perf testsuite: Add common output checking helper

As a form of validation, it is a common practice to check the outputs
of commands whether they contain expected patterns or match a certain
regular expression.

This output checking helper is designed to allow checking stderr output
of perf commands for unexpected messages, while ignoring messages that
are known to be harmless, e.g.:
  "Lowering default frequency rate to \d+\."
  "\d+ out of order events recorded."
  etc.

Signed-off-by: Veronika Molnarova <vmolnaro@redhat.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240702110849.31904-10-vmolnaro@redhat.com
Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/tests/shell/common/check_errors_whitelisted.pl b/tools/perf/tests/shell/common/check_errors_whitelisted.pl
new file mode 100755 (executable)
index 0000000..c57d355
--- /dev/null
+++ b/tools/perf/tests/shell/common/check_errors_whitelisted.pl
@@ -0,0 +1,51 @@
+#!/usr/bin/perl
+# SPDX-License-Identifier: GPL-2.0
+
+$whitelist_file = shift;
+
+if (defined $whitelist_file)
+{
+       open (INFILE, $whitelist_file) or die "Checker error: Unable to open the whitelist file: $whitelist_file\n";
+       @regexps = <INFILE>;
+       close INFILE or die "Checker error: Unable to close the whitelist file: $whitelist_file\n";
+}
+else
+{
+       @regexps = ();
+}
+
+$max_printed_lines = 20;
+$max_printed_lines = $ENV{TESTLOG_ERR_MSG_MAX_LINES} if (defined $ENV{TESTLOG_ERR_MSG_MAX_LINES});
+
+$quiet = 1;
+$quiet = 0 if (defined $ENV{TESTLOG_VERBOSITY} && $ENV{TESTLOG_VERBOSITY} ge 2);
+
+$passed = 1;
+$lines_printed = 0;
+
+while (<STDIN>)
+{
+       s/\n//;
+
+       $line_matched = 0;
+       for $r (@regexps)
+       {
+               chomp $r;
+               if (/$r/)
+               {
+                       $line_matched = 1;
+                       last;
+               }
+       }
+
+       unless ($line_matched)
+       {
+               if ($lines_printed++ < $max_printed_lines)
+               {
+                       print "Line did not match any pattern: \"$_\"\n" unless $quiet;
+               }
+               $passed = 0;
+       }
+}
+
+exit ($passed == 0);