Initial project import

tools/v/vlib/os/filelock/lib_windows.c.v

@@ -0,0 +1,99 @@
+module filelock
+
+#insert "@VEXEROOT/vlib/os/filelock/filelock_helpers.h"
+
+fn C.DeleteFileW(&u16) bool
+fn C.CreateFileW(&u16, u32, u32, voidptr, u32, u32, voidptr) voidptr
+fn C.CloseHandle(voidptr) bool
+fn C.v_filelock_lock(voidptr, int, int, u64, u64) int
+fn C.v_filelock_unlock(voidptr, u64, u64) int
+
+fn (l &FileLock) open_lock() i64 {
+	if l.target == .file {
+		return open_existing_file(l.name, l.mode)
+	}
+	return open_lockfile(l.name)
+}
+
+fn open_lockfile(path string) i64 {
+	path_wide := path.to_wide()
+	handle := C.CreateFileW(path_wide, C.GENERIC_READ | C.GENERIC_WRITE, 0, 0, C.OPEN_ALWAYS,
+		C.FILE_ATTRIBUTE_NORMAL, 0)
+	return file_handle(handle)
+}
+
+fn open_existing_file(path string, mode LockMode) i64 {
+	path_wide := path.to_wide()
+	access := if mode == .shared { C.GENERIC_READ } else { C.GENERIC_READ | C.GENERIC_WRITE }
+	share_mode := C.FILE_SHARE_READ | C.FILE_SHARE_WRITE | C.FILE_SHARE_DELETE
+	handle := C.CreateFileW(path_wide, access, share_mode, 0, C.OPEN_EXISTING,
+		C.FILE_ATTRIBUTE_NORMAL, 0)
+	return file_handle(handle)
+}
+
+fn file_handle(handle voidptr) i64 {
+	return if handle == voidptr(-1) { -1 } else { i64(handle) }
+}
+
+fn (l &FileLock) lock_handle(handle voidptr, immediate bool) bool {
+	if l.target != .file {
+		return true
+	}
+	return C.v_filelock_lock(handle, int(l.mode == .exclusive), int(immediate), l.start, l.len) == 0
+}
+
+fn (mut l FileLock) close_lock() {
+	if l.fd == -1 {
+		return
+	}
+	handle := voidptr(l.fd)
+	if l.target == .file {
+		C.v_filelock_unlock(handle, l.start, l.len)
+		C.CloseHandle(handle)
+	} else {
+		C.CloseHandle(handle)
+		path_wide := l.name.to_wide()
+		C.DeleteFileW(path_wide)
+	}
+	l.fd = -1
+}
+
+// acquire blocks until the lock is acquired.
+pub fn (mut l FileLock) acquire() ! {
+	if l.fd != -1 {
+		return error_with_code('lock already acquired by this instance', 1)
+	}
+	fd := l.open_lock()
+	if fd == -1 {
+		msg := if l.target == .file {
+			'cannot open file ${l.name}'
+		} else {
+			'cannot create lock file ${l.name}'
+		}
+		return error_with_code(msg, -1)
+	}
+	handle := voidptr(fd)
+	if !l.lock_handle(handle, false) {
+		C.CloseHandle(handle)
+		return error_with_code('cannot lock ${l.name}', -2)
+	}
+	l.fd = fd
+}
+
+// try_acquire tries to acquire the lock without blocking.
+pub fn (mut l FileLock) try_acquire() bool {
+	if l.fd != -1 {
+		return true
+	}
+	fd := l.open_lock()
+	if fd == -1 {
+		return false
+	}
+	handle := voidptr(fd)
+	if !l.lock_handle(handle, true) {
+		C.CloseHandle(handle)
+		return false
+	}
+	l.fd = fd
+	return true
+}