rom/dos/exit.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: English
   7 */
   8
   9 #include <setjmp.h>
  10
  11 #include "dos_intern.h"
  12
  13 /*
  14  * On m68k exiting a program can be performed by setting SP
  15  * to (FindTask(NULL)->pr_ReturnAddr - 4), and performing an rts.
  16  *
  17  * For the complete code, see arch/m68k-amiga/dos/exit.c and
  18  * arch/m68k-amiga/dos/bcpl.S, "BCPL Exit"
  19  *
  20  * pr_ReturnAddr points to the actual stack size.
  21  *
  22  * Similar construction should work on all CPUs. I guess this is what
  23  * is used by Exit() routine.
  24  *
  25  * For other CPUs we don't keep exact stack layout and consider it
  26  * private. Only Exit() knows what to do with it. However we keep stack
  27  * size value where it was, some code relies on it.
  28  */
  29 struct StackState
  30 {
  31     IPTR stackSize;
  32     APTR stackLower;
  33     APTR stackUpper;
  34     ULONG retval;
  35     jmp_buf state;
  36 };
  37
  38 /*****************************************************************************
  39
  40     NAME */
  41 #include <proto/dos.h>
  42
  43         AROS_LH1(void, Exit,
  44
  45 /*  SYNOPSIS */
  46         AROS_LHA(LONG, returnCode, D1),
  47
  48 /*  LOCATION */
  49         struct DosLibrary *, DOSBase, 24, Dos)
  50
  51 /*  FUNCTION
  52         Instantly terminate the program.
  53
  54     INPUTS
  55         returnCode - Process' return code.
  56
  57     RESULT
  58         None.
  59
  60     NOTES
  61         Calling this function bypasses normal termination sequence of your program.
  62         Automatically opened libraries will not be closed, destructors will not be
  63         called, etc. Do this only if you really know what are you doing. It's not
  64         adviced to use this function at all.
  65
  66     EXAMPLE
  67
  68     BUGS
  69
  70     SEE ALSO
  71
  72     INTERNALS
  73
  74 *****************************************************************************/
  75 {
  76     AROS_LIBFUNC_INIT
  77
  78     struct Process *me = (struct Process *)FindTask(NULL);
  79     struct StackState *ss = me->pr_ReturnAddr;
  80
  81     /* Return code can be zero, so we can't pass it via longjmp() */
  82     ss->retval = returnCode;
  83
  84     /* Close dos.library because the program has opened it in order to obtain DOSBase */
  85     CloseLibrary(&DOSBase->dl_lib);
  86
  87     /* Disable() because we may have to swap stack limits */
  88     Disable();
  89     longjmp(ss->state, 1);
  90
  91     AROS_LIBFUNC_EXIT
  92 } /* Exit */
  93
  94 /*
  95  * CallEntry() is also defined here because it is closely associated with
  96  * Exit() implementation.
  97  * For different CPUs we may have optimized versions of these two functions in asm.
  98  */
  99 ULONG CallEntry(STRPTR argptr, ULONG argsize, LONG_FUNC entry, struct Process *me)
 100 {
 101     struct StackState ss;
 102
 103     /* Set the first IPTR to something like on AmigaOS(tm) */
 104     ss.stackSize  = (APTR)&ss - me->pr_Task.tc_SPLower;
 105     /* Remember stack limits for Exit() */
 106     ss.stackLower = me->pr_Task.tc_SPLower;
 107     ss.stackUpper = me->pr_Task.tc_SPUpper;
 108     me->pr_ReturnAddr = &ss;
 109
 110     if (setjmp(ss.state))
 111     {
 112         /*
 113          * We came here from Exit().
 114          * Restore stack limits because the program might have swapped stack.
 115          * We are clever enough to recover from this.
 116          */
 117         me->pr_Task.tc_SPLower = ss.stackLower;
 118         me->pr_Task.tc_SPUpper = ss.stackUpper;
 119
 120         Enable(); /* We Disable()d in Exit() */
 121
 122         return ss.retval;
 123     }
 124     else
 125         return AROS_UFC3(ULONG, entry,
 126                          AROS_UFCA(STRPTR, argptr, A0),
 127                          AROS_UFCA(ULONG, argsize, D0),
 128                          AROS_UFCA(struct ExecBase *, SysBase, A6));
 129 }