1 files changed, 54 insertions, 0 deletions
diff --git a/win32/win32.c b/win32/win32.c
index e6dfb6b024..9a0f910b42 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -1120,3 +1120,57 @@ stolen_get_osfhandle(int fd)
 {
     return pIOSubSystem->pfn_get_osfhandle(fd);
 }
+
+
+/*
+ * Extras.
+ */
+
+/* simulate flock by locking a range on the file */
+
+#define LK_ERR(f,i)	((f) ? (i = 0) : (errno = GetLastError()))
+#define LK_LEN		0xffff0000
+
+DllExport int
+win32_flock(int fd, int oper)
+{
+    OVERLAPPED o;
+    int i = -1;
+    HANDLE fh;
+
+    if (!IsWinNT()) {
+	croak("flock() unimplemented on this platform");
+	return -1;
+    }
+
+    fh = (HANDLE)stolen_get_osfhandle(fd);
+    memset(&o, 0, sizeof(o));
+
+    switch(oper) {
+    case LOCK_SH:		/* shared lock */
+	LK_ERR(LockFileEx(fh, 0, 0, LK_LEN, 0, &o),i);
+	break;
+    case LOCK_EX:		/* exclusive lock */
+	LK_ERR(LockFileEx(fh, LOCKFILE_EXCLUSIVE_LOCK, 0, LK_LEN, 0, &o),i);
+	break;
+    case LOCK_SH|LOCK_NB:	/* non-blocking shared lock */
+	LK_ERR(LockFileEx(fh, LOCKFILE_FAIL_IMMEDIATELY, 0, LK_LEN, 0, &o),i);
+	break;
+    case LOCK_EX|LOCK_NB:	/* non-blocking exclusive lock */
+	LK_ERR(LockFileEx(fh,
+		       LOCKFILE_EXCLUSIVE_LOCK|LOCKFILE_FAIL_IMMEDIATELY,
+		       0, LK_LEN, 0, &o),i);
+	break;
+    case LOCK_UN:		/* unlock lock */
+	LK_ERR(UnlockFileEx(fh, 0, LK_LEN, 0, &o),i);
+	break;
+    default:			/* unknown */
+	errno = EINVAL;
+	break;
+    }
+    return i;
+}
+
+#undef LK_ERR
+#undef LK_LEN
+