Sample clang-format enforcement on kernel_log_monitor

- Formats kernel_log_monitor/main.cc
- Example format_test enforcing the file stays formatted correctly
- Creates a symlink to the root .clang-tidy file within the bazel
  workspace

Assisted-by: Jetski <jetski@google.com>
Bug: b/512215781

Author: Databean

base/cvd/.clang-format

@@ -0,0 +1 @@
+../../.clang-format

base/cvd/BUILD.bazel

@@ -12,7 +12,10 @@ package(
     default_visibility = ["//:android_cuttlefish"],
 )
 
-exports_files([".clang-tidy"])
+exports_files([
+    ".clang-format",
+    ".clang-tidy",
+])
 
 genrule(
     name = "build_compilation_mode_txt",

base/cvd/cuttlefish/host/commands/kernel_log_monitor/BUILD.bazel

@@ -1,4 +1,5 @@
 load("//cuttlefish/bazel:rules.bzl", "cf_cc_binary", "cf_cc_library")
+load("@aspect_rules_lint//format:defs.bzl", "format_test")
 
 package(
     default_visibility = ["//:android_cuttlefish"],
@@ -28,6 +29,13 @@ cf_cc_binary(
     ],
 )
 
+format_test(
+    name = "kernel_log_monitor_format_test",
+    cc = "//tools/format:clang_format",
+    disable_git_attribute_checks = True,
+    srcs = ["main.cc"],
+)
+
 cf_cc_library(
     name = "kernel_log_monitor_utils",
     srcs = [

base/cvd/cuttlefish/host/commands/kernel_log_monitor/main.cc

@@ -23,11 +23,11 @@
 #include <string>
 #include <vector>
 
-#include "absl/strings/str_split.h"
-#include <gflags/gflags.h>
-#include <json/value.h>
 #include "absl/log/check.h"
 #include "absl/log/log.h"
+#include "absl/strings/str_split.h"
+#include "gflags/gflags.h"
+#include "json/value.h"
 
 #include "cuttlefish/common/libs/fs/shared_fd.h"
 #include "cuttlefish/common/libs/fs/shared_select.h"
@@ -42,17 +42,18 @@ DEFINE_int32(log_pipe_fd, -1,
              "A file descriptor representing a (UNIX) socket from which to "
              "read the logs. If -1 is given the socket is created according to "
              "the instance configuration");
-DEFINE_string(subscriber_fds, "",
-             "A comma separated list of file descriptors (most likely pipes) to"
-             " send kernel log events to.");
+DEFINE_string(
+    subscriber_fds, "",
+    "A comma separated list of file descriptors (most likely pipes) to"
+    " send kernel log events to.");
 
 namespace cuttlefish::monitor {
 namespace {
 
 std::vector<SharedFD> SubscribersFromCmdline() {
   // Validate the parameter
   std::string fd_list = FLAGS_subscriber_fds;
-  for (auto c: fd_list) {
+  for (auto c : fd_list) {
     if (c != ',' && (c < '0' || c > '9')) {
       LOG(ERROR) << "Invalid file descriptor list: " << fd_list;
       std::exit(1);
@@ -61,7 +62,7 @@ std::vector<SharedFD> SubscribersFromCmdline() {
 
   std::vector<std::string> fds = absl::StrSplit(FLAGS_subscriber_fds, ',');
   std::vector<SharedFD> shared_fds;
-  for (auto& fd_str: fds) {
+  for (auto& fd_str : fds) {
     auto fd = std::stoi(fd_str);
     auto shared_fd = SharedFD::Dup(fd);
     close(fd);
@@ -84,8 +85,7 @@ int KernelLogMonitorMain(int argc, char** argv) {
   auto subscriber_fds = SubscribersFromCmdline();
 
   // Disable default handling of SIGPIPE
-  struct sigaction new_action {
-  }, old_action{};
+  struct sigaction new_action{}, old_action{};
   new_action.sa_handler = SIG_IGN;
   sigaction(SIGPIPE, &new_action, &old_action);
 
@@ -105,7 +105,7 @@ int KernelLogMonitorMain(int argc, char** argv) {
 
   KernelLogServer klog{pipe, instance.PerInstanceLogPath(kLogNameKernel)};
 
-  for (auto subscriber_fd: subscriber_fds) {
+  for (auto subscriber_fd : subscriber_fds) {
     if (subscriber_fd->IsOpen()) {
       klog.SubscribeToEvents([subscriber_fd](Json::Value message) {
         if (!WriteEvent(subscriber_fd, message)) {

base/cvd/tools/format/BUILD.bazel

@@ -0,0 +1,12 @@
+load("@bazel_skylib//rules:native_binary.bzl", "native_binary")
+
+package(
+    default_visibility = ["//:android_cuttlefish"],
+)
+
+native_binary(
+    name = "clang_format",
+    src = "@llvm_toolchain//:clang-format",
+    out = "clang_format",
+    data = ["//:.clang-format"],
+)