SIGFPE

SIGFPE is a signal defined by POSIX and used by Unix-like systems to indicate an arithmetic exception. It is delivered to a process when an arithmetic operation fails, typically due to errors such as integer division by zero, or floating-point errors that trigger a trap on some architectures.

The signal is delivered synchronously to the thread that caused the fault. The default action is to terminate the process and, if enabled, produce a core dump. Its occurrence depends on the system and the language runtime; some cases, especially floating-point errors, may not generate SIGFPE if the hardware or software masks such exceptions.

Common causes include integer division by zero, integer overflow on architectures that raise a trap for it, floating-point division by zero, floating-point overflow or underflow, and other invalid floating-point operations. In modern systems, floating-point exceptions are often masked, and arithmetic results like Inf or NaN may be produced without delivering SIGFPE.

Handling SIGFPE is possible through signal handling facilities such as signal() or sigaction(). With sigaction and SA_SIGINFO, a handler can receive extended information, including codes like FPE_INTDIV (integer division by zero), FPE_INTOVF (integer overflow), FPE_FLTDIV (floating-point division by zero), FPE_FLTOVF (floating-point overflow), and FPE_FLTINV (invalid floating-point operation). A handler may terminate the process, attempt recovery (for example via setjmp/longjmp), or take corrective action.

Notes: in C, integer overflow is undefined behavior rather than guaranteed to raise SIGFPE, and floating-point behavior depends on the environment and hardware traps. SIGFPE remains a modality for signaling arithmetic faults on many Unix-like systems, but its exact behavior can vary across platforms.