[FW]C Coding Standards Quick Reference[4]

A return type of a function shall always be explicitly specified.

A function shall never return a reference or a pointer to a local variable.

Functions that return pointers shall return a NULL on a failure condition.

If a function can fail, the function shall return a status indicating a failure.

Declaring the magnitude of a single dimensional array in an argument declaration shall not be used.

A main function shall return a value indication the completion status.

Structures shall not be passed as arguments to functions and functions shall not return structures.