Fix clang-tidy performance warnings in syste/core.

* Use const reference type for parameters to avoid unnecessary copy.
* Suppress warning of not using faster overloaded string find function.

Bug: 30407689
Bug: 30411878
Change-Id: I6cfdbbd50cf5e8f3db6e5263076d3a17a9a791ee
Test: build with WITH_TIDY=1
Merged-In: Ie79dbe21899867bc62031f8618bb1322b8071525

adb/adb_utils_test.cpp

@@ -111,7 +111,7 @@ TEST(adb_utils, adb_dirname) {
   EXPECT_EQ("/system/bin", adb_dirname("/system/bin/sh/"));
 }
 
-void test_mkdirs(const std::string basepath) {
+void test_mkdirs(const std::string& basepath) {
   // Test creating a directory hierarchy.
   EXPECT_TRUE(mkdirs(basepath));
   // Test finding an existing directory hierarchy.

adb/commandline.cpp

@@ -1275,9 +1275,10 @@ static std::string find_product_out_path(const std::string& hint) {
         return hint;
     }
 
-    // If there are any slashes in it, assume it's a relative path;
+    // If any of the OS_PATH_SEPARATORS is found, assume it's a relative path;
     // make it absolute.
-    if (hint.find_first_of(OS_PATH_SEPARATORS) != std::string::npos) {
+    // NOLINT: Do not complain if OS_PATH_SEPARATORS has only one character.
+    if (hint.find_first_of(OS_PATH_SEPARATORS) != std::string::npos) {  // NOLINT
         std::string cwd;
         if (!getcwd(&cwd)) {
             fprintf(stderr, "adb: getcwd failed: %s\n", strerror(errno));

adb/file_sync_client.cpp

@@ -433,7 +433,7 @@ class SyncConnection {
 typedef void (sync_ls_cb)(unsigned mode, unsigned size, unsigned time, const char* name);
 
 static bool sync_ls(SyncConnection& sc, const char* path,
-                    std::function<sync_ls_cb> func) {
+                    const std::function<sync_ls_cb>& func) {
     if (!sc.SendRequest(ID_LIST, path)) return false;
 
     while (true) {

fastboot/fastboot.cpp

@@ -835,7 +835,7 @@ static std::string verify_slot(Transport* transport, const char *slot) {
 }
 
 static void do_for_partition(Transport* transport, const char *part, const char *slot,
-                             std::function<void(const std::string&)> func, bool force_slot) {
+                             const std::function<void(const std::string&)>& func, bool force_slot) {
     std::string has_slot;
     std::string current_slot;
 
@@ -867,7 +867,7 @@ static void do_for_partition(Transport* transport, const char *part, const char
  * partition does not support slots.
  */
 static void do_for_partitions(Transport* transport, const char *part, const char *slot,
-                              std::function<void(const std::string&)> func, bool force_slot) {
+                              const std::function<void(const std::string&)>& func, bool force_slot) {
     std::string has_slot;
 
     if (slot && strcmp(slot, "all") == 0) {

fastboot/socket_test.cpp

@@ -34,7 +34,7 @@ static constexpr int kTestTimeoutMs = 3000;
 // Creates connected sockets |server| and |client|. Returns true on success.
 bool MakeConnectedSockets(Socket::Protocol protocol, std::unique_ptr<Socket>* server,
                           std::unique_ptr<Socket>* client,
-                          const std::string hostname = "localhost") {
+                          const std::string& hostname = "localhost") {
     *server = Socket::NewServer(protocol, 0);
     if (*server == nullptr) {
         ADD_FAILURE() << "Failed to create server.";

init/service.cpp

@@ -850,7 +850,7 @@ Service* ServiceManager::FindServiceByKeychord(int keychord_id) const {
     return nullptr;
 }
 
-void ServiceManager::ForEachService(std::function<void(Service*)> callback) const {
+void ServiceManager::ForEachService(const std::function<void(Service*)>& callback) const {
     for (const auto& s : services_) {
         callback(s.get());
     }

init/service.h

@@ -177,7 +177,7 @@ public:
     Service* FindServiceByName(const std::string& name) const;
     Service* FindServiceByPid(pid_t pid) const;
     Service* FindServiceByKeychord(int keychord_id) const;
-    void ForEachService(std::function<void(Service*)> callback) const;
+    void ForEachService(const std::function<void(Service*)>& callback) const;
     void ForEachServiceInClass(const std::string& classname,
                                void (*func)(Service* svc)) const;
     void ForEachServiceWithFlags(unsigned matchflags,

init/util.cpp

@@ -317,7 +317,7 @@ int wait_for_file(const char *filename, int timeout)
 }
 
 void import_kernel_cmdline(bool in_qemu,
-                           std::function<void(const std::string&, const std::string&, bool)> fn) {
+                           const std::function<void(const std::string&, const std::string&, bool)>& fn) {
     std::string cmdline;
     android::base::ReadFileToString("/proc/cmdline", &cmdline);
 

init/util.h

@@ -55,7 +55,7 @@ void make_link_init(const char *oldpath, const char *newpath);
 void remove_link(const char *oldpath, const char *newpath);
 int wait_for_file(const char *filename, int timeout);
 void import_kernel_cmdline(bool in_qemu,
-                           std::function<void(const std::string&, const std::string&, bool)>);
+                           const std::function<void(const std::string&, const std::string&, bool)>&);
 int make_dir(const char *path, mode_t mode);
 int restorecon(const char *pathname);
 int restorecon_recursive(const char *pathname);

libbacktrace/backtrace_offline_test.cpp

@@ -73,7 +73,7 @@ static ucontext_t GetUContextFromUnwContext(const unw_context_t& unw_context) {
   return ucontext;
 }
 
-static void OfflineBacktraceFunctionCall(std::function<int(void (*)(void*), void*)> function,
+static void OfflineBacktraceFunctionCall(const std::function<int(void (*)(void*), void*)>& function,
                                          std::vector<uintptr_t>* pc_values) {
   // Create a thread to generate the needed stack and registers information.
   g_exit_flag = false;