go/src/cmd/go/internal/lockedfile/lockedfile.go

type File …

type osFile …

// OpenFile is like os.OpenFile, but returns a locked file.
// If flag includes os.O_WRONLY or os.O_RDWR, the file is write-locked;
// otherwise, it is read-locked.
func OpenFile(name string, flag int, perm fs.FileMode) (*File, error) { … }

// Open is like os.Open, but returns a read-locked file.
func Open(name string) (*File, error) { … }

// Create is like os.Create, but returns a write-locked file.
func Create(name string) (*File, error) { … }

// Edit creates the named file with mode 0666 (before umask),
// but does not truncate existing contents.
//
// If Edit succeeds, methods on the returned File can be used for I/O.
// The associated file descriptor has mode O_RDWR and the file is write-locked.
func Edit(name string) (*File, error) { … }

// Close unlocks and closes the underlying file.
//
// Close may be called multiple times; all calls after the first will return a
// non-nil error.
func (f *File) Close() error { … }

// Read opens the named file with a read-lock and returns its contents.
func Read(name string) ([]byte, error) { … }

// Write opens the named file (creating it with the given permissions if needed),
// then write-locks it and overwrites it with the given content.
func Write(name string, content io.Reader, perm fs.FileMode) (err error) { … }

// Transform invokes t with the result of reading the named file, with its lock
// still held.
//
// If t returns a nil error, Transform then writes the returned contents back to
// the file, making a best effort to preserve existing contents on error.
//
// t must not modify the slice passed to it.
func Transform(name string, t func([]byte) ([]byte, error)) (err error) { … }