Initial project import

tools/v/vlib/os/filelock/filelock_helpers.h

@@ -0,0 +1,63 @@
+#ifndef V_OS_FILELOCK_HELPERS_H
+#define V_OS_FILELOCK_HELPERS_H
+
+#include <string.h>
+
+#ifdef _WIN32
+#include <windows.h>
+
+static int v_filelock_lock(HANDLE handle, int exclusive, int immediate,
+	unsigned long long start, unsigned long long len) {
+	OVERLAPPED overlap;
+	memset(&overlap, 0, sizeof(overlap));
+	overlap.Offset = (DWORD)(start & 0xffffffffULL);
+	overlap.OffsetHigh = (DWORD)(start >> 32);
+	DWORD flags = immediate ? LOCKFILE_FAIL_IMMEDIATELY : 0;
+	if (exclusive) {
+		flags |= LOCKFILE_EXCLUSIVE_LOCK;
+	}
+	DWORD low = len == 0 ? MAXDWORD : (DWORD)(len & 0xffffffffULL);
+	DWORD high = len == 0 ? MAXDWORD : (DWORD)(len >> 32);
+	return LockFileEx(handle, flags, 0, low, high, &overlap) ? 0 : -1;
+}
+
+static int v_filelock_unlock(HANDLE handle, unsigned long long start,
+	unsigned long long len) {
+	OVERLAPPED overlap;
+	memset(&overlap, 0, sizeof(overlap));
+	overlap.Offset = (DWORD)(start & 0xffffffffULL);
+	overlap.OffsetHigh = (DWORD)(start >> 32);
+	DWORD low = len == 0 ? MAXDWORD : (DWORD)(len & 0xffffffffULL);
+	DWORD high = len == 0 ? MAXDWORD : (DWORD)(len >> 32);
+	return UnlockFileEx(handle, 0, low, high, &overlap) ? 0 : -1;
+}
+
+#else
+#include <fcntl.h>
+#include <unistd.h>
+
+static int v_filelock_lock(int fd, int exclusive, int immediate,
+	unsigned long long start, unsigned long long len) {
+	struct flock fl;
+	memset(&fl, 0, sizeof(fl));
+	fl.l_type = exclusive ? F_WRLCK : F_RDLCK;
+	fl.l_whence = SEEK_SET;
+	fl.l_start = (off_t)start;
+	fl.l_len = len == 0 ? 0 : (off_t)len;
+	return fcntl(fd, immediate ? F_SETLK : F_SETLKW, &fl);
+}
+
+static int v_filelock_unlock(int fd, unsigned long long start,
+	unsigned long long len) {
+	struct flock fl;
+	memset(&fl, 0, sizeof(fl));
+	fl.l_type = F_UNLCK;
+	fl.l_whence = SEEK_SET;
+	fl.l_start = (off_t)start;
+	fl.l_len = len == 0 ? 0 : (off_t)len;
+	return fcntl(fd, F_SETLK, &fl);
+}
+
+#endif
+
+#endif