src/unexalpha.c

   1 /* Unexec for DEC alpha.  schoepf@sc.ZIB-Berlin.DE (Rainer Schoepf).
   2
   3    Copyright (C) 1994 Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs; see the file COPYING.  If not, write to
  19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 \f
  23 #include <config.h>
  24 #include <sys/types.h>
  25 #include <sys/file.h>
  26 #include <sys/stat.h>
  27 #include <sys/mman.h>
  28 #include <stdio.h>
  29 #include <varargs.h>
  30 #include <filehdr.h>
  31 #include <aouthdr.h>
  32 #include <scnhdr.h>
  33 #include <syms.h>
  34 #ifndef __linux__
  35 # include <reloc.h>
  36 # include <elf_abi.h>
  37 #endif
  38
  39 static void fatal_unexec ();
  40 static void mark_x ();
  41
  42 #define READ(_fd, _buffer, _size, _error_message, _error_arg) \
  43         errno = EEOF; \
  44         if (read (_fd, _buffer, _size) != _size) \
  45           fatal_unexec (_error_message, _error_arg);
  46
  47 #define WRITE(_fd, _buffer, _size, _error_message, _error_arg) \
  48         if (write (_fd, _buffer, _size) != _size) \
  49           fatal_unexec (_error_message, _error_arg);
  50
  51 #define SEEK(_fd, _position, _error_message, _error_arg) \
  52         errno = EEOF; \
  53         if (lseek (_fd, _position, L_SET) != _position) \
  54           fatal_unexec (_error_message, _error_arg);
  55
  56 extern int errno;
  57 extern char *strerror ();
  58
  59 void *sbrk ();
  60
  61 #define EEOF -1
  62
  63 static struct scnhdr *text_section;
  64 static struct scnhdr *rel_dyn_section;
  65 static struct scnhdr *dynstr_section;
  66 static struct scnhdr *dynsym_section;
  67 static struct scnhdr *init_section;
  68 static struct scnhdr *finit_section;
  69 static struct scnhdr *rdata_section;
  70 static struct scnhdr *rconst_section;
  71 static struct scnhdr *data_section;
  72 static struct scnhdr *pdata_section;
  73 static struct scnhdr *xdata_section;
  74 static struct scnhdr *got_section;
  75 static struct scnhdr *lit8_section;
  76 static struct scnhdr *lit4_section;
  77 static struct scnhdr *sdata_section;
  78 static struct scnhdr *sbss_section;
  79 static struct scnhdr *bss_section;
  80
  81 static struct scnhdr old_data_scnhdr;
  82
  83 static unsigned long Brk;
  84
  85 struct headers {
  86     struct filehdr fhdr;
  87     struct aouthdr aout;
  88     struct scnhdr section[_MIPS_NSCNS_MAX];
  89 };
  90
  91
  92
  93 /* Define name of label for entry point for the dumped executable.  */
  94
  95 #ifndef DEFAULT_ENTRY_ADDRESS
  96 #define DEFAULT_ENTRY_ADDRESS __start
  97 #endif
  98 \f
  99 unexec (new_name, a_name, data_start, bss_start, entry_address)
 100      char *new_name, *a_name;
 101      unsigned long data_start, bss_start, entry_address;
 102 {
 103   int new, old;
 104   char * oldptr;
 105   struct headers ohdr, nhdr;
 106   struct stat stat;
 107   long pagesize, brk;
 108   long newsyms, symrel;
 109   int nread;
 110   int i;
 111   long vaddr, scnptr;
 112 #define BUFSIZE 8192
 113   char buffer[BUFSIZE];
 114
 115   if ((old = open (a_name, O_RDONLY)) < 0)
 116     fatal_unexec ("opening %s", a_name);
 117
 118   new = creat (new_name, 0666);
 119   if (new < 0) fatal_unexec ("creating %s", new_name);
 120
 121   if ((fstat (old, &stat) == -1))
 122     fatal_unexec ("fstat %s", a_name);
 123
 124   oldptr = (char *)mmap (0, stat.st_size, PROT_READ, MAP_FILE|MAP_SHARED, old, 0);
 125
 126   if (oldptr == (char *)-1)
 127     fatal_unexec ("mmap %s", a_name);
 128
 129   close (old);
 130
 131   /* This is a copy of the a.out header of the original executable */
 132
 133   ohdr = (*(struct headers *)oldptr);
 134
 135   /* This is where we build the new header from the in-memory copy */
 136
 137   nhdr = *((struct headers *)TEXT_START);
 138
 139   /* First do some consistency checks */
 140
 141   if (nhdr.fhdr.f_magic != ALPHAMAGIC
 142       && nhdr.fhdr.f_magic != ALPHAUMAGIC)
 143     {
 144       fprintf (stderr, "unexec: input file magic number is %x, not %x or %x.\n",
 145                nhdr.fhdr.f_magic, ALPHAMAGIC, ALPHAUMAGIC);
 146       exit (1);
 147     }
 148
 149   if (nhdr.fhdr.f_opthdr != sizeof (nhdr.aout))
 150     {
 151       fprintf (stderr, "unexec: input a.out header is %d bytes, not %d.\n",
 152                nhdr.fhdr.f_opthdr, sizeof (nhdr.aout));
 153       exit (1);
 154     }
 155   if (nhdr.aout.magic != ZMAGIC)
 156     {
 157       fprintf (stderr, "unexec: input file a.out magic number is %o, not %o.\n",
 158                nhdr.aout.magic, ZMAGIC);
 159       exit (1);
 160     }
 161
 162
 163   /* Now check the existence of certain header section and grab
 164      their addresses. */
 165
 166 #define CHECK_SCNHDR(ptr, name, flags)                                  \
 167   ptr = NULL;                                                           \
 168   for (i = 0; i < nhdr.fhdr.f_nscns && !ptr; i++)                       \
 169     if (strncmp (nhdr.section[i].s_name, name, 8) == 0)                 \
 170       {                                                                 \
 171         if (nhdr.section[i].s_flags != flags)                           \
 172           fprintf (stderr, "unexec: %x flags (%x expected) in %s section.\n", \
 173                    nhdr.section[i].s_flags, flags, name);               \
 174         ptr = nhdr.section + i;                                         \
 175       }                                                                 \
 176
 177   CHECK_SCNHDR (text_section,  _TEXT,  STYP_TEXT);
 178   CHECK_SCNHDR (init_section,  _INIT,  STYP_INIT);
 179 #ifdef _REL_DYN
 180   CHECK_SCNHDR (rel_dyn_section, _REL_DYN,  STYP_REL_DYN);
 181 #endif /* _REL_DYN */
 182 #ifdef _DYNSYM
 183   CHECK_SCNHDR (dynsym_section, _DYNSYM,  STYP_DYNSYM);
 184 #endif /* _REL_DYN */
 185 #ifdef _DYNSTR
 186   CHECK_SCNHDR (dynstr_section, _DYNSTR,  STYP_DYNSTR);
 187 #endif /* _REL_DYN */
 188 #ifdef _FINI
 189   CHECK_SCNHDR (finit_section, _FINI,  STYP_FINI);
 190 #endif /* _FINI */
 191   CHECK_SCNHDR (rdata_section, _RDATA, STYP_RDATA);
 192 #ifdef _RCONST
 193   CHECK_SCNHDR (rconst_section, _RCONST, STYP_RCONST);
 194 #endif
 195 #ifdef _PDATA
 196   CHECK_SCNHDR (pdata_section, _PDATA, STYP_PDATA);
 197 #endif _PDATA
 198 #ifdef _GOT
 199   CHECK_SCNHDR (got_section,   _GOT,   STYP_GOT);
 200 #endif _GOT
 201   CHECK_SCNHDR (data_section,  _DATA,  STYP_DATA);
 202 #ifdef _XDATA
 203   CHECK_SCNHDR (xdata_section, _XDATA, STYP_XDATA);
 204 #endif /* _XDATA */
 205 #ifdef _LIT8
 206   CHECK_SCNHDR (lit8_section,  _LIT8,  STYP_LIT8);
 207   CHECK_SCNHDR (lit4_section,  _LIT4,  STYP_LIT4);
 208 #endif /* _LIT8 */
 209   CHECK_SCNHDR (sdata_section, _SDATA, STYP_SDATA);
 210   CHECK_SCNHDR (sbss_section,  _SBSS,  STYP_SBSS);
 211   CHECK_SCNHDR (bss_section,   _BSS,   STYP_BSS);
 212
 213
 214   pagesize = getpagesize ();
 215   brk = (((long) (sbrk (0))) + pagesize - 1) & (-pagesize);
 216
 217   /* Remember the current break */
 218
 219   Brk = brk;
 220
 221   bcopy (data_section, &old_data_scnhdr, sizeof (old_data_scnhdr));
 222
 223   nhdr.aout.dsize = brk - DATA_START;
 224   nhdr.aout.bsize = 0;
 225   if (entry_address == 0)
 226     {
 227       extern DEFAULT_ENTRY_ADDRESS ();
 228       nhdr.aout.entry = (unsigned long)DEFAULT_ENTRY_ADDRESS;
 229     }
 230   else
 231     nhdr.aout.entry = entry_address;
 232
 233   nhdr.aout.bss_start = nhdr.aout.data_start + nhdr.aout.dsize;
 234
 235   if (rdata_section != NULL)
 236     {
 237       rdata_section->s_size = data_start - DATA_START;
 238
 239       /* Adjust start and virtual addresses of rdata_section, too.  */
 240       rdata_section->s_vaddr = DATA_START;
 241       rdata_section->s_paddr = DATA_START;
 242       rdata_section->s_scnptr = text_section->s_scnptr + nhdr.aout.tsize;
 243     }
 244
 245   data_section->s_vaddr = data_start;
 246   data_section->s_paddr = data_start;
 247   data_section->s_size = brk - data_start;
 248
 249   if (rdata_section != NULL)
 250     {
 251       data_section->s_scnptr = rdata_section->s_scnptr + rdata_section->s_size;
 252     }
 253
 254   vaddr = data_section->s_vaddr + data_section->s_size;
 255   scnptr = data_section->s_scnptr + data_section->s_size;
 256   if (lit8_section != NULL)
 257     {
 258       lit8_section->s_vaddr = vaddr;
 259       lit8_section->s_paddr = vaddr;
 260       lit8_section->s_size = 0;
 261       lit8_section->s_scnptr = scnptr;
 262     }
 263   if (lit4_section != NULL)
 264     {
 265       lit4_section->s_vaddr = vaddr;
 266       lit4_section->s_paddr = vaddr;
 267       lit4_section->s_size = 0;
 268       lit4_section->s_scnptr = scnptr;
 269     }
 270   if (sdata_section != NULL)
 271     {
 272       sdata_section->s_vaddr = vaddr;
 273       sdata_section->s_paddr = vaddr;
 274       sdata_section->s_size = 0;
 275       sdata_section->s_scnptr = scnptr;
 276     }
 277 #ifdef _XDATA
 278   if (xdata_section != NULL)
 279     {
 280       xdata_section->s_vaddr = vaddr;
 281       xdata_section->s_paddr = vaddr;
 282       xdata_section->s_size = 0;
 283       xdata_section->s_scnptr = scnptr;
 284     }
 285 #endif
 286 #ifdef _GOT
 287   if (got_section != NULL)
 288     {
 289       bcopy (got_section, buffer, sizeof (struct scnhdr));
 290
 291       got_section->s_vaddr = vaddr;
 292       got_section->s_paddr = vaddr;
 293       got_section->s_size = 0;
 294       got_section->s_scnptr = scnptr;
 295     }
 296 #endif /*_GOT */
 297   if (sbss_section != NULL)
 298     {
 299       sbss_section->s_vaddr = vaddr;
 300       sbss_section->s_paddr = vaddr;
 301       sbss_section->s_size = 0;
 302       sbss_section->s_scnptr = scnptr;
 303     }
 304   if (bss_section != NULL)
 305     {
 306       bss_section->s_vaddr = vaddr;
 307       bss_section->s_paddr = vaddr;
 308       bss_section->s_size = 0;
 309       bss_section->s_scnptr = scnptr;
 310     }
 311
 312   WRITE (new, (char *)TEXT_START, nhdr.aout.tsize,
 313          "writing text section to %s", new_name);
 314   WRITE (new, (char *)DATA_START, nhdr.aout.dsize,
 315          "writing data section to %s", new_name);
 316
 317 #ifdef _GOT
 318 #define old_got_section ((struct scnhdr *)buffer)
 319
 320   if (got_section != NULL)
 321     {
 322       SEEK (new, old_got_section->s_scnptr,
 323             "seeking to start of got_section in %s", new_name);
 324       WRITE (new, oldptr + old_got_section->s_scnptr, old_got_section->s_size,
 325              "writing new got_section of %s", new_name);
 326       SEEK (new, nhdr.aout.tsize + nhdr.aout.dsize,
 327             "seeking to end of data section of %s", new_name);
 328     }
 329
 330 #undef old_got_section
 331 #endif
 332
 333   /*
 334    * Construct new symbol table header
 335    */
 336
 337   bcopy (oldptr + nhdr.fhdr.f_symptr, buffer, cbHDRR);
 338
 339 #define symhdr ((pHDRR)buffer)
 340   newsyms = nhdr.aout.tsize + nhdr.aout.dsize;
 341   symrel = newsyms - nhdr.fhdr.f_symptr;
 342   nhdr.fhdr.f_symptr = newsyms;
 343   symhdr->cbLineOffset += symrel;
 344   symhdr->cbDnOffset += symrel;
 345   symhdr->cbPdOffset += symrel;
 346   symhdr->cbSymOffset += symrel;
 347   symhdr->cbOptOffset += symrel;
 348   symhdr->cbAuxOffset += symrel;
 349   symhdr->cbSsOffset += symrel;
 350   symhdr->cbSsExtOffset += symrel;
 351   symhdr->cbFdOffset += symrel;
 352   symhdr->cbRfdOffset += symrel;
 353   symhdr->cbExtOffset += symrel;
 354
 355   WRITE (new, buffer, cbHDRR, "writing symbol table header of %s", new_name);
 356
 357   /*
 358    * Copy the symbol table and line numbers
 359    */
 360   WRITE (new, oldptr + ohdr.fhdr.f_symptr + cbHDRR,
 361          stat.st_size - ohdr.fhdr.f_symptr - cbHDRR,
 362          "writing symbol table of %s", new_name);
 363
 364 #ifndef __linux__
 365   update_dynamic_symbols (oldptr, new_name, new, nhdr.aout);
 366 #endif
 367
 368 #undef symhdr
 369
 370   SEEK (new, 0, "seeking to start of header in %s", new_name);
 371   WRITE (new, &nhdr, sizeof (nhdr),
 372          "writing header of %s", new_name);
 373
 374   close (old);
 375   close (new);
 376   mark_x (new_name);
 377 }
 378
 379
 380
 381
 382 #ifndef __linux__
 383
 384 update_dynamic_symbols (old, new_name, new, aout)
 385      char *old;                 /* Pointer to old executable */
 386      char *new_name;            /* Name of new executable */
 387      int new;                   /* File descriptor for new executable */
 388      struct aouthdr aout;       /* a.out info from the file header */
 389 {
 390   typedef struct dynrel_info {
 391     char * addr;
 392     unsigned type:8;
 393     unsigned index:24;
 394     unsigned info:8;
 395     unsigned pad:8;
 396   } dr_info;
 397
 398   int nsyms = rel_dyn_section->s_size / sizeof (struct dynrel_info);
 399   int i;
 400   dr_info * rd_base = (dr_info *) (old + rel_dyn_section->s_scnptr);
 401   Elf32_Sym * ds_base = (Elf32_Sym *) (old + dynsym_section->s_scnptr);
 402
 403   for (i = 0; i < nsyms; i++) {
 404     register Elf32_Sym x;
 405
 406     if (rd_base[i].index == 0)
 407       continue;
 408
 409     x = ds_base[rd_base[i].index];
 410
 411 #if 0
 412       fprintf (stderr, "Object inspected: %s, addr = %lx, shndx = %x",
 413                old + dynstr_section->s_scnptr + x.st_name, rd_base[i].addr, x.st_shndx);
 414 #endif
 415
 416
 417     if ((ELF32_ST_BIND (x.st_info) == STB_GLOBAL)
 418         && (x.st_shndx == 0)
 419         /* && (x.st_value == NULL) */
 420         ) {
 421       /* OK, this is probably a reference to an object in a shared
 422          library, so copy the old value. This is done in several steps:
 423          1. reladdr is the address of the location in question relative to
 424             the start of the data section,
 425          2. oldref is the addr is the mapped in temacs executable,
 426          3. newref is the address of the location in question in the
 427             undumped executable,
 428          4. len is the size of the object reference in bytes --
 429             currently only 4 (long) and 8 (quad) are supported.
 430             */
 431       register unsigned long reladdr = rd_base[i].addr - old_data_scnhdr.s_vaddr;
 432       char * oldref = old + old_data_scnhdr.s_scnptr + reladdr;
 433       unsigned long newref = aout.tsize + reladdr;
 434       int len;
 435
 436 #if 0
 437       fprintf (stderr, "...relocated\n");
 438 #endif
 439
 440       if (rd_base[i].type == R_REFLONG)
 441         len = 4;
 442       else if (rd_base[i].type == R_REFQUAD)
 443         len = 8;
 444       else
 445         fatal_unexec ("unrecognized relocation type in .dyn.rel section (symbol #%d)", i);
 446
 447       SEEK (new, newref, "seeking to dynamic symbol in %s", new_name);
 448       WRITE (new, oldref, len, "writing old dynrel info in %s", new_name);
 449     }
 450
 451 #if 0
 452     else
 453       fprintf (stderr, "...not relocated\n");
 454 #endif
 455
 456   }
 457
 458 }
 459
 460 #endif /* !__linux__ */
 461
 462 \f
 463 /*
 464  * mark_x
 465  *
 466  * After successfully building the new a.out, mark it executable
 467  */
 468
 469 static void
 470 mark_x (name)
 471      char *name;
 472 {
 473   struct stat sbuf;
 474   int um = umask (777);
 475   umask (um);
 476   if (stat (name, &sbuf) < 0)
 477     fatal_unexec ("getting protection on %s", name);
 478   sbuf.st_mode |= 0111 & ~um;
 479   if (chmod (name, sbuf.st_mode) < 0)
 480     fatal_unexec ("setting protection on %s", name);
 481 }
 482
 483 static void
 484 fatal_unexec (s, arg)
 485      char *s;
 486      char *arg;
 487 {
 488   if (errno == EEOF)
 489     fputs ("unexec: unexpected end of file, ", stderr);
 490   else
 491     fprintf (stderr, "unexec: %s, ", strerror (errno));
 492   fprintf (stderr, s, arg);
 493   fputs (".\n", stderr);
 494   exit (1);
 495 }