Address miscellaneous clang-tidy warnings

Also add configuration with suppressions.

.clang-tidy

@@ -0,0 +1,26 @@
+Checks: '
+    -*,
+    bugprone-*,
+    google-*,
+    -google-build-using-namespace,
+    -google-readability-casting,
+    -google-readability-todo,
+    -google-runtime-int,
+    -google-runtime-references,
+    misc-*,
+    -misc-misplaced-const,
+    -misc-redundant-expression,
+    -misc-unused-parameters,
+    modernize-*,
+    -modernize-deprecated-headers,
+    -modernize-loop-convert,
+    -modernize-use-auto,
+    -modernize-use-nullptr,
+    -modernize-use-using,
+    performance-*,
+    portability-*,
+    readability-*,
+    -readability-else-after-return,
+    -readability-implicit-bool-conversion,
+    -readability-named-parameter,
+    -readability-simplify-boolean-expr'

src/fdcache.cpp

@@ -1471,7 +1471,7 @@ int FdEntity::RowFlush(const char* tpath, bool force_sync)
         // enough disk space
         // Load all uninitialized area
         result = Load();
-        FdManager::get()->FreeReservedDiskSpace(restsize);
+        FdManager::FreeReservedDiskSpace(restsize);
         if(0 != result){
           S3FS_PRN_ERR("failed to upload all area(errno=%d)", result);
           return static_cast<ssize_t>(result);
@@ -1646,7 +1646,7 @@ ssize_t FdEntity::Read(char* bytes, off_t start, size_t size, bool force_load)
       result = Load(start, load_size);
     }
 
-    FdManager::get()->FreeReservedDiskSpace(load_size);
+    FdManager::FreeReservedDiskSpace(load_size);
 
     if(0 != result){
       S3FS_PRN_ERR("could not download. start(%jd), size(%zu), errno(%d)", (intmax_t)start, size, result);
@@ -1698,7 +1698,7 @@ ssize_t FdEntity::Write(const char* bytes, off_t start, size_t size)
       if(0 < start){
         result = Load(0, static_cast<size_t>(start));
       }
-      FdManager::get()->FreeReservedDiskSpace(restsize);
+      FdManager::FreeReservedDiskSpace(restsize);
       if(0 != result){
         S3FS_PRN_ERR("failed to load uninitialized area before writing(errno=%d)", result);
         return static_cast<ssize_t>(result);

src/s3fs.cpp

@@ -822,9 +822,9 @@ static int put_headers(const char* path, headers_t& meta, bool is_copy)
   }
 
   FdEntity* ent = NULL;
-  if(NULL == (ent = FdManager::get()->ExistOpen(path, -1, !(FdManager::get()->IsCacheDir())))){
+  if(NULL == (ent = FdManager::get()->ExistOpen(path, -1, !FdManager::IsCacheDir()))){
     // no opened fd
-    if(FdManager::get()->IsCacheDir()){
+    if(FdManager::IsCacheDir()){
       // create cache file if be needed
       ent = FdManager::get()->Open(path, &meta, static_cast<ssize_t>(buf.st_size), -1, false, true);
     }
@@ -2564,8 +2564,9 @@ static int list_bucket(const char* path, S3ObjList& head, const char* delimiter,
     // reset(initialize) curl object
     s3fscurl.DestroyCurlHandle();
 
-    if (check_content_only)
+    if(check_content_only){
       break;
+    }
   }
   S3FS_MALLOCTRIM(0);
 
@@ -4341,7 +4342,7 @@ static int my_fuse_opt_proc(void* data, const char* arg, int key, struct fuse_ar
     }
 
     // the second NONOPT option is the mountpoint(not utility mode)
-    if(mountpoint.empty() && 0 == utility_mode){
+    if(mountpoint.empty() && !utility_mode){
       // save the mountpoint and do some basic error checking
       mountpoint = arg;
       struct stat stbuf;
@@ -4379,7 +4380,7 @@ static int my_fuse_opt_proc(void* data, const char* arg, int key, struct fuse_ar
     }
 
     // Unknown option
-    if(0 == utility_mode){
+    if(!utility_mode){
       S3FS_PRN_EXIT("specified unknown third option(%s).", arg);
     }else{
       S3FS_PRN_EXIT("specified unknown second option(%s). you don't need to specify second option(mountpoint) for utility mode(-u).", arg);
@@ -4988,7 +4989,7 @@ int main(int argc, char* argv[])
     case 's':
       break;
     case 'u':
-      utility_mode = 1;
+      utility_mode = true;
       break;
     default:
       exit(EXIT_FAILURE);
@@ -5080,7 +5081,7 @@ int main(int argc, char* argv[])
   // if the option was given, we all ready checked for a
   // readable, non-empty directory, this checks determines
   // if the mountpoint option was ever supplied
-  if(utility_mode == 0){
+  if(!utility_mode){
     if(mountpoint.empty()){
       S3FS_PRN_EXIT("missing MOUNTPOINT argument.");
       show_usage();

src/s3fs_util.cpp

@@ -419,7 +419,6 @@ void free_mvnodes(MVNODE *head)
     free(my_head->new_path);
     free(my_head);
   }
-  return;
 }
 
 //-------------------------------------------------------------------
@@ -1362,7 +1361,6 @@ void show_help ()
     "\n"
     "s3fs home page: <https://github.com/s3fs-fuse/s3fs-fuse>\n"
   );
-  return;
 }
 
 void show_version()
@@ -1374,7 +1372,6 @@ void show_version()
   "This is free software: you are free to change and redistribute it.\n"
   "There is NO WARRANTY, to the extent permitted by law.\n",
   VERSION, COMMIT_HASH_VAL, s3fs_crypt_lib_name());
-  return;
 }
 
 /*