rom/dos/exit.c

   1 /*
   2     Copyright © 1995-2013, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: English
   7 */
   8
   9 #include <aros/debug.h>
  10 #include <setjmp.h>
  11
  12 #include "dos_intern.h"
  13
  14 /*
  15  * On m68k exiting a program can be performed by setting SP
  16  * to (FindTask(NULL)->pr_ReturnAddr - 4), and performing an rts.
  17  *
  18  * For the complete code, see arch/m68k-amiga/dos/exit.c and
  19  * arch/m68k-amiga/dos/bcpl.S, "BCPL Exit"
  20  *
  21  * pr_ReturnAddr points to the actual stack size.
  22  *
  23  * Similar construction should work on all CPUs. I guess this is what
  24  * is used by Exit() routine.
  25  *
  26  * For other CPUs we don't keep exact stack layout and consider it
  27  * private. Only Exit() knows what to do with it. However we keep stack
  28  * size value where it was, some code relies on it.
  29  */
  30 struct StackState
  31 {
  32     IPTR stackSize;
  33     APTR stackLower;
  34     APTR stackUpper;
  35     ULONG retval;
  36     jmp_buf state;
  37 };
  38
  39 /*****************************************************************************
  40
  41     NAME */
  42 #include <proto/dos.h>
  43
  44         AROS_LH1(void, Exit,
  45
  46 /*  SYNOPSIS */
  47         AROS_LHA(LONG, returnCode, D1),
  48
  49 /*  LOCATION */
  50         struct DosLibrary *, DOSBase, 24, Dos)
  51
  52 /*  FUNCTION
  53         Instantly terminate the program.
  54
  55     INPUTS
  56         returnCode - Process' return code.
  57
  58     RESULT
  59         None.
  60
  61     NOTES
  62         Calling this function bypasses normal termination sequence of your program.
  63         Automatically opened libraries will not be closed, destructors will not be
  64         called, etc. Do this only if you really know what are you doing. It's not
  65         advised to use this function at all.
  66
  67     EXAMPLE
  68
  69     BUGS
  70
  71     SEE ALSO
  72
  73     INTERNALS
  74
  75 *****************************************************************************/
  76 {
  77     AROS_LIBFUNC_INIT
  78
  79     struct Process *me = (struct Process *)FindTask(NULL);
  80     struct StackState *ss;
  81
  82     ASSERT_VALID_PROCESS(me);
  83     ss = me->pr_ReturnAddr;
  84
  85     /* Return code can be zero, so we can't pass it via longjmp() */
  86     ss->retval = returnCode;
  87
  88     /* Close dos.library because the program has opened it in order to obtain DOSBase */
  89     CloseLibrary(&DOSBase->dl_lib);
  90
  91     /* Disable() because we may have to swap stack limits */
  92     Disable();
  93     longjmp(ss->state, 1);
  94
  95     AROS_LIBFUNC_EXIT
  96 } /* Exit */
  97
  98 /*
  99  * CallEntry() is also defined here because it is closely associated with
 100  * Exit() implementation.
 101  * For different CPUs we may have optimized versions of these two functions in asm.
 102  */
 103 ULONG CallEntry(STRPTR argptr, ULONG argsize, LONG_FUNC entry, struct Process *me)
 104 {
 105     struct StackState ss;
 106
 107     /* Set the first IPTR to something like on AmigaOS(tm) */
 108     ss.stackSize  = (APTR)&ss - me->pr_Task.tc_SPLower;
 109     /* Remember stack limits for Exit() */
 110     ss.stackLower = me->pr_Task.tc_SPLower;
 111     ss.stackUpper = me->pr_Task.tc_SPUpper;
 112     me->pr_ReturnAddr = &ss;
 113
 114     if (setjmp(ss.state))
 115     {
 116         /*
 117          * We came here from Exit().
 118          * Restore stack limits because the program might have swapped stack.
 119          * We are clever enough to recover from this.
 120          */
 121         me->pr_Task.tc_SPLower = ss.stackLower;
 122         me->pr_Task.tc_SPUpper = ss.stackUpper;
 123
 124         Enable(); /* We Disable()d in Exit() */
 125
 126         return ss.retval;
 127     }
 128     else
 129         return AROS_UFC3(ULONG, entry,
 130                          AROS_UFCA(STRPTR, argptr, A0),
 131                          AROS_UFCA(ULONG, argsize, D0),
 132                          AROS_UFCA(struct ExecBase *, SysBase, A6));
 133 }