emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
6c4f87e411
busybox/shell
History
Denys Vlasenko 6c4f87e411 ash: exec: Stricter pathopt parsing 
Upstream comment:

    Date: Sat, 19 May 2018 02:39:50 +0800
    exec: Stricter pathopt parsing

    This patch changes the parsing of pathopt.  First of all only
    %builtin and %func (with arbitrary suffixes) will be recognised.
    Any other pathopt will be treated as a normal directory.

    Furthermore, pathopt can now be specified before the directory,
    rather than after it.  In fact, a future version may remove support
    for pathopt suffixes.

    Wherever the pathopt is placed, an optional % may be placed after
    it to terminate the pathopt.

    This is so that it is less likely that a genuine directory containing
    a % sign is parsed as a pathopt.

    Users of padvance outside of exec.c have also been modified:

    1) cd(1) will always treat % characters as part of the path.
    2) chkmail will continue to accept arbitrary pathopt.
    3) find_dot_file will ignore the %builtin pathopt instead of trying
    to do a stat in the accompanying directory (which is usually the
    current directory).

    The patch also removes the clearcmdentry optimisation where we
    attempt to only partially flush the table where possible.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2020-02-17 16:02:40 +01:00
..
ash_test ash: expand: Fix trailing newlines processing in backquote expanding 2020-02-17 10:24:32 +01:00
hush_test ash: expand: Fix trailing newlines processing in backquote expanding 2020-02-17 10:24:32 +01:00
ash_doc.txt ash: fix TRACE commands 2009-03-19 23:09:58 +00:00
ash_ptr_hack.c *: make GNU licensing statement forms more regular 2010-08-16 20:14:46 +02:00
ash.c ash: exec: Stricter pathopt parsing 2020-02-17 16:02:40 +01:00
brace.txt hush: wait for cmd to complete, and immediately store its exitcode in $? 2009-11-15 19:58:19 +01:00
Config.src shell: implement optional "BASE#nnnn" numeric literals 2019-05-19 17:23:31 +02:00
cttyhack.c config: update size information 2018-12-28 03:20:17 +01:00
hush_doc.txt hush: implement break and continue 2008-07-28 23:04:34 +00:00
hush_leaktool.sh hush: fix "export not_yet_defined_var", fix parsing of "cmd | }" 2009-04-19 23:07:51 +00:00
hush.c ash,hush: allow builtins to be tab-completed, closes 7532 2020-01-29 15:23:17 +01:00
Kbuild.src Make it possible to select "sh" and "bash" aliases without selecting ash or hush 2016-12-23 16:56:43 +01:00
match.c hush: fix a='a\\'; echo "${a%\\\\}" 2018-03-02 20:48:36 +01:00
match.h hush: optimize #[#] and %[%] for speed. size -2 bytes. 2010-09-04 21:21:07 +02:00
math.c shell: better comments in BASE#nn code 2019-10-22 14:25:43 +02:00
math.h shell: move all definitions of strto_arith_t() together 2019-05-26 14:02:10 +02:00
random.c whitespace fixes 2018-07-17 15:04:17 +02:00
random.h ash,hush: improve randomness of $RANDOM, add easy-ish way to test it 2014-03-13 12:52:43 +01:00
README update shell/README 2010-05-20 12:56:14 +02:00
README.job
shell_common.c shell/ulimit: code shrink 2019-10-21 16:47:09 +02:00
shell_common.h hush: fix "export PS1=xyz" and "local PS1=xyz" messing up prompt 2019-05-14 18:56:04 +02:00

README 

http://www.opengroup.org/onlinepubs/9699919799/
Open Group Base Specifications Issue 7


http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap01.html
Shell & Utilities

It says that any of the standard utilities may be implemented
as a regular shell built-in. It gives a list of utilities which
are usually implemented that way (and some of them can only
be implemented as built-ins, like "alias"):

alias
bg
cd
command
false
fc
fg
getopts
jobs
kill
newgrp
pwd
read
true
umask
unalias
wait


http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
Shell Command Language

It says that shell must implement special built-ins. Special built-ins
differ from regular ones by the fact that variable assignments
done on special builtin are *PRESERVED*. That is,

VAR=VAL special_builtin; echo $VAR

should print VAL.

(Another distinction is that an error in special built-in should
abort the shell, but this is not such a critical difference,
and moreover, at least bash's "set" does not follow this rule,
which is even codified in autoconf configure logic now...)

List of special builtins:

. file
: [argument...]
break [n]
continue [n]
eval [argument...]
exec [command [argument...]]
exit [n]
export name[=word]...
export -p
readonly name[=word]...
readonly -p
return [n]
set [-abCefhmnuvx] [-o option] [argument...]
set [+abCefhmnuvx] [+o option] [argument...]
set -- [argument...]
set -o
set +o
shift [n]
times
trap n [condition...]
trap [action condition...]
unset [-fv] name...

In practice, no one uses this obscure feature - none of these builtins
gives any special reasons to play such dirty tricks.

However. This section also says that *function invocation* should act
similar to special built-in. That is, variable assignments
done on function invocation should be preserved after function invocation.

This is significant: it is not unthinkable to want to run a function
with some variables set to special values. But because of the above,
it does not work: variable will "leak" out of the function.