dlls/winedos/relay.c

   1 /*
   2  * Routines for dynamically building calls to Wine from
   3  * protected mode applications.
   4  *
   5  * Copyright 2002 Jukka Heinonen
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  20  */
  21 #include "dosexe.h"
  22 #include "wine/winbase16.h"
  23 #include "wine/debug.h"
  24
  25 WINE_DEFAULT_DEBUG_CHANNEL(int);
  26
  27 /*
  28  * Magic DWORD used to check stack integrity.
  29  */
  30 #define RELAY_MAGIC 0xabcdef00
  31
  32 /*
  33  * Memory block for temporary 16-bit stacks used with relay calls.
  34  */
  35 typedef struct {
  36     DWORD inuse;          /* non-zero if stack block is in use */
  37     DWORD eip;            /* saved ip */
  38     DWORD seg_cs;         /* saved cs */
  39     DWORD esp;            /* saved sp */
  40     DWORD seg_ss;         /* saved ss */
  41     DWORD stack_bottom;   /* guard dword */
  42     BYTE  stack[256-7*4]; /* 16-bit stack */
  43     DWORD stack_top;      /* guard dword */
  44 } RELAY_Stack16;
  45
  46
  47 /**********************************************************************
  48  *          RELAY_GetPointer
  49  *
  50  * Get pointer to stack block when given esp pointing to 16-bit stack
  51  * inside relay data segment.
  52  */
  53 static RELAY_Stack16 *RELAY_GetPointer( DWORD offset )
  54 {
  55     offset = offset / sizeof(RELAY_Stack16) * sizeof(RELAY_Stack16);
  56     return MapSL(MAKESEGPTR(DOSVM_dpmi_segments->relay_data_sel, offset));
  57 }
  58
  59
  60 /**********************************************************************
  61  *          RELAY_MakeShortContext
  62  *
  63  * Allocate separate 16-bit stack, make stack pointer point to this
  64  * stack and make code pointer point to stub that restores everything.
  65  * So, after this routine, SS and CS are guaranteed to be 16-bit.
  66  *
  67  * Note: This might be called from signal handler, so the stack
  68  *       allocation algorithm must be signal safe.
  69  */
  70 static void RELAY_MakeShortContext( CONTEXT86 *context )
  71 {
  72     DWORD offset = offsetof(RELAY_Stack16, stack_top);
  73     RELAY_Stack16 *stack = RELAY_GetPointer( 0 );
  74
  75     while (stack->inuse && offset < DOSVM_RELAY_DATA_SIZE) {
  76         stack++;
  77         offset += sizeof(RELAY_Stack16);
  78     }
  79
  80     if (offset >= DOSVM_RELAY_DATA_SIZE)
  81         ERR( "Too many nested interrupts!\n" );
  82
  83     stack->inuse = 1;
  84     stack->eip = context->Eip;
  85     stack->seg_cs = context->SegCs;
  86     stack->esp = context->Esp;
  87     stack->seg_ss = context->SegSs;
  88
  89     stack->stack_bottom = RELAY_MAGIC;
  90     stack->stack_top = RELAY_MAGIC;
  91
  92     context->SegSs = DOSVM_dpmi_segments->relay_data_sel;
  93     context->Esp = offset;
  94     context->SegCs = DOSVM_dpmi_segments->relay_code_sel;
  95     context->Eip = 3;
  96 }
  97
  98
  99 /**********************************************************************
 100  *          RELAY_RelayStub
 101  *
 102  * This stub is called by __wine_call_from_16_regs in order to marshall
 103  * relay parameters.
 104  */
 105 static void __stdcall RELAY_RelayStub( DOSRELAY       proc,
 106                                        unsigned char *args,
 107                                        void          *ctx86 )
 108 {
 109     if (proc)
 110     {
 111         CONTEXT86     *context    = (CONTEXT86*)ctx86;
 112         RELAY_Stack16 *stack      = RELAY_GetPointer( context->Esp );
 113
 114         DWORD          old_seg_cs = context->SegCs;
 115         DWORD          old_eip    = context->Eip;
 116         DWORD          old_seg_ss = context->SegSs;
 117         DWORD          old_esp    = context->Esp;
 118
 119         context->SegCs = stack->seg_cs;
 120         context->Eip   = stack->eip;
 121         context->SegSs = stack->seg_ss;
 122         context->Esp   = stack->esp;
 123
 124         proc( context, *(LPVOID *)args );
 125
 126         stack->seg_cs = context->SegCs;
 127         stack->eip    = context->Eip;
 128         stack->seg_ss = context->SegSs;
 129         stack->esp    = context->Esp;
 130
 131         context->SegCs = old_seg_cs;
 132         context->Eip   = old_eip;
 133         context->SegSs = old_seg_ss;
 134         context->Esp   = old_esp;
 135     }
 136 }
 137
 138
 139 /**********************************************************************
 140  *          DOSVM_RelayHandler
 141  *
 142  * Restore saved code and stack pointers and release stack block.
 143  */
 144 void DOSVM_RelayHandler( CONTEXT86 *context )
 145 {
 146     RELAY_Stack16 *stack = RELAY_GetPointer( context->Esp );
 147
 148     context->SegSs = stack->seg_ss;
 149     context->Esp = stack->esp;
 150     context->SegCs = stack->seg_cs;
 151     context->Eip = stack->eip;
 152
 153     if (!stack->inuse ||
 154         stack->stack_bottom != RELAY_MAGIC ||
 155         stack->stack_top != RELAY_MAGIC)
 156         ERR( "Stack corrupted!\n" );
 157
 158     stack->inuse = 0;
 159 }
 160
 161
 162 /**********************************************************************
 163  *          DOSVM_BuildCallFrame
 164  *
 165  * Modifies the context so that return to context calls DOSRELAY and
 166  * only after return from DOSRELAY the original context will be returned to.
 167  */
 168 void DOSVM_BuildCallFrame( CONTEXT86 *context, DOSRELAY relay, LPVOID data )
 169 {
 170     static void (*__wine_call_from_16_regs_ptr)();
 171     WORD  code_sel = DOSVM_dpmi_segments->relay_code_sel;
 172
 173     /*
 174      * Allocate separate stack for relay call.
 175      */
 176     RELAY_MakeShortContext( context );
 177
 178     /*
 179      * Build call frame.
 180      */
 181     PUSH_WORD16( context, HIWORD(data) );            /* argument.hiword */
 182     PUSH_WORD16( context, LOWORD(data) );            /* argument.loword */
 183     PUSH_WORD16( context, context->SegCs );          /* STACK16FRAME.cs */
 184     PUSH_WORD16( context, LOWORD(context->Eip) );    /* STACK16FRAME.ip */
 185     PUSH_WORD16( context, LOWORD(context->Ebp) );    /* STACK16FRAME.bp */
 186     PUSH_WORD16( context, HIWORD(relay) );           /* STACK16FRAME.entry_point.hiword */
 187     PUSH_WORD16( context, LOWORD(relay) );           /* STACK16FRAME.entry_point.loword */
 188     PUSH_WORD16( context, 0 );                       /* STACK16FRAME.entry_ip */
 189     PUSH_WORD16( context, HIWORD(RELAY_RelayStub) ); /* STACK16FRAME.relay.hiword */
 190     PUSH_WORD16( context, LOWORD(RELAY_RelayStub) ); /* STACK16FRAME.relay.loword */
 191     PUSH_WORD16( context, 0 );                       /* STACK16FRAME.module_cs.hiword */
 192     PUSH_WORD16( context, code_sel );                /* STACK16FRAME.module_cs.loword */
 193     PUSH_WORD16( context, 0 );                       /* STACK16FRAME.callfrom_ip.hiword */
 194     PUSH_WORD16( context, 0 );                       /* STACK16FRAME.callfrom_ip.loword */
 195
 196     /*
 197      * Adjust code pointer.
 198      */
 199     if (!__wine_call_from_16_regs_ptr)
 200         __wine_call_from_16_regs_ptr = (void *)GetProcAddress(GetModuleHandleA("kernel32.dll"),
 201                                                               "__wine_call_from_16_regs" );
 202     context->SegCs = wine_get_cs();
 203     context->Eip = (DWORD)__wine_call_from_16_regs_ptr;
 204 }