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Re: ctrl-w oddity on bash-4.4


From: Eduardo A . Bustamante López
Subject: Re: ctrl-w oddity on bash-4.4
Date: Sun, 22 Oct 2017 23:46:03 -0500
User-agent: NeoMutt/20170609 (1.8.3)

On Sun, Oct 22, 2017 at 10:15:54PM -0400, Aron Griffis wrote:
[...]
> Thanks Eduardo. The clue there about bind-tty-special-chars is helpful,
> since previously I hadn't been able to make unix-word-rubout work either!
> 
> However this doesn't seem to explain the case where ctrl-w doesn't work at
> all, which is the bug I'm reporting.

Yes, you're right.

I'm looking at the POSIX specification for the shell vi-mode:

 
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html#tag_20_117_13_03

(emphasis is mine)

| <control>-W
|  Delete the characters from /the one preceding the cursor/ to the preceding
|  word boundary. The word boundary in this case is the closer to the cursor of
|  either the beginning of the line or a character that is in neither the blank
|  nor punct character classification of the current locale.

And function `rl_vi_unix_word_rubout':

| address@hidden:~/src/gnu/bash/lib/readline$ cat -n vi_mode.c | sed -n 
1601,1605p
|   1601                  /* If we're at the start of a word, move back to word 
boundary so we
|   1602                     move back to the `preceding' word */
|   1603                  if (rl_point > 0 && (vi_unix_word_boundary 
(rl_line_buffer[rl_point]) == 0) &&
|   1604                        vi_unix_word_boundary (rl_line_buffer[rl_point 
- 1]))
|   1605                    rl_point--;

So if we have:

            v-- cursor here
>>true --foo=bar<<
           ^-- character preceding the cursor

Then:

- rl_line_buffer[rl_point] -> `='      &  vi_unix_word_boundary(...) -> 1 
- rl_line_buffer[rl_point - 1] -> `o'  &  vi_unix_word_boundary(...) -> 0

So the test in lines 1603-1604 fails, and rl_point is not decreased.


According to my reading of the standard, it should decrease rl_point
unconditionally. See my proposed fix below.


diff --git a/lib/readline/vi_mode.c b/lib/readline/vi_mode.c
index 3cb7e8c9..238a77e9 100644
--- a/lib/readline/vi_mode.c
+++ b/lib/readline/vi_mode.c
@@ -1598,10 +1598,8 @@ rl_vi_unix_word_rubout (int count, int key)
            while (--rl_point > 0 && whitespace (rl_line_buffer[rl_point]))
              ;
 
-         /* If we're at the start of a word, move back to word boundary so we
-            move back to the `preceding' word */
-         if (rl_point > 0 && (vi_unix_word_boundary (rl_line_buffer[rl_point]) 
== 0) &&
-               vi_unix_word_boundary (rl_line_buffer[rl_point - 1]))
+         /* We start deleting at the character preceding the cursor */
+         if (rl_point > 0)
            rl_point--;
 
          /* If we are at a word boundary (whitespace/punct), move backward

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