util: Add new utility to find non-exec lines

Add a new utility that reads one or more lcov files, and reads each
executable line from that file, and then tries to verify if that line
is actually executable code or not.

This should help when playing whack-a-mole with strange pre-processor
off-by-one errors.

BRANCH=None
BUG=b:272518464
TEST=Ran it on a known bad commit

Change-Id: I89b43f73e59f14854b45855322ada626146658b6
Signed-off-by: Jeremy Bettis <jbettis@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4426796
Commit-Queue: Jeremy Bettis <jbettis@chromium.org>
Auto-Submit: Jeremy Bettis <jbettis@chromium.org>
Tested-by: Jeremy Bettis <jbettis@chromium.org>
Reviewed-by: Tristan Honscheid <honscheid@google.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/util/find_non_exec_lines.py b/util/find_non_exec_lines.py
new file mode 100755
index 0000000000..e88d3f61ff
--- /dev/null
+++ b/util/find_non_exec_lines.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+# Copyright 2023 The ChromiumOS Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Read lcov files, and find lines that are probably not executable.
+
+Example run:
+zmake build --coverage -a && \
+./util/find_non_exec_lines.py build/zephyr/all_builds.info && \
+echo SUCCESS
+"""
+
+import re
+import sys
+
+
+BAD_COVERAGE = re.compile(r"^$|\*/\s*$")
+
+
+def main() -> int:
+    """Read lcov files, and find lines that are probably not executable."""
+    exit_code = 0
+    for input_file in sys.argv:
+        with open(input_file, encoding="utf-8") as lcov:
+            active_file = None
+            active_line = 0
+            active_name = ""
+            for line in lcov:
+                line = line.strip()
+                if line.startswith("SF:"):
+                    if active_file:
+                        active_file.close()
+                        active_file = None
+                    active_line = 0
+                    active_name = line[3:]
+                    # There are several files in zephyr that have odd coverage
+                    # but it seems consistent.
+                    if not "src/third_party/zephyr" in active_name:
+                        active_file = open(  # pylint: disable=R1732
+                            active_name, encoding="utf-8"
+                        )
+                if active_file and line.startswith("DA:"):
+                    target_line = int(line[3:].split(",", 1)[0])
+                    target = "NO SUCH LINE\n"
+                    while target and target_line > active_line:
+                        target = active_file.readline()
+                        active_line += 1
+                    if target and target_line == active_line:
+                        target = target.strip()
+                        if BAD_COVERAGE.match(target):
+                            print(f"{active_name}:{active_line}={target}")
+                            exit_code = 1
+            if active_file:
+                active_file.close()
+                active_file = None
+
+    return exit_code
+
+
+if __name__ == "__main__":
+    sys.exit(main())  # next section explains the use of sys.exit