bfd/bfdio.c

   1 /* Low-level I/O routines for BFDs.
   2
   3    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   4    1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   5    Free Software Foundation, Inc.
   6
   7    Written by Cygnus Support.
   8
   9    This file is part of BFD, the Binary File Descriptor library.
  10
  11    This program is free software; you can redistribute it and/or modify
  12    it under the terms of the GNU General Public License as published by
  13    the Free Software Foundation; either version 3 of the License, or
  14    (at your option) any later version.
  15
  16    This program is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19    GNU General Public License for more details.
  20
  21    You should have received a copy of the GNU General Public License
  22    along with this program; if not, write to the Free Software
  23    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  24    MA 02110-1301, USA.  */
  25
  26 #include "sysdep.h"
  27 #include <limits.h>
  28 #include "bfd.h"
  29 #include "libbfd.h"
  30
  31 #ifndef S_IXUSR
  32 #define S_IXUSR 0100    /* Execute by owner.  */
  33 #endif
  34 #ifndef S_IXGRP
  35 #define S_IXGRP 0010    /* Execute by group.  */
  36 #endif
  37 #ifndef S_IXOTH
  38 #define S_IXOTH 0001    /* Execute by others.  */
  39 #endif
  40
  41 #ifndef FD_CLOEXEC
  42 #define FD_CLOEXEC 1
  43 #endif
  44
  45 file_ptr
  46 real_ftell (FILE *file)
  47 {
  48 #if defined (HAVE_FTELLO64)
  49   return ftello64 (file);
  50 #elif defined (HAVE_FTELLO)
  51   return ftello (file);
  52 #else
  53   return ftell (file);
  54 #endif
  55 }
  56
  57 int
  58 real_fseek (FILE *file, file_ptr offset, int whence)
  59 {
  60 #if defined (HAVE_FSEEKO64)
  61   return fseeko64 (file, offset, whence);
  62 #elif defined (HAVE_FSEEKO)
  63   return fseeko (file, offset, whence);
  64 #else
  65   return fseek (file, offset, whence);
  66 #endif
  67 }
  68
  69 /* Mark FILE as close-on-exec.  Return FILE.  FILE may be NULL, in
  70    which case nothing is done.  */
  71 static FILE *
  72 close_on_exec (FILE *file)
  73 {
  74 #if defined (HAVE_FILENO) && defined (F_GETFD)
  75   if (file)
  76     {
  77       int fd = fileno (file);
  78       int old = fcntl (fd, F_GETFD, 0);
  79       if (old >= 0)
  80         fcntl (fd, F_SETFD, old | FD_CLOEXEC);
  81     }
  82 #endif
  83   return file;
  84 }
  85
  86 FILE *
  87 real_fopen (const char *filename, const char *modes)
  88 {
  89 #ifdef VMS
  90   char vms_modes[4];
  91   char *vms_attr;
  92
  93   /* On VMS, fopen allows file attributes as optionnal arguments.
  94      We need to use them but we'd better to use the common prototype.
  95      In fopen-vms.h, they are separated from the mode with a comma.
  96      Split here.  */
  97   vms_attr = strchr (modes, ',');
  98   if (vms_attr == NULL)
  99     {
 100       /* No attributes.  */
 101       return close_on_exec (fopen (filename, modes));
 102     }
 103   else
 104     {
 105       /* Attributes found.  Split.  */
 106       size_t modes_len = strlen (modes) + 1;
 107       char attrs[modes_len + 1];
 108       char *at[3];
 109       int i;
 110
 111       memcpy (attrs, modes, modes_len);
 112       at[0] = attrs;
 113       for (i = 0; i < 2; i++)
 114         {
 115           at[i + 1] = strchr (at[i], ',');
 116           BFD_ASSERT (at[i + 1] != NULL);
 117           *(at[i + 1]++) = 0; /* Replace ',' with a nul, and skip it.  */
 118         }
 119       return close_on_exec (fopen (filename, at[0], at[1], at[2]));
 120     }
 121 #else /* !VMS */
 122 #if defined (HAVE_FOPEN64)
 123   return close_on_exec (fopen64 (filename, modes));
 124 #else
 125   return close_on_exec (fopen (filename, modes));
 126 #endif
 127 #endif /* !VMS */
 128 }
 129
 130 /*
 131 INTERNAL_DEFINITION
 132         struct bfd_iovec
 133
 134 DESCRIPTION
 135
 136         The <<struct bfd_iovec>> contains the internal file I/O class.
 137         Each <<BFD>> has an instance of this class and all file I/O is
 138         routed through it (it is assumed that the instance implements
 139         all methods listed below).
 140
 141 .struct bfd_iovec
 142 .{
 143 .  {* To avoid problems with macros, a "b" rather than "f"
 144 .     prefix is prepended to each method name.  *}
 145 .  {* Attempt to read/write NBYTES on ABFD's IOSTREAM storing/fetching
 146 .     bytes starting at PTR.  Return the number of bytes actually
 147 .     transfered (a read past end-of-file returns less than NBYTES),
 148 .     or -1 (setting <<bfd_error>>) if an error occurs.  *}
 149 .  file_ptr (*bread) (struct bfd *abfd, void *ptr, file_ptr nbytes);
 150 .  file_ptr (*bwrite) (struct bfd *abfd, const void *ptr,
 151 .                      file_ptr nbytes);
 152 .  {* Return the current IOSTREAM file offset, or -1 (setting <<bfd_error>>
 153 .     if an error occurs.  *}
 154 .  file_ptr (*btell) (struct bfd *abfd);
 155 .  {* For the following, on successful completion a value of 0 is returned.
 156 .     Otherwise, a value of -1 is returned (and  <<bfd_error>> is set).  *}
 157 .  int (*bseek) (struct bfd *abfd, file_ptr offset, int whence);
 158 .  int (*bclose) (struct bfd *abfd);
 159 .  int (*bflush) (struct bfd *abfd);
 160 .  int (*bstat) (struct bfd *abfd, struct stat *sb);
 161 .  {* Just like mmap: (void*)-1 on failure, mmapped address on success.  *}
 162 .  void *(*bmmap) (struct bfd *abfd, void *addr, bfd_size_type len,
 163 .                  int prot, int flags, file_ptr offset);
 164 .};
 165
 166 */
 167
 168
 169 /* Return value is amount read.  */
 170
 171 bfd_size_type
 172 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
 173 {
 174   size_t nread;
 175
 176   /* If this is an archive element, don't read past the end of
 177      this element.  */
 178   if (abfd->arelt_data != NULL)
 179     {
 180       size_t maxbytes = ((struct areltdata *) abfd->arelt_data)->parsed_size;
 181       if (size > maxbytes)
 182         size = maxbytes;
 183     }
 184
 185   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 186     {
 187       struct bfd_in_memory *bim;
 188       bfd_size_type get;
 189
 190       bim = (struct bfd_in_memory *) abfd->iostream;
 191       get = size;
 192       if (abfd->where + get > bim->size)
 193         {
 194           if (bim->size < (bfd_size_type) abfd->where)
 195             get = 0;
 196           else
 197             get = bim->size - abfd->where;
 198           bfd_set_error (bfd_error_file_truncated);
 199         }
 200       memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
 201       abfd->where += get;
 202       return get;
 203     }
 204
 205   if (abfd->iovec)
 206     nread = abfd->iovec->bread (abfd, ptr, size);
 207   else
 208     nread = 0;
 209   if (nread != (size_t) -1)
 210     abfd->where += nread;
 211
 212   return nread;
 213 }
 214
 215 bfd_size_type
 216 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 217 {
 218   size_t nwrote;
 219
 220   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 221     {
 222       struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 223
 224       size = (size_t) size;
 225       if (abfd->where + size > bim->size)
 226         {
 227           bfd_size_type newsize, oldsize;
 228
 229           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 230           bim->size = abfd->where + size;
 231           /* Round up to cut down on memory fragmentation */
 232           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 233           if (newsize > oldsize)
 234             {
 235               bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer,
 236                                                               newsize);
 237               if (bim->buffer == NULL)
 238                 {
 239                   bim->size = 0;
 240                   return 0;
 241                 }
 242               if (newsize > bim->size)
 243                 memset (bim->buffer + bim->size, 0, newsize - bim->size);
 244             }
 245         }
 246       memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 247       abfd->where += size;
 248       return size;
 249     }
 250
 251   if (abfd->iovec)
 252     nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 253   else
 254     nwrote = 0;
 255
 256   if (nwrote != (size_t) -1)
 257     abfd->where += nwrote;
 258   if (nwrote != size)
 259     {
 260 #ifdef ENOSPC
 261       errno = ENOSPC;
 262 #endif
 263       bfd_set_error (bfd_error_system_call);
 264     }
 265   return nwrote;
 266 }
 267
 268 file_ptr
 269 bfd_tell (bfd *abfd)
 270 {
 271   file_ptr ptr;
 272
 273   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 274     return abfd->where;
 275
 276   if (abfd->iovec)
 277     {
 278       ptr = abfd->iovec->btell (abfd);
 279
 280       if (abfd->my_archive)
 281         ptr -= abfd->origin;
 282     }
 283   else
 284     ptr = 0;
 285
 286   abfd->where = ptr;
 287   return ptr;
 288 }
 289
 290 int
 291 bfd_flush (bfd *abfd)
 292 {
 293   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 294     return 0;
 295
 296   if (abfd->iovec)
 297     return abfd->iovec->bflush (abfd);
 298   return 0;
 299 }
 300
 301 /* Returns 0 for success, negative value for failure (in which case
 302    bfd_get_error can retrieve the error code).  */
 303 int
 304 bfd_stat (bfd *abfd, struct stat *statbuf)
 305 {
 306   int result;
 307
 308   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 309     abort ();
 310
 311   if (abfd->iovec)
 312     result = abfd->iovec->bstat (abfd, statbuf);
 313   else
 314     result = -1;
 315
 316   if (result < 0)
 317     bfd_set_error (bfd_error_system_call);
 318   return result;
 319 }
 320
 321 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 322    can retrieve the error code).  */
 323
 324 int
 325 bfd_seek (bfd *abfd, file_ptr position, int direction)
 326 {
 327   int result;
 328   file_ptr file_position;
 329   /* For the time being, a BFD may not seek to it's end.  The problem
 330      is that we don't easily have a way to recognize the end of an
 331      element in an archive.  */
 332
 333   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 334
 335   if (direction == SEEK_CUR && position == 0)
 336     return 0;
 337
 338   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 339     {
 340       struct bfd_in_memory *bim;
 341
 342       bim = (struct bfd_in_memory *) abfd->iostream;
 343
 344       if (direction == SEEK_SET)
 345         abfd->where = position;
 346       else
 347         abfd->where += position;
 348
 349       if (abfd->where > bim->size)
 350         {
 351           if (abfd->direction == write_direction
 352               || abfd->direction == both_direction)
 353             {
 354               bfd_size_type newsize, oldsize;
 355
 356               oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 357               bim->size = abfd->where;
 358               /* Round up to cut down on memory fragmentation */
 359               newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 360               if (newsize > oldsize)
 361                 {
 362                   bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer,
 363                                                                   newsize);
 364                   if (bim->buffer == NULL)
 365                     {
 366                       bim->size = 0;
 367                       return -1;
 368                     }
 369                   memset (bim->buffer + oldsize, 0, newsize - oldsize);
 370                 }
 371             }
 372           else
 373             {
 374               abfd->where = bim->size;
 375               bfd_set_error (bfd_error_file_truncated);
 376               return -1;
 377             }
 378         }
 379       return 0;
 380     }
 381
 382   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 383     {
 384       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 385         return 0;
 386     }
 387   else
 388     {
 389       /* We need something smarter to optimize access to archives.
 390          Currently, anything inside an archive is read via the file
 391          handle for the archive.  Which means that a bfd_seek on one
 392          component affects the `current position' in the archive, as
 393          well as in any other component.
 394
 395          It might be sufficient to put a spike through the cache
 396          abstraction, and look to the archive for the file position,
 397          but I think we should try for something cleaner.
 398
 399          In the meantime, no optimization for archives.  */
 400     }
 401
 402   file_position = position;
 403   if (direction == SEEK_SET && abfd->my_archive != NULL)
 404     file_position += abfd->origin;
 405
 406   if (abfd->iovec)
 407     result = abfd->iovec->bseek (abfd, file_position, direction);
 408   else
 409     result = -1;
 410
 411   if (result != 0)
 412     {
 413       int hold_errno = errno;
 414
 415       /* Force redetermination of `where' field.  */
 416       bfd_tell (abfd);
 417
 418       /* An EINVAL error probably means that the file offset was
 419          absurd.  */
 420       if (hold_errno == EINVAL)
 421         bfd_set_error (bfd_error_file_truncated);
 422       else
 423         {
 424           bfd_set_error (bfd_error_system_call);
 425           errno = hold_errno;
 426         }
 427     }
 428   else
 429     {
 430       /* Adjust `where' field.  */
 431       if (direction == SEEK_SET)
 432         abfd->where = position;
 433       else
 434         abfd->where += position;
 435     }
 436   return result;
 437 }
 438
 439 /*
 440 FUNCTION
 441         bfd_get_mtime
 442
 443 SYNOPSIS
 444         long bfd_get_mtime (bfd *abfd);
 445
 446 DESCRIPTION
 447         Return the file modification time (as read from the file system, or
 448         from the archive header for archive members).
 449
 450 */
 451
 452 long
 453 bfd_get_mtime (bfd *abfd)
 454 {
 455   struct stat buf;
 456
 457   if (abfd->mtime_set)
 458     return abfd->mtime;
 459
 460   if (abfd->iovec == NULL)
 461     return 0;
 462
 463   if (abfd->iovec->bstat (abfd, &buf) != 0)
 464     return 0;
 465
 466   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 467   return buf.st_mtime;
 468 }
 469
 470 /*
 471 FUNCTION
 472         bfd_get_size
 473
 474 SYNOPSIS
 475         file_ptr bfd_get_size (bfd *abfd);
 476
 477 DESCRIPTION
 478         Return the file size (as read from file system) for the file
 479         associated with BFD @var{abfd}.
 480
 481         The initial motivation for, and use of, this routine is not
 482         so we can get the exact size of the object the BFD applies to, since
 483         that might not be generally possible (archive members for example).
 484         It would be ideal if someone could eventually modify
 485         it so that such results were guaranteed.
 486
 487         Instead, we want to ask questions like "is this NNN byte sized
 488         object I'm about to try read from file offset YYY reasonable?"
 489         As as example of where we might do this, some object formats
 490         use string tables for which the first <<sizeof (long)>> bytes of the
 491         table contain the size of the table itself, including the size bytes.
 492         If an application tries to read what it thinks is one of these
 493         string tables, without some way to validate the size, and for
 494         some reason the size is wrong (byte swapping error, wrong location
 495         for the string table, etc.), the only clue is likely to be a read
 496         error when it tries to read the table, or a "virtual memory
 497         exhausted" error when it tries to allocate 15 bazillon bytes
 498         of space for the 15 bazillon byte table it is about to read.
 499         This function at least allows us to answer the question, "is the
 500         size reasonable?".
 501 */
 502
 503 file_ptr
 504 bfd_get_size (bfd *abfd)
 505 {
 506   struct stat buf;
 507
 508   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 509     return ((struct bfd_in_memory *) abfd->iostream)->size;
 510
 511   if (abfd->iovec == NULL)
 512     return 0;
 513
 514   if (abfd->iovec->bstat (abfd, &buf) != 0)
 515     return 0;
 516
 517   return buf.st_size;
 518 }
 519
 520
 521 /*
 522 FUNCTION
 523         bfd_mmap
 524
 525 SYNOPSIS
 526         void *bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 527                         int prot, int flags, file_ptr offset);
 528
 529 DESCRIPTION
 530         Return mmap()ed region of the file, if possible and implemented.
 531
 532 */
 533
 534 void *
 535 bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 536           int prot, int flags, file_ptr offset)
 537 {
 538   void *ret = (void *)-1;
 539   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 540     return ret;
 541
 542   if (abfd->iovec == NULL)
 543     return ret;
 544
 545   return abfd->iovec->bmmap (abfd, addr, len, prot, flags, offset);
 546 }