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bug#8496: some file locking code in insert-file-contents cannot be right
From: |
Eli Zaretskii |
Subject: |
bug#8496: some file locking code in insert-file-contents cannot be right |
Date: |
Thu, 14 Apr 2011 02:48:28 -0400 |
> Date: Wed, 13 Apr 2011 17:40:49 -0700
> From: Paul Eggert <eggert@cs.ucla.edu>
>
> As a result of the "mark unexported symbols 'static'" patch that I'm
> working on, in the Emacs trunk I found some file-locking code inside
> insert-file-contents that cannot be right:
>
> if (NILP (visit) && inserted > 0)
> {
> #ifdef CLASH_DETECTION
> if (!NILP (BVAR (current_buffer, file_truename))
> /* Make binding buffer-file-name to nil effective. */
> && !NILP (BVAR (current_buffer, filename))
> && SAVE_MODIFF >= MODIFF)
> we_locked_file = 1;
> #endif /* CLASH_DETECTION */
> prepare_to_modify_buffer (GPT, GPT, NULL);
> }
>
> The above code is equivalent to a no-op, since 'inserted' must
> be zero here.
In Emacs 21.4a, the corresponding code was this:
if (!NILP (visit))
{
...
#ifdef CLASH_DETECTION
if (NILP (handler))
{
if (!NILP (current_buffer->file_truename))
unlock_file (current_buffer->file_truename);
unlock_file (filename);
}
#endif /* CLASH_DETECTION */
The change to the present form was between 21.4a and 22.1. It appears
in the trunk history as part of a huge merge from a branch, probably
the Emacs 22.1 release branch. I need more forensic work to find out
why the change was made, but at this point it certainly looks like
someone goofed with the condition.
What platforms use CLASH_DETECTION?