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authorDenys Vlasenko <vda.linux@googlemail.com>2018-08-07 18:54:52 +0200
committerDenys Vlasenko <vda.linux@googlemail.com>2018-08-07 18:58:02 +0200
commiteb54ca8be0b45a101f9bdcf6efa26645c6b94a08 (patch)
tree45239397eb341f58cf4f448544ee44c0d77e74f6 /shell/ash_doc.txt
parent77c18491b8647832422be3f95187e5aa5270e044 (diff)
downloadbusybox-eb54ca8be0b45a101f9bdcf6efa26645c6b94a08.tar.gz
ash: expand: Do not quote backslashes in unquoted parameter expansion
Upstream commit: Date: Wed, 28 Mar 2018 18:37:51 +0800 expand: Do not quote backslashes in unquoted parameter expansion Here is a better example: a="/*/\nullx" b="/*/\null"; printf "%s\n" $a $b dash currently prints /*/\nullx /*/\null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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