output/outaout.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2009 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  * outaout.c    output routines for the Netwide Assembler to produce
  36  *              Linux a.out object files
  37  */
  38
  39 #include "compiler.h"
  40
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <ctype.h>
  45 #include <inttypes.h>
  46
  47 #include "nasm.h"
  48 #include "nasmlib.h"
  49 #include "saa.h"
  50 #include "raa.h"
  51 #include "stdscan.h"
  52 #include "output/outform.h"
  53 #include "output/outlib.h"
  54
  55 #if defined OF_AOUT || defined OF_AOUTB
  56
  57 #define RELTYPE_ABSOLUTE 0x00
  58 #define RELTYPE_RELATIVE 0x01
  59 #define RELTYPE_GOTPC    0x01   /* no explicit GOTPC in a.out */
  60 #define RELTYPE_GOTOFF   0x10
  61 #define RELTYPE_GOT      0x10   /* distinct from GOTOFF bcos sym not sect */
  62 #define RELTYPE_PLT      0x21
  63 #define RELTYPE_SYMFLAG  0x08
  64
  65 struct Reloc {
  66     struct Reloc *next;
  67     int32_t address;               /* relative to _start_ of section */
  68     int32_t symbol;                /* symbol number or -ve section id */
  69     int bytes;                  /* 2 or 4 */
  70     int reltype;                /* see above */
  71 };
  72
  73 struct Symbol {
  74     int32_t strpos;                /* string table position of name */
  75     int type;                   /* symbol type - see flags below */
  76     int32_t value;                 /* address, or COMMON variable size */
  77     int32_t size;                  /* size for data or function exports */
  78     int32_t segment;               /* back-reference used by gsym_reloc */
  79     struct Symbol *next;        /* list of globals in each section */
  80     struct Symbol *nextfwd;     /* list of unresolved-size symbols */
  81     char *name;                 /* for unresolved-size symbols */
  82     int32_t symnum;                /* index into symbol table */
  83 };
  84
  85 /*
  86  * Section IDs - used in Reloc.symbol when negative, and in
  87  * Symbol.type when positive.
  88  */
  89 #define SECT_ABS 2              /* absolute value */
  90 #define SECT_TEXT 4             /* text section */
  91 #define SECT_DATA 6             /* data section */
  92 #define SECT_BSS 8              /* bss section */
  93 #define SECT_MASK 0xE           /* mask out any of the above */
  94
  95 /*
  96  * More flags used in Symbol.type.
  97  */
  98 #define SYM_GLOBAL 1            /* it's a global symbol */
  99 #define SYM_DATA 0x100          /* used for shared libs */
 100 #define SYM_FUNCTION 0x200      /* used for shared libs */
 101 #define SYM_WITH_SIZE 0x4000    /* not output; internal only */
 102
 103 /*
 104  * Bit more explanation of symbol types: SECT_xxx denotes a local
 105  * symbol. SECT_xxx|SYM_GLOBAL denotes a global symbol, defined in
 106  * this module. Just SYM_GLOBAL, with zero value, denotes an
 107  * external symbol referenced in this module. And just SYM_GLOBAL,
 108  * but with a non-zero value, declares a C `common' variable, of
 109  * size `value'.
 110  */
 111
 112 struct Section {
 113     struct SAA *data;
 114     uint32_t len, size, nrelocs;
 115     int32_t index;
 116     struct Reloc *head, **tail;
 117     struct Symbol *gsyms, *asym;
 118 };
 119
 120 static struct Section stext, sdata, sbss;
 121
 122 static struct SAA *syms;
 123 static uint32_t nsyms;
 124
 125 static struct RAA *bsym;
 126
 127 static struct SAA *strs;
 128 static uint32_t strslen;
 129
 130 static struct Symbol *fwds;
 131
 132 static FILE *aoutfp;
 133 static efunc error;
 134 static evalfunc evaluate;
 135
 136 static int bsd;
 137 static int is_pic;
 138
 139 static void aout_write(void);
 140 static void aout_write_relocs(struct Reloc *);
 141 static void aout_write_syms(void);
 142 static void aout_sect_write(struct Section *, const uint8_t *,
 143                             uint32_t);
 144 static void aout_pad_sections(void);
 145 static void aout_fixup_relocs(struct Section *);
 146
 147 /*
 148  * Special section numbers which are used to define special
 149  * symbols, which can be used with WRT to provide PIC relocation
 150  * types.
 151  */
 152 static int32_t aout_gotpc_sect, aout_gotoff_sect;
 153 static int32_t aout_got_sect, aout_plt_sect;
 154 static int32_t aout_sym_sect;
 155
 156 static void aoutg_init(FILE * fp, efunc errfunc, ldfunc ldef,
 157                        evalfunc eval)
 158 {
 159     aoutfp = fp;
 160     error = errfunc;
 161     evaluate = eval;
 162     (void)ldef;                 /* placate optimisers */
 163     stext.data = saa_init(1L);
 164     stext.head = NULL;
 165     stext.tail = &stext.head;
 166     sdata.data = saa_init(1L);
 167     sdata.head = NULL;
 168     sdata.tail = &sdata.head;
 169     stext.len = stext.size = sdata.len = sdata.size = sbss.len = 0;
 170     stext.nrelocs = sdata.nrelocs = 0;
 171     stext.gsyms = sdata.gsyms = sbss.gsyms = NULL;
 172     stext.index = seg_alloc();
 173     sdata.index = seg_alloc();
 174     sbss.index = seg_alloc();
 175     stext.asym = sdata.asym = sbss.asym = NULL;
 176     syms = saa_init((int32_t)sizeof(struct Symbol));
 177     nsyms = 0;
 178     bsym = raa_init();
 179     strs = saa_init(1L);
 180     strslen = 0;
 181     fwds = NULL;
 182 }
 183
 184 #ifdef OF_AOUT
 185
 186 static void aout_init(FILE * fp, efunc errfunc, ldfunc ldef, evalfunc eval)
 187 {
 188     bsd = false;
 189     aoutg_init(fp, errfunc, ldef, eval);
 190
 191     aout_gotpc_sect = aout_gotoff_sect = aout_got_sect =
 192         aout_plt_sect = aout_sym_sect = NO_SEG;
 193 }
 194
 195 #endif
 196
 197 #ifdef OF_AOUTB
 198
 199 extern struct ofmt of_aoutb;
 200
 201 static void aoutb_init(FILE * fp, efunc errfunc, ldfunc ldef,
 202                        evalfunc eval)
 203 {
 204     bsd = true;
 205     aoutg_init(fp, errfunc, ldef, eval);
 206
 207     is_pic = 0x00;              /* may become 0x40 */
 208
 209     aout_gotpc_sect = seg_alloc();
 210     ldef("..gotpc", aout_gotpc_sect + 1, 0L, NULL, false, false, &of_aoutb,
 211          error);
 212     aout_gotoff_sect = seg_alloc();
 213     ldef("..gotoff", aout_gotoff_sect + 1, 0L, NULL, false, false,
 214          &of_aoutb, error);
 215     aout_got_sect = seg_alloc();
 216     ldef("..got", aout_got_sect + 1, 0L, NULL, false, false, &of_aoutb,
 217          error);
 218     aout_plt_sect = seg_alloc();
 219     ldef("..plt", aout_plt_sect + 1, 0L, NULL, false, false, &of_aoutb,
 220          error);
 221     aout_sym_sect = seg_alloc();
 222     ldef("..sym", aout_sym_sect + 1, 0L, NULL, false, false, &of_aoutb,
 223          error);
 224 }
 225
 226 #endif
 227
 228 static void aout_cleanup(int debuginfo)
 229 {
 230     struct Reloc *r;
 231
 232     (void)debuginfo;
 233
 234     aout_pad_sections();
 235     aout_fixup_relocs(&stext);
 236     aout_fixup_relocs(&sdata);
 237     aout_write();
 238     fclose(aoutfp);
 239     saa_free(stext.data);
 240     while (stext.head) {
 241         r = stext.head;
 242         stext.head = stext.head->next;
 243         nasm_free(r);
 244     }
 245     saa_free(sdata.data);
 246     while (sdata.head) {
 247         r = sdata.head;
 248         sdata.head = sdata.head->next;
 249         nasm_free(r);
 250     }
 251     saa_free(syms);
 252     raa_free(bsym);
 253     saa_free(strs);
 254 }
 255
 256 static int32_t aout_section_names(char *name, int pass, int *bits)
 257 {
 258
 259     (void)pass;
 260
 261     /*
 262      * Default to 32 bits.
 263      */
 264     if (!name)
 265         *bits = 32;
 266
 267     if (!name)
 268         return stext.index;
 269
 270     if (!strcmp(name, ".text"))
 271         return stext.index;
 272     else if (!strcmp(name, ".data"))
 273         return sdata.index;
 274     else if (!strcmp(name, ".bss"))
 275         return sbss.index;
 276     else
 277         return NO_SEG;
 278 }
 279
 280 static void aout_deflabel(char *name, int32_t segment, int64_t offset,
 281                           int is_global, char *special)
 282 {
 283     int pos = strslen + 4;
 284     struct Symbol *sym;
 285     int special_used = false;
 286
 287     if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
 288         /*
 289          * This is a NASM special symbol. We never allow it into
 290          * the a.out symbol table, even if it's a valid one. If it
 291          * _isn't_ a valid one, we should barf immediately.
 292          */
 293         if (strcmp(name, "..gotpc") && strcmp(name, "..gotoff") &&
 294             strcmp(name, "..got") && strcmp(name, "..plt") &&
 295             strcmp(name, "..sym"))
 296             error(ERR_NONFATAL, "unrecognised special symbol `%s'", name);
 297         return;
 298     }
 299
 300     if (is_global == 3) {
 301         struct Symbol **s;
 302         /*
 303          * Fix up a forward-reference symbol size from the first
 304          * pass.
 305          */
 306         for (s = &fwds; *s; s = &(*s)->nextfwd)
 307             if (!strcmp((*s)->name, name)) {
 308                 struct tokenval tokval;
 309                 expr *e;
 310                 char *p = special;
 311
 312                 while (*p && !nasm_isspace(*p))
 313                     p++;
 314                 while (*p && nasm_isspace(*p))
 315                     p++;
 316                 stdscan_reset();
 317                 stdscan_bufptr = p;
 318                 tokval.t_type = TOKEN_INVALID;
 319                 e = evaluate(stdscan, NULL, &tokval, NULL, 1, error, NULL);
 320                 if (e) {
 321                     if (!is_simple(e))
 322                         error(ERR_NONFATAL, "cannot use relocatable"
 323                               " expression as symbol size");
 324                     else
 325                         (*s)->size = reloc_value(e);
 326                 }
 327
 328                 /*
 329                  * Remove it from the list of unresolved sizes.
 330                  */
 331                 nasm_free((*s)->name);
 332                 *s = (*s)->nextfwd;
 333                 return;
 334             }
 335         return;                 /* it wasn't an important one */
 336     }
 337
 338     saa_wbytes(strs, name, (int32_t)(1 + strlen(name)));
 339     strslen += 1 + strlen(name);
 340
 341     sym = saa_wstruct(syms);
 342
 343     sym->strpos = pos;
 344     sym->type = is_global ? SYM_GLOBAL : 0;
 345     sym->segment = segment;
 346     if (segment == NO_SEG)
 347         sym->type |= SECT_ABS;
 348     else if (segment == stext.index) {
 349         sym->type |= SECT_TEXT;
 350         if (is_global) {
 351             sym->next = stext.gsyms;
 352             stext.gsyms = sym;
 353         } else if (!stext.asym)
 354             stext.asym = sym;
 355     } else if (segment == sdata.index) {
 356         sym->type |= SECT_DATA;
 357         if (is_global) {
 358             sym->next = sdata.gsyms;
 359             sdata.gsyms = sym;
 360         } else if (!sdata.asym)
 361             sdata.asym = sym;
 362     } else if (segment == sbss.index) {
 363         sym->type |= SECT_BSS;
 364         if (is_global) {
 365             sym->next = sbss.gsyms;
 366             sbss.gsyms = sym;
 367         } else if (!sbss.asym)
 368             sbss.asym = sym;
 369     } else
 370         sym->type = SYM_GLOBAL;
 371     if (is_global == 2)
 372         sym->value = offset;
 373     else
 374         sym->value = (sym->type == SYM_GLOBAL ? 0 : offset);
 375
 376     if (is_global && sym->type != SYM_GLOBAL) {
 377         /*
 378          * Global symbol exported _from_ this module. We must check
 379          * the special text for type information.
 380          */
 381
 382         if (special) {
 383             int n = strcspn(special, " ");
 384
 385             if (!nasm_strnicmp(special, "function", n))
 386                 sym->type |= SYM_FUNCTION;
 387             else if (!nasm_strnicmp(special, "data", n) ||
 388                      !nasm_strnicmp(special, "object", n))
 389                 sym->type |= SYM_DATA;
 390             else
 391                 error(ERR_NONFATAL, "unrecognised symbol type `%.*s'",
 392                       n, special);
 393             if (special[n]) {
 394                 struct tokenval tokval;
 395                 expr *e;
 396                 int fwd = false;
 397                 char *saveme = stdscan_bufptr;  /* bugfix? fbk 8/10/00 */
 398
 399                 if (!bsd) {
 400                     error(ERR_NONFATAL, "Linux a.out does not support"
 401                           " symbol size information");
 402                 } else {
 403                     while (special[n] && nasm_isspace(special[n]))
 404                         n++;
 405                     /*
 406                      * We have a size expression; attempt to
 407                      * evaluate it.
 408                      */
 409                     sym->type |= SYM_WITH_SIZE;
 410                     stdscan_reset();
 411                     stdscan_bufptr = special + n;
 412                     tokval.t_type = TOKEN_INVALID;
 413                     e = evaluate(stdscan, NULL, &tokval, &fwd, 0, error,
 414                                  NULL);
 415                     if (fwd) {
 416                         sym->nextfwd = fwds;
 417                         fwds = sym;
 418                         sym->name = nasm_strdup(name);
 419                     } else if (e) {
 420                         if (!is_simple(e))
 421                             error(ERR_NONFATAL, "cannot use relocatable"
 422                                   " expression as symbol size");
 423                         else
 424                             sym->size = reloc_value(e);
 425                     }
 426                 }
 427                 stdscan_bufptr = saveme;        /* bugfix? fbk 8/10/00 */
 428             }
 429             special_used = true;
 430         }
 431     }
 432
 433     /*
 434      * define the references from external-symbol segment numbers
 435      * to these symbol records.
 436      */
 437     if (segment != NO_SEG && segment != stext.index &&
 438         segment != sdata.index && segment != sbss.index)
 439         bsym = raa_write(bsym, segment, nsyms);
 440     sym->symnum = nsyms;
 441
 442     nsyms++;
 443     if (sym->type & SYM_WITH_SIZE)
 444         nsyms++;                /* and another for the size */
 445
 446     if (special && !special_used)
 447         error(ERR_NONFATAL, "no special symbol features supported here");
 448 }
 449
 450 static void aout_add_reloc(struct Section *sect, int32_t segment,
 451                            int reltype, int bytes)
 452 {
 453     struct Reloc *r;
 454
 455     r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
 456     sect->tail = &r->next;
 457     r->next = NULL;
 458
 459     r->address = sect->len;
 460     r->symbol = (segment == NO_SEG ? -SECT_ABS :
 461                  segment == stext.index ? -SECT_TEXT :
 462                  segment == sdata.index ? -SECT_DATA :
 463                  segment == sbss.index ? -SECT_BSS :
 464                  raa_read(bsym, segment));
 465     r->reltype = reltype;
 466     if (r->symbol >= 0)
 467         r->reltype |= RELTYPE_SYMFLAG;
 468     r->bytes = bytes;
 469
 470     sect->nrelocs++;
 471 }
 472
 473 /*
 474  * This routine deals with ..got and ..sym relocations: the more
 475  * complicated kinds. In shared-library writing, some relocations
 476  * with respect to global symbols must refer to the precise symbol
 477  * rather than referring to an offset from the base of the section
 478  * _containing_ the symbol. Such relocations call to this routine,
 479  * which searches the symbol list for the symbol in question.
 480  *
 481  * RELTYPE_GOT references require the _exact_ symbol address to be
 482  * used; RELTYPE_ABSOLUTE references can be at an offset from the
 483  * symbol. The boolean argument `exact' tells us this.
 484  *
 485  * Return value is the adjusted value of `addr', having become an
 486  * offset from the symbol rather than the section. Should always be
 487  * zero when returning from an exact call.
 488  *
 489  * Limitation: if you define two symbols at the same place,
 490  * confusion will occur.
 491  *
 492  * Inefficiency: we search, currently, using a linked list which
 493  * isn't even necessarily sorted.
 494  */
 495 static int32_t aout_add_gsym_reloc(struct Section *sect,
 496                                 int32_t segment, int32_t offset,
 497                                 int type, int bytes, int exact)
 498 {
 499     struct Symbol *sym, *sm, *shead;
 500     struct Reloc *r;
 501
 502     /*
 503      * First look up the segment to find whether it's text, data,
 504      * bss or an external symbol.
 505      */
 506     shead = NULL;
 507     if (segment == stext.index)
 508         shead = stext.gsyms;
 509     else if (segment == sdata.index)
 510         shead = sdata.gsyms;
 511     else if (segment == sbss.index)
 512         shead = sbss.gsyms;
 513     if (!shead) {
 514         if (exact && offset != 0)
 515             error(ERR_NONFATAL, "unable to find a suitable global symbol"
 516                   " for this reference");
 517         else
 518             aout_add_reloc(sect, segment, type, bytes);
 519         return offset;
 520     }
 521
 522     if (exact) {
 523         /*
 524          * Find a symbol pointing _exactly_ at this one.
 525          */
 526         for (sym = shead; sym; sym = sym->next)
 527             if (sym->value == offset)
 528                 break;
 529     } else {
 530         /*
 531          * Find the nearest symbol below this one.
 532          */
 533         sym = NULL;
 534         for (sm = shead; sm; sm = sm->next)
 535             if (sm->value <= offset && (!sym || sm->value > sym->value))
 536                 sym = sm;
 537     }
 538     if (!sym && exact) {
 539         error(ERR_NONFATAL, "unable to find a suitable global symbol"
 540               " for this reference");
 541         return 0;
 542     }
 543
 544     r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
 545     sect->tail = &r->next;
 546     r->next = NULL;
 547
 548     r->address = sect->len;
 549     r->symbol = sym->symnum;
 550     r->reltype = type | RELTYPE_SYMFLAG;
 551     r->bytes = bytes;
 552
 553     sect->nrelocs++;
 554
 555     return offset - sym->value;
 556 }
 557
 558 /*
 559  * This routine deals with ..gotoff relocations. These _must_ refer
 560  * to a symbol, due to a perversity of *BSD's PIC implementation,
 561  * and it must be a non-global one as well; so we store `asym', the
 562  * first nonglobal symbol defined in each section, and always work
 563  * from that. Relocation type is always RELTYPE_GOTOFF.
 564  *
 565  * Return value is the adjusted value of `addr', having become an
 566  * offset from the `asym' symbol rather than the section.
 567  */
 568 static int32_t aout_add_gotoff_reloc(struct Section *sect, int32_t segment,
 569                                   int32_t offset, int bytes)
 570 {
 571     struct Reloc *r;
 572     struct Symbol *asym;
 573
 574     /*
 575      * First look up the segment to find whether it's text, data,
 576      * bss or an external symbol.
 577      */
 578     asym = NULL;
 579     if (segment == stext.index)
 580         asym = stext.asym;
 581     else if (segment == sdata.index)
 582         asym = sdata.asym;
 583     else if (segment == sbss.index)
 584         asym = sbss.asym;
 585     if (!asym)
 586         error(ERR_NONFATAL, "`..gotoff' relocations require a non-global"
 587               " symbol in the section");
 588
 589     r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
 590     sect->tail = &r->next;
 591     r->next = NULL;
 592
 593     r->address = sect->len;
 594     r->symbol = asym->symnum;
 595     r->reltype = RELTYPE_GOTOFF;
 596     r->bytes = bytes;
 597
 598     sect->nrelocs++;
 599
 600     return offset - asym->value;
 601 }
 602
 603 static void aout_out(int32_t segto, const void *data,
 604                      enum out_type type, uint64_t size,
 605                      int32_t segment, int32_t wrt)
 606 {
 607     struct Section *s;
 608     int32_t addr;
 609     uint8_t mydata[4], *p;
 610
 611     /*
 612      * handle absolute-assembly (structure definitions)
 613      */
 614     if (segto == NO_SEG) {
 615         if (type != OUT_RESERVE)
 616             error(ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]"
 617                   " space");
 618         return;
 619     }
 620
 621     if (segto == stext.index)
 622         s = &stext;
 623     else if (segto == sdata.index)
 624         s = &sdata;
 625     else if (segto == sbss.index)
 626         s = NULL;
 627     else {
 628         error(ERR_WARNING, "attempt to assemble code in"
 629               " segment %d: defaulting to `.text'", segto);
 630         s = &stext;
 631     }
 632
 633     if (!s && type != OUT_RESERVE) {
 634         error(ERR_WARNING, "attempt to initialize memory in the"
 635               " BSS section: ignored");
 636         sbss.len += realsize(type, size);
 637         return;
 638     }
 639
 640     if (type == OUT_RESERVE) {
 641         if (s) {
 642             error(ERR_WARNING, "uninitialized space declared in"
 643                   " %s section: zeroing",
 644                   (segto == stext.index ? "code" : "data"));
 645             aout_sect_write(s, NULL, size);
 646         } else
 647             sbss.len += size;
 648     } else if (type == OUT_RAWDATA) {
 649         if (segment != NO_SEG)
 650             error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 651         aout_sect_write(s, data, size);
 652     } else if (type == OUT_ADDRESS) {
 653         addr = *(int64_t *)data;
 654         if (segment != NO_SEG) {
 655             if (segment % 2) {
 656                 error(ERR_NONFATAL, "a.out format does not support"
 657                       " segment base references");
 658             } else {
 659                 if (wrt == NO_SEG) {
 660                     aout_add_reloc(s, segment, RELTYPE_ABSOLUTE,
 661                                    size);
 662                 } else if (!bsd) {
 663                     error(ERR_NONFATAL,
 664                           "Linux a.out format does not support"
 665                           " any use of WRT");
 666                     wrt = NO_SEG;       /* we can at least _try_ to continue */
 667                 } else if (wrt == aout_gotpc_sect + 1) {
 668                     is_pic = 0x40;
 669                     aout_add_reloc(s, segment, RELTYPE_GOTPC, size);
 670                 } else if (wrt == aout_gotoff_sect + 1) {
 671                     is_pic = 0x40;
 672                     addr = aout_add_gotoff_reloc(s, segment,
 673                                                  addr, size);
 674                 } else if (wrt == aout_got_sect + 1) {
 675                     is_pic = 0x40;
 676                     addr =
 677                         aout_add_gsym_reloc(s, segment, addr, RELTYPE_GOT,
 678                                             size, true);
 679                 } else if (wrt == aout_sym_sect + 1) {
 680                     addr = aout_add_gsym_reloc(s, segment, addr,
 681                                                RELTYPE_ABSOLUTE, size,
 682                                                false);
 683                 } else if (wrt == aout_plt_sect + 1) {
 684                     is_pic = 0x40;
 685                     error(ERR_NONFATAL,
 686                           "a.out format cannot produce non-PC-"
 687                           "relative PLT references");
 688                 } else {
 689                     error(ERR_NONFATAL,
 690                           "a.out format does not support this"
 691                           " use of WRT");
 692                     wrt = NO_SEG;       /* we can at least _try_ to continue */
 693                 }
 694             }
 695         }
 696         p = mydata;
 697         if (size == 2)
 698             WRITESHORT(p, addr);
 699         else
 700             WRITELONG(p, addr);
 701         aout_sect_write(s, mydata, size);
 702     } else if (type == OUT_REL2ADR) {
 703         if (segment == segto)
 704             error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 705         if (segment != NO_SEG && segment % 2) {
 706             error(ERR_NONFATAL, "a.out format does not support"
 707                   " segment base references");
 708         } else {
 709             if (wrt == NO_SEG) {
 710                 aout_add_reloc(s, segment, RELTYPE_RELATIVE, 2);
 711             } else if (!bsd) {
 712                 error(ERR_NONFATAL, "Linux a.out format does not support"
 713                       " any use of WRT");
 714                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 715             } else if (wrt == aout_plt_sect + 1) {
 716                 is_pic = 0x40;
 717                 aout_add_reloc(s, segment, RELTYPE_PLT, 2);
 718             } else if (wrt == aout_gotpc_sect + 1 ||
 719                        wrt == aout_gotoff_sect + 1 ||
 720                        wrt == aout_got_sect + 1) {
 721                 error(ERR_NONFATAL, "a.out format cannot produce PC-"
 722                       "relative GOT references");
 723             } else {
 724                 error(ERR_NONFATAL, "a.out format does not support this"
 725                       " use of WRT");
 726                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 727             }
 728         }
 729         p = mydata;
 730         WRITESHORT(p, *(int64_t *)data - (size + s->len));
 731         aout_sect_write(s, mydata, 2L);
 732     } else if (type == OUT_REL4ADR) {
 733         if (segment == segto)
 734             error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 735         if (segment != NO_SEG && segment % 2) {
 736             error(ERR_NONFATAL, "a.out format does not support"
 737                   " segment base references");
 738         } else {
 739             if (wrt == NO_SEG) {
 740                 aout_add_reloc(s, segment, RELTYPE_RELATIVE, 4);
 741             } else if (!bsd) {
 742                 error(ERR_NONFATAL, "Linux a.out format does not support"
 743                       " any use of WRT");
 744                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 745             } else if (wrt == aout_plt_sect + 1) {
 746                 is_pic = 0x40;
 747                 aout_add_reloc(s, segment, RELTYPE_PLT, 4);
 748             } else if (wrt == aout_gotpc_sect + 1 ||
 749                        wrt == aout_gotoff_sect + 1 ||
 750                        wrt == aout_got_sect + 1) {
 751                 error(ERR_NONFATAL, "a.out format cannot produce PC-"
 752                       "relative GOT references");
 753             } else {
 754                 error(ERR_NONFATAL, "a.out format does not support this"
 755                       " use of WRT");
 756                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 757             }
 758         }
 759         p = mydata;
 760         WRITELONG(p, *(int64_t *)data - (size + s->len));
 761         aout_sect_write(s, mydata, 4L);
 762     }
 763 }
 764
 765 static void aout_pad_sections(void)
 766 {
 767     static uint8_t pad[] = { 0x90, 0x90, 0x90, 0x90 };
 768     /*
 769      * Pad each of the text and data sections with NOPs until their
 770      * length is a multiple of four. (NOP == 0x90.) Also increase
 771      * the length of the BSS section similarly.
 772      */
 773     aout_sect_write(&stext, pad, (-(int32_t)stext.len) & 3);
 774     aout_sect_write(&sdata, pad, (-(int32_t)sdata.len) & 3);
 775     sbss.len = (sbss.len + 3) & ~3;
 776 }
 777
 778 /*
 779  * a.out files have the curious property that all references to
 780  * things in the data or bss sections are done by addresses which
 781  * are actually relative to the start of the _text_ section, in the
 782  * _file_. (No relation to what happens after linking. No idea why
 783  * this should be so. It's very strange.) So we have to go through
 784  * the relocation table, _after_ the final size of each section is
 785  * known, and fix up the relocations pointed to.
 786  */
 787 static void aout_fixup_relocs(struct Section *sect)
 788 {
 789     struct Reloc *r;
 790
 791     saa_rewind(sect->data);
 792     for (r = sect->head; r; r = r->next) {
 793         uint8_t *p, *q, blk[4];
 794         int32_t l;
 795
 796         saa_fread(sect->data, r->address, blk, (int32_t)r->bytes);
 797         p = q = blk;
 798         l = *p++;
 799         if (r->bytes > 1) {
 800             l += ((int32_t)*p++) << 8;
 801             if (r->bytes == 4) {
 802                 l += ((int32_t)*p++) << 16;
 803                 l += ((int32_t)*p++) << 24;
 804             }
 805         }
 806         if (r->symbol == -SECT_DATA)
 807             l += stext.len;
 808         else if (r->symbol == -SECT_BSS)
 809             l += stext.len + sdata.len;
 810         if (r->bytes == 4)
 811             WRITELONG(q, l);
 812         else if (r->bytes == 2)
 813             WRITESHORT(q, l);
 814         else
 815             *q++ = l & 0xFF;
 816         saa_fwrite(sect->data, r->address, blk, (int32_t)r->bytes);
 817     }
 818 }
 819
 820 static void aout_write(void)
 821 {
 822     /*
 823      * Emit the a.out header.
 824      */
 825     /* OMAGIC, M_386 or MID_I386, no flags */
 826     fwriteint32_t(bsd ? 0x07018600 | is_pic : 0x640107L, aoutfp);
 827     fwriteint32_t(stext.len, aoutfp);
 828     fwriteint32_t(sdata.len, aoutfp);
 829     fwriteint32_t(sbss.len, aoutfp);
 830     fwriteint32_t(nsyms * 12, aoutfp);     /* length of symbol table */
 831     fwriteint32_t(0L, aoutfp);     /* object files have no entry point */
 832     fwriteint32_t(stext.nrelocs * 8, aoutfp);      /* size of text relocs */
 833     fwriteint32_t(sdata.nrelocs * 8, aoutfp);      /* size of data relocs */
 834
 835     /*
 836      * Write out the code section and the data section.
 837      */
 838     saa_fpwrite(stext.data, aoutfp);
 839     saa_fpwrite(sdata.data, aoutfp);
 840
 841     /*
 842      * Write out the relocations.
 843      */
 844     aout_write_relocs(stext.head);
 845     aout_write_relocs(sdata.head);
 846
 847     /*
 848      * Write the symbol table.
 849      */
 850     aout_write_syms();
 851
 852     /*
 853      * And the string table.
 854      */
 855     fwriteint32_t(strslen + 4, aoutfp);    /* length includes length count */
 856     saa_fpwrite(strs, aoutfp);
 857 }
 858
 859 static void aout_write_relocs(struct Reloc *r)
 860 {
 861     while (r) {
 862         uint32_t word2;
 863
 864         fwriteint32_t(r->address, aoutfp);
 865
 866         if (r->symbol >= 0)
 867             word2 = r->symbol;
 868         else
 869             word2 = -r->symbol;
 870         word2 |= r->reltype << 24;
 871         word2 |= (r->bytes == 1 ? 0 :
 872                   r->bytes == 2 ? 0x2000000L : 0x4000000L);
 873         fwriteint32_t(word2, aoutfp);
 874
 875         r = r->next;
 876     }
 877 }
 878
 879 static void aout_write_syms(void)
 880 {
 881     uint32_t i;
 882
 883     saa_rewind(syms);
 884     for (i = 0; i < nsyms; i++) {
 885         struct Symbol *sym = saa_rstruct(syms);
 886         fwriteint32_t(sym->strpos, aoutfp);
 887         fwriteint32_t((int32_t)sym->type & ~SYM_WITH_SIZE, aoutfp);
 888         /*
 889          * Fix up the symbol value now we know the final section
 890          * sizes.
 891          */
 892         if ((sym->type & SECT_MASK) == SECT_DATA)
 893             sym->value += stext.len;
 894         if ((sym->type & SECT_MASK) == SECT_BSS)
 895             sym->value += stext.len + sdata.len;
 896         fwriteint32_t(sym->value, aoutfp);
 897         /*
 898          * Output a size record if necessary.
 899          */
 900         if (sym->type & SYM_WITH_SIZE) {
 901             fwriteint32_t(sym->strpos, aoutfp);
 902             fwriteint32_t(0x0DL, aoutfp);  /* special value: means size */
 903             fwriteint32_t(sym->size, aoutfp);
 904             i++;                /* use up another of `nsyms' */
 905         }
 906     }
 907 }
 908
 909 static void aout_sect_write(struct Section *sect,
 910                             const uint8_t *data, uint32_t len)
 911 {
 912     saa_wbytes(sect->data, data, len);
 913     sect->len += len;
 914 }
 915
 916 static int32_t aout_segbase(int32_t segment)
 917 {
 918     return segment;
 919 }
 920
 921 static int aout_directive(char *directive, char *value, int pass)
 922 {
 923     (void)directive;
 924     (void)value;
 925     (void)pass;
 926     return 0;
 927 }
 928
 929 static void aout_filename(char *inname, char *outname, efunc error)
 930 {
 931     standard_extension(inname, outname, ".o", error);
 932 }
 933
 934 extern macros_t aout_stdmac[];
 935
 936 static int aout_set_info(enum geninfo type, char **val)
 937 {
 938     (void)type;
 939     (void)val;
 940     return 0;
 941 }
 942 #endif                          /* OF_AOUT || OF_AOUTB */
 943
 944 #ifdef OF_AOUT
 945
 946 struct ofmt of_aout = {
 947     "Linux a.out object files",
 948     "aout",
 949     NULL,
 950     null_debug_arr,
 951     &null_debug_form,
 952     aout_stdmac,
 953     aout_init,
 954     aout_set_info,
 955     aout_out,
 956     aout_deflabel,
 957     aout_section_names,
 958     aout_segbase,
 959     aout_directive,
 960     aout_filename,
 961     aout_cleanup
 962 };
 963
 964 #endif
 965
 966 #ifdef OF_AOUTB
 967
 968 struct ofmt of_aoutb = {
 969     "NetBSD/FreeBSD a.out object files",
 970     "aoutb",
 971     NULL,
 972     null_debug_arr,
 973     &null_debug_form,
 974     aout_stdmac,
 975     aoutb_init,
 976     aout_set_info,
 977     aout_out,
 978     aout_deflabel,
 979     aout_section_names,
 980     aout_segbase,
 981     aout_directive,
 982     aout_filename,
 983     aout_cleanup
 984 };
 985
 986 #endif