(%q, %+v) failed: %v", tc.path, tc.options, err) } } if _, err := pf.WriteString("replaced:" + tc.name); err != nil { t.Errorf("Write() failed: %v", err) } if err := pf.CloseAtomicallyReplace(); err != nil { t.Errorf("CloseAtomicallyReplace() failed: %v", err) } if _, err := pf.Write(nil); !errors.Is(err, os.ErrClosed) { t.Errorf("Write() after CloseAtomicallyReplace didn't fail with ErrClosed: %v", err) } if err := pf.Cleanup(); err != nil { t.Errorf("Cleanup() failed: %v", err) } if got, err := ioutil.ReadFile(tc.path); err != nil { t.Errorf("ReadFile(%q) failed: %v", tc.path, err) } else if string(got) != tc.want { t.Errorf("Read unexpected content %q from %q, want %q", string(got), tc.path, tc.want) } if fi, err := os.Stat(tc.path); err != nil { t.Errorf("Stat(%q) failed: %v", tc.path, err) } else if got := fi.Mode() & os.ModePerm; got != tc.wantPerm { t.Errorf("%q has permissions 0%o, want 0%o", tc.path, got, tc.wantPerm) } }) } } func TestTempFileNoCommit(t *testing.T) { pathNew := filepath.Join(t.TempDir(), "new.txt") pathExisting := filepath.Join(t.TempDir(), "existing.txt") if err := ioutil.WriteFile(pathExisting, []byte("foobar"), 0644); err != nil { t.Errorf("WriteFile(%q) failed: %v", pathExisting, err) } for _, tc := range []struct { name string path string }{ { name: "new file", path: pathNew, }, { name: "existing", path: pathExisting, }, } { t.Run(tc.name, func(t *testing.T) { pf, err := TempFile("", tc.path) if err != nil { t.Errorf("TempFile(%q) failed: %v", tc.path, err) } for i := 0; i < 3; i++ { if err := pf.Cleanup(); err != nil { t.Errorf("Cleanup() failed: %v", err) } } }) } if _, err := os.Stat(pathNew); !os.IsNotExist(err) { t.Errorf("Stat(%q) didn't report that file doesn't exist: %v", pathNew, err) } if got, err := ioutil.ReadFile(pathExisting); err != nil { t.Errorf("ReadFile(%q) failed: %v", pathExisting, err) } else if want := "foobar"; string(got) != want { t.Errorf("Read unexpected content %q from %q, want %q", string(got), pathExisting, want) } } renameio-2.0.0/writefile.go000066400000000000000000000021571412601760300156360ustar00rootroot00000000000000// Copyright 2018 Google Inc. // // 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. //go:build !windows // +build !windows package renameio import "os" // WriteFile mirrors ioutil.WriteFile, replacing an existing file with the same // name atomically. func WriteFile(filename string, data []byte, perm os.FileMode, opts ...Option) error { opts = append([]Option{ WithPermissions(perm), WithExistingPermissions(), }, opts...) t, err := NewPendingFile(filename, opts...) if err != nil { return err } defer t.Cleanup() if _, err := t.Write(data); err != nil { return err } return t.CloseAtomicallyReplace() } renameio-2.0.0/writefile_test.go000066400000000000000000000103261412601760300166720ustar00rootroot00000000000000// Copyright 2018 Google Inc. // // 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. //go:build !windows // +build !windows package renameio import ( "bytes" "fmt" "io/ioutil" "os" "path/filepath" "testing" ) func TestWriteFile(t *testing.T) { for _, perm := range []os.FileMode{0o755, 0o644, 0o400, 0o765} { t.Run(fmt.Sprintf("perm%04o", perm), func(t *testing.T) { for _, umask := range []os.FileMode{0o000, 0o011, 0o007, 0o027, 0o077} { t.Run(fmt.Sprintf("umask%04o", umask), func(t *testing.T) { withUmask(t, umask) maskedPerm := perm & ^umask filename := filepath.Join(t.TempDir(), "hello.sh") wantData := []byte("#!/bin/sh\necho \"Hello World\"\n") if err := WriteFile(filename, wantData, perm); err != nil { t.Fatal(err) } gotData, err := ioutil.ReadFile(filename) if err != nil { t.Fatal(err) } if !bytes.Equal(gotData, wantData) { t.Errorf("got data %v, want data %v", gotData, wantData) } fi, err := os.Stat(filename) if err != nil { t.Fatal(err) } if gotPerm := fi.Mode() & os.ModePerm; gotPerm != maskedPerm { t.Errorf("got permissions %04o, want %04o", gotPerm, maskedPerm) } }) } }) } } func TestWriteFileIgnoreUmask(t *testing.T) { withUmask(t, 0o077) filename := filepath.Join(t.TempDir(), "file") const wantPerm os.FileMode = 0o765 if err := WriteFile(filename, nil, wantPerm, IgnoreUmask()); err != nil { t.Fatal(err) } fi, err := os.Stat(filename) if err != nil { t.Fatal(err) } if gotPerm := fi.Mode() & os.ModePerm; gotPerm != wantPerm { t.Errorf("got permissions %04o, want %04o", gotPerm, wantPerm) } } func TestWriteFileEquivalence(t *testing.T) { type writeFunc func(string, []byte, os.FileMode, ...Option) error type test struct { name string fn writeFunc perm os.FileMode umask os.FileMode exists bool } var tests []test for _, wf := range []struct { name string fn writeFunc }{ { name: "WriteFile", fn: WriteFile, }, { name: "ioutil", fn: func(filename string, data []byte, perm os.FileMode, opts ...Option) error { return ioutil.WriteFile(filename, data, perm) }, }, } { for _, perm := range []os.FileMode{0o755, 0o644, 0o400, 0o765} { for _, umask := range []os.FileMode{0o000, 0o011, 0o007, 0o027, 0o077} { for _, exists := range []bool{false, true} { name := fmt.Sprintf("%s/perm%04o/umask%04o", wf.name, perm, umask) if exists { name += "/exists" } tests = append(tests, test{ name: name, fn: wf.fn, perm: perm, umask: umask, exists: exists, }) } } } } const existingPerm os.FileMode = 0o654 for _, tc := range tests { t.Run(tc.name, func(t *testing.T) { withUmask(t, tc.umask) maskedPerm := tc.perm & ^tc.umask filename := filepath.Join(t.TempDir(), "test.txt") if tc.exists { // Create file in preparation for replacement fh, err := os.Create(filename) if err != nil { t.Errorf("Create(%q) failed: %v", filename, err) } if err := fh.Chmod(existingPerm); err != nil { t.Errorf("Chmod() failed: %v", err) } fh.Close() maskedPerm = existingPerm } wantData := []byte("content\n") if err := tc.fn(filename, wantData, tc.perm); err != nil { t.Fatal(err) } gotData, err := ioutil.ReadFile(filename) if err != nil { t.Fatal(err) } if !bytes.Equal(gotData, wantData) { t.Errorf("got data %v, want data %v", gotData, wantData) } fi, err := os.Stat(filename) if err != nil { t.Fatal(err) } if gotPerm := fi.Mode() & os.ModePerm; gotPerm != maskedPerm { t.Errorf("got permissions %04o, want %04o", gotPerm, maskedPerm) } }) } }