Eric Blake <ebl...@redhat.com> čálii: > On 11/04/2016 05:51 AM, Kevin Brubeck Unhammer wrote:
[...]
>> C=''
>> for i in "$@"; do
>> i=$(echo "$i" | sed 's/\\/\\\\/g; s/\"/\\\"/g')
>> C="$C \"$i\""
>> done
>> echo "$C"
>
> That works (although we'd want to tweak it to not pollute outside the
> autoconf namespace), but adds a number of forks to what is otherwise a
> fork-free output of "$@". It's probably possible to optimize for the
> common case of arguments that don't need shell quoting to reduce some of
> the cost. Since both lib/autoconf/general.m4 and lib/autoconf/status.m4
> output an invocation line, it's probably worth factoring out a common
> helper macro, probably to lib/m4sugar/m4sh.m4; would you like to try
> your hand at a patch? If not, I can probably do it.
I've tested the following to work under both dash and bash; and it only
runs sed if the argument contains a ‘'’.
#!/bin/sh
C=''
for i in "$@"; do
case "$i" in
*\'*)
i=`printf "%s" "$i" | sed "s/'/'\"'\"'/g"`
;;
*) :
;;
esac
C="$C '$i'"
done
printf " $0%s\n" "$C"
I tested by making a script containing
#!/bin/sh
C=''
for i in "$@"; do
case "$i" in
*\'*)
echo 'fork!' >&2
i=`printf "%s" "$i" | sed "s/'/'\"'\"'/g"`
;;
*) :
;;
esac
C="$C '$i'"
done
printf "%s\n" "$@" >/tmp/gold
echo "Copy-paste this line, should give no output:"
printf " printf \"%%s\\\n\" %s >/tmp/test; diff /tmp/gold /tmp/test\n" "$C"
and
running e.g.
$ dash /tmp/esc.sh 'foo bar' 'x\"y' 'x\\"y' 'x\\\"y' 'x\\ \"y!' '!!' "foo'bar"
and copy-pasting the output. Seems to hold …
I don't know much about m4 though (and don't have much free time – but
then who does), so maybe it's best if you turn that into a real patch,
otherwise it's going to take quite a while :)
best regards,
Kevin Brubeck Unhammer
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