Add preupload hook for checking unwanted c functions

Add a new script check-unwanted-c-functions.py in devtools, and add it
to the preupload hook for checking unwanted functions.

check-unwanted-c-functions.py checks blocked_functions.json for blocked
functions and the recommended replacements.

BUG=b:320231979
TEST=Add blocked function atoi usage and check that preupload check
fails

Change-Id: I09f3720cd9e2634d47ed65f1f7b5e4b1fd66d48f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/5211170
Tested-by: chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com <chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com>
Reviewed-by: Li-Yu Yu <aaronyu@google.com>
Commit-Queue: Baili Deng <bailideng@google.com>

PRESUBMIT.cfg

@@ -3,6 +3,7 @@ xmllint: cras/dbus_bindings/xmllint.py --ignore-non-dbus-xml-files ${PRESUBMIT_F
 check-header-format: devtools/check-header-format.py ${PRESUBMIT_FILES}
 cros format: cros format --exclude=*.rs --check --commit ${PRESUBMIT_COMMIT} -- ${PRESUBMIT_FILES}
 rustfmt: devtools/rustfmt.py --check -- ${PRESUBMIT_FILES}
+check-unwanted-cpp-functions: devtools/check-unwanted-cpp-functions.py --commit ${PRESUBMIT_COMMIT}
 
 [Hook Overrides]
 tab_check: false

devtools/blocked_functions.json

@@ -0,0 +1,52 @@
+{
+  "blocked_functions": [
+    {
+      "regex": "atoi",
+      "replacement": "strtol"
+    },
+    {
+      "regex": "atof",
+      "replacement": "strtof"
+    },
+    {
+      "regex": "sprintf",
+      "replacement": "snprintf or scnprintf if using the return value"
+    },
+    {
+      "regex": "strcmp",
+      "replacement": "strncmp"
+    },
+    {
+      "regex": "strcpy",
+      "replacement": "strlcpy"
+    },
+    {
+      "regex": "strncpy",
+      "replacement": "strlcpy"
+    },
+    {
+      "regex": "strlen",
+      "replacement": "strnlen"
+    },
+    {
+      "regex": "strdup",
+      "replacement": "strndup"
+    },
+    {
+      "regex": "strstr",
+      "replacement": "strnstr"
+    },
+    {
+      "regex": "strchr",
+      "replacement": "strnchr"
+    },
+    {
+      "regex": "strcasecmp",
+      "replacement": "strncasecmp"
+    },
+    {
+      "regex": "strdupa",
+      "replacement": "strndupa"
+    }
+  ]
+}

devtools/check-unwanted-cpp-functions.py

@@ -0,0 +1,160 @@
+#!/usr/bin/env vpython3
+# Copyright 2024 The ChromiumOS Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+
+Check for blocked functions.
+
+[VPYTHON:BEGIN]
+python_version: "3.8"
+[VPYTHON:END]
+"""
+
+import argparse
+import importlib
+import json
+import os
+from pathlib import Path
+import re
+import stat
+import sys
+
+
+# Path to the devtools directory.
+DEVTOOLS_DIR = Path(__file__).resolve().parent
+BLOCKED_FUNCTIONS_FILE = "blocked_functions.json"
+PRE_SUBMIT = "pre-submit"
+CHROMEOS_CHECKOUT_DIR = DEVTOOLS_DIR.parent.parent.parent.parent
+
+if __name__ in ("__builtin__", "builtins"):
+    # If repo imports us, the __name__ will be __builtin__, and the cwd will be
+    # in the top level of the checkout (i.e. $CHROMEOS_CHECKOUT).  chromite will
+    # be in that directory, so add it to our path.  This works whether we're
+    # running the repo in $CHROMEOS_CHECKOUT/.repo/repo/ or a custom version in
+    # a completely different tree.
+    sys.path.insert(0, os.getcwd())
+
+
+if __name__ == "__main__":
+    # If we're run directly, we'll find chromite relative to the devtools dir
+    # in $CHROMEOS_CHECKOUT.
+    sys.path.insert(0, str(CHROMEOS_CHECKOUT_DIR))
+
+sys.path.insert(0, str(CHROMEOS_CHECKOUT_DIR) + "/src/repohooks")
+
+preupload = importlib.import_module("pre-upload")
+
+
+def _get_file_lines(path):
+    """Add line number to file"""
+    with open(path) as file:
+        content = file.read()
+    return list(enumerate(content.splitlines(), 1))
+
+
+def _get_affected_c_files(commit):
+    """Returns list of c file paths that were modified/added.
+    For c files, we want to check the source ".c" and ".h" files
+
+    Args:
+        commit: The commit
+
+    Returns:
+        A list of modified/added c files
+    """
+
+    path = os.getcwd()
+    files = preupload._get_all_affected_files(commit, path)
+
+    # Filter out symlinks and deletes.
+    files = [x for x in files if not stat.S_ISLNK(int(x.dst_mode, 8))]
+    files = [x for x in files if x.status != "D"]
+
+    # git diff has two files, the src(original), and dst(modified)
+    # Used the modified files if able.
+    files = [x.dst_file if x.dst_file else x.src_file for x in files]
+
+    # Filter for c libraries and sources (.c and .h) files
+    files = [x for x in files if x.endswith(('.h', '.c'))]
+
+    return files
+
+
+def _read_blocked_functions_file(blocked_functions_file):
+    """Read list of blocked functions and recommended replacement from file."""
+    with open(blocked_functions_file) as f:
+        blocked_functions_json = json.load(f)
+
+    return blocked_functions_json["blocked_functions"]
+
+
+def _check_functions_in_file(commit, file, blocked_functions):
+    """Checks there are no blocked functions in a file being changed."""
+
+    def _check_line(line):
+        # Ignore lines that end with nocheck, typically in a comment.
+        # This enables devs to bypass this check line by line.
+        if line.endswith(" nocheck") or line.endswith(" nocheck */"):
+            return None
+
+        for function in blocked_functions:
+            match = re.search(function["regex"], line)
+            if match:
+                return f'Found usage of "{function["regex"]}", please replace it with "{function["replacement"]}"'
+        return None
+
+    error_list = []
+    if commit is not None:
+        file_lines = preupload._get_file_diff(file, commit)
+    else:
+        file_lines = _get_file_lines(file)
+    for line_num, line in file_lines:
+        result = _check_line(line)
+        if result is not None:
+            msg = f"{file}, line {line_num}: {result}"
+            error_list.append(msg)
+    return error_list
+
+
+def _check_functions(commit, check_all_files):
+    """Checks there are no blocked functions in commit content."""
+
+    # Read blocked functions list.
+    blocked_functions_file = DEVTOOLS_DIR / BLOCKED_FUNCTIONS_FILE
+    blocked_functions = _read_blocked_functions_file(blocked_functions_file)
+
+    if commit is not None:
+        files = _get_affected_c_files(commit)
+
+    if check_all_files:
+        files = Path('.').glob('**/*.[ch]')
+
+    error_list = []
+    for file in files:
+        errs = _check_functions_in_file(commit, file, blocked_functions)
+        if errs:
+            error_list.extend(errs)
+
+    if error_list:
+        print("Blocked functions found:")
+        for error in error_list:
+            print(error)
+
+    return bool(error_list)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Check for unwanted C functions')
+    parser.add_argument(
+        '--commit',
+        help='The git commit to check for unwanted C functions. If --commit is used, then the only the lines changed in the commit are checked.',
+    )
+    parser.add_argument(
+        '--check_all_files',
+        action='store_true',
+        help='Check all .c and .h files under current directory',
+    )
+    args = parser.parse_args()
+    sys.exit(_check_functions(args.commit, args.check_all_files))