tests/run-stack-live-test.sh: prototype 'live' eu-stack testing

Missing a few pieces, but worth sharing as an RFC. My idea is to
ensure better test coverage for eu-stack and then
eu-stacktrace+libdwfl_stacktrace by running against a live process
with known content, stopped at a known location, and aggressively
scrubbing output that's known to vary from testrun to testrun.

This is a very basic preview of how that might look. If the approach
is sound, I hope to make it more sophisticated/reliable.

Unanswered questions:
- Scrub more data (e.g. libc symvers) from a more known program.
  Scrub stack frame numbers to account for a case where extra frames
  appear / are missing at the bottom of the stack?
- Something better than sed for the scrubbing?
- An equivalent eu-stacktrace test will require privileged perf_events
  access for profiling data and therefore likely to be skipped by
  default. How feasible is it to be enabled on the buildbots, though?

* tests/run-stack-live-test.sh: New test with wild and fuzzy
  testrun_compare variant that scrubs inherently unpredictable parts of
  the data. Needs to scrub even more.
* tests/Makefile.am (TESTS): Add run-stack-live-test.sh.

2 files changed, 66 insertions, 1 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 00ba754d..ecd514c7 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -191,7 +191,8 @@ TESTS = run-arextract.sh run-arsymtest.sh run-ar.sh newfile test-nlist \
 	run-backtrace-core-s390x.sh run-backtrace-core-s390.sh \
 	run-backtrace-core-aarch64.sh run-backtrace-core-sparc.sh \
 	run-backtrace-demangle.sh run-stack-d-test.sh run-stack-i-test.sh \
-	run-stack-demangled-test.sh run-readelf-zx.sh run-readelf-zp.sh \
+	run-stack-demangled-test.sh run-stack-live-test.sh \
+	run-readelf-zx.sh run-readelf-zp.sh \
 	run-readelf-arm-flags.sh \
 	run-readelf-addr.sh run-readelf-str.sh \
 	run-readelf-multi-noline.sh \
diff --git a/tests/run-stack-live-test.sh b/tests/run-stack-live-test.sh
new file mode 100755
index 00000000..808421bb
--- /dev/null
+++ b/tests/run-stack-live-test.sh
@@ -0,0 +1,64 @@
+#! /bin/sh
+# Copyright (C) 2025 Red Hat, Inc.
+# This file is part of elfutils.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# elfutils is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/test-subr.sh
+
+# Depending on whether we are running make check or make installcheck
+# the actual binary name under test might be different. It is used in
+# the error message, which we also try to match.
+if test "$elfutils_testrun" = "installed"; then
+STACKCMD=${bindir}/`program_transform stack`    
+else
+STACKCMD=${abs_top_builddir}/src/stack
+fi
+
+# TODO(REVIEW): Can we make the data-scrubbing generic enough
+# (across multiple eu-stack/eu-stacktrace test cases) to move
+# to test_subr.sh?
+#
+# TODO(REVIEW): Better shell-isms for comparing file and regex?
+# \(\s\e\d\)\+\i\s\a\d\d\i\c\t\e\d\\t\o\b\a\ck\s\l\a\s\h\e\s
+testrun_compare_fuzzy()
+{
+    outfile="${1##*/}.out"
+    testrun_out $outfile "$@"
+    sed -i 's/\(PID\|TID\|#[0-9]\+\)\( \+\)\(\(0x\)\?[0-9a-f]\+\)/\1\2nn/g' $outfile
+    diff -u $outfile -
+}
+
+# TODO: Need to scrub more data (e.g. GLIBC_ bits),
+# and use a program whose inner content we control:
+sleep 10 &
+PID=$!
+testrun_compare_fuzzy ${abs_top_builddir}/src/stack -p $PID <<EOF
+PID nn - process
+TID nn:
+#0  nn clock_nanosleep@GLIBC_2.2.5
+#1  nn __nanosleep
+#2  nn main
+#3  nn __libc_start_call_main
+#4  nn __libc_start_main@@GLIBC_2.34
+#5  nn _start
+EOF
+# PID 169385 - process
+# TID 169385:
+# #0  0x00007f04a98adbd7 clock_nanosleep@GLIBC_2.2.5
+# #1  0x00007f04a98b9c47 __nanosleep
+# #2  0x0000561e7fdd9a9f main
+# #3  0x00007f04a97f4088 __libc_start_call_main
+# #4  0x00007f04a97f414b __libc_start_main@@GLIBC_2.34
+# #5  0x0000561e7fdd9c05 _start