src/ucontext/generic/swapcontext.c

   1 /*
   2  * Copyright (c) 2007, 2009 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 /*
  25  * Copyright (c) 2001 Daniel M. Eischen <deischen@freebsd.org>
  26  * All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Neither the name of the author nor the names of its contributors
  34  *    may be used to endorse or promote products derived from this software
  35  *    without specific prior written permission.
  36  *
  37  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  38  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  39  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  40  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  41  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  42  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  43  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  45  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  46  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  47  * SUCH DAMAGE.
  48  */
  49
  50 #define _XOPEN_SOURCE 600L
  51 #include <ucontext.h>
  52 #include <errno.h>
  53
  54 #if defined(__x86_64__) || defined(__i386__)
  55 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
  56
  57 #include <sys/param.h>
  58 #include <sys/signal.h>
  59 #include <stddef.h>
  60
  61 #define uc_flags uc_onstack
  62 #define UCF_SWAPPED 0x80000000
  63
  64 int
  65 swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
  66 {
  67         int ret;
  68
  69         if ((oucp == NULL) || (ucp == NULL)) {
  70                 errno = EINVAL;
  71                 return (-1);
  72         }
  73         oucp->uc_flags &= ~UCF_SWAPPED;
  74         ret = getcontext(oucp);
  75         if ((ret == 0) && !(oucp->uc_flags & UCF_SWAPPED)) {
  76                 oucp->uc_flags |= UCF_SWAPPED;
  77                 ret = setcontext(ucp);
  78         }
  79         asm(""); // Prevent tailcall <rdar://problem/12581792>
  80         return (ret);
  81 }
  82
  83 #else
  84
  85 int
  86 swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
  87 {
  88         errno = ENOTSUP;
  89         return -1;
  90 }
  91
  92 #endif