output/outrdf.c

   1 /* outrdf.c     output routines for the Netwide Assembler to produce
   2  *              RDOFF format object files (which are intended mainly
   3  *              for use in proprietary projects, as the code to load and
   4  *              execute them is very simple). They will also be used
   5  *              for device drivers and possibly some executable files
   6  *              in the MOSCOW operating system. See Rdoff.txt for
   7  *              details.
   8  *
   9  * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
  10  * Julian Hall. All rights reserved. The software is
  11  * redistributable under the licence given in the file "Licence"
  12  * distributed in the NASM archive.
  13  */
  14
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <ctype.h>
  19 #include <assert.h>
  20
  21 #include "nasm.h"
  22 #include "nasmlib.h"
  23 #include "outform.h"
  24
  25 /* VERBOSE_WARNINGS: define this to add some extra warnings... */
  26 #define VERBOSE_WARNINGS
  27
  28 #ifdef OF_RDF
  29
  30 typedef short int16;            /* not sure if this will be required to be altered
  31                                    at all... best to typedef it just in case */
  32
  33 static const char *RDOFFId = "RDOFF1";  /* written to start of RDOFF files */
  34
  35 /* the records that can be found in the RDOFF header */
  36
  37 /* Note that whenever a segment is referred to in the RDOFF file, its number
  38  * is always half of the segment number that NASM uses to refer to it; this
  39  * is because NASM only allocates even numbered segments, so as to not
  40  * waste any of the 16 bits of segment number written to the file - this
  41  * allows up to 65533 external labels to be defined; otherwise it would be
  42  * 32764. */
  43
  44 struct RelocRec {
  45     char type;                  /* must be 1 */
  46     char segment;               /* only 0 for code, or 1 for data supported,
  47                                  * but add 64 for relative refs (ie do not require
  48                                  * reloc @ loadtime, only linkage) */
  49     long offset;                /* from start of segment in which reference is loc'd */
  50     char length;                /* 1 2 or 4 bytes */
  51     int16 refseg;               /* segment to which reference refers to */
  52 };
  53
  54 struct ImportRec {
  55     char type;                  /* must be 2 */
  56     int16 segment;              /* segment number allocated to the label for reloc
  57                                  * records - label is assumed to be at offset zero
  58                                  * in this segment, so linker must fix up with offset
  59                                  * of segment and of offset within segment */
  60     char label[33];             /* zero terminated... should be written to file until
  61                                  * the zero, but not after it - max len = 32 chars */
  62 };
  63
  64 struct ExportRec {
  65     char type;                  /* must be 3 */
  66     char segment;               /* segment referred to (0/1) */
  67     long offset;                /* offset within segment */
  68     char label[33];             /* zero terminated as above. max len = 32 chars */
  69 };
  70
  71 struct DLLRec {
  72     char type;                  /* must be 4 */
  73     char libname[128];          /* name of library to link with at load time */
  74 };
  75
  76 struct BSSRec {
  77     char type;                  /* must be 5 */
  78     long amount;                /* number of bytes BSS to reserve */
  79 };
  80
  81 /* code for managing buffers needed to seperate code and data into individual
  82  * sections until they are ready to be written to the file.
  83  * We'd better hope that it all fits in memory else we're buggered... */
  84
  85 #define BUF_BLOCK_LEN 4088      /* selected to match page size (4096)
  86                                  * on 80x86 machines for efficiency */
  87
  88 typedef struct memorybuffer {
  89     int length;
  90     char buffer[BUF_BLOCK_LEN];
  91     struct memorybuffer *next;
  92 } memorybuffer;
  93
  94 static memorybuffer *newmembuf(void)
  95 {
  96     memorybuffer *t;
  97
  98     t = nasm_malloc(sizeof(memorybuffer));
  99
 100     t->length = 0;
 101     t->next = NULL;
 102     return t;
 103 }
 104
 105 static void membufwrite(memorybuffer * b, void *data, int bytes)
 106 {
 107     int16 w;
 108     long l;
 109
 110     if (b->next) {              /* memory buffer full - use next buffer */
 111         membufwrite(b->next, data, bytes);
 112         return;
 113     }
 114     if ((bytes < 0 && b->length - bytes > BUF_BLOCK_LEN)
 115         || (bytes > 0 && b->length + bytes > BUF_BLOCK_LEN)) {
 116
 117         /* buffer full and no next allocated... allocate and initialise next
 118          * buffer */
 119
 120         b->next = newmembuf();
 121         membufwrite(b->next, data, bytes);
 122         return;
 123     }
 124
 125     switch (bytes) {
 126     case -4:                   /* convert to little-endian */
 127         l = *(long *)data;
 128         b->buffer[b->length++] = l & 0xFF;
 129         l >>= 8;
 130         b->buffer[b->length++] = l & 0xFF;
 131         l >>= 8;
 132         b->buffer[b->length++] = l & 0xFF;
 133         l >>= 8;
 134         b->buffer[b->length++] = l & 0xFF;
 135         break;
 136
 137     case -2:
 138         w = *(int16 *) data;
 139         b->buffer[b->length++] = w & 0xFF;
 140         w >>= 8;
 141         b->buffer[b->length++] = w & 0xFF;
 142         break;
 143
 144     default:
 145         while (bytes--) {
 146             b->buffer[b->length++] = *(*(unsigned char **)&data);
 147
 148             (*(unsigned char **)&data)++;
 149         }
 150         break;
 151     }
 152 }
 153
 154 static void membufdump(memorybuffer * b, FILE * fp)
 155 {
 156     if (!b)
 157         return;
 158
 159     fwrite(b->buffer, 1, b->length, fp);
 160
 161     membufdump(b->next, fp);
 162 }
 163
 164 static int membuflength(memorybuffer * b)
 165 {
 166     if (!b)
 167         return 0;
 168     return b->length + membuflength(b->next);
 169 }
 170
 171 static void freemembuf(memorybuffer * b)
 172 {
 173     if (!b)
 174         return;
 175     freemembuf(b->next);
 176     nasm_free(b);
 177 }
 178
 179 /***********************************************************************
 180  * Actual code to deal with RDOFF ouput format begins here...
 181  */
 182
 183 /* global variables set during the initialisation phase */
 184
 185 static memorybuffer *seg[2];    /* seg 0 = code, seg 1 = data */
 186 static memorybuffer *header;    /* relocation/import/export records */
 187
 188 static FILE *ofile;
 189
 190 static efunc error;
 191
 192 static int segtext, segdata, segbss;
 193 static long bsslength;
 194
 195 static void rdf_init(FILE * fp, efunc errfunc, ldfunc ldef, evalfunc eval)
 196 {
 197     ofile = fp;
 198     error = errfunc;
 199     seg[0] = newmembuf();
 200     seg[1] = newmembuf();
 201     header = newmembuf();
 202     segtext = seg_alloc();
 203     segdata = seg_alloc();
 204     segbss = seg_alloc();
 205     if (segtext != 0 || segdata != 2 || segbss != 4)
 206         error(ERR_PANIC,
 207               "rdf segment numbers not allocated as expected (%d,%d,%d)",
 208               segtext, segdata, segbss);
 209     bsslength = 0;
 210 }
 211
 212 static long rdf_section_names(char *name, int pass, int *bits)
 213 {
 214     /*
 215      * Default is 32 bits.
 216      */
 217     if (!name)
 218         *bits = 32;
 219
 220     if (!name)
 221         return 0;
 222     if (!strcmp(name, ".text"))
 223         return 0;
 224     else if (!strcmp(name, ".data"))
 225         return 2;
 226     else if (!strcmp(name, ".bss"))
 227         return 4;
 228     else
 229         return NO_SEG;
 230 }
 231
 232 static void write_reloc_rec(struct RelocRec *r)
 233 {
 234     if (r->refseg != NO_SEG && (r->refseg & 1))
 235         error(ERR_NONFATAL, "RDF format does not support segment base"
 236               " references");
 237
 238     r->refseg >>= 1;            /* adjust segment nos to RDF rather than NASM */
 239
 240     membufwrite(header, &r->type, 1);
 241     membufwrite(header, &r->segment, 1);
 242     membufwrite(header, &r->offset, -4);
 243     membufwrite(header, &r->length, 1);
 244     membufwrite(header, &r->refseg, -2);        /* 9 bytes written */
 245 }
 246
 247 static void write_export_rec(struct ExportRec *r)
 248 {
 249     r->segment >>= 1;
 250
 251     membufwrite(header, &r->type, 1);
 252     membufwrite(header, &r->segment, 1);
 253     membufwrite(header, &r->offset, -4);
 254     membufwrite(header, r->label, strlen(r->label) + 1);
 255 }
 256
 257 static void write_import_rec(struct ImportRec *r)
 258 {
 259     r->segment >>= 1;
 260
 261     membufwrite(header, &r->type, 1);
 262     membufwrite(header, &r->segment, -2);
 263     membufwrite(header, r->label, strlen(r->label) + 1);
 264 }
 265
 266 static void write_bss_rec(struct BSSRec *r)
 267 {
 268     membufwrite(header, &r->type, 1);
 269     membufwrite(header, &r->amount, -4);
 270 }
 271
 272 static void write_dll_rec(struct DLLRec *r)
 273 {
 274     membufwrite(header, &r->type, 1);
 275     membufwrite(header, r->libname, strlen(r->libname) + 1);
 276 }
 277
 278 static void rdf_deflabel(char *name, long segment, long offset,
 279                          int is_global, char *special)
 280 {
 281     struct ExportRec r;
 282     struct ImportRec ri;
 283 #ifdef VERBOSE_WARNINGS
 284     static int warned_common = 0;
 285 #endif
 286
 287     if (special)
 288         error(ERR_NONFATAL, "RDOFF format does not support any"
 289               " special symbol types");
 290
 291     if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
 292         error(ERR_NONFATAL, "unrecognised special symbol `%s'", name);
 293         return;
 294     }
 295
 296     if (is_global == 2) {
 297 #ifdef VERBOSE_WARNINGS
 298         if (!warned_common) {
 299             error(ERR_WARNING,
 300                   "common declarations not supported: using extern");
 301             warned_common = 1;
 302         }
 303 #endif
 304         is_global = 1;
 305     }
 306
 307     if (segment > 4) {          /* EXTERN declaration */
 308         ri.type = 2;
 309         ri.segment = segment;
 310         strncpy(ri.label, name, 32);
 311         ri.label[32] = 0;
 312         write_import_rec(&ri);
 313     } else if (is_global) {
 314         r.type = 3;
 315         r.segment = segment;
 316         r.offset = offset;
 317         strncpy(r.label, name, 32);
 318         r.label[32] = 0;
 319         write_export_rec(&r);
 320     }
 321 }
 322
 323 static void rdf_out(long segto, void *data, unsigned long type,
 324                     long segment, long wrt)
 325 {
 326     long bytes = type & OUT_SIZMASK;
 327     struct RelocRec rr;
 328     unsigned char databuf[4], *pd;
 329
 330     if (segto == NO_SEG) {
 331         if ((type & OUT_TYPMASK) != OUT_RESERVE)
 332             error(ERR_NONFATAL,
 333                   "attempt to assemble code in ABSOLUTE space");
 334         return;
 335     }
 336
 337     segto >>= 1;                /* convert NASM segment no to RDF number */
 338
 339     if (segto != 0 && segto != 1 && segto != 2) {
 340         error(ERR_NONFATAL,
 341               "specified segment not supported by rdf output format");
 342         return;
 343     }
 344
 345     if (wrt != NO_SEG) {
 346         wrt = NO_SEG;           /* continue to do _something_ */
 347         error(ERR_NONFATAL, "WRT not supported by rdf output format");
 348     }
 349
 350     type &= OUT_TYPMASK;
 351
 352     if (segto == 2 && type != OUT_RESERVE) {
 353         error(ERR_NONFATAL, "BSS segments may not be initialised");
 354
 355         /* just reserve the space for now... */
 356
 357         if (type == OUT_REL2ADR)
 358             bytes = 2;
 359         else
 360             bytes = 4;
 361         type = OUT_RESERVE;
 362     }
 363
 364     if (type == OUT_RESERVE) {
 365         if (segto == 2)         /* BSS segment space reserverd */
 366             bsslength += bytes;
 367         else
 368             while (bytes--)
 369                 membufwrite(seg[segto], databuf, 1);
 370     } else if (type == OUT_RAWDATA) {
 371         if (segment != NO_SEG)
 372             error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG");
 373         membufwrite(seg[segto], data, bytes);
 374     } else if (type == OUT_ADDRESS) {
 375
 376         /* if segment == NO_SEG then we are writing an address of an
 377            object within the same segment - do not produce reloc rec. */
 378
 379         if (segment != NO_SEG) {
 380
 381             /* it's an address, so we must write a relocation record */
 382
 383             rr.type = 1;        /* type signature */
 384             rr.segment = segto; /* segment we're currently in */
 385             rr.offset = membuflength(seg[segto]);       /* current offset */
 386             rr.length = bytes;  /* length of reference */
 387             rr.refseg = segment;        /* segment referred to */
 388             write_reloc_rec(&rr);
 389         }
 390
 391         pd = databuf;           /* convert address to little-endian */
 392         if (bytes == 2)
 393             WRITESHORT(pd, *(long *)data);
 394         else
 395             WRITELONG(pd, *(long *)data);
 396
 397         membufwrite(seg[segto], databuf, bytes);
 398
 399     } else if (type == OUT_REL2ADR) {
 400         if (segment == segto)
 401             error(ERR_PANIC, "intra-segment OUT_REL2ADR");
 402         if (segment != NO_SEG && segment % 2) {
 403             error(ERR_NONFATAL,
 404                   "rdf format does not support segment base refs");
 405         }
 406
 407         rr.type = 1;            /* type signature */
 408         rr.segment = segto + 64;        /* segment we're currently in + rel flag */
 409         rr.offset = membuflength(seg[segto]);   /* current offset */
 410         rr.length = 2;          /* length of reference */
 411         rr.refseg = segment;    /* segment referred to */
 412         write_reloc_rec(&rr);
 413
 414         /* work out what to put in the code: offset of the end of this operand,
 415          * subtracted from any data specified, so that loader can just add
 416          * address of imported symbol onto it to get address relative to end of
 417          * instruction: import_address + data(offset) - end_of_instrn */
 418
 419         rr.offset = *(long *)data - (rr.offset + bytes);
 420
 421         membufwrite(seg[segto], &rr.offset, -2);
 422     } else if (type == OUT_REL4ADR) {
 423         if (segment == segto)
 424             error(ERR_PANIC, "intra-segment OUT_REL4ADR");
 425         if (segment != NO_SEG && segment % 2) {
 426             error(ERR_NONFATAL,
 427                   "rdf format does not support segment base refs");
 428         }
 429
 430         rr.type = 1;            /* type signature */
 431         rr.segment = segto + 64;        /* segment we're currently in + rel tag */
 432         rr.offset = membuflength(seg[segto]);   /* current offset */
 433         rr.length = 4;          /* length of reference */
 434         rr.refseg = segment;    /* segment referred to */
 435         write_reloc_rec(&rr);
 436
 437         rr.offset = *(long *)data - (rr.offset + bytes);
 438         membufwrite(seg[segto], &rr.offset, -4);
 439     }
 440 }
 441
 442 static void rdf_cleanup(int debuginfo)
 443 {
 444     long l;
 445     unsigned char b[4], *d;
 446     struct BSSRec bs;
 447
 448     (void)debuginfo;
 449
 450     /* should write imported & exported symbol declarations to header here */
 451
 452     /* generate the output file... */
 453     fwrite(RDOFFId, 6, 1, ofile);       /* file type magic number */
 454
 455     if (bsslength != 0) {       /* reserve BSS */
 456         bs.type = 5;
 457         bs.amount = bsslength;
 458         write_bss_rec(&bs);
 459     }
 460
 461     l = membuflength(header);
 462     d = b;
 463     WRITELONG(d, l);
 464
 465     fwrite(b, 4, 1, ofile);     /* write length of header */
 466     membufdump(header, ofile);  /* dump header */
 467
 468     l = membuflength(seg[0]);
 469     d = b;                      /* code segment */
 470     WRITELONG(d, l);
 471
 472     fwrite(b, 4, 1, ofile);
 473     membufdump(seg[0], ofile);
 474
 475     l = membuflength(seg[1]);
 476     d = b;                      /* data segment */
 477     WRITELONG(d, l);
 478
 479     fwrite(b, 4, 1, ofile);
 480     membufdump(seg[1], ofile);
 481
 482     freemembuf(header);
 483     freemembuf(seg[0]);
 484     freemembuf(seg[1]);
 485     fclose(ofile);
 486 }
 487
 488 static long rdf_segbase(long segment)
 489 {
 490     return segment;
 491 }
 492
 493 static int rdf_directive(char *directive, char *value, int pass)
 494 {
 495     struct DLLRec r;
 496
 497     if (!strcmp(directive, "library")) {
 498         if (pass == 1) {
 499             r.type = 4;
 500             strcpy(r.libname, value);
 501             write_dll_rec(&r);
 502         }
 503         return 1;
 504     }
 505
 506     return 0;
 507 }
 508
 509 static void rdf_filename(char *inname, char *outname, efunc error)
 510 {
 511     standard_extension(inname, outname, ".rdf", error);
 512 }
 513
 514 static char *rdf_stdmac[] = {
 515     "%define __SECT__ [section .text]",
 516     "%imacro library 1+.nolist",
 517     "[library %1]",
 518     "%endmacro",
 519     "%macro __NASM_CDecl__ 1",
 520     "%endmacro",
 521     NULL
 522 };
 523
 524 static int rdf_set_info(enum geninfo type, char **val)
 525 {
 526     return 0;
 527 }
 528
 529 struct ofmt of_rdf = {
 530     "Relocatable Dynamic Object File Format v1.1",
 531 #ifdef OF_RDF2
 532     "oldrdf",
 533 #else
 534     "rdf",
 535 #endif
 536     NULL,
 537     null_debug_arr,
 538     &null_debug_form,
 539     rdf_stdmac,
 540     rdf_init,
 541     rdf_set_info,
 542     rdf_out,
 543     rdf_deflabel,
 544     rdf_section_names,
 545     rdf_segbase,
 546     rdf_directive,
 547     rdf_filename,
 548     rdf_cleanup
 549 };
 550
 551 #endif                          /* OF_RDF */