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set_constraint_handler_s, abort_handler_s, ignore_handler_s – runtime-constraint violation handling



Standard C Library (libc, -lc)


#define __STDC_WANT_LIB_EXT1__ 1
#include <stdlib.h>

set_constraint_handler_s(constraint_handler_t handler);

Handler Prototype

typedef void
(*constraint_handler_t)(const char * restrict msg, void * restrict ptr, errno_t error);

Predefined Handlers

abort_handler_s(const char * restrict msg, void * restrict ptr, errno_t error);

ignore_handler_s(const char * restrict msg, void * restrict ptr, errno_t error);


The set_constraint_handler_s() function sets the runtime-constraint violation handler to be handler.

The runtime-constraint handler is the callback function invoked when a library function detects a runtime-constraint violation.

The arguments are as follows:
  A pointer to a character string describing the runtime-constraint violation.
  A NULL pointer.
  If the function calling the handler has a return type declared as errno_t, the return value of the function is passed. Otherwise, a positive value of type errno_t is passed.

Only the most recent handler registered with set_constraint_handler_s() is called when a runtime-constraint violation occurs.

The implementation has a default constraint handler that is used if no calls to the set_constraint_handler_s() function have been made. If the handler argument to set_constraint_handler_s() is a NULL pointer, the default handler becomes the current constraint handler.

The abort_handler_s() and ignore_handler_s() are the standard-defined runtime-constraint handlers provided by the C library.

The abort_handler_s() function writes the error message including the msg to stderr and calls the abort(3) function. The abort_handler_s() is currently the default runtime-constraint handler.

The ignore_handler_s() simply returns to its caller.


The set_constraint_handler_s() function returns a pointer to the previously registered handler, or NULL if none was previously registered.

The abort_handler_s() function does not return to its caller.

The ignore_handler_s() function returns no value.


The set_constraint_handler_s() function conforms to ISO/IEC K.


This manual page was written by Yuri Pankov <Mt yuripv@yuripv.net>.

SET_CONSTRAINT_HANDLER_S (3) August 18, 2018

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