Package: emacs;
Reported by: Anders Lindgren <andlind <at> gmail.com>
Date: Tue, 28 Jan 2014 09:10:02 UTC
Severity: normal
Done: Eli Zaretskii <eliz <at> gnu.org>
Bug is archived. No further changes may be made.
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From: help-debbugs <at> gnu.org (GNU bug Tracking System) To: Anders Lindgren <andlind <at> gmail.com> Subject: bug#16576: closed (Re: bug#16576: Binding `standard-output' to a function doesn't work -- function sometimes called with garbage) Date: Wed, 29 Jan 2014 18:03:03 +0000
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Your bug report #16576: Binding `standard-output' to a function doesn't work -- function sometimes called with garbage which was filed against the emacs package, has been closed. The explanation is attached below, along with your original report. If you require more details, please reply to 16576 <at> debbugs.gnu.org. -- 16576: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=16576 GNU Bug Tracking System Contact help-debbugs <at> gnu.org with problems
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From: Eli Zaretskii <eliz <at> gnu.org> To: Anders Lindgren <andlind <at> gmail.com> Cc: 16576-done <at> debbugs.gnu.org Subject: Re: bug#16576: Binding `standard-output' to a function doesn't work -- function sometimes called with garbage Date: Wed, 29 Jan 2014 20:01:57 +0200> Date: Tue, 28 Jan 2014 23:00:32 +0100 > From: Anders Lindgren <andlind <at> gmail.com> > Cc: 16576 <at> debbugs.gnu.org > > Well, the main issue here is if this is a real bug or not. You originally > thought this was simply a mistake in the example I provided -- do you still > think so? There was indeed a bug, now fixed on the trunk, which caused the problem. It was a very old bug, it went unnoticed until now because, I guess, no one conses a string one character at a time -- this is a terrible idea in Emacs Lisp. Use a temporary buffer instead. There was nothing wrong with prin1 per se, btw, it's just that its subroutine which prints a string wasn't safe when GC hit in the middle of a prin1 call. The code protected the string from GC, but that doesn't preclude relocation of string data, so holding to C 'char *' pointers is not safe in these situations. And printing a 800-character string like you did triggers GC every time, because it creates 800 string objects for a grand total of about 320000 bytes. Anyway, problem solved, and I'm closing the bug. Thanks.
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From: Anders Lindgren <andlind <at> gmail.com> To: bug-gnu-emacs <at> gnu.org Subject: Binding `standard-output' to a function doesn't work -- function sometimes called with garbage Date: Tue, 28 Jan 2014 10:09:08 +0100[Message part 4 (text/plain, inline)]Hi! When binding `standard-output' to a function, is seems as though the function sometimes is called with garbage, like random control characters or part of the string in "random" order. I've seen this problem in Emacs 22 and Emacs 24.3. I haven't been able to reproduce it on the Emacs trunk, but I've seen some problems (although less frequent) that could be explained if the problem existed there as well. Steps to repeat: emacs -Q Eval the following: (defvar bug-bind-output-str nil) (defun bug-bind-output-function (char) (setq bug-bind-output-str (concat bug-bind-output-str (list char)))) (defun bug-bind-output-test () (interactive) (let ((bug-bind-output-str "") (standard-output 'bug-bind-output-function) (s "(\\(co\\(?:mbine-after-change-calls\\|nd\\(?:ition-case\\(?:-unless-debug\\)?\\)?\\)\\|eval-\\(?:a\\(?:fter-load\\|nd-compile\\)\\|next-after-load\\|when\\(?:-compile\\)?\\)\\|i\\(?:f\\|nline\\)\\|l\\(?:ambda\\|et\\(?:\\*\\|rec\\)?\\)\\|p\\(?:case\\(?:-let\\*?\\)?\\|rog[*12nv]?\\)\\|save-\\(?:current-buffer\\|excursion\\|match-data\\|restriction\\|selected-window\\|window-excursion\\)\\|track-mouse\\|unwind-protect\\|w\\(?:hile\\(?:-no-input\\)?\\|ith-\\(?:c\\(?:a\\(?:\\(?:se\\|tegory\\)-table\\)\\|urrent-buffer\\)\\|demoted-errors\\|electric-help\\|local-quit\\|no-warnings\\|output-to-\\(?:string\\|temp-buffer\\)\\|s\\(?:elected-\\(?:frame\\|window\\)\\|ilent-modifications\\|yntax-table\\)\\|t\\(?:emp-\\(?:buffer\\|\\(?:fil\\|messag\\)e\\)\\|imeout\\(?:-handler\\)?\\)\\|wrapper-hook\\)\\)\\)\\>") s0) (prin1 s) bug-bind-output-str)) Type this a number of times: M-x (bug-bind-output-test) RET A correct output looks like: "\"(\\\\(co\\\\(?:mbine-after-change-calls\\\\|nd\\\\(?:ition-case\\\\(?:-unless-debug\\\\)?\\\\)?\\\\)\\\\|eval-\\\\(?:a\\\\(?:fter-load\\\\|nd-compile\\\\)\\\\|next-after-load\\\\|when\\\\(?:-compile\\\\)?\\\\)\\\\|i\\\\(?:f\\\\|nline\\\\)\\\\|l\\\\(?:ambda\\\\|et\\\\(?:\\\\*\\\\|rec\\\\)?\\\\)\\\\|p\\\\(?:case\\\\(?:-let\\\\*?\\\\)?\\\\|rog[*12nv]?\\\\)\\\\|save-\\\\(?:current-buffer\\\\|excursion\\\\|match-data\\\\|restriction\\\\|selected-window\\\\|window-excursion\\\\)\\\\|track-mouse\\\\|unwind-protect\\\\|w\\\\(?:hile\\\\(?:-no-input\\\\)?\\\\|ith-\\\\(?:c\\\\(?:a\\\\(?:\\\\(?:se\\\\|tegory\\\\)-table\\\\)\\\\|urrent-buffer\\\\)\\\\|demoted-errors\\\\|electric-help\\\\|local-quit\\\\|no-warnings\\\\|output-to-\\\\(?:string\\\\|temp-buffer\\\\)\\\\|s\\\\(?:elected-\\\\(?:frame\\\\|window\\\\)\\\\|ilent-modifications\\\\|yntax-table\\\\)\\\\|t\\\\(?:emp-\\\\(?:buffer\\\\|\\\\(?:fil\\\\|messag\\\\)e\\\\)\\\\|imeout\\\\(?:-handler\\\\)?\\\\)\\\\|wrapper-hook\\\\)\\\\)\\\\)\\\\>\"" This is an example of bad output, here, the last couple of lines does not correspond to the string being printed. "\"(\\\\(co\\\\(?:mbine-after-change-calls\\\\|nd\\\\(?:ition-case\\\\(?:-unless-debug\\\\)?\\\\)?\\\\)\\\\|eval-\\\\(?:a\\\\(?:fter-load\\\\|nd-compile\\\\)\\\\|next-after-load\\\\|when\\\\(?:-compile\\\\)?\\\\)\\\\|i\\\\(?:f\\\\|nline\\\\)\\\\|l\\\\(?:ambda\\\\|et\\\\(?:\\\\*\\\\|rec\\\\)?\\\\)\\\\|p\\\\(?:case\\\\(?:-let\\\\*?\\\\)?\\\\|rog[*12nv]?\\\\)\\\\|save-\\\\(?:current-buffer\\\\|excursion\\\\|match-data\\\\|restriction\\\\|selected-window\\\\|window-excursion\\\\)\\\\|track-mouse\\\\|unwind-protect\\\\|w\\\\(?:hile\\\\(?:-no-input\\\\)?\\\\|ith-\\\\(?:c\\\\(?:a\\\\(?:\\\\(?:se\\\\|tegory\\\\\\\\(?:-no-input\\\\\\\\)?\\\\\\\\|ith-\\\\\\\\(?:c\\\\\\\\(?:a\\\\\\\\(?:\\\\\\\\(?:se\\\\\\\\|tegory\\\\locaw\\\"(\\\\\\\\(co\\\\\\\\(?:mbine-after-change-calls\\\\\\\\|nd\\\\\\\\(?:ition-case\\\\\\\\(?:-unless-debug\\\\\\\\)?\\\\\\\\)?\\\\\\\\)\\\\\\\\|eval-\\\\\\\\(?:a\\\\\\\\(?:fter-load\\\\\\\\|nd-compile\\\\\\\\)\\\\\\\\|next-after-load\\\\\\\\|when\\\\\\\\(?:-compile\\\\\\\\)?\\\\\\\\)\\\\\\\\|i\\\\\\\\(?:f\\\\\\\\|nline\\\\\\\\)\\\\\\\\|l\\\\\\\\(?:ambd\"" Other examples of bad output is if the string contains random control characters. I've noticed that this is intermittent. Sometimes, say, every tenth call returns a broken string. Sometimes it feels as though you can call the function any number of times without getting a bad string. Sincerely, Anders Lindgren If Emacs crashed, and you have the Emacs process in the gdb debugger, please include the output from the following gdb commands: `bt full' and `xbacktrace'. For information about debugging Emacs, please read the file /Applications/Emacs24.3.app/Contents/Resources/etc/DEBUG. In GNU Emacs 24.3.1 (x86_64-apple-darwin, NS apple-appkit-1038.36) of 2013-03-13 on bob.porkrind.org Windowing system distributor `Apple', version 10.3.1265 Configured using: `configure '--host=x86_64-apple-darwin' '--build=i686-apple-darwin' '--with-ns' 'build_alias=i686-apple-darwin' 'host_alias=x86_64-apple-darwin' 'CC=gcc -mmacosx-version-min=10.7 -isystem /Users/david/Xcode-10.7_4.5.2/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk/usr/include/ -F/Users/david/Xcode-10.7_4.5.2/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk/System/Library/Frameworks'' Important settings: value of $LC_CTYPE: UTF-8 locale-coding-system: utf-8-unix default enable-multibyte-characters: t Major mode: Emacs-Lisp Minor modes in effect: tooltip-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t line-number-mode: t transient-mark-mode: t Recent input: <down> <right> <right> <escape> C-x <down> <down> <down> <escape> C-x <down> <down> <down> <down> <down> <down> <escape> C-x <escape> : ( b i g <backspace> <backspace> u g - b i <tab> t <tab> ) <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> : <up> <return> <escape> x e m a c s - b u <tab> C-g <escape> x m <backspace> e m a c s - b i <backspace> u g <tab> <s-backspace> <s-backspace> <escape> <backspace> <escape> <backspace> <escape> C-g r e p o r t - e m <tab> <return> Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Loading vc-svn...done bug-bind-output-str bug-bind-output-function bug-bind-output-test "\"(\\\\(co\\\\(?:mbine-after-change-calls\\\\|nd\\\\(?:ition-case\\\\(?:-unless-debug\\\\)?\\\\)?\\\\)\\\\|eval-\\\\(?:a\\\\(?:fter-load\\\\|nd-compile\\\\)\\\\|next-after-load\\\\|when\\\\(?:-compile\\\\)?\\\\)\\\\|i\\\\(?:f\\\\|nline\\\\)\\\\|l\\\\(?:ambda\\\\|et\\\\(?:\\\\*\\\\|rec\\\\)?\\\\)\\\\|p\\\\(?:case\\\\(?:-let\\\\*?\\\\)?\\\\|rog[*12nv]?\\\\)\\\\|save-\\\\(?:current-buffer\\\\|excursion\\\\|match-data\\\\|restriction\\\\|selected-window\\\\|window-excursion\\\\)\\\\|track-mouse\\\\|unwind-protect\\\\|w\\\\(?:hile\\\\(?:-no-input\\\\)?\\\\|ith-\\\\(?:c\\\\(?:a\\\\(?:\\\\(?:se\\\\|tegory\\\\)-table\\\\)\\\\|urrent-buffer\\\\)\\\\|demoted-errors\\\\|electric-help\\\\|local-quit\\\\|no-warnings\\\\|output-to-\\\\(?:string\\\\|temp-buffer\\\\)\\\\|s\\\\(?:elected-\\\\(?:frame\\\\|window\\\\)\\\\|ilent-modifications\\\\|yntax-table\\\\)\\\\|t\\\\(?:emp-\\\\(?:buffer\\\\|\\\\(?:fil\\\\|messag\\\\)e\\\\)\\\\|imeout\\\\(?:-handler\\\\)?\\\\)\\\\|wrapper-hook\\\\)\\\\)\\\\)\\\\>\"" [11 times] "\"(\\\\(co\\\\(?:mbine-after-change-calls\\\\|nd\\\\(?:ition-case\\\\(?:-unless-debug\\\\)?\\\\)?\\\\)\\\\|eval-\\\\(?:a\\\\(?:fter-load\\\\|nd-compile\\\\)\\\\|next-after-load\\\\|when\\\\(?:-compile\\\\)?\\\\)\\\\|i\\\\(?:f\\\\|nline\\\\)\\\\|l\\\\(?:ambda\\\\|et\\\\(?:\\\\*\\\\|rec\\\\)?\\\\)\\\\|p\\\\(?:case\\\\(?:-let\\\\*?\\\\)?\\\\|rog[*12nv]?\\\\)\\\\|save-\\\\(?:current-buffer\\\\|excursion\\\\|match-data\\\\|restriction\\\\|selected-window\\\\|window-excursion\\\\)\\\\|track-mouse\\\\|unwind-protect\\\\|w\\\\(?:hile\\\\(?:-no-input\\\\)?\\\\|ith-\\\\(?:c\\\\(?:a\\\\(?:\\\\(?:se\\\\|tegory\\\\\\\\(?:-no-input\\\\\\\\)?\\\\\\\\|ith-\\\\\\\\(?:c\\\\\\\\(?:a\\\\\\\\(?:\\\\\\\\(?:se\\\\\\\\|tegory\\\\locaw\\\"(\\\\\\\\(co\\\\\\\\(?:mbine-after-change-calls\\\\\\\\|nd\\\\\\\\(?:ition-case\\\\\\\\(?:-unless-debug\\\\\\\\)?\\\\\\\\)?\\\\\\\\)\\\\\\\\|eval-\\\\\\\\(?:a\\\\\\\\(?:fter-load\\\\\\\\|nd-compile\\\\\\\\)\\\\\\\\|next-after-load\\\\\\\\|when\\\\\\\\(?:-compile\\\\\\\\)?\\\\\\\\)\\\\\\\\|i\\\\\\\\(?:f\\\\\\\\|nline\\\\\\\\)\\\\\\\\|l\\\\\\\\(?:ambd\"" Quit Load-path shadows: None found. 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