text: /*-
   * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   *
   * Copyright (c) 2002 Jonathan Mini <mini@freebsd.org>
   * All rights reserved.
   *
   * 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 AUTHOR 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 AUTHOR 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.
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD$");
  
  #include <sys/param.h>
  #include <sys/ucontext.h>
  #include <machine/psl.h>
  #include <machine/sigframe.h>
  #include <signal.h>
  #include <strings.h>
  
  __weak_reference(__signalcontext, signalcontext);
  
  extern void _ctx_start(ucontext_t *, int argc, ...);
  
  int
  __signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
  {
  	register_t *p;
  	struct sigframe *sfp;
  
  	/*-
  	 * Set up stack.
  	 * (n = sizeof(int))
  	 * 2n+sizeof(struct sigframe)	ucp
  	 * 2n				struct sigframe
  	 * 1n				&func
  	 * 0n				&_ctx_start
  	 */
  	p = (register_t *)(void *)(intptr_t)ucp->uc_mcontext.mc_esp;
  	*--p = (register_t)(intptr_t)ucp;
  	p = (register_t *)((u_register_t)p & ~0xF);  /* Align to 16 bytes. */
  	p = (register_t *)((u_register_t)p - sizeof(struct sigframe));
  	sfp = (struct sigframe *)p;
  	bzero(sfp, sizeof(struct sigframe));
  	sfp->sf_signum = sig;
  	sfp->sf_siginfo = (register_t)(intptr_t)&sfp->sf_si;
  	sfp->sf_ucontext = (register_t)(intptr_t)&sfp->sf_uc;
  	sfp->sf_ahu.sf_action = (__siginfohandler_t *)func;
  	bcopy(ucp, &sfp->sf_uc, sizeof(ucontext_t));
  	sfp->sf_si.si_signo = sig;
  	*--p = (register_t)(intptr_t)func;
  
  	/*
  	 * Set up ucontext_t.
  	 */
  	ucp->uc_mcontext.mc_esi = ucp->uc_mcontext.mc_esp - sizeof(int);
  	ucp->uc_mcontext.mc_esp = (register_t)(intptr_t)p;
  	ucp->uc_mcontext.mc_eip = (register_t)(intptr_t)_ctx_start;
  	ucp->uc_mcontext.mc_eflags &= ~PSL_T;
  	ucp->uc_link = &sfp->sf_uc;
  	sigdelset(&ucp->uc_sigmask, sig);
  	return (0);
  }
  