Re: [kvm-unit-tests PATCH 09/10] scripts: Implement multiline strings for extra_params

[Nina Schoetterl-Glausch <nsg@linux.ibm.com>]

On Wed, 2023-10-25 at 19:50 +0200, Thomas Huth wrote:
> On 20/10/2023 16.48, Nina Schoetterl-Glausch wrote:
> > Implement a rudimentary form only.
> > extra_params can get long when passing a lot of arguments to qemu.
> > Multiline strings help with readability of the .cfg file.
> > Multiline strings begin and end with """, which must occur on separate
> > lines.
> > 
> > For example:
> > extra_params = """-cpu max,ctop=on -smp cpus=1,cores=16,maxcpus=128 \
> > -append '-drawers 2 -books 2 -sockets 2 -cores 16' \
> > -device max-s390x-cpu,core-id=31,drawer-id=0,book-id=0,socket-id=0"""
> > 
> > The command string built with extra_params is eval'ed by the runtime
> > script, so the newlines need to be escaped with \.
> > 
> > Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
> > ---
> >   scripts/common.bash  | 16 ++++++++++++++++
> >   scripts/runtime.bash |  4 ++--
> >   2 files changed, 18 insertions(+), 2 deletions(-)
> > 
> > diff --git a/scripts/common.bash b/scripts/common.bash
> > index 7b983f7d..b9413d68 100644
> > --- a/scripts/common.bash
> > +++ b/scripts/common.bash
> > @@ -36,6 +36,22 @@ function for_each_unittest()
> >   			kernel=$TEST_DIR/${BASH_REMATCH[1]}
> >   		elif [[ $line =~ ^smp\ *=\ *(.*)$ ]]; then
> >   			smp=${BASH_REMATCH[1]}
> > +		elif [[ $line =~ ^extra_params\ *=\ *'"""'(.*)$ ]]; then
> > +			opts=${BASH_REMATCH[1]}$'\n'
> > +			while read -r -u $fd; do
> > +				#escape backslash newline, but not double backslash
> > +				if [[ $opts =~ [^\\]*(\\*)$'\n'$ ]]; then
> > +					if (( ${#BASH_REMATCH[1]} % 2 == 1 )); then
> > +						opts=${opts%\\$'\n'}
> > +					fi
> > +				fi
> > +				if [[ "$REPLY" =~ ^(.*)'"""'[:blank:]*$ ]]; then
> > +					opts+=${BASH_REMATCH[1]}
> > +					break
> > +				else
> > +					opts+=$REPLY$'\n'
> > +				fi
> > +			done
> 
> Phew, TIL that there is something like $'\n' in bash ...
> Now with that knowledge, the regular expression make sense 8-)

Uh yeah, it's very write only, with backslash escaping, " inside ' and $'\n'.
> 
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> 
Thanks!