iotests: Run iotests with sanitizers

Commit 2cc4d1c5ea ("tests/check-block: Skip iotests when sanitizers
are enabled") changed iotests to skip when sanitizers are enabled.
The rationale is that AddressSanitizer emits warnings and reports leaks,
which results in test breakage. Later, sanitizers that are enabled for
production environments (safe-stack and cfi-icall) were exempted.

However, this approach has a few problems.

- It requires rebuild to disable sanitizers if the existing build has
  them enabled.
- It disables other useful non-production sanitizers.
- The exemption of safe-stack and cfi-icall is not correctly
  implemented, so qemu-iotests are incorrectly enabled whenever either
  safe-stack or cfi-icall is enabled *and*, even if there is another
  sanitizer like AddressSanitizer.

To solve these problems, direct AddressSanitizer warnings to separate
files to avoid changing the test results, and selectively disable
leak detection at runtime instead of requiring to disable all
sanitizers at buildtime.

Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Message-ID: <20251023-iotests-v1-2-fab143ca4c2f@rsg.ci.i.u-tokyo.ac.jp>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/meson.build

@@ -2,14 +2,6 @@ if not have_tools or host_os == 'windows'
   subdir_done()
 endif
 
-foreach cflag: qemu_ldflags
-  if cflag.startswith('-fsanitize') and \
-     not cflag.contains('safe-stack') and not cflag.contains('cfi-icall')
-    message('Sanitizers are enabled ==> Disabled the qemu-iotests.')
-    subdir_done()
-  endif
-endforeach
-
 bash = find_program('bash', required: false, version: '>= 4.0')
 if not bash.found()
   message('bash >= v4.0 not available ==> Disabled the qemu-iotests.')

tests/qemu-iotests/testrunner.py

@@ -263,10 +263,21 @@ class TestRunner(contextlib.AbstractContextManager['TestRunner']):
             Path(env[d]).mkdir(parents=True, exist_ok=True)
 
         test_dir = env['TEST_DIR']
+        f_asan = Path(test_dir, f_test.name + '.out.asan')
         f_bad = Path(test_dir, f_test.name + '.out.bad')
         f_notrun = Path(test_dir, f_test.name + '.notrun')
         f_casenotrun = Path(test_dir, f_test.name + '.casenotrun')
 
+        env['ASAN_OPTIONS'] = f'detect_leaks=0:log_path={f_asan}'
+
+        def unlink_asan():
+            with os.scandir(test_dir) as it:
+                for entry in it:
+                    if entry.name.startswith(f_asan.name):
+                        os.unlink(entry)
+
+        unlink_asan()
+
         for p in (f_notrun, f_casenotrun):
             silent_unlink(p)
 
@@ -312,6 +323,7 @@ class TestRunner(contextlib.AbstractContextManager['TestRunner']):
                               description=f'output mismatch (see {f_bad})',
                               diff=diff, casenotrun=casenotrun)
         else:
+            unlink_asan()
             f_bad.unlink()
             return TestResult(status='pass', elapsed=elapsed,
                               casenotrun=casenotrun)