uspace/lib/c/generic/setjmp.c

   1 /*
   2  * Copyright (c) 2013 Vojtech Horky
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * - Redistributions of source code must retain the above copyright
  10  *   notice, this list of conditions and the following disclaimer.
  11  * - Redistributions in binary form must reproduce the above copyright
  12  *   notice, this list of conditions and the following disclaimer in the
  13  *   documentation and/or other materials provided with the distribution.
  14  * - The name of the author may not be used to endorse or promote products
  15  *   derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /** @addtogroup libc
  30  * @{
  31  */
  32 /** @file Long jump implementation.
  33  *
  34  * Implementation inspired by Jiri Zarevucky's code from
  35  * http://bazaar.launchpad.net/~zarevucky-jiri/helenos/stdc/revision/1544/uspace/lib/posix/setjmp.h
  36  */
  37
  38 #include <setjmp.h>
  39 #include <libarch/fibril.h>
  40 #include <fibril.h>
  41
  42 struct jmp_buf_interal {
  43         context_t context;
  44         int return_value;
  45 };
  46
  47 /**
  48  * Save current environment (registers).
  49  *
  50  * This function may return twice.
  51  *
  52  * @param env Variable where to save the environment.
  53  * @return Whether the call returned after longjmp.
  54  * @retval 0 Environment was saved, normal execution.
  55  * @retval other longjmp was executed and returned here.
  56  */
  57 int setjmp(jmp_buf env) {
  58         env->return_value = 0;
  59         context_save(&env[0].context);
  60         return env->return_value;
  61 }
  62
  63 /**
  64  * Restore environment previously stored by setjmp.
  65  *
  66  * This function never returns.
  67  *
  68  * @param env Variable with the environment previously stored by call
  69  * to setjmp.
  70  * @param val Value to fake when returning from setjmp (0 is transformed to 1).
  71  */
  72 void longjmp(jmp_buf env, int val) {
  73         env[0].return_value = (val == 0) ? 1 : val;
  74         context_restore(&env[0].context);
  75         __builtin_unreachable();
  76 }
  77
  78 /** @}
  79  */