set_constraint_handler_s, constraint_handler_t - cppreference.com (original) (raw)
| Defined in header <stdlib.h> | ||
|---|---|---|
| constraint_handler_t set_constraint_handler_s( constraint_handler_t handler ); | (1) | (since C11) |
| typedef void (*constraint_handler_t)( const char* restrict msg, void* restrict ptr, errno_t error ); | (2) | (since C11) |
Configures the handler to be called by all bounds-checked functions on a runtime constraint violation or restores the default handler (if handler is a null pointer).
The pointer to a handler that will be called on a runtime constraint violation.
If set_constraint_handler_s is never called, the default handler is implementation-defined: it may be abort_handler_s, ignore_handler_s, or some other implementation-defined handler.
As with all bounds-checked functions, set_constraint_handler_s and constraint_handler_t are only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before including <stdlib.h>.
[edit] Parameters
| handler | - | pointer to function of type constraint_handler_t or a null pointer |
|---|---|---|
| msg | - | pointer to character string that describes the error |
| ptr | - | pointer to an implementation-defined object or a null pointer. Examples of implementation-defined objects are objects that give the name of the function that detected the violation and the line number when the violation was detected |
| error | - | the error about to be returned by the calling function, if it happens to be one of the functions that return errno_t |
[edit] Return value
A pointer to the previously-installed runtime constraints handler. (Note: this pointer is never a null pointer because calling set_constraint_handler_s(NULL) sets up the system default handler).
[edit] Example
#define STDC_WANT_LIB_EXT1 1 #include <string.h> #include <stdio.h> #include <stdlib.h> int main(void) { #ifdef STDC_LIB_EXT1 char dst[2]; set_constraint_handler_s(ignore_handler_s); int r = strcpy_s(dst, sizeof dst, "Too long!"); printf("dst = "%s", r = %d\n", dst, r); set_constraint_handler_s(abort_handler_s); r = strcpy_s(dst, sizeof dst, "Too long!"); printf("dst = "%s", r = %d\n", dst, r); #endif }
Possible output:
dst = "", r = 22 abort_handler_s was called in response to a runtime-constraint violation. The runtime-constraint violation was caused by the following expression in strcpy_s: (s1max <= (s2_len=strnlen_s(s2, s1max)) ) (in string_s.c:62) Note to end users: This program was terminated as a result of a bug present in the software. Please reach out to your software's vendor to get more help. Aborted
[edit] References
C23 standard (ISO/IEC 9899:2024):
K.3.6/2 constraint_handler_t (p: TBD)
K.3.6.1.1 The set_constraint_handler_s function (p: TBD)
C17 standard (ISO/IEC 9899:2018):
K.3.6/2 constraint_handler_t (p: TBD)
K.3.6.1.1 The set_constraint_handler_s function (p: TBD)
C11 standard (ISO/IEC 9899:2011):
K.3.6/2 constraint_handler_t (p: 604)
K.3.6.1.1 The set_constraint_handler_s function (p: 604-605)