From: "rctay (Tay Ray Chuan)" Date: 2012-06-17T17:23:13+09:00 Subject: [ruby-core:45682] [ruby-trunk - Bug #6601][Open] [readline] Issue #6601 has been reported by rctay (Tay Ray Chuan). ---------------------------------------- Bug #6601: [readline] https://bugs.ruby-lang.org/issues/6601 Author: rctay (Tay Ray Chuan) Status: Open Priority: Normal Assignee: Category: Target version: ruby -v: ruby 1.9.3p236 (2012-06-11) [x86_64-linux] =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 -- http://bugs.ruby-lang.org/