.\" Copyright 2018 Yuri Pankov .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" .Dd August 18, 2018 .Dt SET_CONSTRAINT_HANDLER_S 3 .Os .Sh NAME .Nm set_constraint_handler_s , .Nm abort_handler_s , .Nm ignore_handler_s .Nd runtime-constraint violation handling .Sh LIBRARY .Lb libc .Sh SYNOPSIS .Fd #define __STDC_WANT_LIB_EXT1__ 1 .In stdlib.h .Ft constraint_handler_t .Fo set_constraint_handler_s .Fa "constraint_handler_t handler" .Fc .Ss Handler Prototype .Ft typedef void .Fo (*constraint_handler_t) .Fa "const char * restrict msg" .Fa "void * restrict ptr" .Fa "errno_t error" .Fc .Ss Predefined Handlers .Ft void .Fo abort_handler_s .Fa "const char * restrict msg" .Fa "void * restrict ptr" .Fa "errno_t error" .Fc .Ft void .Fo ignore_handler_s .Fa "const char * restrict msg" .Fa "void * restrict ptr" .Fa "errno_t error" .Fc .Sh DESCRIPTION The .Fn set_constraint_handler_s function sets the runtime-constraint violation handler to be .Fa handler . .Pp The runtime-constraint handler is the callback function invoked when a library function detects a runtime-constraint violation. .Pp The arguments are as follows: .Bl -tag -width "error" .It Fa msg A pointer to a character string describing the runtime-constraint violation. .It Fa ptr A .Dv NULL pointer. .It Fa error If the function calling the handler has a return type declared as .Vt errno_t , the return value of the function is passed. Otherwise, a positive value of type .Vt errno_t is passed. .El .Pp Only the most recent handler registered with .Fn set_constraint_handler_s is called when a runtime-constraint violation occurs. .Pp The implementation has a default constraint handler that is used if no calls to the .Fn set_constraint_handler_s function have been made. If the .Fa handler argument to .Fn set_constraint_handler_s is a .Dv NULL pointer, the default handler becomes the current constraint handler. .Pp The .Fn abort_handler_s and .Fn ignore_handler_s are the standard-defined runtime-constraint handlers provided by the C library. .Pp The .Fn abort_handler_s function writes the error message including the .Fa msg to .Dv stderr and calls the .Xr abort 3 function. The .Fn abort_handler_s is currently the default runtime-constraint handler. .Pp The .Fn ignore_handler_s simply returns to its caller. .Sh RETURN VALUES The .Fn set_constraint_handler_s function returns a pointer to the previously registered handler, or .Dv NULL if none was previously registered. .Pp The .Fn abort_handler_s function does not return to its caller. .Pp The .Fn ignore_handler_s function returns no value. .Sh STANDARDS The .Fn set_constraint_handler_s function conforms to .St -isoC-2011 K.3.6.1.1. .Sh AUTHORS This manual page was written by .An Yuri Pankov Aq Mt yuripv@yuripv.net .