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     saa_free(stext.data);
 239     while (stext.head) {
 240         r = stext.head;
 241         stext.head = stext.head->next;
 242         nasm_free(r);
 243     }
 244     saa_free(sdata.data);
 245     while (sdata.head) {
 246         r = sdata.head;
 247         sdata.head = sdata.head->next;
 248         nasm_free(r);
 249     }
 250     saa_free(syms);
 251     raa_free(bsym);
 252     saa_free(strs);
 253 }
 254
 255 static int32_t aout_section_names(char *name, int pass, int *bits)
 256 {
 257
 258     (void)pass;
 259
 260     /*
 261      * Default to 32 bits.
 262      */
 263     if (!name)
 264         *bits = 32;
 265
 266     if (!name)
 267         return stext.index;
 268
 269     if (!strcmp(name, ".text"))
 270         return stext.index;
 271     else if (!strcmp(name, ".data"))
 272         return sdata.index;
 273     else if (!strcmp(name, ".bss"))
 274         return sbss.index;
 275     else
 276         return NO_SEG;
 277 }
 278
 279 static void aout_deflabel(char *name, int32_t segment, int64_t offset,
 280                           int is_global, char *special)
 281 {
 282     int pos = strslen + 4;
 283     struct Symbol *sym;
 284     int special_used = false;
 285
 286     if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
 287         /*
 288          * This is a NASM special symbol. We never allow it into
 289          * the a.out symbol table, even if it's a valid one. If it
 290          * _isn't_ a valid one, we should barf immediately.
 291          */
 292         if (strcmp(name, "..gotpc") && strcmp(name, "..gotoff") &&
 293             strcmp(name, "..got") && strcmp(name, "..plt") &&
 294             strcmp(name, "..sym"))
 295             error(ERR_NONFATAL, "unrecognised special symbol `%s'", name);
 296         return;
 297     }
 298
 299     if (is_global == 3) {
 300         struct Symbol **s;
 301         /*
 302          * Fix up a forward-reference symbol size from the first
 303          * pass.
 304          */
 305         for (s = &fwds; *s; s = &(*s)->nextfwd)
 306             if (!strcmp((*s)->name, name)) {
 307                 struct tokenval tokval;
 308                 expr *e;
 309                 char *p = special;
 310
 311                 while (*p && !nasm_isspace(*p))
 312                     p++;
 313                 while (*p && nasm_isspace(*p))
 314                     p++;
 315                 stdscan_reset();
 316                 stdscan_bufptr = p;
 317                 tokval.t_type = TOKEN_INVALID;
 318                 e = evaluate(stdscan, NULL, &tokval, NULL, 1, error, NULL);
 319                 if (e) {
 320                     if (!is_simple(e))
 321                         error(ERR_NONFATAL, "cannot use relocatable"
 322                               " expression as symbol size");
 323                     else
 324                         (*s)->size = reloc_value(e);
 325                 }
 326
 327                 /*
 328                  * Remove it from the list of unresolved sizes.
 329                  */
 330                 nasm_free((*s)->name);
 331                 *s = (*s)->nextfwd;
 332                 return;
 333             }
 334         return;                 /* it wasn't an important one */
 335     }
 336
 337     saa_wbytes(strs, name, (int32_t)(1 + strlen(name)));
 338     strslen += 1 + strlen(name);
 339
 340     sym = saa_wstruct(syms);
 341
 342     sym->strpos = pos;
 343     sym->type = is_global ? SYM_GLOBAL : 0;
 344     sym->segment = segment;
 345     if (segment == NO_SEG)
 346         sym->type |= SECT_ABS;
 347     else if (segment == stext.index) {
 348         sym->type |= SECT_TEXT;
 349         if (is_global) {
 350             sym->next = stext.gsyms;
 351             stext.gsyms = sym;
 352         } else if (!stext.asym)
 353             stext.asym = sym;
 354     } else if (segment == sdata.index) {
 355         sym->type |= SECT_DATA;
 356         if (is_global) {
 357             sym->next = sdata.gsyms;
 358             sdata.gsyms = sym;
 359         } else if (!sdata.asym)
 360             sdata.asym = sym;
 361     } else if (segment == sbss.index) {
 362         sym->type |= SECT_BSS;
 363         if (is_global) {
 364             sym->next = sbss.gsyms;
 365             sbss.gsyms = sym;
 366         } else if (!sbss.asym)
 367             sbss.asym = sym;
 368     } else
 369         sym->type = SYM_GLOBAL;
 370     if (is_global == 2)
 371         sym->value = offset;
 372     else
 373         sym->value = (sym->type == SYM_GLOBAL ? 0 : offset);
 374
 375     if (is_global && sym->type != SYM_GLOBAL) {
 376         /*
 377          * Global symbol exported _from_ this module. We must check
 378          * the special text for type information.
 379          */
 380
 381         if (special) {
 382             int n = strcspn(special, " ");
 383
 384             if (!nasm_strnicmp(special, "function", n))
 385                 sym->type |= SYM_FUNCTION;
 386             else if (!nasm_strnicmp(special, "data", n) ||
 387                      !nasm_strnicmp(special, "object", n))
 388                 sym->type |= SYM_DATA;
 389             else
 390                 error(ERR_NONFATAL, "unrecognised symbol type `%.*s'",
 391                       n, special);
 392             if (special[n]) {
 393                 struct tokenval tokval;
 394                 expr *e;
 395                 int fwd = false;
 396                 char *saveme = stdscan_bufptr;  /* bugfix? fbk 8/10/00 */
 397
 398                 if (!bsd) {
 399                     error(ERR_NONFATAL, "Linux a.out does not support"
 400                           " symbol size information");
 401                 } else {
 402                     while (special[n] && nasm_isspace(special[n]))
 403                         n++;
 404                     /*
 405                      * We have a size expression; attempt to
 406                      * evaluate it.
 407                      */
 408                     sym->type |= SYM_WITH_SIZE;
 409                     stdscan_reset();
 410                     stdscan_bufptr = special + n;
 411                     tokval.t_type = TOKEN_INVALID;
 412                     e = evaluate(stdscan, NULL, &tokval, &fwd, 0, error,
 413                                  NULL);
 414                     if (fwd) {
 415                         sym->nextfwd = fwds;
 416                         fwds = sym;
 417                         sym->name = nasm_strdup(name);
 418                     } else if (e) {
 419                         if (!is_simple(e))
 420                             error(ERR_NONFATAL, "cannot use relocatable"
 421                                   " expression as symbol size");
 422                         else
 423                             sym->size = reloc_value(e);
 424                     }
 425                 }
 426                 stdscan_bufptr = saveme;        /* bugfix? fbk 8/10/00 */
 427             }
 428             special_used = true;
 429         }
 430     }
 431
 432     /*
 433      * define the references from external-symbol segment numbers
 434      * to these symbol records.
 435      */
 436     if (segment != NO_SEG && segment != stext.index &&
 437         segment != sdata.index && segment != sbss.index)
 438         bsym = raa_write(bsym, segment, nsyms);
 439     sym->symnum = nsyms;
 440
 441     nsyms++;
 442     if (sym->type & SYM_WITH_SIZE)
 443         nsyms++;                /* and another for the size */
 444
 445     if (special && !special_used)
 446         error(ERR_NONFATAL, "no special symbol features supported here");
 447 }
 448
 449 static void aout_add_reloc(struct Section *sect, int32_t segment,
 450                            int reltype, int bytes)
 451 {
 452     struct Reloc *r;
 453
 454     r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
 455     sect->tail = &r->next;
 456     r->next = NULL;
 457
 458     r->address = sect->len;
 459     r->symbol = (segment == NO_SEG ? -SECT_ABS :
 460                  segment == stext.index ? -SECT_TEXT :
 461                  segment == sdata.index ? -SECT_DATA :
 462                  segment == sbss.index ? -SECT_BSS :
 463                  raa_read(bsym, segment));
 464     r->reltype = reltype;
 465     if (r->symbol >= 0)
 466         r->reltype |= RELTYPE_SYMFLAG;
 467     r->bytes = bytes;
 468
 469     sect->nrelocs++;
 470 }
 471
 472 /*
 473  * This routine deals with ..got and ..sym relocations: the more
 474  * complicated kinds. In shared-library writing, some relocations
 475  * with respect to global symbols must refer to the precise symbol
 476  * rather than referring to an offset from the base of the section
 477  * _containing_ the symbol. Such relocations call to this routine,
 478  * which searches the symbol list for the symbol in question.
 479  *
 480  * RELTYPE_GOT references require the _exact_ symbol address to be
 481  * used; RELTYPE_ABSOLUTE references can be at an offset from the
 482  * symbol. The boolean argument `exact' tells us this.
 483  *
 484  * Return value is the adjusted value of `addr', having become an
 485  * offset from the symbol rather than the section. Should always be
 486  * zero when returning from an exact call.
 487  *
 488  * Limitation: if you define two symbols at the same place,
 489  * confusion will occur.
 490  *
 491  * Inefficiency: we search, currently, using a linked list which
 492  * isn't even necessarily sorted.
 493  */
 494 static int32_t aout_add_gsym_reloc(struct Section *sect,
 495                                 int32_t segment, int32_t offset,
 496                                 int type, int bytes, int exact)
 497 {
 498     struct Symbol *sym, *sm, *shead;
 499     struct Reloc *r;
 500
 501     /*
 502      * First look up the segment to find whether it's text, data,
 503      * bss or an external symbol.
 504      */
 505     shead = NULL;
 506     if (segment == stext.index)
 507         shead = stext.gsyms;
 508     else if (segment == sdata.index)
 509         shead = sdata.gsyms;
 510     else if (segment == sbss.index)
 511         shead = sbss.gsyms;
 512     if (!shead) {
 513         if (exact && offset != 0)
 514             error(ERR_NONFATAL, "unable to find a suitable global symbol"
 515                   " for this reference");
 516         else
 517             aout_add_reloc(sect, segment, type, bytes);
 518         return offset;
 519     }
 520
 521     if (exact) {
 522         /*
 523          * Find a symbol pointing _exactly_ at this one.
 524          */
 525         for (sym = shead; sym; sym = sym->next)
 526             if (sym->value == offset)
 527                 break;
 528     } else {
 529         /*
 530          * Find the nearest symbol below this one.
 531          */
 532         sym = NULL;
 533         for (sm = shead; sm; sm = sm->next)
 534             if (sm->value <= offset && (!sym || sm->value > sym->value))
 535                 sym = sm;
 536     }
 537     if (!sym && exact) {
 538         error(ERR_NONFATAL, "unable to find a suitable global symbol"
 539               " for this reference");
 540         return 0;
 541     }
 542
 543     r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
 544     sect->tail = &r->next;
 545     r->next = NULL;
 546
 547     r->address = sect->len;
 548     r->symbol = sym->symnum;
 549     r->reltype = type | RELTYPE_SYMFLAG;
 550     r->bytes = bytes;
 551
 552     sect->nrelocs++;
 553
 554     return offset - sym->value;
 555 }
 556
 557 /*
 558  * This routine deals with ..gotoff relocations. These _must_ refer
 559  * to a symbol, due to a perversity of *BSD's PIC implementation,
 560  * and it must be a non-global one as well; so we store `asym', the
 561  * first nonglobal symbol defined in each section, and always work
 562  * from that. Relocation type is always RELTYPE_GOTOFF.
 563  *
 564  * Return value is the adjusted value of `addr', having become an
 565  * offset from the `asym' symbol rather than the section.
 566  */
 567 static int32_t aout_add_gotoff_reloc(struct Section *sect, int32_t segment,
 568                                   int32_t offset, int bytes)
 569 {
 570     struct Reloc *r;
 571     struct Symbol *asym;
 572
 573     /*
 574      * First look up the segment to find whether it's text, data,
 575      * bss or an external symbol.
 576      */
 577     asym = NULL;
 578     if (segment == stext.index)
 579         asym = stext.asym;
 580     else if (segment == sdata.index)
 581         asym = sdata.asym;
 582     else if (segment == sbss.index)
 583         asym = sbss.asym;
 584     if (!asym)
 585         error(ERR_NONFATAL, "`..gotoff' relocations require a non-global"
 586               " symbol in the section");
 587
 588     r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
 589     sect->tail = &r->next;
 590     r->next = NULL;
 591
 592     r->address = sect->len;
 593     r->symbol = asym->symnum;
 594     r->reltype = RELTYPE_GOTOFF;
 595     r->bytes = bytes;
 596
 597     sect->nrelocs++;
 598
 599     return offset - asym->value;
 600 }
 601
 602 static void aout_out(int32_t segto, const void *data,
 603                      enum out_type type, uint64_t size,
 604                      int32_t segment, int32_t wrt)
 605 {
 606     struct Section *s;
 607     int32_t addr;
 608     uint8_t mydata[4], *p;
 609
 610     /*
 611      * handle absolute-assembly (structure definitions)
 612      */
 613     if (segto == NO_SEG) {
 614         if (type != OUT_RESERVE)
 615             error(ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]"
 616                   " space");
 617         return;
 618     }
 619
 620     if (segto == stext.index)
 621         s = &stext;
 622     else if (segto == sdata.index)
 623         s = &sdata;
 624     else if (segto == sbss.index)
 625         s = NULL;
 626     else {
 627         error(ERR_WARNING, "attempt to assemble code in"
 628               " segment %d: defaulting to `.text'", segto);
 629         s = &stext;
 630     }
 631
 632     if (!s && type != OUT_RESERVE) {
 633         error(ERR_WARNING, "attempt to initialize memory in the"
 634               " BSS section: ignored");
 635         sbss.len += realsize(type, size);
 636         return;
 637     }
 638
 639     if (type == OUT_RESERVE) {
 640         if (s) {
 641             error(ERR_WARNING, "uninitialized space declared in"
 642                   " %s section: zeroing",
 643                   (segto == stext.index ? "code" : "data"));
 644             aout_sect_write(s, NULL, size);
 645         } else
 646             sbss.len += size;
 647     } else if (type == OUT_RAWDATA) {
 648         if (segment != NO_SEG)
 649             error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 650         aout_sect_write(s, data, size);
 651     } else if (type == OUT_ADDRESS) {
 652         addr = *(int64_t *)data;
 653         if (segment != NO_SEG) {
 654             if (segment % 2) {
 655                 error(ERR_NONFATAL, "a.out format does not support"
 656                       " segment base references");
 657             } else {
 658                 if (wrt == NO_SEG) {
 659                     aout_add_reloc(s, segment, RELTYPE_ABSOLUTE,
 660                                    size);
 661                 } else if (!bsd) {
 662                     error(ERR_NONFATAL,
 663                           "Linux a.out format does not support"
 664                           " any use of WRT");
 665                     wrt = NO_SEG;       /* we can at least _try_ to continue */
 666                 } else if (wrt == aout_gotpc_sect + 1) {
 667                     is_pic = 0x40;
 668                     aout_add_reloc(s, segment, RELTYPE_GOTPC, size);
 669                 } else if (wrt == aout_gotoff_sect + 1) {
 670                     is_pic = 0x40;
 671                     addr = aout_add_gotoff_reloc(s, segment,
 672                                                  addr, size);
 673                 } else if (wrt == aout_got_sect + 1) {
 674                     is_pic = 0x40;
 675                     addr =
 676                         aout_add_gsym_reloc(s, segment, addr, RELTYPE_GOT,
 677                                             size, true);
 678                 } else if (wrt == aout_sym_sect + 1) {
 679                     addr = aout_add_gsym_reloc(s, segment, addr,
 680                                                RELTYPE_ABSOLUTE, size,
 681                                                false);
 682                 } else if (wrt == aout_plt_sect + 1) {
 683                     is_pic = 0x40;
 684                     error(ERR_NONFATAL,
 685                           "a.out format cannot produce non-PC-"
 686                           "relative PLT references");
 687                 } else {
 688                     error(ERR_NONFATAL,
 689                           "a.out format does not support this"
 690                           " use of WRT");
 691                     wrt = NO_SEG;       /* we can at least _try_ to continue */
 692                 }
 693             }
 694         }
 695         p = mydata;
 696         if (size == 2)
 697             WRITESHORT(p, addr);
 698         else
 699             WRITELONG(p, addr);
 700         aout_sect_write(s, mydata, size);
 701     } else if (type == OUT_REL2ADR) {
 702         if (segment == segto)
 703             error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 704         if (segment != NO_SEG && segment % 2) {
 705             error(ERR_NONFATAL, "a.out format does not support"
 706                   " segment base references");
 707         } else {
 708             if (wrt == NO_SEG) {
 709                 aout_add_reloc(s, segment, RELTYPE_RELATIVE, 2);
 710             } else if (!bsd) {
 711                 error(ERR_NONFATAL, "Linux a.out format does not support"
 712                       " any use of WRT");
 713                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 714             } else if (wrt == aout_plt_sect + 1) {
 715                 is_pic = 0x40;
 716                 aout_add_reloc(s, segment, RELTYPE_PLT, 2);
 717             } else if (wrt == aout_gotpc_sect + 1 ||
 718                        wrt == aout_gotoff_sect + 1 ||
 719                        wrt == aout_got_sect + 1) {
 720                 error(ERR_NONFATAL, "a.out format cannot produce PC-"
 721                       "relative GOT references");
 722             } else {
 723                 error(ERR_NONFATAL, "a.out format does not support this"
 724                       " use of WRT");
 725                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 726             }
 727         }
 728         p = mydata;
 729         WRITESHORT(p, *(int64_t *)data - (size + s->len));
 730         aout_sect_write(s, mydata, 2L);
 731     } else if (type == OUT_REL4ADR) {
 732         if (segment == segto)
 733             error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 734         if (segment != NO_SEG && segment % 2) {
 735             error(ERR_NONFATAL, "a.out format does not support"
 736                   " segment base references");
 737         } else {
 738             if (wrt == NO_SEG) {
 739                 aout_add_reloc(s, segment, RELTYPE_RELATIVE, 4);
 740             } else if (!bsd) {
 741                 error(ERR_NONFATAL, "Linux a.out format does not support"
 742                       " any use of WRT");
 743                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 744             } else if (wrt == aout_plt_sect + 1) {
 745                 is_pic = 0x40;
 746                 aout_add_reloc(s, segment, RELTYPE_PLT, 4);
 747             } else if (wrt == aout_gotpc_sect + 1 ||
 748                        wrt == aout_gotoff_sect + 1 ||
 749                        wrt == aout_got_sect + 1) {
 750                 error(ERR_NONFATAL, "a.out format cannot produce PC-"
 751                       "relative GOT references");
 752             } else {
 753                 error(ERR_NONFATAL, "a.out format does not support this"
 754                       " use of WRT");
 755                 wrt = NO_SEG;   /* we can at least _try_ to continue */
 756             }
 757         }
 758         p = mydata;
 759         WRITELONG(p, *(int64_t *)data - (size + s->len));
 760         aout_sect_write(s, mydata, 4L);
 761     }
 762 }
 763
 764 static void aout_pad_sections(void)
 765 {
 766     static uint8_t pad[] = { 0x90, 0x90, 0x90, 0x90 };
 767     /*
 768      * Pad each of the text and data sections with NOPs until their
 769      * length is a multiple of four. (NOP == 0x90.) Also increase
 770      * the length of the BSS section similarly.
 771      */
 772     aout_sect_write(&stext, pad, (-(int32_t)stext.len) & 3);
 773     aout_sect_write(&sdata, pad, (-(int32_t)sdata.len) & 3);
 774     sbss.len = (sbss.len + 3) & ~3;
 775 }
 776
 777 /*
 778  * a.out files have the curious property that all references to
 779  * things in the data or bss sections are done by addresses which
 780  * are actually relative to the start of the _text_ section, in the
 781  * _file_. (No relation to what happens after linking. No idea why
 782  * this should be so. It's very strange.) So we have to go through
 783  * the relocation table, _after_ the final size of each section is
 784  * known, and fix up the relocations pointed to.
 785  */
 786 static void aout_fixup_relocs(struct Section *sect)
 787 {
 788     struct Reloc *r;
 789
 790     saa_rewind(sect->data);
 791     for (r = sect->head; r; r = r->next) {
 792         uint8_t *p, *q, blk[4];
 793         int32_t l;
 794
 795         saa_fread(sect->data, r->address, blk, (int32_t)r->bytes);
 796         p = q = blk;
 797         l = *p++;
 798         if (r->bytes > 1) {
 799             l += ((int32_t)*p++) << 8;
 800             if (r->bytes == 4) {
 801                 l += ((int32_t)*p++) << 16;
 802                 l += ((int32_t)*p++) << 24;
 803             }
 804         }
 805         if (r->symbol == -SECT_DATA)
 806             l += stext.len;
 807         else if (r->symbol == -SECT_BSS)
 808             l += stext.len + sdata.len;
 809         if (r->bytes == 4)
 810             WRITELONG(q, l);
 811         else if (r->bytes == 2)
 812             WRITESHORT(q, l);
 813         else
 814             *q++ = l & 0xFF;
 815         saa_fwrite(sect->data, r->address, blk, (int32_t)r->bytes);
 816     }
 817 }
 818
 819 static void aout_write(void)
 820 {
 821     /*
 822      * Emit the a.out header.
 823      */
 824     /* OMAGIC, M_386 or MID_I386, no flags */
 825     fwriteint32_t(bsd ? 0x07018600 | is_pic : 0x640107L, aoutfp);
 826     fwriteint32_t(stext.len, aoutfp);
 827     fwriteint32_t(sdata.len, aoutfp);
 828     fwriteint32_t(sbss.len, aoutfp);
 829     fwriteint32_t(nsyms * 12, aoutfp);     /* length of symbol table */
 830     fwriteint32_t(0L, aoutfp);     /* object files have no entry point */
 831     fwriteint32_t(stext.nrelocs * 8, aoutfp);      /* size of text relocs */
 832     fwriteint32_t(sdata.nrelocs * 8, aoutfp);      /* size of data relocs */
 833
 834     /*
 835      * Write out the code section and the data section.
 836      */
 837     saa_fpwrite(stext.data, aoutfp);
 838     saa_fpwrite(sdata.data, aoutfp);
 839
 840     /*
 841      * Write out the relocations.
 842      */
 843     aout_write_relocs(stext.head);
 844     aout_write_relocs(sdata.head);
 845
 846     /*
 847      * Write the symbol table.
 848      */
 849     aout_write_syms();
 850
 851     /*
 852      * And the string table.
 853      */
 854     fwriteint32_t(strslen + 4, aoutfp);    /* length includes length count */
 855     saa_fpwrite(strs, aoutfp);
 856 }
 857
 858 static void aout_write_relocs(struct Reloc *r)
 859 {
 860     while (r) {
 861         uint32_t word2;
 862
 863         fwriteint32_t(r->address, aoutfp);
 864
 865         if (r->symbol >= 0)
 866             word2 = r->symbol;
 867         else
 868             word2 = -r->symbol;
 869         word2 |= r->reltype << 24;
 870         word2 |= (r->bytes == 1 ? 0 :
 871                   r->bytes == 2 ? 0x2000000L : 0x4000000L);
 872         fwriteint32_t(word2, aoutfp);
 873
 874         r = r->next;
 875     }
 876 }
 877
 878 static void aout_write_syms(void)
 879 {
 880     uint32_t i;
 881
 882     saa_rewind(syms);
 883     for (i = 0; i < nsyms; i++) {
 884         struct Symbol *sym = saa_rstruct(syms);
 885         fwriteint32_t(sym->strpos, aoutfp);
 886         fwriteint32_t((int32_t)sym->type & ~SYM_WITH_SIZE, aoutfp);
 887         /*
 888          * Fix up the symbol value now we know the final section
 889          * sizes.
 890          */
 891         if ((sym->type & SECT_MASK) == SECT_DATA)
 892             sym->value += stext.len;
 893         if ((sym->type & SECT_MASK) == SECT_BSS)
 894             sym->value += stext.len + sdata.len;
 895         fwriteint32_t(sym->value, aoutfp);
 896         /*
 897          * Output a size record if necessary.
 898          */
 899         if (sym->type & SYM_WITH_SIZE) {
 900             fwriteint32_t(sym->strpos, aoutfp);
 901             fwriteint32_t(0x0DL, aoutfp);  /* special value: means size */
 902             fwriteint32_t(sym->size, aoutfp);
 903             i++;                /* use up another of `nsyms' */
 904         }
 905     }
 906 }
 907
 908 static void aout_sect_write(struct Section *sect,
 909                             const uint8_t *data, uint32_t len)
 910 {
 911     saa_wbytes(sect->data, data, len);
 912     sect->len += len;
 913 }
 914
 915 static int32_t aout_segbase(int32_t segment)
 916 {
 917     return segment;
 918 }
 919
 920 static void aout_filename(char *inname, char *outname, efunc error)
 921 {
 922     standard_extension(inname, outname, ".o", error);
 923 }
 924
 925 extern macros_t aout_stdmac[];
 926
 927 #endif                          /* OF_AOUT || OF_AOUTB */
 928
 929 #ifdef OF_AOUT
 930
 931 struct ofmt of_aout = {
 932     "Linux a.out object files",
 933     "aout",
 934     0,
 935     null_debug_arr,
 936     &null_debug_form,
 937     aout_stdmac,
 938     aout_init,
 939     null_setinfo,
 940     aout_out,
 941     aout_deflabel,
 942     aout_section_names,
 943     aout_segbase,
 944     null_directive,
 945     aout_filename,
 946     aout_cleanup
 947 };
 948
 949 #endif
 950
 951 #ifdef OF_AOUTB
 952
 953 struct ofmt of_aoutb = {
 954     "NetBSD/FreeBSD a.out object files",
 955     "aoutb",
 956     0,
 957     null_debug_arr,
 958     &null_debug_form,
 959     aout_stdmac,
 960     aoutb_init,
 961     null_setinfo,
 962     aout_out,
 963     aout_deflabel,
 964     aout_section_names,
 965     aout_segbase,
 966     null_directive,
 967     aout_filename,
 968     aout_cleanup
 969 };
 970
 971 #endif