tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

ntgc.c (2949B)

      1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* This Source Code Form is subject to the terms of the Mozilla Public
      3 * License, v. 2.0. If a copy of the MPL was not distributed with this
      4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      5 
      6 /*
      7 * GC related routines
      8 *
      9 */
     10 #include <windows.h>
     11 #include "primpl.h"
     12 
     13 PRWord* _MD_HomeGCRegisters(PRThread* t, int isCurrent, int* np) {
     14 #if defined(_X86_)
     15  CONTEXT context;
     16  context.ContextFlags = CONTEXT_INTEGER;
     17 
     18  if (_PR_IS_NATIVE_THREAD(t)) {
     19    context.ContextFlags |= CONTEXT_CONTROL;
     20    if (GetThreadContext(t->md.handle, &context)) {
     21      t->md.gcContext[0] = context.Eax;
     22      t->md.gcContext[1] = context.Ebx;
     23      t->md.gcContext[2] = context.Ecx;
     24      t->md.gcContext[3] = context.Edx;
     25      t->md.gcContext[4] = context.Esi;
     26      t->md.gcContext[5] = context.Edi;
     27      t->md.gcContext[6] = context.Esp;
     28      t->md.gcContext[7] = context.Ebp;
     29      *np = PR_NUM_GCREGS;
     30    } else {
     31      PR_ASSERT(0); /* XXX */
     32    }
     33  } else {
     34    /* WARNING WARNING WARNING WARNING WARNING WARNING WARNING
     35     *
     36     * This code is extremely machine dependant and completely
     37     * undocumented by MS.  Its only known to work experimentally.
     38     * Ready for a walk on the wild * side?
     39     *
     40     * WARNING WARNING WARNING WARNING WARNING WARNING WARNING */
     41 
     42 #  if !defined WIN95  // Win95 does not have fibers
     43    int* fiberData = t->md.fiber_id;
     44 
     45    /* I found these offsets by disassembling SwitchToFiber().
     46     * Are your palms sweating yet?
     47     */
     48 
     49    /*
     50    ** EAX is on the stack (ESP+0)
     51    ** EDX is on the stack (ESP+4)
     52    ** ECX is on the stack (ESP+8)
     53    */
     54    t->md.gcContext[0] = 0;               /* context.Eax */
     55    t->md.gcContext[1] = fiberData[0x2e]; /* context.Ebx */
     56    t->md.gcContext[2] = 0;               /* context.Ecx */
     57    t->md.gcContext[3] = 0;               /* context.Edx */
     58    t->md.gcContext[4] = fiberData[0x2d]; /* context.Esi */
     59    t->md.gcContext[5] = fiberData[0x2c]; /* context.Edi */
     60    t->md.gcContext[6] = fiberData[0x36]; /* context.Esp */
     61    t->md.gcContext[7] = fiberData[0x32]; /* context.Ebp */
     62    *np = PR_NUM_GCREGS;
     63 #  endif
     64  }
     65  return (PRWord*)&t->md.gcContext;
     66 #else
     67  PR_NOT_REACHED("not implemented");
     68  return NULL;
     69 #endif /* defined(_X86_) */
     70 }
     71 
     72 /* This function is not used right now, but is left as a reference.
     73 * If you ever need to get the fiberID from the currently running fiber,
     74 * this is it.
     75 */
     76 void* GetMyFiberID() {
     77 #if defined(_X86_) && !defined(__MINGW32__)
     78  void* fiberData;
     79 
     80  /* A pointer to our tib entry is found at FS:[18]
     81   * At offset 10h is the fiberData pointer.  The context of the
     82   * fiber is stored in there.
     83   */
     84  __asm {
     85        mov    EDX, FS:[18h]
     86        mov    EAX, DWORD PTR [EDX+10h]
     87        mov    [fiberData], EAX
     88  }
     89 
     90  return fiberData;
     91 #else
     92  PR_NOT_REACHED("not implemented");
     93  return NULL;
     94 #endif /* defined(_X86_) */
     95 }