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
  35 static void fatal_unexec ();
  36 static void mark_x ();
  37
  38 #define READ(_fd, _buffer, _size, _error_message, _error_arg) \
  39         errno = EEOF; \
  40         if (read (_fd, _buffer, _size) != _size) \
  41           fatal_unexec (_error_message, _error_arg);
  42
  43 #define WRITE(_fd, _buffer, _size, _error_message, _error_arg) \
  44         if (write (_fd, _buffer, _size) != _size) \
  45           fatal_unexec (_error_message, _error_arg);
  46
  47 #define SEEK(_fd, _position, _error_message, _error_arg) \
  48         errno = EEOF; \
  49         if (lseek (_fd, _position, L_SET) != _position) \
  50           fatal_unexec (_error_message, _error_arg);
  51
  52 extern int errno;
  53 extern char *strerror ();
  54
  55 void *sbrk();
  56
  57 #define EEOF -1
  58
  59 static struct scnhdr *text_section;
  60 static struct scnhdr *init_section;
  61 static struct scnhdr *finit_section;
  62 static struct scnhdr *rdata_section;
  63 static struct scnhdr *rconst_section;
  64 static struct scnhdr *data_section;
  65 static struct scnhdr *pdata_section;
  66 static struct scnhdr *xdata_section;
  67 static struct scnhdr *got_section;
  68 static struct scnhdr *lit8_section;
  69 static struct scnhdr *lit4_section;
  70 static struct scnhdr *sdata_section;
  71 static struct scnhdr *sbss_section;
  72 static struct scnhdr *bss_section;
  73
  74 static unsigned long Brk;
  75
  76 struct headers {
  77     struct filehdr fhdr;
  78     struct aouthdr aout;
  79     struct scnhdr section[_MIPS_NSCNS_MAX];
  80 };
  81
  82
  83
  84 /* Define name of label for entry point for the dumped executable.  */
  85
  86 #ifndef DEFAULT_ENTRY_ADDRESS
  87 #define DEFAULT_ENTRY_ADDRESS __start
  88 #endif
  89 \f
  90 unexec (new_name, a_name, data_start, bss_start, entry_address)
  91      char *new_name, *a_name;
  92      unsigned long data_start, bss_start, entry_address;
  93 {
  94   int new, old;
  95   char * oldptr;
  96   struct headers ohdr, nhdr;
  97   struct stat stat;
  98   long pagesize, brk;
  99   long newsyms, symrel;
 100   int nread;
 101   int i;
 102   long vaddr, scnptr;
 103 #define BUFSIZE 8192
 104   char buffer[BUFSIZE];
 105
 106   if ((old = open (a_name, O_RDONLY)) < 0)
 107     fatal_unexec ("opening %s", a_name);
 108
 109   new = creat (new_name, 0666);
 110   if (new < 0) fatal_unexec ("creating %s", new_name);
 111
 112   if ((fstat (old, &stat) == -1))
 113     fatal_unexec ("fstat %s", a_name);
 114
 115   oldptr = (char *)mmap (0, stat.st_size, PROT_READ, MAP_FILE|MAP_SHARED, old, 0);
 116
 117   if (oldptr == (char *)-1)
 118     fatal_unexec ("mmap %s", a_name);
 119
 120   close (old);
 121
 122   /* This is a copy of the a.out header of the original executable */
 123
 124   ohdr = (*(struct headers *)oldptr);
 125
 126   /* This is where we build the new header from the in-memory copy */
 127
 128   nhdr = *((struct headers *)TEXT_START);
 129
 130   /* First do some consistency checks */
 131
 132   if (nhdr.fhdr.f_magic != ALPHAMAGIC
 133       && nhdr.fhdr.f_magic != ALPHAUMAGIC)
 134     {
 135       fprintf (stderr, "unexec: input file magic number is %x, not %x or %x.\n",
 136                nhdr.fhdr.f_magic, ALPHAMAGIC, ALPHAUMAGIC);
 137       exit (1);
 138     }
 139
 140   if (nhdr.fhdr.f_opthdr != sizeof (nhdr.aout))
 141     {
 142       fprintf (stderr, "unexec: input a.out header is %d bytes, not %d.\n",
 143                nhdr.fhdr.f_opthdr, sizeof (nhdr.aout));
 144       exit (1);
 145     }
 146   if (nhdr.aout.magic != ZMAGIC)
 147     {
 148       fprintf (stderr, "unexec: input file a.out magic number is %o, not %o.\n",
 149                nhdr.aout.magic, ZMAGIC);
 150       exit (1);
 151     }
 152
 153
 154   /* Now check the existence of certain header section and grab
 155      their addresses. */
 156
 157 #define CHECK_SCNHDR(ptr, name, flags)                                  \
 158   ptr = NULL;                                                           \
 159   for (i = 0; i < nhdr.fhdr.f_nscns && !ptr; i++)                       \
 160     if (strcmp (nhdr.section[i].s_name, name) == 0)                     \
 161       {                                                                 \
 162         if (nhdr.section[i].s_flags != flags)                           \
 163           fprintf (stderr, "unexec: %x flags (%x expected) in %s section.\n", \
 164                    nhdr.section[i].s_flags, flags, name);               \
 165         ptr = nhdr.section + i;                                         \
 166       }                                                                 \
 167
 168   CHECK_SCNHDR (text_section,  _TEXT,  STYP_TEXT);
 169   CHECK_SCNHDR (init_section,  _INIT,  STYP_INIT);
 170 #ifdef _FINI
 171   CHECK_SCNHDR (finit_section, _FINI,  STYP_FINI);
 172 #endif /* _FINI */
 173   CHECK_SCNHDR (rdata_section, _RDATA, STYP_RDATA);
 174 #ifdef _RCONST
 175   CHECK_SCNHDR (rconst_section, _RCONST, STYP_RCONST);
 176 #endif
 177 #ifdef _PDATA
 178   CHECK_SCNHDR (pdata_section, _PDATA, STYP_PDATA);
 179 #endif _PDATA
 180 #ifdef _GOT
 181   CHECK_SCNHDR (got_section,   _GOT,   STYP_GOT);
 182 #endif _GOT
 183   CHECK_SCNHDR (data_section,  _DATA,  STYP_DATA);
 184 #ifdef _XDATA
 185   CHECK_SCNHDR (xdata_section, _XDATA, STYP_XDATA);
 186 #endif /* _XDATA */
 187 #ifdef _LIT8
 188   CHECK_SCNHDR (lit8_section,  _LIT8,  STYP_LIT8);
 189   CHECK_SCNHDR (lit4_section,  _LIT4,  STYP_LIT4);
 190 #endif /* _LIT8 */
 191   CHECK_SCNHDR (sdata_section, _SDATA, STYP_SDATA);
 192   CHECK_SCNHDR (sbss_section,  _SBSS,  STYP_SBSS);
 193   CHECK_SCNHDR (bss_section,   _BSS,   STYP_BSS);
 194
 195
 196   pagesize = getpagesize ();
 197   brk = (((long) (sbrk (0))) + pagesize - 1) & (-pagesize);
 198
 199   /* Remember the current break */
 200
 201   Brk = brk;
 202
 203   nhdr.aout.dsize = brk - DATA_START;
 204   nhdr.aout.bsize = 0;
 205   if (entry_address == 0)
 206     {
 207       extern DEFAULT_ENTRY_ADDRESS ();
 208       nhdr.aout.entry = (unsigned long)DEFAULT_ENTRY_ADDRESS;
 209     }
 210   else
 211     nhdr.aout.entry = entry_address;
 212
 213   nhdr.aout.bss_start = nhdr.aout.data_start + nhdr.aout.dsize;
 214
 215   if (rdata_section != NULL)
 216     {
 217       rdata_section->s_size = data_start - DATA_START;
 218
 219       /* Adjust start and virtual addresses of rdata_section, too.  */
 220       rdata_section->s_vaddr = DATA_START;
 221       rdata_section->s_paddr = DATA_START;
 222       rdata_section->s_scnptr = text_section->s_scnptr + nhdr.aout.tsize;
 223     }
 224
 225   data_section->s_vaddr = data_start;
 226   data_section->s_paddr = data_start;
 227   data_section->s_size = brk - data_start;
 228
 229   if (rdata_section != NULL)
 230     {
 231       data_section->s_scnptr = rdata_section->s_scnptr + rdata_section->s_size;
 232     }
 233
 234   vaddr = data_section->s_vaddr + data_section->s_size;
 235   scnptr = data_section->s_scnptr + data_section->s_size;
 236   if (lit8_section != NULL)
 237     {
 238       lit8_section->s_vaddr = vaddr;
 239       lit8_section->s_paddr = vaddr;
 240       lit8_section->s_size = 0;
 241       lit8_section->s_scnptr = scnptr;
 242     }
 243   if (lit4_section != NULL)
 244     {
 245       lit4_section->s_vaddr = vaddr;
 246       lit4_section->s_paddr = vaddr;
 247       lit4_section->s_size = 0;
 248       lit4_section->s_scnptr = scnptr;
 249     }
 250   if (sdata_section != NULL)
 251     {
 252       sdata_section->s_vaddr = vaddr;
 253       sdata_section->s_paddr = vaddr;
 254       sdata_section->s_size = 0;
 255       sdata_section->s_scnptr = scnptr;
 256     }
 257 #ifdef _XDATA
 258   if (xdata_section != NULL)
 259     {
 260       xdata_section->s_vaddr = vaddr;
 261       xdata_section->s_paddr = vaddr;
 262       xdata_section->s_size = 0;
 263       xdata_section->s_scnptr = scnptr;
 264     }
 265 #endif
 266 #ifdef _GOT
 267   if (got_section != NULL)
 268     {
 269       got_section->s_vaddr = vaddr;
 270       got_section->s_paddr = vaddr;
 271       got_section->s_size = 0;
 272       got_section->s_scnptr = scnptr;
 273     }
 274 #endif /*_GOT */
 275   if (sbss_section != NULL)
 276     {
 277       sbss_section->s_vaddr = vaddr;
 278       sbss_section->s_paddr = vaddr;
 279       sbss_section->s_size = 0;
 280       sbss_section->s_scnptr = scnptr;
 281     }
 282   if (bss_section != NULL)
 283     {
 284       bss_section->s_vaddr = vaddr;
 285       bss_section->s_paddr = vaddr;
 286       bss_section->s_size = 0;
 287       bss_section->s_scnptr = scnptr;
 288     }
 289
 290   WRITE (new, (char *)TEXT_START, nhdr.aout.tsize,
 291          "writing text section to %s", new_name);
 292   WRITE (new, (char *)DATA_START, nhdr.aout.dsize,
 293          "writing data section to %s", new_name);
 294
 295
 296   /*
 297    * Construct new symbol table header
 298    */
 299
 300   bcopy (oldptr + nhdr.fhdr.f_symptr, buffer, cbHDRR);
 301
 302 #define symhdr ((pHDRR)buffer)
 303   newsyms = nhdr.aout.tsize + nhdr.aout.dsize;
 304   symrel = newsyms - nhdr.fhdr.f_symptr;
 305   nhdr.fhdr.f_symptr = newsyms;
 306   symhdr->cbLineOffset += symrel;
 307   symhdr->cbDnOffset += symrel;
 308   symhdr->cbPdOffset += symrel;
 309   symhdr->cbSymOffset += symrel;
 310   symhdr->cbOptOffset += symrel;
 311   symhdr->cbAuxOffset += symrel;
 312   symhdr->cbSsOffset += symrel;
 313   symhdr->cbSsExtOffset += symrel;
 314   symhdr->cbFdOffset += symrel;
 315   symhdr->cbRfdOffset += symrel;
 316   symhdr->cbExtOffset += symrel;
 317
 318   WRITE (new, buffer, cbHDRR, "writing symbol table header of %s", new_name);
 319
 320   /*
 321    * Copy the symbol table and line numbers
 322    */
 323   WRITE (new, oldptr + ohdr.fhdr.f_symptr + cbHDRR,
 324          stat.st_size - ohdr.fhdr.f_symptr - cbHDRR,
 325          "writing symbol table of %s", new_name);
 326
 327 #if 0
 328
 329 /* Not needed for now */
 330
 331   update_dynamic_symbols (oldptr, new_name, new, newsyms,
 332                           ((pHDRR) (oldptr + ohdr.fhdr.f_symptr))->issExtMax,
 333                           ((pHDRR) (oldptr + ohdr.fhdr.f_symptr))->cbExtOffset,
 334                           ((pHDRR) (oldptr + ohdr.fhdr.f_symptr))->cbSsExtOffset);
 335
 336 #endif
 337
 338 #undef symhdr
 339
 340   SEEK (new, 0, "seeking to start of header in %s", new_name);
 341   WRITE (new, &nhdr, sizeof (nhdr),
 342          "writing header of %s", new_name);
 343
 344   close (old);
 345   close (new);
 346   mark_x (new_name);
 347 }
 348
 349
 350 #if 0
 351
 352 /* Not needed for now */
 353
 354 /* The following function updates the values of some symbols
 355    that are used by the dynamic loader:
 356
 357    _edata
 358    _end
 359
 360 */
 361
 362
 363 update_dynamic_symbols (old, new_name, new, newsyms, nsyms, symoff, stroff)
 364      char *old;                 /* Pointer to old executable */
 365      char *new_name;            /* Name of new executable */
 366      int new;                   /* File descriptor for new executable */
 367      long newsyms;              /* Offset of Symbol table in new executable */
 368      int nsyms;                 /* Number of symbol table entries */
 369      long symoff;               /* Offset of External Symbols in old file */
 370      long stroff;               /* Offset of string table in old file */
 371 {
 372   long i;
 373   int found = 0;
 374   EXTR n_end, n_edata;
 375
 376   /* We go through the symbol table entries until we have found the two
 377      symbols. */
 378
 379   /* cbEXTR is the size of an external symbol table entry */
 380
 381   for (i = 0; i < nsyms && found < 2; i += cbEXTR)
 382     {
 383       register pEXTR x = (pEXTR) (old + symoff + i);
 384       char *s;
 385
 386       s = old + stroff + x->asym.iss; /* name of the symbol */
 387
 388       if (!strcmp(s,"_edata"))
 389         {
 390           found++;
 391           bcopy (x, &n_edata, cbEXTR);
 392           n_edata.asym.value = Brk;
 393           SEEK (new, newsyms + cbHDRR + i,
 394                 "seeking to symbol _edata in %s", new_name);
 395           WRITE (new, &n_edata, cbEXTR,
 396                  "writing symbol table entry for _edata into %s", new_name);
 397         }
 398       else if (!strcmp(s,"_end"))
 399         {
 400           found++;
 401           bcopy (x, &n_end, cbEXTR);
 402           n_end.asym.value = Brk;
 403           SEEK (new, newsyms + cbHDRR + i,
 404                 "seeking to symbol _end in %s", new_name);
 405           WRITE (new, &n_end, cbEXTR,
 406                  "writing symbol table entry for _end into %s", new_name);
 407         }
 408     }
 409
 410 }
 411
 412 #endif
 413
 414 \f
 415 /*
 416  * mark_x
 417  *
 418  * After successfully building the new a.out, mark it executable
 419  */
 420
 421 static void
 422 mark_x (name)
 423      char *name;
 424 {
 425   struct stat sbuf;
 426   int um = umask (777);
 427   umask (um);
 428   if (stat (name, &sbuf) < 0)
 429     fatal_unexec ("getting protection on %s", name);
 430   sbuf.st_mode |= 0111 & ~um;
 431   if (chmod (name, sbuf.st_mode) < 0)
 432     fatal_unexec ("setting protection on %s", name);
 433 }
 434
 435 static void
 436 fatal_unexec (s, arg)
 437      char *s;
 438      char *arg;
 439 {
 440   if (errno == EEOF)
 441     fputs ("unexec: unexpected end of file, ", stderr);
 442   else
 443     fprintf (stderr, "unexec: %s, ", strerror (errno));
 444   fprintf (stderr, s, arg);
 445   fputs (".\n", stderr);
 446   exit (1);
 447 }