memory/selector.c

   1 /*
   2  * Selector manipulation functions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include <string.h>
   8 #include "windows.h"
   9 #include "ldt.h"
  10 #include "selectors.h"
  11 #include "stackframe.h"
  12 #include "stddebug.h"
  13 #include "debug.h"
  14
  15
  16 #define FIRST_LDT_ENTRY_TO_ALLOC  6
  17
  18
  19 /***********************************************************************
  20  *           AllocSelectorArray   (KERNEL.206)
  21  */
  22 WORD AllocSelectorArray( WORD count )
  23 {
  24     WORD i, size = 0;
  25
  26     if (!count) return 0;
  27     for (i = FIRST_LDT_ENTRY_TO_ALLOC; i < LDT_SIZE; i++)
  28     {
  29         if (!IS_LDT_ENTRY_FREE(i)) size = 0;
  30         else if (++size >= count) break;
  31     }
  32     if (i == LDT_SIZE) return 0;
  33     /* Mark selector as allocated */
  34     while (size--) ldt_flags_copy[i--] |= LDT_FLAGS_ALLOCATED;
  35     return ENTRY_TO_SELECTOR( i + 1 );
  36 }
  37
  38
  39 /***********************************************************************
  40  *           AllocSelector   (KERNEL.175)
  41  */
  42 WORD AllocSelector( WORD sel )
  43 {
  44     WORD newsel, count, i;
  45
  46     count = sel ? ((GET_SEL_LIMIT(sel) >> 16) + 1) : 1;
  47     newsel = AllocSelectorArray( count );
  48     dprintf_selector( stddeb, "AllocSelector(%04x): returning %04x\n",
  49                       sel, newsel );
  50     if (!newsel) return 0;
  51     if (!sel) return newsel;  /* nothing to copy */
  52     for (i = 0; i < count; i++)
  53     {
  54         ldt_entry entry;
  55         LDT_GetEntry( SELECTOR_TO_ENTRY(sel) + i, &entry );
  56         LDT_SetEntry( SELECTOR_TO_ENTRY(newsel) + i, &entry );
  57     }
  58     return newsel;
  59 }
  60
  61
  62 /***********************************************************************
  63  *           FreeSelector   (KERNEL.176)
  64  */
  65 WORD FreeSelector( WORD sel )
  66 {
  67     WORD i, count;
  68     ldt_entry entry;
  69     STACK16FRAME *frame;
  70
  71     dprintf_selector( stddeb, "FreeSelector(%04x)\n", sel );
  72     if (IS_SELECTOR_FREE(sel)) return sel;  /* error */
  73     count = (GET_SEL_LIMIT(sel) >> 16) + 1;
  74     memset( &entry, 0, sizeof(entry) );  /* clear the LDT entries */
  75     /* FIXME: is it correct to free the whole array? */
  76     for (i = SELECTOR_TO_ENTRY(sel); count; i++, count--)
  77     {
  78         LDT_SetEntry( i, &entry );
  79         ldt_flags_copy[i] &= ~LDT_FLAGS_ALLOCATED;
  80     }
  81
  82     /* Clear the saved 16-bit selector */
  83 #ifndef WINELIB
  84     frame = CURRENT_STACK16;
  85     while (frame)
  86     {
  87         if (frame->ds == sel) frame->ds = 0;
  88         if (frame->es == sel) frame->es = 0;
  89         frame = PTR_SEG_OFF_TO_LIN(frame->saved_ss, frame->saved_sp);
  90     }
  91 #endif
  92     return 0;
  93 }
  94
  95
  96 /***********************************************************************
  97  *           SELECTOR_SetEntries
  98  *
  99  * Set the LDT entries for an array of selectors.
 100  */
 101 static void SELECTOR_SetEntries( WORD sel, const void *base, DWORD size,
 102                                  enum seg_type type, BOOL is32bit,
 103                                  BOOL readonly )
 104 {
 105     ldt_entry entry;
 106     WORD i, count;
 107
 108     /* The limit for the first selector is the whole */
 109     /* block. The next selectors get a 64k limit.    */
 110     entry.base           = (unsigned long)base;
 111     entry.type           = type;
 112     entry.seg_32bit      = is32bit;
 113     entry.read_only      = readonly;
 114     entry.limit_in_pages = (size > 0x100000);
 115     if (entry.limit_in_pages) entry.limit = ((size + 0xfff) >> 12) - 1;
 116     else entry.limit = size - 1;
 117     /* Make sure base and limit are not 0 together if the size is not 0 */
 118     if (!base && !entry.limit && size) entry.limit = 1;
 119     count = (size + 0xffff) / 0x10000;
 120     for (i = 0; i < count; i++)
 121     {
 122         LDT_SetEntry( SELECTOR_TO_ENTRY(sel) + i, &entry );
 123         entry.base += 0x10000;
 124         size -= 0x10000;
 125         entry.limit = (size > 0x10000) ? 0xffff : size-1;
 126         entry.limit_in_pages = 0;
 127     }
 128 }
 129
 130
 131 /***********************************************************************
 132  *           SELECTOR_AllocBlock
 133  *
 134  * Allocate selectors for a block of linear memory.
 135  */
 136 WORD SELECTOR_AllocBlock( const void *base, DWORD size, enum seg_type type,
 137                           BOOL is32bit, BOOL readonly )
 138 {
 139     WORD sel, count;
 140
 141     if (!size) return 0;
 142     count = (size + 0xffff) / 0x10000;
 143     sel = AllocSelectorArray( count );
 144     if (sel) SELECTOR_SetEntries( sel, base, size, type, is32bit, readonly );
 145     return sel;
 146 }
 147
 148
 149 /***********************************************************************
 150  *           SELECTOR_ReallocBlock
 151  *
 152  * Change the size of a block of selectors.
 153  */
 154 WORD SELECTOR_ReallocBlock( WORD sel, const void *base, DWORD size,
 155                             enum seg_type type, BOOL is32bit, BOOL readonly )
 156 {
 157     WORD i, oldcount, newcount;
 158     ldt_entry entry;
 159
 160     if (!size) size = 1;
 161     oldcount = (GET_SEL_LIMIT(sel) >> 16) + 1;
 162     newcount = (size + 0xffff) >> 16;
 163
 164     if (oldcount < newcount)  /* We need to add selectors */
 165     {
 166           /* Check if the next selectors are free */
 167         if (SELECTOR_TO_ENTRY(sel) + newcount > LDT_SIZE) i = oldcount;
 168         else
 169             for (i = oldcount; i < newcount; i++)
 170                 if (!IS_LDT_ENTRY_FREE(SELECTOR_TO_ENTRY(sel)+i)) break;
 171
 172         if (i < newcount)  /* they are not free */
 173         {
 174             FreeSelector( sel );
 175             sel = AllocSelectorArray( newcount );
 176         }
 177         else  /* mark the selectors as allocated */
 178         {
 179             for (i = oldcount; i < newcount; i++)
 180                 ldt_flags_copy[SELECTOR_TO_ENTRY(sel)+i] |=LDT_FLAGS_ALLOCATED;
 181         }
 182     }
 183     else if (oldcount > newcount) /* We need to remove selectors */
 184     {
 185         memset( &entry, 0, sizeof(entry) );  /* clear the LDT entries */
 186         for (i = oldcount; i < newcount; i++)
 187         {
 188             LDT_SetEntry( SELECTOR_TO_ENTRY(sel) + i, &entry );
 189             ldt_flags_copy[SELECTOR_TO_ENTRY(sel) + i] &= ~LDT_FLAGS_ALLOCATED;
 190         }
 191     }
 192     if (sel) SELECTOR_SetEntries( sel, base, size, type, is32bit, readonly );
 193     return sel;
 194 }
 195
 196
 197 /***********************************************************************
 198  *           PrestoChangoSelector   (KERNEL.177)
 199  */
 200 WORD PrestoChangoSelector( WORD selSrc, WORD selDst )
 201 {
 202     ldt_entry entry;
 203     LDT_GetEntry( SELECTOR_TO_ENTRY( selSrc ), &entry );
 204     entry.type ^= SEGMENT_CODE;  /* toggle the executable bit */
 205     LDT_SetEntry( SELECTOR_TO_ENTRY( selDst ), &entry );
 206     return selDst;
 207 }
 208
 209
 210 /***********************************************************************
 211  *           AllocCStoDSAlias   (KERNEL.170)
 212  */
 213 WORD AllocCStoDSAlias( WORD sel )
 214 {
 215     WORD newsel;
 216     ldt_entry entry;
 217
 218     newsel = AllocSelectorArray( 1 );
 219     dprintf_selector( stddeb, "AllocCStoDSAlias(%04x): returning %04x\n",
 220                       sel, newsel );
 221     if (!newsel) return 0;
 222     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 223     entry.type = SEGMENT_DATA;
 224     LDT_SetEntry( SELECTOR_TO_ENTRY(newsel), &entry );
 225     return newsel;
 226 }
 227
 228
 229 /***********************************************************************
 230  *           AllocDStoCSAlias   (KERNEL.171)
 231  */
 232 WORD AllocDStoCSAlias( WORD sel )
 233 {
 234     WORD newsel;
 235     ldt_entry entry;
 236
 237     newsel = AllocSelectorArray( 1 );
 238     dprintf_selector( stddeb, "AllocDStoCSAlias(%04x): returning %04x\n",
 239                       sel, newsel );
 240     if (!newsel) return 0;
 241     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 242     entry.type = SEGMENT_CODE;
 243     LDT_SetEntry( SELECTOR_TO_ENTRY(newsel), &entry );
 244     return newsel;
 245 }
 246
 247
 248 /***********************************************************************
 249  *           LongPtrAdd   (KERNEL.180)
 250  */
 251 void LongPtrAdd( DWORD ptr, DWORD add )
 252 {
 253     ldt_entry entry;
 254     LDT_GetEntry( SELECTOR_TO_ENTRY(SELECTOROF(ptr)), &entry );
 255     entry.base += add;
 256     LDT_SetEntry( SELECTOR_TO_ENTRY(SELECTOROF(ptr)), &entry );
 257 }
 258
 259
 260 /***********************************************************************
 261  *           GetSelectorBase   (KERNEL.186)
 262  */
 263 DWORD GetSelectorBase( WORD sel )
 264 {
 265     return GET_SEL_BASE(sel);
 266 }
 267
 268
 269 /***********************************************************************
 270  *           SetSelectorBase   (KERNEL.187)
 271  */
 272 WORD SetSelectorBase( WORD sel, DWORD base )
 273 {
 274     ldt_entry entry;
 275     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 276     entry.base = base;
 277     LDT_SetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 278     return sel;
 279 }
 280
 281
 282 /***********************************************************************
 283  *           GetSelectorLimit   (KERNEL.188)
 284  */
 285 DWORD GetSelectorLimit( WORD sel )
 286 {
 287     return GET_SEL_LIMIT(sel);
 288 }
 289
 290
 291 /***********************************************************************
 292  *           SetSelectorLimit   (KERNEL.189)
 293  */
 294 WORD SetSelectorLimit( WORD sel, DWORD limit )
 295 {
 296     ldt_entry entry;
 297     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 298     entry.limit = limit;
 299     LDT_SetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 300     return sel;
 301 }
 302
 303
 304 /***********************************************************************
 305  *           SelectorAccessRights   (KERNEL.196)
 306  */
 307 WORD SelectorAccessRights( WORD sel, WORD op, WORD val )
 308 {
 309     ldt_entry entry;
 310     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 311     if (op == 0)  /* get */
 312     {
 313         return 0x01 | /* accessed */
 314                0x10 | /* not system */
 315                0x60 | /* DPL 3 */
 316                0x80 | /* present */
 317                ((entry.read_only == 0) << 1) |
 318                (entry.type << 2) |
 319                (entry.seg_32bit << 14) |
 320                (entry.limit_in_pages << 15);
 321     }
 322     else  /* set */
 323     {
 324         entry.read_only = ((val & 2) == 0);
 325         entry.type = (val >> 2) & 3;
 326         entry.seg_32bit = val & 0x4000;
 327         entry.limit_in_pages = val & 0x8000;
 328         LDT_SetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 329         return 0;
 330     }
 331 }
 332
 333
 334 /***********************************************************************
 335  *           IsBadCodePtr   (KERNEL.336)
 336  */
 337 BOOL IsBadCodePtr( SEGPTR lpfn )
 338 {
 339     WORD sel;
 340     ldt_entry entry;
 341
 342     sel = SELECTOROF(lpfn);
 343     if (!sel) return TRUE;
 344     if (IS_SELECTOR_FREE(sel)) return TRUE;
 345     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 346     if (entry.type != SEGMENT_CODE) return TRUE;
 347     if (OFFSETOF(lpfn) > entry.limit) return TRUE;
 348     return FALSE;
 349 }
 350
 351
 352 /***********************************************************************
 353  *           IsBadStringPtr   (KERNEL.337)
 354  */
 355 BOOL IsBadStringPtr( SEGPTR ptr, WORD size )
 356 {
 357     WORD sel;
 358     ldt_entry entry;
 359
 360     sel = SELECTOROF(ptr);
 361     if (!sel) return TRUE;
 362     if (IS_SELECTOR_FREE(sel)) return TRUE;
 363     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 364     if ((entry.type == SEGMENT_CODE) && entry.read_only) return TRUE;
 365     if (strlen(PTR_SEG_TO_LIN(ptr)) < size) size = strlen(PTR_SEG_TO_LIN(ptr));
 366     if (OFFSETOF(ptr) + size - 1 > entry.limit) return TRUE;
 367     return FALSE;
 368 }
 369
 370
 371 /***********************************************************************
 372  *           IsBadHugeReadPtr   (KERNEL.346)
 373  */
 374 BOOL IsBadHugeReadPtr( SEGPTR ptr, DWORD size )
 375 {
 376     WORD sel;
 377     ldt_entry entry;
 378
 379     sel = SELECTOROF(ptr);
 380     if (!sel) return TRUE;
 381     if (IS_SELECTOR_FREE(sel)) return TRUE;
 382     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 383     if ((entry.type == SEGMENT_CODE) && entry.read_only) return TRUE;
 384     if (OFFSETOF(ptr) + size - 1 > entry.limit) return TRUE;
 385     return FALSE;
 386 }
 387
 388
 389 /***********************************************************************
 390  *           IsBadHugeWritePtr   (KERNEL.347)
 391  */
 392 BOOL IsBadHugeWritePtr( SEGPTR ptr, DWORD size )
 393 {
 394     WORD sel;
 395     ldt_entry entry;
 396
 397     sel = SELECTOROF(ptr);
 398     if (!sel) return TRUE;
 399     if (IS_SELECTOR_FREE(sel)) return TRUE;
 400     LDT_GetEntry( SELECTOR_TO_ENTRY(sel), &entry );
 401     if ((entry.type == SEGMENT_CODE) || entry.read_only) return TRUE;
 402     if (OFFSETOF(ptr) + size - 1 > entry.limit) return TRUE;
 403     return FALSE;
 404 }
 405
 406 /***********************************************************************
 407  *           IsBadReadPtr   (KERNEL.334)
 408  */
 409 BOOL IsBadReadPtr( SEGPTR ptr, WORD size )
 410 {
 411     return IsBadHugeReadPtr( ptr, size );
 412 }
 413
 414
 415 /***********************************************************************
 416  *           IsBadWritePtr   (KERNEL.335)
 417  */
 418 BOOL IsBadWritePtr( SEGPTR ptr, WORD size )
 419 {
 420     return IsBadHugeWritePtr( ptr, size );
 421 }
 422
 423
 424 /***********************************************************************
 425  *           MemoryRead   (TOOLHELP.78)
 426  */
 427 DWORD MemoryRead( WORD sel, DWORD offset, void *buffer, DWORD count )
 428 {
 429     if (IS_SELECTOR_FREE(sel)) return 0;
 430     if (offset > GET_SEL_LIMIT(sel)) return 0;
 431     if (offset + count > GET_SEL_LIMIT(sel) + 1)
 432         count = GET_SEL_LIMIT(sel) + 1 - offset;
 433     memcpy( buffer, ((char *)GET_SEL_BASE(sel)) + offset, count );
 434     return count;
 435 }
 436
 437
 438 /***********************************************************************
 439  *           MemoryWrite   (TOOLHELP.79)
 440  */
 441 DWORD MemoryWrite( WORD sel, DWORD offset, void *buffer, DWORD count )
 442 {
 443     if (IS_SELECTOR_FREE(sel)) return 0;
 444     if (offset > GET_SEL_LIMIT(sel)) return 0;
 445     if (offset + count > GET_SEL_LIMIT(sel) + 1)
 446         count = GET_SEL_LIMIT(sel) + 1 - offset;
 447     memcpy( ((char *)GET_SEL_BASE(sel)) + offset, buffer, count );
 448     return count;
 449 }
 450
 451 #ifndef WINELIB
 452 SEGPTR MAKE_SEGPTR(void * ptr)
 453
 454 {
 455     SEGPTR result;
 456     int entry;
 457
 458     if (!ptr)
 459         return ptr;
 460     if (!((unsigned)ptr & 0xffff0000)) {
 461         fprintf(stderr, "Invalid pointer %p has been passed to MAKE_SEGPTR. This was\n", ptr);
 462         fprintf(stderr, "probably caused by an unnecessary call to PTR_SEG_TO_LIN.\n");
 463         fprintf(stderr, "Forcing call to debugger\n");
 464         ptr = *(void **)0;
 465     }
 466     result = (SEGPTR) (IF1632_Stack32_base) +
 467              ((DWORD)(ptr) - (DWORD) PTR_SEG_TO_LIN(IF1632_Stack32_base));
 468     if (PTR_SEG_TO_LIN(result) == ptr)
 469         return result;
 470
 471     for (entry = 0; entry < LDT_SIZE; entry++) {
 472         if (ldt_copy[entry].base &&
 473             (ldt_copy[entry].limit < 0x10000) &&
 474             ((unsigned) ptr >= ldt_copy[entry].base) &&
 475             ((unsigned) ptr < (ldt_copy[entry].base + ldt_copy[entry].limit))) {
 476                 return ((ENTRY_TO_SELECTOR(entry) << 16) |
 477                        ((unsigned) ptr - ldt_copy[entry].base));
 478         }
 479     }
 480     entry = SELECTOR_AllocBlock((void *)((unsigned)ptr & 0xffff0000), 0x10000, SEGMENT_DATA, 0, 0);
 481     return ((entry << 16) | ((unsigned) ptr & 0xffff));
 482 }
 483 #endif