[issue15122] Add an option to always rewrite single-file mailboxes in-place.

[Petri Lehtinen]

Petri Lehtinen <petri at digip.org> added the comment:

I looked at the source code of mutt to see how it rewrites mbox files. It does roughly this:

1. Block some signals.

2. Lock the mbox file (with dotlock, fcntl and flock).

3. Create a temporary file in /tmp.

4. Write messages to the temporary file, from the point where the first change is up to the end of the mbox file. This saves a lot of writing when the first change is near the end of the file.

5. Write changes from the temporary file to the mbox file, modifying the mbox file in-place.

6. Truncate the mbox file to the correct length.

7. Unblock signals.

If writing the changes back to the mbox file fails, the temporary file is copied from /tmp to near the mbox file.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue15122>
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