C condition handling semantics

This section describes C condition handling in a POSIX(OFF) environment. If you run applications that contain POSIX functions, you should also read Language Environment and POSIX signal handling interactions, which discusses the interaction between POSIX signal handling and Language Environment condition handling.

C employs a global condition handling model, which, on initialization, defines the actions that are taken when a condition is raised. The actions defined by C apply to an entire enclave, not just to a routine or block within an enclave. You can alter a specific action that the C condition handler takes when a condition is raised, however, by coding signal() function calls in your applications.

C recognizes a number of errors; some correspond directly to the errors detected by the hardware or the operating system, and some are unique to C. All actions for condition handling are controlled by the contents of the C global error table. Table 1 contains default C-language error handling semantics.

Table 1. C conditions and default system actions
C Condition	Origin	Default action
SIGILL	Execute exception Operation exception Privileged operation `raise(SIGILL)`	Abnormal termination (return code=3000)
SIGSEGV	Addressing exception Protection exception Specification exception `raise(SIGSEGV)`	Abnormal termination (return code=3000)
SIGFPE	Data exception Decimal divide Exponent overflow Fixed-point divide Floating-point divide `raise(SIGFPE)`	Abnormal termination (return code=3000)
SIGABRT	`abort()` function `raise(SIGABRT)`	Abnormal termination (return code=2000)
SIGABND	Abend the function	Abnormal termination (return code=3000)
SIGTERM	Termination request `raise(SIGTERM)`	Abnormal termination (return code = 3000)
SIGINT	Attention condition	Abnormal termination (return code = 3000)
SIGIOERR	I/O errors	Ignore the condition
SIGUSR1	User-defined condition	Abnormal termination (return code=3000)
SIGUSR2	User-defined condition	Abnormal termination (return code=3000)
Masked	Fixed-point overflow HFP exponent underflow HFP significance	These exceptions are disabled. They are ignored during the condition handling process, even if you try to enable them using the CEE3SPM callable service.