unofficial mirror of bug-gnu-emacs@gnu.org 
 help / color / mirror / code / Atom feed
From: Paul Eggert <eggert@cs.ucla.edu>
To: 8496@debbugs.gnu.org
Subject: bug#8496: some file locking code in insert-file-contents cannot be right
Date: Wed, 13 Apr 2011 17:40:49 -0700	[thread overview]
Message-ID: <4DA64291.5060207@cs.ucla.edu> (raw)

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.  There's later code:

   #ifdef CLASH_DETECTION
	 if (we_locked_file)
	   unlock_file (BVAR (current_buffer, file_truename));
   #endif

that is also a no-op, because 'we_locked_file' must be zero.

GCC merrily optimizes all this code away, but I don't think
that was intended.  What *is* intended here?





             reply	other threads:[~2011-04-14  0:40 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-14  0:40 Paul Eggert [this message]
2011-04-14  6:48 ` bug#8496: some file locking code in insert-file-contents cannot be right Eli Zaretskii
2011-04-14  7:53   ` Paul Eggert
2011-04-14  8:07     ` Eli Zaretskii
2011-04-14  8:55   ` Eli Zaretskii
2011-04-14  8:00 ` Andreas Schwab

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.gnu.org/software/emacs/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4DA64291.5060207@cs.ucla.edu \
    --to=eggert@cs.ucla.edu \
    --cc=8496@debbugs.gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).