src/ucontext/generic/getmcontext.c

   1 /*
   2  * Copyright (c) 2007, 2008, 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 #define _XOPEN_SOURCE 600L
  25 #include <ucontext.h>
  26 #include <errno.h>
  27
  28 #if defined(__x86_64__) || defined(__i386__)
  29
  30 #include <sys/resource.h>
  31 #include <stddef.h>
  32 #include <stdint.h>
  33 #include <signal.h>
  34
  35 extern int __sigaltstack(const stack_t * __restrict, stack_t * __restrict);
  36
  37 #ifdef __DYNAMIC__
  38 extern int __in_sigtramp;
  39 #endif /* __DYNAMIC_ */
  40
  41 __attribute__((visibility("hidden")))
  42 mcontext_t
  43 getmcontext(ucontext_t *uctx, void *sp)
  44 {
  45         mcontext_t mctx = (mcontext_t)&uctx->__mcontext_data;
  46         size_t stacksize = 0;
  47         stack_t stack;
  48
  49         uctx->uc_stack.ss_sp = sp;
  50         uctx->uc_stack.ss_flags = 0;
  51
  52         if (0 == __sigaltstack(NULL, &stack)) {
  53                 if (stack.ss_flags & SS_ONSTACK) {
  54                         uctx->uc_stack = stack;
  55                         stacksize = stack.ss_size;
  56                 }
  57         }
  58
  59         if (stacksize == 0) {
  60                 struct rlimit rlim;
  61                 if (0 == getrlimit(RLIMIT_STACK, &rlim))
  62                         stacksize = rlim.rlim_cur;
  63         }
  64
  65         uctx->uc_stack.ss_size = stacksize;
  66
  67         if (uctx->uc_mcontext != mctx) {
  68                 uctx->uc_mcontext = mctx;
  69
  70 #ifdef __DYNAMIC__
  71                 uctx->uc_link = (ucontext_t*)(uintptr_t)__in_sigtramp; /* non-zero if in signal handler */
  72 #else  /* !__DYNAMIC__ */
  73                 uctx->uc_link = 0;
  74 #endif /* __DYNAMIC__ */
  75
  76         }
  77
  78         sigprocmask(0, NULL, &uctx->uc_sigmask);
  79         return mctx;
  80 }
  81
  82 #else
  83
  84 int
  85 getcontext(ucontext_t *u)
  86 {
  87         errno = ENOTSUP;
  88         return -1;
  89 }
  90
  91 #endif