--- shutil-2.7.py	2010-10-02 14:45:09.329896108 +0100
+++ shutil-2.7-mod.py	2010-10-02 15:08:50.250894735 +0100
@@ -42,13 +42,23 @@
 except NameError:
     WindowsError = None
 
-def copyfileobj(fsrc, fdst, length=16*1024):
+SPARSE_AUTO   = 0
+SPARSE_ALWAYS = 1
+SPARSE_NEVER  = 2
+
+def copyfileobj(fsrc, fdst, length=16*1024, make_sparse=False):
     """copy data from file-like object fsrc to file-like object fdst"""
     while 1:
         buf = fsrc.read(length)
         if not buf:
             break
-        fdst.write(buf)
+        if make_sparse and buf == '\0'*len(buf):
+            fdst.seek(len(buf), os.SEEK_CUR)
+        else:
+            fdst.write(buf)
+    if make_sparse:
+        # Make sure the file ends where it should, even if padded out.
+        fdst.truncate()
 
 def _samefile(src, dst):
     # Macintosh, Unix.
@@ -62,7 +72,7 @@
     return (os.path.normcase(os.path.abspath(src)) ==
             os.path.normcase(os.path.abspath(dst)))
 
-def copyfile(src, dst):
+def copyfile(src, dst, sparse_mode=SPARSE_AUTO):
     """Copy data from src to dst"""
     if _samefile(src, dst):
         raise Error("`%s` and `%s` are the same file" % (src, dst))
@@ -79,8 +89,20 @@
                 raise SpecialFileError("`%s` is a named pipe" % fn)
 
     with open(src, 'rb') as fsrc:
+        if sparse_mode == SPARSE_NEVER:
+            make_sparse = False
+        elif sparse_mode == SPARSE_ALWAYS:
+            make_sparse = True
+        else:
+            # Assume it's AUTO
+            stat = os.fstat(fsrc.fileno())
+            if hasattr(stat, 'st_blocks') and hasattr(stat, 'st_blksize'):
+                disksize = stat.st_blocks * stat.st_blksize
+                make_sparse = (disksize < stat.st_size)
+            else:
+                make_sparse = False
         with open(dst, 'wb') as fdst:
-            copyfileobj(fsrc, fdst)
+            copyfileobj(fsrc, fdst, make_sparse=make_sparse)
 
 def copymode(src, dst):
     """Copy mode bits from src to dst"""