#14807: move undocumented tarfile.filemode() to stat.filemode(). Add tarfile.filemode alias with deprecation warning.

Lib/stat.py

@@ -107,3 +107,43 @@ SF_IMMUTABLE = 0x00020000  # file may not be changed
 SF_APPEND    = 0x00040000  # file may only be appended to
 SF_NOUNLINK  = 0x00100000  # file may not be renamed or deleted
 SF_SNAPSHOT  = 0x00200000  # file is a snapshot file
+
+
+_filemode_table = (
+    ((S_IFLNK,         "l"),
+     (S_IFREG,         "-"),
+     (S_IFBLK,         "b"),
+     (S_IFDIR,         "d"),
+     (S_IFCHR,         "c"),
+     (S_IFIFO,         "p")),
+
+    ((S_IRUSR,         "r"),),
+    ((S_IWUSR,         "w"),),
+    ((S_IXUSR|S_ISUID, "s"),
+     (S_ISUID,         "S"),
+     (S_IXUSR,         "x")),
+
+    ((S_IRGRP,         "r"),),
+    ((S_IWGRP,         "w"),),
+    ((S_IXGRP|S_ISGID, "s"),
+     (S_ISGID,         "S"),
+     (S_IXGRP,         "x")),
+
+    ((S_IROTH,         "r"),),
+    ((S_IWOTH,         "w"),),
+    ((S_IXOTH|S_ISVTX, "t"),
+     (S_ISVTX,         "T"),
+     (S_IXOTH,         "x"))
+)
+
+def filemode(mode):
+    """Convert a file's mode to a string of the form '-rwxrwxrwx'."""
+    perm = []
+    for table in _filemode_table:
+        for bit, char in table:
+            if mode & bit == bit:
+                perm.append(char)
+                break
+        else:
+            perm.append("-")
+    return "".join(perm)