If you pass a message of type const char * to RCUTILS_SAFE_FWRITE_TO_STDERR e.g.

then the sizeof(msg) calculation in the macro gives the size of the pointer:

From what I can tell the count passed to fwrite is not a max size, but the size, so I think this line can cause buffer overrun if the msg is less than length 8. That doesn't happen with our existing code because they're all longer (instead our messages get truncated), but it could happen.

What's the appropriate fix here?

• continue using sizeof(msg) and only use this macro with static buffers
• switch to strlen(msg) and only use this macro will null-terminated buffers (also a risk)