view tests/svn-safe-append.py @ 31209:dd2364f5180a

localrepo: handle rename with hardlinks properly

In "aftertrans", we rename "journal.*" to "undo.*". We expect "journal.*"
files to disappear after renaming.

However, if "journal.foo" and "undo.foo" refer to a same file (hardlink),
rename may be a no-op, leaving both files on disk, according to Linux
manpage [1]:

    If oldpath and newpath are existing hard links referring to the same
    file, then rename() does nothing, and returns  a  suc‐ cess status.

The POSIX specification [2] is not very clear about what to do.

To be safe, remove "undo.*" before the rename so "journal.*" cannot be left
on disk.

[1]: http://man7.org/linux/man-pages/man2/rename.2.html
[2]: http://pubs.opengroup.org/onlinepubs/9699919799/

#!/usr/bin/env python

from __future__ import absolute_import

__doc__ = """Same as `echo a >> b`, but ensures a changed mtime of b.
Without this svn will not detect workspace changes."""

import os
import sys

text = sys.argv[1]
fname = sys.argv[2]

f = open(fname, "ab")
try:
    before = os.fstat(f.fileno()).st_mtime
    f.write(text)
    f.write("\n")
finally:
    f.close()
inc = 1
now = os.stat(fname).st_mtime
while now == before:
    t = now + inc
    inc += 1
    os.utime(fname, (t, t))
    now = os.stat(fname).st_mtime