Background

Here we document style rules for C usage in the gRPC Core library.

General

Layout rules are defined by clang-format, and all code should be passed through clang-format. A (docker-based) script to do so is included in tools/distrib/clang\_format\_code.sh.

Header Files

Public header files (those in the include/grpc tree) should compile as pedantic C89.
Public header files should be includable from C++ programs. That is, they should include the following: ```c #ifdef __cplusplus extern "C" {
endif

/* ... body of file ...

#ifdef __cplusplus }

endif

```

Header files should be self-contained and end in .h.
All header files should have a #define guard to prevent multiple inclusion. To guarantee uniqueness they should be based on the file's path.

For public headers: include/grpc/grpc.h → GRPC_GRPC_H

For private headers: src/core/channel/channel_stack.h → GRPC_INTERNAL_CORE_CHANNEL_CHANNEL_STACK_H

Variable Initialization

When declaring a (non-static) pointer variable, always initialize it to NULL. Even in the case of static pointer variables, it's recommended to explicitly initialize them to NULL.

C99 Features

Variable sized arrays are not allowed.
Do not use the 'inline' keyword.
Flexible array members are allowed (https://en.wikipedia.org/wiki/Flexible_array_member).

Comments

Within public header files, only /* comments are allowed.

Within implementation files and private headers, either single line // or multi line /* comments are allowed. Only one comment style per file is allowed however (i.e. if single line comments are used anywhere within a file, ALL comments within that file must be single line comments).

Symbol Names

Non-static functions must be prefixed by grpc_
Static functions must not be prefixed by grpc_
Enumeration values and #define names must be uppercase. All other values must be lowercase.
Multiple word identifiers use underscore as a delimiter, never camel case. E.g. variable_name.

Functions

The use of `atexit()` is in forbidden in libgrpc.