This package is a fork of the internal package "cmd/go/internal/lockedfile/internal/filelock" providing an advisory file locking interface. The package attempts to expose filelocks as an interface similar to sync.RWMutex. Internally, this package uses flock(2) with fallback to fcntl(2) advisory record locking for UNIX systems and uses the win32 file API for Windows.

Although this package attempts to provide a cross-platform interface, there are some minor platform-dependent discrepancies the programmer should be aware of:

• For POSIX systems that relies on fcntl(2) advisory file locking (e.g. Solaris) each process can hold only one read-lock per inode. Additional read-locks within the same process will block until the initial lock is released.
• While UNIX systems places advisory file locks, Windows enforces the filelocks on any I/O operation performed on the file. That is, an I/O operation on a locked file will block until released.