fileutil

Documentation

Index

• func AtomicWrite(path string, data []byte) error
• func AtomicWriteWithPerm(path string, data []byte, perm os.FileMode) error
• func DirOf(path string) string
• type FileLock
  • func NewFileLock(path string) *FileLock
  • func (fl *FileLock) Lock() error
  • func (fl *FileLock) TryLock() (bool, error)
  • func (fl *FileLock) Unlock() error

Functions

func AtomicWrite

func AtomicWrite(path string, data []byte) error

AtomicWrite writes data to path atomically using a temp file in the same directory followed by a rename. This ensures that a crash mid-write leaves the existing file intact. If the target file already exists, its permissions are preserved; otherwise 0644 is used.

func AtomicWriteWithPerm

func AtomicWriteWithPerm(path string, data []byte, perm os.FileMode) error

AtomicWriteWithPerm writes data to path atomically using a temp file in the same directory followed by a rename. The perm parameter is the fallback permission used when the target file does not yet exist. If the target file already exists, its current permissions are preserved (H-19).

func DirOf

func DirOf(path string) string

DirOf returns the directory component of path, similar to filepath.Dir but optimized for simple path strings without calling filepath.Dir.

Types

type FileLock

type FileLock struct {
	// contains filtered or unexported fields
}

FileLock provides advisory file locking using flock(2). Used to prevent concurrent M31A instances from corrupting shared session files in the same project directory.

func NewFileLock

func NewFileLock(path string) *FileLock

NewFileLock creates a FileLock for the given path. The lock file is created on Lock() if it doesn't exist.

func (*FileLock) Lock

func (fl *FileLock) Lock() error

Lock acquires an exclusive lock on the file. Blocks until the lock is available. Returns an error if the file cannot be opened.

func (*FileLock) TryLock

func (fl *FileLock) TryLock() (bool, error)

TryLock attempts to acquire an exclusive lock without blocking. Returns false if the lock is already held by another process.

func (*FileLock) Unlock

func (fl *FileLock) Unlock() error

Unlock releases the lock and closes the file.