Fix clonefile across filesystems (#1737)

Fixes #1736

tools/bundletool/bundletool_experimental.py

@@ -46,21 +46,23 @@
       bundle is complete but before it is signed.
 """
 
+import errno
 import filecmp
 import json
 import os
 import shutil
 import sys
 import zipfile
-from ctypes import cdll, c_char_p, c_int
+from ctypes import CDLL, c_char_p, c_int, get_errno
 
 _CLONEFILE = None
+_USE_CLONEFILE = sys.platform == "darwin"
 def _load_clonefile():
   global _CLONEFILE
   if _CLONEFILE:
     return _CLONEFILE
 
-  system = cdll.LoadLibrary('/usr/lib/libSystem.dylib')
+  system = CDLL('/usr/lib/libSystem.dylib', use_errno=True)
   _CLONEFILE = system.clonefile
   _CLONEFILE.argtypes = [c_char_p, c_char_p, c_int] # src, dest, flags
   _CLONEFILE.restype = c_int  # 0 on success
@@ -212,11 +214,16 @@ def _copy_file(self, src, dest, executable, bundle_root):
       raise BundleConflictError(dest)
 
     self._makedirs_safely(os.path.dirname(full_dest))
-    if sys.platform == "darwin":
+    global _USE_CLONEFILE
+    if _USE_CLONEFILE:
       clonefile = _load_clonefile()
       result = clonefile(src.encode(), full_dest.encode(), 0)
       if result != 0:
-        raise Exception(f"failed to clonefile {src} to {full_dest}")
+        if get_errno() in (errno.EXDEV, errno.ENOTSUP):
+          _USE_CLONEFILE = False
+          shutil.copy(src, full_dest)
+        else:
+          raise Exception(f"failed to clonefile {src} to {full_dest}")
     else:
       shutil.copy(src, full_dest)
     os.chmod(full_dest, 0o755 if executable else 0o644)