Project

General

Profile

Actions

Bug #6601

closed

[readline] Alt-* commands do not work in reverse-i-search

Added by rctay (Tay Ray Chuan) almost 12 years ago. Updated almost 12 years ago.

Status:
Closed
Target version:
ruby -v:
ruby 1.9.3p236 (2012-06-11) [x86_64-linux]
Backport:
[ruby-core:45682]

Description

=begin
= Steps to reproduce
Below are the steps to reproduce from an (({irb})) session. ^ is used to denote the cursor position on the screen.

  • Type ((%puts :a%)) then ((%Enter%)). This is to populate the history for reverse-i-search.
    irb(main):001:0> puts :a
    a
    => nil

  • Hit ((%Ctrl-R%)) (for reverse-i-search), followed by ((%u%)):
    (reverse-i-search)`u': puts :a
    ^

  • Hit ((%Alt-F%)) (for forward-word).

Observed: reverse-i-search terminated, with an 'f' inserted at cursor position.
irb(main):002:0> pfuts :a
^

Expected: reverse-i-search terminated, nothing inserted, cursor moves to end of the word (({puts})):
irb(main):002:0> puts :a
^

Note that other ((%Alt-*%)) commands don't work too (ie ((%x%)) is inserted instead of the command ((%Alt-x%)) being performed), including

  • ((%Alt-B%)) (move backward a word)
  • ((%Alt-C%)) (capitalize letter)
  • ((%Alt-D%)) (delete till end of word)

= Fix

When we hit ((%Alt-F%)) from reverse-i-search, execution arrives at this piece of code in libreadline's (({isearch.c})):

387 /* ESC still terminates the search, but if there is pending
388 input or if input arrives within 0.1 seconds (on systems
389 with select(2)) it is used as a prefix character
390 with rl_execute_next. WATCH OUT FOR THIS! This is intended
391 to allow the arrow keys to be used like ^F and ^B are used
392 to terminate the search and execute the movement command.
393 XXX - since _rl_input_available depends on the application-
394 settable keyboard timeout value, this could alternatively
395 use _rl_input_queued(100000) */
396 if (cxt->lastc == ESC && _rl_input_available ())
397 rl_execute_next (ESC);

Due to (({readline_getc()})), our (({rl_getc_function()})) implementation, (({IO::getbyte()})) is called, causing all input characters to be "swallowed" into our byte buffer in (({readline_instream})). Thus (({_rl_input_available()})) incorrectly returns false, and the keystrokes (eg. Alt, F) fail to be recognized as a binding for a command.

The proposed fix (attached) uses (({rb_io_read_pending()})) to emulate (({_rl_input_available()})), and calls (({rl_execute_next()})), as libreadline does.

= Affected Versions

Ruby trunk and 1.9.3 (latest) exhibits this issue.

Ruby 1.8 also has exhibits this issue, but the fix would be different since (({rl_getc_function()})) isn't overriden in (({ext/readline/readline.c})).

Tested on readline 6.2; blame'ing the above snippet shows that readline as far back as 5.1 should also give this behaviour.

=end


Files

readline.diff (852 Bytes) readline.diff applies cleanly on trunk and Backport93 rctay (Tay Ray Chuan), 06/17/2012 05:23 PM

Related issues 1 (0 open1 closed)

Related to Ruby master - Bug #6262: [readline] reverse-i-search with multibyte charsClosedkouji (Kouji Takao)04/06/2012Actions
Actions

Also available in: Atom PDF

Like0
Like0Like0Like0Like0Like0