Use heuristics to run sepolicy_tests faster
We are compiling regex more than 300000 times, and it's a main
bottleneck for slow sepolicy_tests. Actually we don't need to compile
regex that much; most of cases can be handled by simple string
comparison. This change introduces heuristics for optimization.
Bug: 301874100
Test: verified that return values of MatchPathPrefix are not changed.
Test: run cProfile, before and after.
Before
ncalls tottime percall cumtime percall filename:lineno(function)
21951 0.923 0.000 56.491 0.003 policy.py:33(MatchPathPrefix)
After
ncalls tottime percall cumtime percall filename:lineno(function)
21951 0.078 0.000 1.159 0.000 policy.py:40(MatchPathPrefix)
Change-Id: I1ebad586c2518e74a8ca67024df5e77d068e3ca5
diff --git a/tests/Android.bp b/tests/Android.bp
index 2c2c9a6..743c856 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -159,3 +159,20 @@
"mini_cil_parser",
],
}
+
+python_test_host {
+ name: "policy_test",
+ srcs: [
+ "fc_sort.py",
+ "policy.py",
+ "policy_test.py",
+ ],
+ test_options: {
+ unit_test: true,
+ },
+ version: {
+ py3: {
+ embedded_launcher: true,
+ },
+ },
+}
diff --git a/tests/policy.py b/tests/policy.py
index 805c451..9fdc43c 100644
--- a/tests/policy.py
+++ b/tests/policy.py
@@ -30,7 +30,46 @@
# 1) there is a match - return True or 2) run out of characters - return
# False.
#
+COMMON_PREFIXES = {
+ "/(vendor|system/vendor)": ["/vendor", "/system/vendor"],
+ "/(odm|vendor/odm)": ["/odm", "/vendor/odm"],
+ "/(product|system/product)": ["/product", "/system/product"],
+ "/(system_ext|system/system_ext)": ["/system_ext", "/system/system_ext"],
+}
+
def MatchPathPrefix(pathregex, prefix):
+ # Before running regex compile loop, try two heuristics, because compiling
+ # regex is too expensive. These two can handle more than 90% out of all
+ # MatchPathPrefix calls.
+
+ # Heuristic 1: handle common prefixes for partitions
+ for c in COMMON_PREFIXES:
+ if not pathregex.startswith(c):
+ continue
+ found = False
+ for p in COMMON_PREFIXES[c]:
+ if prefix.startswith(p):
+ found = True
+ prefix = prefix[len(p):]
+ pathregex = pathregex[len(c):]
+ break
+ if not found:
+ return False
+
+ # Heuristic 2: compare normal characters as long as possible
+ idx = 0
+ while idx < len(prefix):
+ if idx == len(pathregex):
+ return False
+ if pathregex[idx] in fc_sort.META_CHARS or pathregex[idx] == '\\':
+ break
+ if pathregex[idx] != prefix[idx]:
+ return False
+ idx += 1
+ if idx == len(prefix):
+ return True
+
+ # Fall back to regex compile loop.
for i in range(len(pathregex), 0, -1):
try:
pattern = re.compile('^' + pathregex[0:i] + "$")
diff --git a/tests/policy_test.py b/tests/policy_test.py
new file mode 100644
index 0000000..3cf4a1b
--- /dev/null
+++ b/tests/policy_test.py
@@ -0,0 +1,56 @@
+# Copyright 2023 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Tests for policy"""
+
+import unittest
+from policy import MatchPathPrefix
+
+# pylint: disable=missing-docstring
+class PolicyTests(unittest.TestCase):
+ def assertMatches(self, path, prefix):
+ self.assertTrue(MatchPathPrefix(path, prefix))
+
+ def assertDoesNotMatch(self, path, prefix):
+ self.assertFalse(MatchPathPrefix(path, prefix))
+
+ # tests
+
+ def test_match_path_prefix(self):
+ # check common prefix heuristics
+ self.assertMatches("/(vendor|system/vendor)/bin/sh", "/vendor/bin")
+ self.assertMatches("/(vendor|system/vendor)/bin/sh", "/system/vendor/bin"),
+ self.assertMatches("/(odm|vendor/odm)/etc/selinux", "/odm/etc"),
+ self.assertMatches("/(odm|vendor/odm)/etc/selinux", "/vendor/odm/etc"),
+ self.assertMatches("/(system_ext|system/system_ext)/bin/foo", "/system_ext/bin"),
+ self.assertMatches("/(system_ext|system/system_ext)/bin/foo", "/system/system_ext/bin"),
+ self.assertMatches("/(product|system/product)/lib/libc.so", "/product/lib"),
+ self.assertMatches("/(product|system/product)/lib/libc.so", "/system/product/lib"),
+ self.assertDoesNotMatch("/(vendor|system/vendor)/bin/sh", "/system/bin"),
+ self.assertDoesNotMatch("/(odm|vendor/odm)/etc/selinux", "/vendor/etc"),
+ self.assertDoesNotMatch("/(system_ext|system/system_ext)/bin/foo", "/system/bin"),
+ self.assertDoesNotMatch("/(product|system/product)/lib/libc.so", "/system/lib"),
+
+ # check generic regex
+ self.assertMatches("(/.*)+", "/system/etc/vintf")
+ self.assertDoesNotMatch("(/.*)+", "foo/bar/baz")
+
+ self.assertMatches("/(system|product)/lib(64)?(/.*)+.*\.so", "/system/lib/hw/libbaz.so")
+ self.assertMatches("/(system|product)/lib(64)?(/.*)+.*\.so", "/system/lib64/")
+ self.assertMatches("/(system|product)/lib(64)?(/.*)+.*\.so", "/product/lib/hw/libbaz.so")
+ self.assertMatches("/(system|product)/lib(64)?(/.*)+.*\.so", "/product/lib64/")
+ self.assertDoesNotMatch("/(system|product)/lib(64)?(/.*)+.*\.so", "/vendor/lib/hw/libbaz.so")
+ self.assertDoesNotMatch("/(system|product)/lib(64)?(/.*)+.*\.so", "/odm/lib64/")
+
+if __name__ == '__main__':
+ unittest.main(verbosity=2)