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eb54ca8be0
Upstream commit:
Date: Wed, 28 Mar 2018 18:37:51 +0800
expand: Do not quote backslashes in unquoted parameter expansion
Here is a better example:
a="/*/\nullx" b="/*/\null"; printf "%s\n" $a $b
dash currently prints
/*/\nullx
/*/\null
bash prints
/*/\nullx
/dev/null
You may argue the bash behaviour is inconsistent but it actually
makes sense. What happens is that quote removal only applies to
the original token as seen by the shell. It is never applied to
the result of parameter expansion.
Now you may ask why on earth does the second line say "/dev/null"
instead of "/dev/\null". Well that's because it is not the quote
removal step that removed the backslash, but the pathname expansion.
The fact that the /de\v does not become /dev even though it exists
is just the result of the optimisation to avoid unnecessarily
calling stat(2). I have checked POSIX and I don't see anything
that forbids this behaviour.
So going back to dash yes I think we should adopt the bash behaviour
for pathname expansion and keep the existing case semantics.
This patch does exactly that. Note that this patch does not work
unless you have already applied
https://patchwork.kernel.org/patch/10306507/
because otherwise the optimisation mentioned above does not get
detected correctly and we will end up doing quote removal twice.
This patch also updates expmeta to handle naked backslashes at
the end of the pattern which is now possible.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
function old new delta
expmeta 618 653 +35
memtodest 146 147 +1
Tested to work with both ASH_INTERNAL_GLOB on and off.
hush does not handle this correctly.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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|---|---|---|
| .. | ||
| ash_test | ||
| hush_test | ||
| ash_doc.txt | ||
| ash_ptr_hack.c | ||
| ash.c | ||
| brace.txt | ||
| Config.src | ||
| cttyhack.c | ||
| hush_doc.txt | ||
| hush_leaktool.sh | ||
| hush.c | ||
| Kbuild.src | ||
| match.c | ||
| match.h | ||
| math.c | ||
| math.h | ||
| random.c | ||
| random.h | ||
| README | ||
| README.job | ||
| shell_common.c | ||
| shell_common.h | ||
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.