Re: [PATCH 3/4] print-symbol-loading.exp: Allow libc symbols to be already loaded

[Kevin Buettner <kevinb@redhat.com>]

On Fri, 11 Jun 2021 15:22:23 -0400
Simon Marchi <simon.marchi@polymtl.ca> wrote:

> On 2021-06-10 1:26 p.m., Kevin Buettner via Gdb-patches wrote:

> > ---
> >  gdb/testsuite/gdb.base/print-symbol-loading.exp | 15 ++++++++++++---
> >  1 file changed, 12 insertions(+), 3 deletions(-)
> > 
> > diff --git a/gdb/testsuite/gdb.base/print-symbol-loading.exp b/gdb/testsuite/gdb.base/print-symbol-loading.exp
> > index b8eb1c844bd..6e176de351e 100644
> > --- a/gdb/testsuite/gdb.base/print-symbol-loading.exp
> > +++ b/gdb/testsuite/gdb.base/print-symbol-loading.exp
> > @@ -96,6 +96,7 @@ test_load_core full
> >  
> >  proc test_load_shlib { print_symbol_loading } {
> >      global binfile
> > +    global gdb_prompt
> >      with_test_prefix "shlib ${print_symbol_loading}" {
> >  	clean_restart ${binfile}
> >  	gdb_test_no_output "set auto-solib-add off"
> > @@ -106,12 +107,20 @@ proc test_load_shlib { print_symbol_loading } {
> >  	set test_name "load shared-lib"
> >  	switch ${print_symbol_loading} {
> >  	    "off" {
> > -		gdb_test_no_output "sharedlibrary .*" \
> > -		    ${test_name}
> > +		set cmd "sharedlibrary .*"
> > +		set cmd_regex [string_to_regexp $cmd]
> > +		gdb_test_multiple $cmd $test_name {
> > +        	    -re "^$cmd_regex\r\n$gdb_prompt $" {
> > +			pass $test_name
> > +		    }
> > +        	    -re "^$cmd_regex\r\nSymbols already loaded for.*?\\/libc\\..*?\r\n$gdb_prompt $" {  
> 
> I'm just wondering about these regexps:
> 
>  - What does the sequence .*? mean in a regexp?
>  - Doesn't having .* risk matching multiple lines, including some
>    unexpected output that we wouldn't want to match?  Should we use the
>    typical [^\r\n]* instead?

The regexp ".*?" is the non-greedy variation of ".*".  I.e. whereas ".*"
matches as much as possible, ".*?" will match as little as possible.
Therefore, ".*?\r\n" will only match only as much as needed until
the next \r is found; therefore it will not match multiple lines.

Kevin