memory/selector.c

   1 /*
   2  * Selector manipulation functions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include <string.h>
   8 #include "winerror.h"
   9 #include "wine/winbase16.h"
  10 #include "ldt.h"
  11 #include "miscemu.h"
  12 #include "selectors.h"
  13 #include "stackframe.h"
  14 #include "process.h"
  15 #include "server.h"
  16 #include "debugtools.h"
  17 #include "toolhelp.h"
  18
  19 DEFAULT_DEBUG_CHANNEL(selector);
  20
  21
  22 /***********************************************************************
  23  *           AllocSelectorArray   (KERNEL.206)
  24  */
  25 WORD WINAPI AllocSelectorArray16( WORD count )
  26 {
  27     WORD i, sel, size = 0;
  28     ldt_entry entry;
  29
  30     if (!count) return 0;
  31     for (i = FIRST_LDT_ENTRY_TO_ALLOC; i < LDT_SIZE; i++)
  32     {
  33         if (!IS_LDT_ENTRY_FREE(i)) size = 0;
  34         else if (++size >= count) break;
  35     }
  36     if (i == LDT_SIZE) return 0;
  37     sel = i - size + 1;
  38
  39     entry.base           = 0;
  40     entry.type           = SEGMENT_DATA;
  41     entry.seg_32bit      = FALSE;
  42     entry.read_only      = FALSE;
  43     entry.limit_in_pages = FALSE;
  44     entry.limit          = 1;  /* avoid 0 base and limit */
  45
  46     for (i = 0; i < count; i++)
  47     {
  48         /* Mark selector as allocated */
  49         ldt_flags_copy[sel + i] |= LDT_FLAGS_ALLOCATED;
  50         LDT_SetEntry( sel + i, &entry );
  51     }
  52     return ENTRY_TO_SELECTOR( sel );
  53 }
  54
  55
  56 /***********************************************************************
  57  *           AllocSelector   (KERNEL.175)
  58  */
  59 WORD WINAPI AllocSelector16( WORD sel )
  60 {
  61     WORD newsel, count, i;
  62
  63     count = sel ? ((GET_SEL_LIMIT(sel) >> 16) + 1) : 1;
  64     newsel = AllocSelectorArray16( count );
  65     TRACE("(%04x): returning %04x\n",
  66                       sel, newsel );
  67     if (!newsel) return 0;
  68     if (!sel) return newsel;  /* nothing to copy */
  69     for (i = 0; i < count; i++)
  70     {
  71         ldt_entry entry;
  72         LDT_GetEntry( SELECTOR_TO_ENTRY(sel) + i, &entry );
  73         LDT_SetEntry( SELECTOR_TO_ENTRY(newsel) + i, &entry );
  74     }
  75     return newsel;
  76 }
  77
  78
  79 /***********************************************************************
  80  *           FreeSelector   (KERNEL.176)
  81  */
  82 WORD WINAPI FreeSelector16( WORD sel )
  83 {
  84     if (IS_SELECTOR_FREE(sel)) return sel;  /* error */
  85     SELECTOR_FreeBlock( sel, 1 );
  86     return 0;
  87 }
  88
  89
  90 /***********************************************************************
  91  *           SELECTOR_SetEntries
  92  *
  93  * Set the LDT entries for an array of selectors.
  94  */
  95 static void SELECTOR_SetEntries( WORD sel, const void *base, DWORD size,
  96                                  enum seg_type type, BOOL is32bit,
  97                                  BOOL readonly )
  98 {
  99     ldt_entry entry;
 100     WORD i, count;
 101
 102     /* The limit for the first selector is the whole */
 103     /* block. The next selectors get a 64k limit.    */
 104     entry.base           = (unsigned long)base;
 105     entry.type           = type;
 106     entry.seg_32bit      = is32bit;
 107     entry.read_only      = readonly;
 108     entry.limit_in_pages = (size > 0x100000);
 109     if (entry.limit_in_pages) entry.limit = ((size + 0xfff) >> 12) - 1;
 110     else entry.limit = size - 1;
 111     /* Make sure base and limit are not 0 together if the size is not 0 */
 112     if (!base && !entry.limit && size) entry.limit = 1;
 113     count = (size + 0xffff) / 0x10000;
 114     for (i = 0; i < count; i++)
 115     {
 116         LDT_SetEntry( SELECTOR_TO_ENTRY(sel) + i, &entry );
 117         entry.base += 0x10000;
 118         /* Apparently the next selectors should *not* get a 64k limit. */
 119         /* Can't remember where I read they should... --AJ */
 120         entry.limit -= entry.limit_in_pages ? 0x10 : 0x10000;
 121     }
 122 }
 123
 124
 125 /***********************************************************************
 126  *           SELECTOR_AllocBlock
 127  *
 128  * Allocate selectors for a block of linear memory.
 129  */
 130 WORD SELECTOR_AllocBlock( const void *base, DWORD size, enum seg_type type,
 131                           BOOL is32bit, BOOL readonly )
 132 {
 133     WORD sel, count;
 134
 135     if (!size) return 0;
 136     count = (size + 0xffff) / 0x10000;
 137     sel = AllocSelectorArray16( count );
 138     if (sel) SELECTOR_SetEntries( sel, base, size, type, is32bit, readonly );
 139     return sel;
 140 }
 141
 142
 143 /***********************************************************************
 144  *           SELECTOR_MoveBlock
 145  *
 146  * Move a block of selectors in linear memory.
 147  */
 148 void SELECTOR_MoveBlock( WORD sel, const void *new_base )
 149 {
 150     WORD i, count = (GET_SEL_LIMIT(sel) >> 16) + 1;
 151
 152     for (i = 0; i < count; i++)
 153     {
 154         ldt_entry entry;
 155         LDT_GetEntry( SELECTOR_TO_ENTRY(sel) + i, &entry );
 156         entry.base = (unsigned long)new_base;
 157         LDT_SetEntry( SELECTOR_TO_ENTRY(sel) + i, &entry );
 158     }
 159 }
 160
 161
 162 /***********************************************************************
 163  *           SELECTOR_FreeBlock
 164  *
 165  * Free a block of selectors.
 166  */
 167 void SELECTOR_FreeBlock( WORD sel, WORD count )
 168 {
 169     WORD i, nextsel;
 170     ldt_entry entry;
 171
 172     TRACE("(%04x,%d)\n", sel, count );
 173     sel &= ~(__AHINCR - 1);  /* clear bottom bits of selector */
 174     nextsel = sel + (count << __AHSHIFT);
 175
 176 #ifdef __i386__
 177     {
 178         /* Check if we are freeing current %fs or %gs selector */
 179
 180         WORD fs, gs;
 181         GET_FS(fs);
 182         if ((fs >= sel) && (fs < nextsel))
 183         {
 184             WARN("Freeing %%fs selector (%04x), not good.\n", fs );
 185             SET_FS( 0 );
 186         }
 187         GET_GS(gs);
 188         if ((gs >= sel) && (gs < nextsel)) SET_GS( 0 );
 189     }
 190 #endif  /* __i386__ */
 191
 192     memset( &entry, 0, sizeof(entry) );  /* clear the LDT entries */
 193     for (i = SELECTOR_TO_ENTRY(sel); count; i++, count--)
 194     {
 195         LDT_SetEntry( i, &entry );
 196         ldt_flags_copy[i] &= ~LDT_FLAGS_ALLOCATED;
 197     }
 198 }
 199
 200
 201 /***********************************************************************
 202  *           SELECTOR_ReallocBlock
 203  *
 204  * Change the size of a block of selectors.
 205  */
 206 WORD SELECTOR_ReallocBlock( WORD sel, const void *base, DWORD size )
 207 {
 208     ldt_entry entry;
 209     WORD i, oldcount, newcount;
 210
 211     if (!size) size = 1;
 212     oldcount = (GET_SEL_LIMIT(sel) >> 16) + 1;
 213     newcount = (size + 0xffff) >> 16;
 214     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 215
 216     if (oldcount < newcount)  /* We need to add selectors */
 217     {
 218           /* Check if the next selectors are free */
 219         if (SELECTOR_TO_ENTRY(sel) + newcount > LDT_SIZE) i = oldcount;
 220         else
 221             for (i = oldcount; i < newcount; i++)
 222                 if (!IS_LDT_ENTRY_FREE(SELECTOR_TO_ENTRY(sel)+i)) break;
 223
 224         if (i < newcount)  /* they are not free */
 225         {
 226             SELECTOR_FreeBlock( sel, oldcount );
 227             sel = AllocSelectorArray16( newcount );
 228         }
 229         else  /* mark the selectors as allocated */
 230         {
 231             for (i = oldcount; i < newcount; i++)
 232                 ldt_flags_copy[SELECTOR_TO_ENTRY(sel)+i] |=LDT_FLAGS_ALLOCATED;
 233         }
 234     }
 235     else if (oldcount > newcount) /* We need to remove selectors */
 236     {
 237         SELECTOR_FreeBlock( ENTRY_TO_SELECTOR(SELECTOR_TO_ENTRY(sel)+newcount),
 238                             oldcount - newcount );
 239     }
 240     if (sel) SELECTOR_SetEntries( sel, base, size, entry.type,
 241                                   entry.seg_32bit, entry.read_only );
 242     return sel;
 243 }
 244
 245
 246 /***********************************************************************
 247  *           PrestoChangoSelector   (KERNEL.177)
 248  */
 249 WORD WINAPI PrestoChangoSelector16( WORD selSrc, WORD selDst )
 250 {
 251     ldt_entry entry;
 252     LDT_GetEntry( SELECTOR_TO_ENTRY( selSrc ), &entry );
 253     entry.type ^= SEGMENT_CODE;  /* toggle the executable bit */
 254     LDT_SetEntry( SELECTOR_TO_ENTRY( selDst ), &entry );
 255     return selDst;
 256 }
 257
 258
 259 /***********************************************************************
 260  *           AllocCStoDSAlias   (KERNEL.170)
 261  */
 262 WORD WINAPI AllocCStoDSAlias16( WORD sel )
 263 {
 264     WORD newsel;
 265     ldt_entry entry;
 266
 267     newsel = AllocSelectorArray16( 1 );
 268     TRACE("(%04x): returning %04x\n",
 269                       sel, newsel );
 270     if (!newsel) return 0;
 271     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 272     entry.type = SEGMENT_DATA;
 273     LDT_SetEntry( SELECTOR_TO_ENTRY(newsel), &entry );
 274     return newsel;
 275 }
 276
 277
 278 /***********************************************************************
 279  *           AllocDStoCSAlias   (KERNEL.171)
 280  */
 281 WORD WINAPI AllocDStoCSAlias16( WORD sel )
 282 {
 283     WORD newsel;
 284     ldt_entry entry;
 285
 286     newsel = AllocSelectorArray16( 1 );
 287     TRACE("(%04x): returning %04x\n",
 288                       sel, newsel );
 289     if (!newsel) return 0;
 290     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 291     entry.type = SEGMENT_CODE;
 292     LDT_SetEntry( SELECTOR_TO_ENTRY(newsel), &entry );
 293     return newsel;
 294 }
 295
 296
 297 /***********************************************************************
 298  *           LongPtrAdd   (KERNEL.180)
 299  */
 300 void WINAPI LongPtrAdd16( DWORD ptr, DWORD add )
 301 {
 302     ldt_entry entry;
 303     LDT_GetEntry( SELECTOR_TO_ENTRY(SELECTOROF(ptr)), &entry );
 304     entry.base += add;
 305     LDT_SetEntry( SELECTOR_TO_ENTRY(SELECTOROF(ptr)), &entry );
 306 }
 307
 308
 309 /***********************************************************************
 310  *           GetSelectorBase   (KERNEL.186)
 311  */
 312 DWORD WINAPI WIN16_GetSelectorBase( WORD sel )
 313 {
 314     /*
 315      * Note: For Win32s processes, the whole linear address space is
 316      *       shifted by 0x10000 relative to the OS linear address space.
 317      *       See the comment in msdos/vxd.c.
 318      */
 319
 320     DWORD base = GetSelectorBase( sel );
 321     return W32S_WINE2APP( base, W32S_APPLICATION() ? W32S_OFFSET : 0 );
 322 }
 323 DWORD WINAPI GetSelectorBase( WORD sel )
 324 {
 325     DWORD base = GET_SEL_BASE(sel);
 326
 327     /* if base points into DOSMEM, assume we have to
 328      * return pointer into physical lower 1MB */
 329
 330     return DOSMEM_MapLinearToDos( (LPVOID)base );
 331 }
 332
 333
 334 /***********************************************************************
 335  *           SetSelectorBase   (KERNEL.187)
 336  */
 337 DWORD WINAPI WIN16_SetSelectorBase( WORD sel, DWORD base )
 338 {
 339     /*
 340      * Note: For Win32s processes, the whole linear address space is
 341      *       shifted by 0x10000 relative to the OS linear address space.
 342      *       See the comment in msdos/vxd.c.
 343      */
 344
 345     SetSelectorBase( sel,
 346         W32S_APP2WINE( base, W32S_APPLICATION() ? W32S_OFFSET : 0 ) );
 347     return sel;
 348 }
 349 WORD WINAPI SetSelectorBase( WORD sel, DWORD base )
 350 {
 351     ldt_entry entry;
 352
 353     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 354
 355     entry.base = (DWORD)DOSMEM_MapDosToLinear(base);
 356
 357     LDT_SetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 358     return sel;
 359 }
 360
 361
 362 /***********************************************************************
 363  *           GetSelectorLimit   (KERNEL.188)
 364  */
 365 DWORD WINAPI GetSelectorLimit16( WORD sel )
 366 {
 367     return GET_SEL_LIMIT(sel);
 368 }
 369
 370
 371 /***********************************************************************
 372  *           SetSelectorLimit   (KERNEL.189)
 373  */
 374 WORD WINAPI SetSelectorLimit16( WORD sel, DWORD limit )
 375 {
 376     ldt_entry entry;
 377     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 378     entry.limit_in_pages = (limit >= 0x100000);
 379     if (entry.limit_in_pages) entry.limit = limit >> 12;
 380     else entry.limit = limit;
 381     LDT_SetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 382     return sel;
 383 }
 384
 385
 386 /***********************************************************************
 387  *           SelectorAccessRights   (KERNEL.196)
 388  */
 389 WORD WINAPI SelectorAccessRights16( WORD sel, WORD op, WORD val )
 390 {
 391     ldt_entry entry;
 392     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 393     if (op == 0)  /* get */
 394     {
 395         return 0x01 | /* accessed */
 396                0x10 | /* not system */
 397                0x60 | /* DPL 3 */
 398                0x80 | /* present */
 399                ((entry.read_only == 0) << 1) |
 400                (entry.type << 2) |
 401                (entry.seg_32bit << 14) |
 402                (entry.limit_in_pages << 15);
 403     }
 404     else  /* set */
 405     {
 406         entry.read_only = ((val & 2) == 0);
 407         entry.type = (val >> 2) & 3;
 408         entry.seg_32bit = val & 0x4000;
 409         entry.limit_in_pages = val & 0x8000;
 410         LDT_SetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 411         return 0;
 412     }
 413 }
 414
 415
 416 /***********************************************************************
 417  *           IsBadCodePtr16   (KERNEL.336)
 418  */
 419 BOOL16 WINAPI IsBadCodePtr16( SEGPTR lpfn )
 420 {
 421     WORD sel;
 422     ldt_entry entry;
 423
 424     sel = SELECTOROF(lpfn);
 425     if (!sel) return TRUE;
 426     if (IS_SELECTOR_FREE(sel)) return TRUE;
 427     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 428     if (entry.type != SEGMENT_CODE) return TRUE;
 429     if (OFFSETOF(lpfn) > GET_SEL_LIMIT(sel)) return TRUE;
 430     return FALSE;
 431 }
 432
 433
 434 /***********************************************************************
 435  *           IsBadStringPtr16   (KERNEL.337)
 436  */
 437 BOOL16 WINAPI IsBadStringPtr16( SEGPTR ptr, UINT16 size )
 438 {
 439     WORD sel;
 440     ldt_entry entry;
 441
 442     sel = SELECTOROF(ptr);
 443     if (!sel) return TRUE;
 444     if (IS_SELECTOR_FREE(sel)) return TRUE;
 445     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 446     if ((entry.type == SEGMENT_CODE) && entry.read_only) return TRUE;
 447     if (strlen(PTR_SEG_TO_LIN(ptr)) < size) size = strlen(PTR_SEG_TO_LIN(ptr)) + 1;
 448     if (size && (OFFSETOF(ptr) + size - 1 > GET_SEL_LIMIT(sel))) return TRUE;
 449     return FALSE;
 450 }
 451
 452
 453 /***********************************************************************
 454  *           IsBadHugeReadPtr16   (KERNEL.346)
 455  */
 456 BOOL16 WINAPI IsBadHugeReadPtr16( SEGPTR ptr, DWORD size )
 457 {
 458     WORD sel;
 459     ldt_entry entry;
 460
 461     sel = SELECTOROF(ptr);
 462     if (!sel) return TRUE;
 463     if (IS_SELECTOR_FREE(sel)) return TRUE;
 464     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 465     if ((entry.type == SEGMENT_CODE) && entry.read_only) return TRUE;
 466     if (size && (OFFSETOF(ptr) + size - 1 > GET_SEL_LIMIT(sel))) return TRUE;
 467     return FALSE;
 468 }
 469
 470
 471 /***********************************************************************
 472  *           IsBadHugeWritePtr16   (KERNEL.347)
 473  */
 474 BOOL16 WINAPI IsBadHugeWritePtr16( SEGPTR ptr, DWORD size )
 475 {
 476     WORD sel;
 477     ldt_entry entry;
 478
 479     sel = SELECTOROF(ptr);
 480     if (!sel) return TRUE;
 481     if (IS_SELECTOR_FREE(sel)) return TRUE;
 482     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 483     if ((entry.type == SEGMENT_CODE) || entry.read_only) return TRUE;
 484     if (size && (OFFSETOF(ptr) + size - 1 > GET_SEL_LIMIT(sel))) return TRUE;
 485     return FALSE;
 486 }
 487
 488 /***********************************************************************
 489  *           IsBadReadPtr16   (KERNEL.334)
 490  */
 491 BOOL16 WINAPI IsBadReadPtr16( SEGPTR ptr, UINT16 size )
 492 {
 493     return IsBadHugeReadPtr16( ptr, size );
 494 }
 495
 496
 497 /***********************************************************************
 498  *           IsBadWritePtr16   (KERNEL.335)
 499  */
 500 BOOL16 WINAPI IsBadWritePtr16( SEGPTR ptr, UINT16 size )
 501 {
 502     return IsBadHugeWritePtr16( ptr, size );
 503 }
 504
 505
 506 /***********************************************************************
 507  *           IsBadFlatReadWritePtr16   (KERNEL.627)
 508  */
 509 BOOL16 WINAPI IsBadFlatReadWritePtr16( SEGPTR ptr, DWORD size, BOOL16 bWrite )
 510 {
 511     return bWrite? IsBadHugeWritePtr16( ptr, size )
 512                  : IsBadHugeReadPtr16( ptr, size );
 513 }
 514
 515
 516 /***********************************************************************
 517  *           MemoryRead   (TOOLHELP.78)
 518  */
 519 DWORD WINAPI MemoryRead16( WORD sel, DWORD offset, void *buffer, DWORD count )
 520 {
 521     if (IS_SELECTOR_FREE(sel)) return 0;
 522     if (offset > GET_SEL_LIMIT(sel)) return 0;
 523     if (offset + count > GET_SEL_LIMIT(sel) + 1)
 524         count = GET_SEL_LIMIT(sel) + 1 - offset;
 525     memcpy( buffer, ((char *)GET_SEL_BASE(sel)) + offset, count );
 526     return count;
 527 }
 528
 529
 530 /***********************************************************************
 531  *           MemoryWrite   (TOOLHELP.79)
 532  */
 533 DWORD WINAPI MemoryWrite16( WORD sel, DWORD offset, void *buffer, DWORD count )
 534 {
 535     if (IS_SELECTOR_FREE(sel)) return 0;
 536     if (offset > GET_SEL_LIMIT(sel)) return 0;
 537     if (offset + count > GET_SEL_LIMIT(sel) + 1)
 538         count = GET_SEL_LIMIT(sel) + 1 - offset;
 539     memcpy( ((char *)GET_SEL_BASE(sel)) + offset, buffer, count );
 540     return count;
 541 }
 542
 543 /************************************* Win95 pointer mapping functions *
 544  *
 545  */
 546
 547 /***********************************************************************
 548  *           MapSL   (KERNEL32.523)
 549  *
 550  * Maps fixed segmented pointer to linear.
 551  */
 552 LPVOID WINAPI MapSL( SEGPTR sptr )
 553 {
 554     return (LPVOID)PTR_SEG_TO_LIN(sptr);
 555 }
 556
 557 /***********************************************************************
 558  *           MapSLFix   (KERNEL32.524)
 559  *
 560  * FIXME: MapSLFix and UnMapSLFixArray should probably prevent
 561  * unexpected linear address change when GlobalCompact() shuffles
 562  * moveable blocks.
 563  */
 564
 565 LPVOID WINAPI MapSLFix( SEGPTR sptr )
 566 {
 567     return (LPVOID)PTR_SEG_TO_LIN(sptr);
 568 }
 569
 570 /***********************************************************************
 571  *           UnMapSLFixArray   (KERNEL32.701)
 572  */
 573
 574 void WINAPI UnMapSLFixArray( SEGPTR sptr[], INT length, CONTEXT86 *context )
 575 {
 576     /* Must not change EAX, hence defined as 'register' function */
 577 }
 578
 579 /***********************************************************************
 580  *           MapLS   (KERNEL32.522)
 581  *
 582  * Maps linear pointer to segmented.
 583  */
 584 SEGPTR WINAPI MapLS( LPVOID ptr )
 585 {
 586     if (!HIWORD(ptr))
 587         return (SEGPTR)ptr;
 588     else
 589     {
 590         WORD sel = SELECTOR_AllocBlock( ptr, 0x10000, SEGMENT_DATA, FALSE, FALSE );
 591         return PTR_SEG_OFF_TO_SEGPTR( sel, 0 );
 592     }
 593 }
 594
 595
 596 /***********************************************************************
 597  *           UnMapLS   (KERNEL32.700)
 598  *
 599  * Free mapped selector.
 600  */
 601 void WINAPI UnMapLS( SEGPTR sptr )
 602 {
 603     if (SELECTOROF(sptr))
 604         SELECTOR_FreeBlock( SELECTOROF(sptr), 1 );
 605 }
 606
 607 /***********************************************************************
 608  *           GetThreadSelectorEntry   (KERNEL32)
 609  */
 610 BOOL WINAPI GetThreadSelectorEntry( HANDLE hthread, DWORD sel, LPLDT_ENTRY ldtent)
 611 {
 612 #ifdef __i386__
 613     struct get_selector_entry_request *req = get_req_buffer();
 614
 615     if (!(sel & 4))  /* GDT selector */
 616     {
 617         WORD seg;
 618         sel &= ~3;  /* ignore RPL */
 619         if (!sel)  /* null selector */
 620         {
 621             memset( ldtent, 0, sizeof(*ldtent) );
 622             return TRUE;
 623         }
 624         ldtent->BaseLow                   = 0;
 625         ldtent->HighWord.Bits.BaseMid     = 0;
 626         ldtent->HighWord.Bits.BaseHi      = 0;
 627         ldtent->LimitLow                  = 0xffff;
 628         ldtent->HighWord.Bits.LimitHi     = 0xf;
 629         ldtent->HighWord.Bits.Dpl         = 3;
 630         ldtent->HighWord.Bits.Sys         = 0;
 631         ldtent->HighWord.Bits.Pres        = 1;
 632         ldtent->HighWord.Bits.Granularity = 1;
 633         ldtent->HighWord.Bits.Default_Big = 1;
 634         ldtent->HighWord.Bits.Type        = 0x12;
 635         /* it has to be one of the system GDT selectors */
 636         GET_DS(seg);
 637         if (sel == (seg & ~3)) return TRUE;
 638         GET_SS(seg);
 639         if (sel == (seg & ~3)) return TRUE;
 640         GET_CS(seg);
 641         if (sel == (seg & ~3))
 642         {
 643             ldtent->HighWord.Bits.Type |= 8;  /* code segment */
 644             return TRUE;
 645         }
 646         SetLastError( ERROR_NOACCESS );
 647         return FALSE;
 648     }
 649
 650     req->handle = hthread;
 651     req->entry = sel >> __AHSHIFT;
 652     if (server_call( REQ_GET_SELECTOR_ENTRY )) return FALSE;
 653
 654     if (!(req->flags & LDT_FLAGS_ALLOCATED))
 655     {
 656         SetLastError( ERROR_MR_MID_NOT_FOUND );  /* sic */
 657         return FALSE;
 658     }
 659     if (req->flags & LDT_FLAGS_BIG) req->limit >>= 12;
 660     ldtent->BaseLow                   = req->base & 0x0000ffff;
 661     ldtent->HighWord.Bits.BaseMid     = (req->base & 0x00ff0000) >> 16;
 662     ldtent->HighWord.Bits.BaseHi      = (req->base & 0xff000000) >> 24;
 663     ldtent->LimitLow                  = req->limit & 0x0000ffff;
 664     ldtent->HighWord.Bits.LimitHi     = (req->limit & 0x000f0000) >> 16;
 665     ldtent->HighWord.Bits.Dpl         = 3;
 666     ldtent->HighWord.Bits.Sys         = 0;
 667     ldtent->HighWord.Bits.Pres        = 1;
 668     ldtent->HighWord.Bits.Granularity = (req->flags & LDT_FLAGS_BIG) !=0;
 669     ldtent->HighWord.Bits.Default_Big = (req->flags & LDT_FLAGS_32BIT) != 0;
 670     ldtent->HighWord.Bits.Type        = ((req->flags & LDT_FLAGS_TYPE) << 2) | 0x10;
 671     if (!(req->flags & LDT_FLAGS_READONLY)) ldtent->HighWord.Bits.Type |= 0x2;
 672     return TRUE;
 673 #else
 674     SetLastError( ERROR_NOT_IMPLEMENTED );
 675     return FALSE;
 676 #endif
 677 }
 678
 679
 680 /**********************************************************************
 681  *              SMapLS*         (KERNEL32)
 682  * These functions map linear pointers at [EBP+xxx] to segmented pointers
 683  * and return them.
 684  * Win95 uses some kind of alias structs, which it stores in [EBP+x] to
 685  * unravel them at SUnMapLS. We just store the segmented pointer there.
 686  */
 687 static void
 688 x_SMapLS_IP_EBP_x(CONTEXT86 *context,int argoff) {
 689     DWORD       val,ptr;
 690
 691     val =*(DWORD*)(EBP_reg(context)+argoff);
 692     if (val<0x10000) {
 693         ptr=val;
 694         *(DWORD*)(EBP_reg(context)+argoff) = 0;
 695     } else {
 696         ptr = MapLS((LPVOID)val);
 697         *(DWORD*)(EBP_reg(context)+argoff) = ptr;
 698     }
 699     EAX_reg(context) = ptr;
 700 }
 701
 702 void WINAPI SMapLS_IP_EBP_8 (CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context, 8);}
 703 void WINAPI SMapLS_IP_EBP_12(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,12);}
 704 void WINAPI SMapLS_IP_EBP_16(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,16);}
 705 void WINAPI SMapLS_IP_EBP_20(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,20);}
 706 void WINAPI SMapLS_IP_EBP_24(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,24);}
 707 void WINAPI SMapLS_IP_EBP_28(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,28);}
 708 void WINAPI SMapLS_IP_EBP_32(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,32);}
 709 void WINAPI SMapLS_IP_EBP_36(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,36);}
 710 void WINAPI SMapLS_IP_EBP_40(CONTEXT86 *context) {x_SMapLS_IP_EBP_x(context,40);}
 711
 712 void WINAPI SMapLS( CONTEXT86 *context )
 713 {
 714     if (EAX_reg(context)>=0x10000) {
 715         EAX_reg(context) = MapLS((LPVOID)EAX_reg(context));
 716         EDX_reg(context) = EAX_reg(context);
 717     } else {
 718         EDX_reg(context) = 0;
 719     }
 720 }
 721
 722 void WINAPI SUnMapLS( CONTEXT86 *context )
 723 {
 724     if (EAX_reg(context)>=0x10000)
 725         UnMapLS((SEGPTR)EAX_reg(context));
 726 }
 727
 728 static void
 729 x_SUnMapLS_IP_EBP_x(CONTEXT86 *context,int argoff) {
 730         if (*(DWORD*)(EBP_reg(context)+argoff))
 731                 UnMapLS(*(DWORD*)(EBP_reg(context)+argoff));
 732         *(DWORD*)(EBP_reg(context)+argoff)=0;
 733 }
 734 void WINAPI SUnMapLS_IP_EBP_8 (CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context, 8); }
 735 void WINAPI SUnMapLS_IP_EBP_12(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,12); }
 736 void WINAPI SUnMapLS_IP_EBP_16(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,16); }
 737 void WINAPI SUnMapLS_IP_EBP_20(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,20); }
 738 void WINAPI SUnMapLS_IP_EBP_24(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,24); }
 739 void WINAPI SUnMapLS_IP_EBP_28(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,28); }
 740 void WINAPI SUnMapLS_IP_EBP_32(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,32); }
 741 void WINAPI SUnMapLS_IP_EBP_36(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,36); }
 742 void WINAPI SUnMapLS_IP_EBP_40(CONTEXT86 *context) { x_SUnMapLS_IP_EBP_x(context,40); }
 743
 744 /**********************************************************************
 745  *              AllocMappedBuffer       (KERNEL32.38)
 746  *
 747  * This is a undocumented KERNEL32 function that
 748  * SMapLS's a GlobalAlloc'ed buffer.
 749  *
 750  * Input:   EDI register: size of buffer to allocate
 751  * Output:  EDI register: pointer to buffer
 752  *
 753  * Note: The buffer is preceeded by 8 bytes:
 754  *        ...
 755  *       edi+0   buffer
 756  *       edi-4   SEGPTR to buffer
 757  *       edi-8   some magic Win95 needs for SUnMapLS
 758  *               (we use it for the memory handle)
 759  *
 760  *       The SEGPTR is used by the caller!
 761  */
 762
 763 void WINAPI AllocMappedBuffer( CONTEXT86 *context )
 764 {
 765     HGLOBAL handle = GlobalAlloc(0, EDI_reg(context) + 8);
 766     DWORD *buffer = (DWORD *)GlobalLock(handle);
 767     SEGPTR ptr = 0;
 768
 769     if (buffer)
 770         if (!(ptr = MapLS(buffer + 2)))
 771         {
 772             GlobalUnlock(handle);
 773             GlobalFree(handle);
 774         }
 775
 776     if (!ptr)
 777         EAX_reg(context) = EDI_reg(context) = 0;
 778     else
 779     {
 780         buffer[0] = handle;
 781         buffer[1] = ptr;
 782
 783         EAX_reg(context) = (DWORD) ptr;
 784         EDI_reg(context) = (DWORD)(buffer + 2);
 785     }
 786 }
 787
 788 /**********************************************************************
 789  *              FreeMappedBuffer        (KERNEL32.39)
 790  *
 791  * Free a buffer allocated by AllocMappedBuffer
 792  *
 793  * Input: EDI register: pointer to buffer
 794  */
 795
 796 void WINAPI FreeMappedBuffer( CONTEXT86 *context )
 797 {
 798     if (EDI_reg(context))
 799     {
 800         DWORD *buffer = (DWORD *)EDI_reg(context) - 2;
 801
 802         UnMapLS(buffer[1]);
 803
 804         GlobalUnlock(buffer[0]);
 805         GlobalFree(buffer[0]);
 806     }
 807 }
 808
 809
 810 /***********************************************************************
 811  *           UTSelectorOffsetToLinear       (WIN32S16.48)
 812  *
 813  * rough guesswork, but seems to work (I had no "reasonable" docu)
 814  */
 815 LPVOID WINAPI UTSelectorOffsetToLinear16(SEGPTR sptr)
 816 {
 817         return PTR_SEG_TO_LIN(sptr);
 818 }
 819
 820 /***********************************************************************
 821  *           UTLinearToSelectorOffset       (WIN32S16.49)
 822  *
 823  * FIXME: I don't know if that's the right way to do linear -> segmented
 824  */
 825 SEGPTR WINAPI UTLinearToSelectorOffset16(LPVOID lptr)
 826 {
 827     return (SEGPTR)lptr;
 828 }