This rule finds calls to a function that ignore the return value. A function call is only marked as a violation if at least 90% of the total calls to that function check the return value. Not checking a return value is a common source of defects from standard library functions like malloc or fread. These functions return the status information and the return values should always be checked to see if the operation succeeded before operating on any data modified or resources allocated by these functions.

This rule uses a white/blacklist of functions the value of which can always be ignored (e.g. select) and those that should always be checked (e.g. fgets). These list can be modified to suit a particular codebase.