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, 2011
   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 .  {* Mmap a part of the files. ADDR, LEN, PROT, FLAGS and OFFSET are the usual
 162 .     mmap parameter, except that LEN and OFFSET do not need to be page
 163 .     aligned.  Returns (void *)-1 on failure, mmapped address on success.
 164 .     Also write in MAP_ADDR the address of the page aligned buffer and in
 165 .     MAP_LEN the size mapped (a page multiple).  Use unmap with MAP_ADDR and
 166 .     MAP_LEN to unmap.  *}
 167 .  void *(*bmmap) (struct bfd *abfd, void *addr, bfd_size_type len,
 168 .                  int prot, int flags, file_ptr offset,
 169 .                  void **map_addr, bfd_size_type *map_len);
 170 .};
 171
 172 .extern const struct bfd_iovec _bfd_memory_iovec;
 173
 174 */
 175
 176
 177 /* Return value is amount read.  */
 178
 179 bfd_size_type
 180 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
 181 {
 182   size_t nread;
 183
 184   /* If this is an archive element, don't read past the end of
 185      this element.  */
 186   if (abfd->arelt_data != NULL)
 187     {
 188       bfd_size_type maxbytes = arelt_size (abfd);
 189
 190       if (abfd->where + size > maxbytes)
 191         {
 192           if (abfd->where >= maxbytes)
 193             return 0;
 194           size = maxbytes - abfd->where;
 195         }
 196     }
 197
 198   if (abfd->iovec)
 199     nread = abfd->iovec->bread (abfd, ptr, size);
 200   else
 201     nread = 0;
 202   if (nread != (size_t) -1)
 203     abfd->where += nread;
 204
 205   return nread;
 206 }
 207
 208 bfd_size_type
 209 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 210 {
 211   size_t nwrote;
 212
 213   if (abfd->iovec)
 214     nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 215   else
 216     nwrote = 0;
 217
 218   if (nwrote != (size_t) -1)
 219     abfd->where += nwrote;
 220   if (nwrote != size)
 221     {
 222 #ifdef ENOSPC
 223       errno = ENOSPC;
 224 #endif
 225       bfd_set_error (bfd_error_system_call);
 226     }
 227   return nwrote;
 228 }
 229
 230 file_ptr
 231 bfd_tell (bfd *abfd)
 232 {
 233   file_ptr ptr;
 234
 235   if (abfd->iovec)
 236     {
 237       bfd *parent_bfd = abfd;
 238       ptr = abfd->iovec->btell (abfd);
 239
 240       while (parent_bfd->my_archive != NULL)
 241         {
 242           ptr -= parent_bfd->origin;
 243           parent_bfd = parent_bfd->my_archive;
 244         }
 245     }
 246   else
 247     ptr = 0;
 248
 249   abfd->where = ptr;
 250   return ptr;
 251 }
 252
 253 int
 254 bfd_flush (bfd *abfd)
 255 {
 256   if (abfd->iovec)
 257     return abfd->iovec->bflush (abfd);
 258   return 0;
 259 }
 260
 261 /* Returns 0 for success, negative value for failure (in which case
 262    bfd_get_error can retrieve the error code).  */
 263 int
 264 bfd_stat (bfd *abfd, struct stat *statbuf)
 265 {
 266   int result;
 267
 268   if (abfd->iovec)
 269     result = abfd->iovec->bstat (abfd, statbuf);
 270   else
 271     result = -1;
 272
 273   if (result < 0)
 274     bfd_set_error (bfd_error_system_call);
 275   return result;
 276 }
 277
 278 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 279    can retrieve the error code).  */
 280
 281 int
 282 bfd_seek (bfd *abfd, file_ptr position, int direction)
 283 {
 284   int result;
 285   file_ptr file_position;
 286   /* For the time being, a BFD may not seek to it's end.  The problem
 287      is that we don't easily have a way to recognize the end of an
 288      element in an archive.  */
 289
 290   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 291
 292   if (direction == SEEK_CUR && position == 0)
 293     return 0;
 294
 295   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 296     {
 297       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 298         return 0;
 299     }
 300   else
 301     {
 302       /* We need something smarter to optimize access to archives.
 303          Currently, anything inside an archive is read via the file
 304          handle for the archive.  Which means that a bfd_seek on one
 305          component affects the `current position' in the archive, as
 306          well as in any other component.
 307
 308          It might be sufficient to put a spike through the cache
 309          abstraction, and look to the archive for the file position,
 310          but I think we should try for something cleaner.
 311
 312          In the meantime, no optimization for archives.  */
 313     }
 314
 315   file_position = position;
 316   if (direction == SEEK_SET)
 317     {
 318       bfd *parent_bfd = abfd;
 319
 320       while (parent_bfd->my_archive != NULL)
 321         {
 322           file_position += parent_bfd->origin;
 323           parent_bfd = parent_bfd->my_archive;
 324         }
 325     }
 326
 327   if (abfd->iovec)
 328     result = abfd->iovec->bseek (abfd, file_position, direction);
 329   else
 330     result = -1;
 331
 332   if (result != 0)
 333     {
 334       int hold_errno = errno;
 335
 336       /* Force redetermination of `where' field.  */
 337       bfd_tell (abfd);
 338
 339       /* An EINVAL error probably means that the file offset was
 340          absurd.  */
 341       if (hold_errno == EINVAL)
 342         bfd_set_error (bfd_error_file_truncated);
 343       else
 344         {
 345           bfd_set_error (bfd_error_system_call);
 346           errno = hold_errno;
 347         }
 348     }
 349   else
 350     {
 351       /* Adjust `where' field.  */
 352       if (direction == SEEK_SET)
 353         abfd->where = position;
 354       else
 355         abfd->where += position;
 356     }
 357   return result;
 358 }
 359
 360 /*
 361 FUNCTION
 362         bfd_get_mtime
 363
 364 SYNOPSIS
 365         long bfd_get_mtime (bfd *abfd);
 366
 367 DESCRIPTION
 368         Return the file modification time (as read from the file system, or
 369         from the archive header for archive members).
 370
 371 */
 372
 373 long
 374 bfd_get_mtime (bfd *abfd)
 375 {
 376   struct stat buf;
 377
 378   if (abfd->mtime_set)
 379     return abfd->mtime;
 380
 381   if (abfd->iovec == NULL)
 382     return 0;
 383
 384   if (abfd->iovec->bstat (abfd, &buf) != 0)
 385     return 0;
 386
 387   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 388   return buf.st_mtime;
 389 }
 390
 391 /*
 392 FUNCTION
 393         bfd_get_size
 394
 395 SYNOPSIS
 396         file_ptr bfd_get_size (bfd *abfd);
 397
 398 DESCRIPTION
 399         Return the file size (as read from file system) for the file
 400         associated with BFD @var{abfd}.
 401
 402         The initial motivation for, and use of, this routine is not
 403         so we can get the exact size of the object the BFD applies to, since
 404         that might not be generally possible (archive members for example).
 405         It would be ideal if someone could eventually modify
 406         it so that such results were guaranteed.
 407
 408         Instead, we want to ask questions like "is this NNN byte sized
 409         object I'm about to try read from file offset YYY reasonable?"
 410         As as example of where we might do this, some object formats
 411         use string tables for which the first <<sizeof (long)>> bytes of the
 412         table contain the size of the table itself, including the size bytes.
 413         If an application tries to read what it thinks is one of these
 414         string tables, without some way to validate the size, and for
 415         some reason the size is wrong (byte swapping error, wrong location
 416         for the string table, etc.), the only clue is likely to be a read
 417         error when it tries to read the table, or a "virtual memory
 418         exhausted" error when it tries to allocate 15 bazillon bytes
 419         of space for the 15 bazillon byte table it is about to read.
 420         This function at least allows us to answer the question, "is the
 421         size reasonable?".
 422 */
 423
 424 file_ptr
 425 bfd_get_size (bfd *abfd)
 426 {
 427   struct stat buf;
 428
 429   if (abfd->iovec == NULL)
 430     return 0;
 431
 432   if (abfd->iovec->bstat (abfd, &buf) != 0)
 433     return 0;
 434
 435   return buf.st_size;
 436 }
 437
 438
 439 /*
 440 FUNCTION
 441         bfd_mmap
 442
 443 SYNOPSIS
 444         void *bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 445                         int prot, int flags, file_ptr offset,
 446                         void **map_addr, bfd_size_type *map_len);
 447
 448 DESCRIPTION
 449         Return mmap()ed region of the file, if possible and implemented.
 450         LEN and OFFSET do not need to be page aligned.  The page aligned
 451         address and length are written to MAP_ADDR and MAP_LEN.
 452
 453 */
 454
 455 void *
 456 bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 457           int prot, int flags, file_ptr offset,
 458           void **map_addr, bfd_size_type *map_len)
 459 {
 460   void *ret = (void *)-1;
 461
 462   if (abfd->iovec == NULL)
 463     return ret;
 464
 465   return abfd->iovec->bmmap (abfd, addr, len, prot, flags, offset,
 466                              map_addr, map_len);
 467 }
 468
 469 /* Memory file I/O operations.  */
 470
 471 static file_ptr
 472 memory_bread (bfd *abfd, void *ptr, file_ptr size)
 473 {
 474   struct bfd_in_memory *bim;
 475   bfd_size_type get;
 476
 477   bim = (struct bfd_in_memory *) abfd->iostream;
 478   get = size;
 479   if (abfd->where + get > bim->size)
 480     {
 481       if (bim->size < (bfd_size_type) abfd->where)
 482         get = 0;
 483       else
 484         get = bim->size - abfd->where;
 485       bfd_set_error (bfd_error_file_truncated);
 486     }
 487   memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
 488   return get;
 489 }
 490
 491 static file_ptr
 492 memory_bwrite (bfd *abfd, const void *ptr, file_ptr size)
 493 {
 494   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 495
 496   if (abfd->where + size > bim->size)
 497     {
 498       bfd_size_type newsize, oldsize;
 499
 500       oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 501       bim->size = abfd->where + size;
 502       /* Round up to cut down on memory fragmentation */
 503       newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 504       if (newsize > oldsize)
 505         {
 506           bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer, newsize);
 507           if (bim->buffer == NULL)
 508             {
 509               bim->size = 0;
 510               return 0;
 511             }
 512           if (newsize > bim->size)
 513             memset (bim->buffer + bim->size, 0, newsize - bim->size);
 514         }
 515     }
 516   memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 517   return size;
 518 }
 519
 520 static file_ptr
 521 memory_btell (bfd *abfd)
 522 {
 523   return abfd->where;
 524 }
 525
 526 static int
 527 memory_bseek (bfd *abfd, file_ptr position, int direction)
 528 {
 529   file_ptr nwhere;
 530   struct bfd_in_memory *bim;
 531
 532   bim = (struct bfd_in_memory *) abfd->iostream;
 533
 534   if (direction == SEEK_SET)
 535     nwhere = position;
 536   else
 537     nwhere = abfd->where + position;
 538
 539   if (nwhere < 0)
 540     {
 541       abfd->where = 0;
 542       errno = EINVAL;
 543       return -1;
 544     }
 545
 546   if ((bfd_size_type)nwhere > bim->size)
 547     {
 548       if (abfd->direction == write_direction
 549           || abfd->direction == both_direction)
 550         {
 551           bfd_size_type newsize, oldsize;
 552
 553           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 554           bim->size = nwhere;
 555           /* Round up to cut down on memory fragmentation */
 556           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 557           if (newsize > oldsize)
 558             {
 559               bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer, newsize);
 560               if (bim->buffer == NULL)
 561                 {
 562                   errno = EINVAL;
 563                   bim->size = 0;
 564                   return -1;
 565                 }
 566               memset (bim->buffer + oldsize, 0, newsize - oldsize);
 567             }
 568         }
 569       else
 570         {
 571           abfd->where = bim->size;
 572           errno = EINVAL;
 573           bfd_set_error (bfd_error_file_truncated);
 574           return -1;
 575         }
 576     }
 577   return 0;
 578 }
 579
 580 static int
 581 memory_bclose (struct bfd *abfd)
 582 {
 583   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 584
 585   if (bim->buffer != NULL)
 586     free (bim->buffer);
 587   free (bim);
 588   abfd->iostream = NULL;
 589
 590   return TRUE;
 591 }
 592
 593 static int
 594 memory_bflush (bfd *abfd ATTRIBUTE_UNUSED)
 595 {
 596   return 0;
 597 }
 598
 599 static int
 600 memory_bstat (bfd *abfd, struct stat *statbuf)
 601 {
 602   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 603
 604   memset (statbuf, 0, sizeof (*statbuf));
 605   statbuf->st_size = bim->size;
 606
 607   return 0;
 608 }
 609
 610 static void *
 611 memory_bmmap (bfd *abfd ATTRIBUTE_UNUSED, void *addr ATTRIBUTE_UNUSED,
 612               bfd_size_type len ATTRIBUTE_UNUSED, int prot ATTRIBUTE_UNUSED,
 613               int flags ATTRIBUTE_UNUSED, file_ptr offset ATTRIBUTE_UNUSED,
 614               void **map_addr ATTRIBUTE_UNUSED,
 615               bfd_size_type *map_len ATTRIBUTE_UNUSED)
 616 {
 617   return (void *)-1;
 618 }
 619
 620 const struct bfd_iovec _bfd_memory_iovec =
 621 {
 622   &memory_bread, &memory_bwrite, &memory_btell, &memory_bseek,
 623   &memory_bclose, &memory_bflush, &memory_bstat, &memory_bmmap
 624 };