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Modification of C library functions for error signaling, error handling, and program exit

All trap or error signals raised by the C library go through the __raise() function. You can re-implement this function or the lower-level functions that it uses.

Caution

The IEEE 754 standard for floating-point processing states that the default response to an exception is to proceed without a trap. You can modify floating-point error handling by tailoring the functions and definitions in fenv.h.

The rt_misc.h header file contains more information on error-related functions.

The following table shows the trap and error-handling functions.

Table 1-9 Trap and error handling

Function	Description
`_sys_exit()`	Called, eventually, by all exits from the library.
`errno`	Is a static variable used with error handling.
`__rt_errno_addr()`	Is called to obtain the address of the variable `errno`.
`__raise()`	Raises a signal to indicate a runtime anomaly.
`__rt_raise()`	Raises a signal to indicate a runtime anomaly.
`__default_signal_handler()`	Displays an error indication to the user.
`_ttywrch()`	Writes a character to the console. The default implementation of `_ttywrch()` is semihosted and, therefore, uses semihosting calls.
`__rt_fp_status_addr()`	This function is called to obtain the address of the floating-point status word.