Re: Read builtin -e (readline) oddities

[Chet Ramey]

On 6/19/17 3:40 PM, Chet Ramey wrote:

>> #3
>> Hit `C-x C-e' thrice. Also, the mapping of `\C-m' became `self-insert' 
>> instead
>> of `accept-line'.
> 
> `read -e' changes it because it's no longer the line delimiter.
> 
>>   dualbus@debian:~$ PATH= EDITOR=: read -e -d ''
>>   
>>   PATH= EDITOR=: read -e -d ''; 
>>   
>>   fc -e "${VISUAL:-${EDITOR:-$(command -v editor || echo emacs)}}"
>>   : /tmp/bash-fc.IZAzmF
>>   PATH= EDITOR=: read -e -d ''; ; 
>>   bash: syntax error near unexpected token `;'
>>   
>>   fc -e "${VISUAL:-${EDITOR:-$(command -v editor || echo emacs)}}"
>>   vim /tmp/bash-fc.35ePED
>>   ^M^M^C
> 
> I'll have to check why it doesn't get restored on ^C.

It does get restored, but the code only has one level of restoration, so
the recursive calls overwrite it.  Who's going to do multiple levels of
edit-and-execute-command?

If you want to run multiple recursive versions of edit-and-execute-
command, you should be savvy enough to get out using ^@ (control-shift-2),
right? :-)

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/

Re: Read builtin -e (readline) oddities

[Chet Ramey]

On 6/18/17 9:39 PM, Eduardo A. Bustamante López wrote:
> I'm trying to figure out a way to fuzz >>read -e -d ""<<, without having the
> fuzzer break due to the temporary files created by fc.
> 
> While doing this, I noticed the oddities described below.
> 
> 
> #1
> Hit `C-x C-e' twice.  The value of PATH seems to be ignored for the second
> line.
> 
>   dualbus@debian:~$ PATH= read -e
>   
>   bash: vim: No such file or directory
>   
>   echo hi
>   hi
> 
> 
> #2
> Spurious `;'s are inserted into the history.
> 
>   dualbus@debian:~$ history -c
>   dualbus@debian:~$ PATH= read -e
>   
>   bash: vim: No such file or directory
>   
>   echo hi
>   hi
>   
>   dualbus@debian:~$ history
>   1  PATH= read -e; ; 
>   2  echo hi
>   3  history
> 
> 
> #3
> Hit `C-x C-e' thrice. Also, the mapping of `\C-m' became `self-insert' instead
> of `accept-line'.

`read -e' changes it because it's no longer the line delimiter.

>   dualbus@debian:~$ PATH= EDITOR=: read -e -d ''
>   
>   PATH= EDITOR=: read -e -d ''; 
>   
>   fc -e "${VISUAL:-${EDITOR:-$(command -v editor || echo emacs)}}"
>   : /tmp/bash-fc.IZAzmF
>   PATH= EDITOR=: read -e -d ''; ; 
>   bash: syntax error near unexpected token `;'
>   
>   fc -e "${VISUAL:-${EDITOR:-$(command -v editor || echo emacs)}}"
>   vim /tmp/bash-fc.35ePED
>   ^M^M^C

I'll have to check why it doesn't get restored on ^C.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/

Re: Read builtin -e (readline) oddities

[Chet Ramey]

On 6/18/17 9:39 PM, Eduardo A. Bustamante López wrote:

> #1
> Hit `C-x C-e' twice.  The value of PATH seems to be ignored for the second
> line.

The shell should ensure that the temporary env is preserved across the
entire execution of any builtin that can call parse_and_execute (like `fc'
and `read' when using `read -e').

> #2
> Spurious `;'s are inserted into the history.

The fc builtin (via edit_and_execute_command) shouldn't try to insert empty
lines into the history list.  The only time this can happen is via
`read -e'.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/

Re: Read builtin -e (readline) oddities

[Eduardo Bustamante]

On Mon, Jun 19, 2017 at 9:57 AM, Eduardo A. Bustamante López
 wrote:
[...]
> Hm, I can still reproduce it under Debian 9, using the `devel' branch, and I'm
> sure no startup files are being sourced.
>
>   dualbus@debian:~/src/gnu/bash-builds/devel$ ./bash --norc --noprofile
>   bash-4.4$ declare -p command-not-found
>   bash: declare: command-not-found: not found

Heh, actually:

dualbus@debian:~/src/gnu/bash-builds/devel$ ./bash --norc --noprofile
bash-4.4$ declare -fp command_not_found_handle
bash: declare: command_not_found_handle: not found

The rest is correct though.

Re: Read builtin -e (readline) oddities

[Eduardo A . Bustamante López]

On Mon, Jun 19, 2017 at 10:08:30AM -0400, Chet Ramey wrote:
[...]
> I can't reproduce this.  I suspect one of your startup files is somehow
> being read and setting PATH. It may also be an interaction with the
> command-not-found hook.

Hm, I can still reproduce it under Debian 9, using the `devel' branch, and I'm
sure no startup files are being sourced.

  dualbus@debian:~/src/gnu/bash-builds/devel$ ./bash --norc --noprofile
  bash-4.4$ declare -p command-not-found
  bash: declare: command-not-found: not found
  bash-4.4$ 
  GNU bash, version 4.4.12(3)-maint (x86_64-unknown-linux-gnu)
  bash-4.4$ PATH= read -e
  
  bash: vim: No such file or directory
  
  echo this is vim
  this is vim

I then patched bash like this:

  dualbus@debian:~/src/gnu/bash$ git diff -- execute_cmd.c
  diff --git a/execute_cmd.c b/execute_cmd.c
  index 0183a105..50f4e2f0 100644
  --- a/execute_cmd.c
  +++ b/execute_cmd.c
  @@ -5550,6 +5550,7 @@ shell_execve (command, args, env)
 char sample[HASH_BANG_BUFSIZ];
 int sample_len;
   
  +  if (strlen(get_string_value ("PATH")) > 0) abort();
 SETOSTYPE (0);   /* Some systems use for USG/POSIX semantics */
 execve (command, args, env);
 i = errno;   /* error from execve() */

And I got (the first `\C-x \C-e' gets to shell_execve, but PATH is empty):

  dualbus@debian:~/src/gnu/bash-builds/devel$ ./bash --norc --noprofile
  bash-4.4$ ulimit -c unlimited
  bash-4.4$ 
  GNU bash, version 4.4.12(9)-maint (x86_64-unknown-linux-gnu)
  bash-4.4$ PATH= read -e
  
  bash: vim: No such file or directory
  
  Aborted (core dumped)
  
  Core was generated by `./bash --norc --noprofile'.
  Program terminated with signal SIGABRT, Aborted.
  #0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
  51  ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
  (gdb) bt
  #0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
  #1  0x7f30b14c93fa in __GI_abort () at abort.c:89
  #2  0x55a0df6527c4 in shell_execve (command=0x55a0e0a21020 
"/usr/bin/vim", args=0x55a0e0a64610, env=0x55a0e0a207f0) at 
../../bash/execute_cmd.c:5553
  #3  0x55a0df6525b1 in execute_disk_command (words=0x55a0e0a63c20, 
redirects=0x0, command_line=0x55a0e0a20f60 "vim /tmp/bash-fc.HTeaRz", 
pipe_in=-1, pipe_out=-1, async=0, 
  fds_to_close=0x55a0e0a42d80, cmdflags=0) at ../../bash/execute_cmd.c:5348
  #4  0x55a0df650d4f in execute_simple_command 
(simple_command=0x55a0e0a62780, pipe_in=-1, pipe_out=-1, async=0, 
fds_to_close=0x55a0e0a42d80) at ../../bash/execute_cmd.c:4466
  #5  0x55a0df64a465 in execute_command_internal (command=0x55a0e0a20e80, 
asynchronous=0, pipe_in=-1, pipe_out=-1, fds_to_close=0x55a0e0a42d80) at 
../../bash/execute_cmd.c:811
  #6  0x55a0df6ad6a8 in parse_and_execute (string=0x55a0e0a61b10 "vim 
/tmp/bash-fc.HTeaRz", from_file=0x55a0df71cecd "fc", flags=4) at 
../../../bash/builtins/evalstring.c:430
  #7  0x55a0df6aee93 in fc_builtin (list=0x0) at 
../../../bash/builtins/../../../bash/builtins/fc.def:438
  #8  0x55a0df6511cb in execute_builtin (builtin=0x55a0df6ae4ae 
, words=0x55a0e0a625d0, flags=0, subshell=0) at 
../../bash/execute_cmd.c:4609
  #9  0x55a0df6520a7 in execute_builtin_or_function (words=0x55a0e0a625d0, 
builtin=0x55a0df6ae4ae , var=0x0, redirects=0x0, 
fds_to_close=0x55a0e0a63df0, flags=0)
  at ../../bash/execute_cmd.c:5107
  #10 0x55a0df650ad1 in execute_simple_command 
(simple_command=0x55a0e0a62540, pipe_in=-1, pipe_out=-1, async=0, 
fds_to_close=0x55a0e0a63df0) at ../../bash/execute_cmd.c:4395
  #11 0x55a0df64a465 in execute_command_internal (command=0x55a0e0a20400, 
asynchronous=0, pipe_in=-1, pipe_out=-1, fds_to_close=0x55a0e0a63df0) at 
../../bash/execute_cmd.c:811
  #12 0x55a0df6ad6a8 in parse_and_execute (string=0x55a0e0a613b0 "fc -e 
\"${VISUAL:-${EDITOR:-emacs}}\"", from_file=0x55a0df70ccd5 "C-xC-e", flags=4)
  at ../../../bash/builtins/evalstring.c:430
  #13 0x55a0df696203 in edit_and_execute_command (count=1, c=5, 
editing_mode=1, edit_command=0x55a0df70cd10 "fc -e 
\"${VISUAL:-${EDITOR:-emacs}}\"") at ../../bash/bashline.c:977
  #14 0x55a0df6962f0 in emacs_edit_and_execute_command (count=1, c=5) at 
../../bash/bashline.c:1013
  #15 0x55a0df6dccd5 in _rl_dispatch_subseq (key=5, map=0x55a0df9461a0 
, got_subseq=0) at 
../../../../bash/lib/readline/readline.c:851
  #16 0x55a0df6dd19a in _rl_dispatch_subseq (key=24, map=0x55a0df944160 
, got_subseq=0) at 
../../../../bash/lib/readline/readline.c:985
  #17 0x55a0df6dca4c in _rl_dispatch (key=-1320386609, map=0x55a0df944160 
) at ../../../../bash/lib/readline/readline.c:797
  #18 0x55a0df6dc6d4 in readline_internal_char () at 
../../../../bash/lib/readline/readline.c:629
  #19 0x55a0df6dc72c in readline_internal_charloop () at 
../../../../bash/lib/readline/readline.c:656
  #20 0x55a0df6dc750 in readline_internal () at 

Re: Read builtin -e (readline) oddities

[Chet Ramey]

On 6/18/17 9:39 PM, Eduardo A. Bustamante López wrote:
> I'm trying to figure out a way to fuzz >>read -e -d ""<<, without having the
> fuzzer break due to the temporary files created by fc.
> 
> While doing this, I noticed the oddities described below.
> 
> 
> #1
> Hit `C-x C-e' twice.  The value of PATH seems to be ignored for the second
> line.

I can't reproduce this.  I suspect one of your startup files is somehow
being read and setting PATH. It may also be an interaction with the
command-not-found hook.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/

Read builtin -e (readline) oddities

[Eduardo A . Bustamante López]

I'm trying to figure out a way to fuzz >>read -e -d ""<<, without having the
fuzzer break due to the temporary files created by fc.

While doing this, I noticed the oddities described below.


#1
Hit `C-x C-e' twice.  The value of PATH seems to be ignored for the second
line.

  dualbus@debian:~$ PATH= read -e
  
  bash: vim: No such file or directory
  
  echo hi
  hi


#2
Spurious `;'s are inserted into the history.

  dualbus@debian:~$ history -c
  dualbus@debian:~$ PATH= read -e
  
  bash: vim: No such file or directory
  
  echo hi
  hi
  
  dualbus@debian:~$ history
  1  PATH= read -e; ; 
  2  echo hi
  3  history


#3
Hit `C-x C-e' thrice. Also, the mapping of `\C-m' became `self-insert' instead
of `accept-line'.

  dualbus@debian:~$ PATH= EDITOR=: read -e -d ''
  
  PATH= EDITOR=: read -e -d ''; 
  
  fc -e "${VISUAL:-${EDITOR:-$(command -v editor || echo emacs)}}"
  : /tmp/bash-fc.IZAzmF
  PATH= EDITOR=: read -e -d ''; ; 
  bash: syntax error near unexpected token `;'
  
  fc -e "${VISUAL:-${EDITOR:-$(command -v editor || echo emacs)}}"
  vim /tmp/bash-fc.35ePED
  ^M^M^C
  dualbus@debian:~$ ^M^M^M^M^M^M^M^M



In relation to my fuzzing goal, it seems this is what I wanted:

  dualbus@debian:~$ (enable -n fc; read -e -d '')
  
  bash: fc: command not found
  
  bash: fc: command not found
  
  bash: fc: command not found
  
  bash: fc: command not found
  
  bash: fc: command not found
  ^C

-- 
Eduardo Bustamante
https://dualbus.me/