labels.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2014 The NASM Authors - All Rights Reserved
   4  *   See the file AUTHORS included with the NASM distribution for
   5  *   the specific copyright holders.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following
   9  *   conditions are met:
  10  *
  11  *   * Redistributions of source code must retain the above copyright
  12  *     notice, this list of conditions and the following disclaimer.
  13  *   * Redistributions in binary form must reproduce the above
  14  *     copyright notice, this list of conditions and the following
  15  *     disclaimer in the documentation and/or other materials provided
  16  *     with the distribution.
  17  *
  18  *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  19  *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  20  *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  21  *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  22  *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  23  *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  29  *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  30  *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * ----------------------------------------------------------------------- */
  33
  34 /*
  35  * labels.c  label handling for the Netwide Assembler
  36  */
  37
  38 #include "compiler.h"
  39
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <stdlib.h>
  43 #include <inttypes.h>
  44
  45 #include "nasm.h"
  46 #include "nasmlib.h"
  47 #include "hashtbl.h"
  48 #include "labels.h"
  49
  50 /*
  51  * A local label is one that begins with exactly one period. Things
  52  * that begin with _two_ periods are NASM-specific things.
  53  *
  54  * If TASM compatibility is enabled, a local label can also begin with
  55  * @@, so @@local is a TASM compatible local label. Note that we only
  56  * check for the first @ symbol, although TASM requires both.
  57  */
  58 #define islocal(l)                                                      \
  59         (tasm_compatible_mode ?                                         \
  60                 (((l)[0] == '.' || (l)[0] == '@') && (l)[1] != '.') :   \
  61                 ((l)[0] == '.' && (l)[1] != '.'))
  62 #define islocalchar(c)                                                  \
  63         (tasm_compatible_mode ?                                         \
  64                 ((c) == '.' || (c) == '@') :                            \
  65                 ((c) == '.'))
  66
  67 #define LABEL_BLOCK     128     /* no. of labels/block */
  68 #define LBLK_SIZE       (LABEL_BLOCK * sizeof(union label))
  69
  70 #define END_LIST        -3      /* don't clash with NO_SEG! */
  71 #define END_BLOCK       -2
  72 #define BOGUS_VALUE     -4
  73
  74 #define PERMTS_SIZE     16384   /* size of text blocks */
  75 #if (PERMTS_SIZE < IDLEN_MAX)
  76  #error "IPERMTS_SIZE must be greater than or equal to IDLEN_MAX"
  77 #endif
  78
  79 /* values for label.defn.is_global */
  80 #define DEFINED_BIT     1
  81 #define GLOBAL_BIT      2
  82 #define EXTERN_BIT      4
  83 #define COMMON_BIT      8
  84
  85 #define NOT_DEFINED_YET         0
  86 #define TYPE_MASK               3
  87 #define LOCAL_SYMBOL            (DEFINED_BIT)
  88 #define GLOBAL_PLACEHOLDER      (GLOBAL_BIT)
  89 #define GLOBAL_SYMBOL           (DEFINED_BIT | GLOBAL_BIT)
  90
  91 union label {                   /* actual label structures */
  92     struct {
  93         int32_t segment;
  94         int64_t offset;
  95         char *label, *special;
  96         int is_global, is_norm;
  97     } defn;
  98     struct {
  99         int32_t movingon;
 100         int64_t dummy;
 101         union label *next;
 102     } admin;
 103 };
 104
 105 struct permts {                 /* permanent text storage */
 106     struct permts *next;        /* for the linked list */
 107     int size, usage;            /* size and used space in ... */
 108     char data[PERMTS_SIZE];     /* ... the data block itself */
 109 };
 110
 111 extern int64_t global_offset_changed;   /* defined in nasm.c */
 112
 113 static struct hash_table ltab;          /* labels hash table */
 114 static union label *ldata;              /* all label data blocks */
 115 static union label *lfree;              /* labels free block */
 116 static struct permts *perm_head;        /* start of perm. text storage */
 117 static struct permts *perm_tail;        /* end of perm. text storage */
 118
 119 static void init_block(union label *blk);
 120 static char *perm_copy(const char *string);
 121
 122 static char *prevlabel;
 123
 124 static bool initialized = false;
 125
 126 char lprefix[PREFIX_MAX] = { 0 };
 127 char lpostfix[PREFIX_MAX] = { 0 };
 128
 129 /*
 130  * Internal routine: finds the `union label' corresponding to the
 131  * given label name. Creates a new one, if it isn't found, and if
 132  * `create' is true.
 133  */
 134 static union label *find_label(char *label, int create)
 135 {
 136     char *prev;
 137     int prevlen, len;
 138     union label *lptr, **lpp;
 139     char label_str[IDLEN_MAX];
 140     struct hash_insert ip;
 141
 142     if (islocal(label)) {
 143         prev = prevlabel;
 144         prevlen = strlen(prev);
 145         len = strlen(label);
 146         if (prevlen + len >= IDLEN_MAX) {
 147             nasm_error(ERR_NONFATAL, "identifier length exceed %i bytes",
 148                        IDLEN_MAX);
 149             return NULL;
 150         }
 151         memcpy(label_str, prev, prevlen);
 152         memcpy(label_str+prevlen, label, len+1);
 153         label = label_str;
 154     } else {
 155         prev = "";
 156         prevlen = 0;
 157     }
 158
 159     lpp = (union label **) hash_find(&ltab, label, &ip);
 160     lptr = lpp ? *lpp : NULL;
 161
 162     if (lptr || !create)
 163         return lptr;
 164
 165     /* Create a new label... */
 166     if (lfree->admin.movingon == END_BLOCK) {
 167         /*
 168          * must allocate a new block
 169          */
 170         lfree->admin.next = (union label *)nasm_malloc(LBLK_SIZE);
 171         lfree = lfree->admin.next;
 172         init_block(lfree);
 173     }
 174
 175     lfree->admin.movingon = BOGUS_VALUE;
 176     lfree->defn.label = perm_copy(label);
 177     lfree->defn.special = NULL;
 178     lfree->defn.is_global = NOT_DEFINED_YET;
 179
 180     hash_add(&ip, lfree->defn.label, lfree);
 181     return lfree++;
 182 }
 183
 184 bool lookup_label(char *label, int32_t *segment, int64_t *offset)
 185 {
 186     union label *lptr;
 187
 188     if (!initialized)
 189         return false;
 190
 191     lptr = find_label(label, 0);
 192     if (lptr && (lptr->defn.is_global & DEFINED_BIT)) {
 193         *segment = lptr->defn.segment;
 194         *offset = lptr->defn.offset;
 195         return true;
 196     }
 197
 198     return false;
 199 }
 200
 201 bool is_extern(char *label)
 202 {
 203     union label *lptr;
 204
 205     if (!initialized)
 206         return false;
 207
 208     lptr = find_label(label, 0);
 209     return (lptr && (lptr->defn.is_global & EXTERN_BIT));
 210 }
 211
 212 void redefine_label(char *label, int32_t segment, int64_t offset, char *special,
 213                     bool is_norm, bool isextrn)
 214 {
 215     union label *lptr;
 216     int exi;
 217
 218     /* This routine possibly ought to check for phase errors.  Most assemblers
 219      * check for phase errors at this point.  I don't know whether phase errors
 220      * are even possible, nor whether they are checked somewhere else
 221      */
 222
 223     (void)special;              /* Don't warn that this parameter is unused */
 224     (void)is_norm;              /* Don't warn that this parameter is unused */
 225     (void)isextrn;              /* Don't warn that this parameter is unused */
 226
 227 #ifdef DEBUG
 228 #if DEBUG < 3
 229     if (!strncmp(label, "debugdump", 9))
 230 #endif
 231         nasm_error(ERR_DEBUG, "redefine_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 232               label, segment, offset, special, is_norm, isextrn);
 233 #endif
 234
 235     lptr = find_label(label, 1);
 236     if (!lptr)
 237         nasm_panic(0, "can't find label `%s' on pass two", label);
 238
 239     if (!islocal(label)) {
 240         if (!islocalchar(*label) && lptr->defn.is_norm)
 241             prevlabel = lptr->defn.label;
 242     }
 243
 244     if (lptr->defn.offset != offset)
 245         global_offset_changed++;
 246
 247     lptr->defn.offset = offset;
 248     lptr->defn.segment = segment;
 249
 250     if (pass0 == 1) {
 251         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 252         if (exi) {
 253             char *xsymbol;
 254             int slen;
 255             slen = strlen(lprefix);
 256             slen += strlen(lptr->defn.label);
 257             slen += strlen(lpostfix);
 258             slen++;             /* room for that null char */
 259             xsymbol = nasm_malloc(slen);
 260             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 261                      lpostfix);
 262
 263             ofmt->symdef(xsymbol, segment, offset, exi,
 264                          special ? special : lptr->defn.special);
 265             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset, exi,
 266                                                special ? special : lptr->defn.special);
 267 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 268         } else {
 269             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) != EXTERN_BIT) {
 270                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 271                              special ? special : lptr->defn.special);
 272                 ofmt->current_dfmt->debug_deflabel(label, segment, offset, exi,
 273                                                    special ? special : lptr->defn.special);
 274             }
 275         }
 276     }   /* if (pass0 == 1) */
 277 }
 278
 279 void define_label(char *label, int32_t segment, int64_t offset, char *special,
 280                   bool is_norm, bool isextrn)
 281 {
 282     union label *lptr;
 283     int exi;
 284
 285 #ifdef DEBUG
 286 #if DEBUG<3
 287     if (!strncmp(label, "debugdump", 9))
 288 #endif
 289         nasm_error(ERR_DEBUG, "define_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 290               label, segment, offset, special, is_norm, isextrn);
 291 #endif
 292     lptr = find_label(label, 1);
 293     if (!lptr)
 294         return;
 295     if (lptr->defn.is_global & DEFINED_BIT) {
 296         nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 297         return;
 298     }
 299     lptr->defn.is_global |= DEFINED_BIT;
 300     if (isextrn)
 301         lptr->defn.is_global |= EXTERN_BIT;
 302
 303     if (!islocalchar(label[0]) && is_norm) {
 304         /* not local, but not special either */
 305         prevlabel = lptr->defn.label;
 306     } else if (islocal(label) && !*prevlabel) {
 307         nasm_error(ERR_NONFATAL, "attempt to define a local label before any"
 308               " non-local labels");
 309     }
 310
 311     lptr->defn.segment = segment;
 312     lptr->defn.offset = offset;
 313     lptr->defn.is_norm = (!islocalchar(label[0]) && is_norm);
 314
 315     if (pass0 == 1 || (!is_norm && !isextrn && (segment > 0) && (segment & 1))) {
 316         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 317         if (exi) {
 318             char *xsymbol;
 319             int slen;
 320             slen = strlen(lprefix);
 321             slen += strlen(lptr->defn.label);
 322             slen += strlen(lpostfix);
 323             slen++;             /* room for that null char */
 324             xsymbol = nasm_malloc(slen);
 325             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 326                      lpostfix);
 327
 328             ofmt->symdef(xsymbol, segment, offset, exi,
 329                          special ? special : lptr->defn.special);
 330             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset, exi,
 331                                                special ? special : lptr->defn.special);
 332 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 333         } else {
 334             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) != EXTERN_BIT) {
 335                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 336                              special ? special : lptr->defn.special);
 337                 ofmt->current_dfmt->debug_deflabel(label, segment, offset, exi,
 338                                                    special ? special : lptr->defn.special);
 339             }
 340         }
 341     }   /* if (pass0 == 1) */
 342 }
 343
 344 void define_common(char *label, int32_t segment, int32_t size, char *special)
 345 {
 346     union label *lptr;
 347
 348     lptr = find_label(label, 1);
 349     if (!lptr)
 350         return;
 351     if ((lptr->defn.is_global & DEFINED_BIT) &&
 352         (passn == 1 || !(lptr->defn.is_global & COMMON_BIT))) {
 353             nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 354             return;
 355     }
 356     lptr->defn.is_global |= DEFINED_BIT|COMMON_BIT;
 357
 358     if (!islocalchar(label[0])) {
 359         prevlabel = lptr->defn.label;
 360     } else {
 361         nasm_error(ERR_NONFATAL, "attempt to define a local label as a "
 362               "common variable");
 363         return;
 364     }
 365
 366     lptr->defn.segment = segment;
 367     lptr->defn.offset = 0;
 368
 369     if (pass0 == 0)
 370         return;
 371
 372     ofmt->symdef(lptr->defn.label, segment, size, 2,
 373                  special ? special : lptr->defn.special);
 374     ofmt->current_dfmt->debug_deflabel(lptr->defn.label, segment, size, 2,
 375                                        special ? special : lptr->defn.special);
 376 }
 377
 378 void declare_as_global(char *label, char *special)
 379 {
 380     union label *lptr;
 381
 382     if (islocal(label)) {
 383         nasm_error(ERR_NONFATAL, "attempt to declare local symbol `%s' as"
 384               " global", label);
 385         return;
 386     }
 387     lptr = find_label(label, 1);
 388     if (!lptr)
 389         return;
 390     switch (lptr->defn.is_global & TYPE_MASK) {
 391     case NOT_DEFINED_YET:
 392         lptr->defn.is_global = GLOBAL_PLACEHOLDER;
 393         lptr->defn.special = special ? perm_copy(special) : NULL;
 394         break;
 395     case GLOBAL_PLACEHOLDER:   /* already done: silently ignore */
 396     case GLOBAL_SYMBOL:
 397         break;
 398     case LOCAL_SYMBOL:
 399         if (!(lptr->defn.is_global & EXTERN_BIT)) {
 400             nasm_error(ERR_WARNING, "symbol `%s': GLOBAL directive "
 401                   "after symbol definition is an experimental feature", label);
 402             lptr->defn.is_global = GLOBAL_SYMBOL;
 403         }
 404         break;
 405     }
 406 }
 407
 408 int init_labels(void)
 409 {
 410     hash_init(&ltab, HASH_LARGE);
 411
 412     ldata = lfree = (union label *)nasm_malloc(LBLK_SIZE);
 413     init_block(lfree);
 414
 415     perm_head = perm_tail =
 416         (struct permts *)nasm_malloc(sizeof(struct permts));
 417
 418     perm_head->next = NULL;
 419     perm_head->size = PERMTS_SIZE;
 420     perm_head->usage = 0;
 421
 422     prevlabel = "";
 423
 424     initialized = true;
 425
 426     return 0;
 427 }
 428
 429 void cleanup_labels(void)
 430 {
 431     union label *lptr, *lhold;
 432
 433     initialized = false;
 434
 435     hash_free(&ltab);
 436
 437     lptr = lhold = ldata;
 438     while (lptr) {
 439         lptr = &lptr[LABEL_BLOCK-1];
 440         lptr = lptr->admin.next;
 441         nasm_free(lhold);
 442         lhold = lptr;
 443     }
 444
 445     while (perm_head) {
 446         perm_tail = perm_head;
 447         perm_head = perm_head->next;
 448         nasm_free(perm_tail);
 449     }
 450 }
 451
 452 static void init_block(union label *blk)
 453 {
 454     int j;
 455
 456     for (j = 0; j < LABEL_BLOCK - 1; j++)
 457         blk[j].admin.movingon = END_LIST;
 458     blk[LABEL_BLOCK - 1].admin.movingon = END_BLOCK;
 459     blk[LABEL_BLOCK - 1].admin.next = NULL;
 460 }
 461
 462 static char *perm_copy(const char *string)
 463 {
 464     char *p;
 465     int len = strlen(string)+1;
 466
 467     nasm_assert(len <= PERMTS_SIZE);
 468
 469     if (perm_tail->size - perm_tail->usage < len) {
 470         perm_tail->next =
 471             (struct permts *)nasm_malloc(sizeof(struct permts));
 472         perm_tail = perm_tail->next;
 473         perm_tail->next = NULL;
 474         perm_tail->size = PERMTS_SIZE;
 475         perm_tail->usage = 0;
 476     }
 477     p = perm_tail->data + perm_tail->usage;
 478     memcpy(p, string, len);
 479     perm_tail->usage += len;
 480
 481     return p;
 482 }
 483
 484 char *local_scope(char *label)
 485 {
 486    return islocal(label) ? prevlabel : "";
 487 }
 488
 489 /*
 490  * Notes regarding bug involving redefinition of external segments.
 491  *
 492  * Up to and including v0.97, the following code didn't work. From 0.97
 493  * developers release 2 onwards, it will generate an error.
 494  *
 495  * EXTERN extlabel
 496  * newlabel EQU extlabel + 1
 497  *
 498  * The results of allowing this code through are that two import records
 499  * are generated, one for 'extlabel' and one for 'newlabel'.
 500  *
 501  * The reason for this is an inadequacy in the defined interface between
 502  * the label manager and the output formats. The problem lies in how the
 503  * output format driver tells that a label is an external label for which
 504  * a label import record must be produced. Most (all except bin?) produce
 505  * the record if the segment number of the label is not one of the internal
 506  * segments that the output driver is producing.
 507  *
 508  * A simple fix to this would be to make the output formats keep track of
 509  * which symbols they've produced import records for, and make them not
 510  * produce import records for segments that are already defined.
 511  *
 512  * The best way, which is slightly harder but reduces duplication of code
 513  * and should therefore make the entire system smaller and more stable is
 514  * to change the interface between assembler, define_label(), and
 515  * the output module. The changes that are needed are:
 516  *
 517  * The semantics of the 'isextern' flag passed to define_label() need
 518  * examining. This information may or may not tell us what we need to
 519  * know (ie should we be generating an import record at this point for this
 520  * label). If these aren't the semantics, the semantics should be changed
 521  * to this.
 522  *
 523  * The output module interface needs changing, so that the `isextern' flag
 524  * is passed to the module, so that it can be easily tested for.
 525  */