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_attr;
  91
  92   /* On VMS, fopen allows file attributes as optionnal arguments.
  93      We need to use them but we'd better to use the common prototype.
  94      In fopen-vms.h, they are separated from the mode with a comma.
  95      Split here.  */
  96   vms_attr = strchr (modes, ',');
  97   if (vms_attr == NULL)
  98     {
  99       /* No attributes.  */
 100       return close_on_exec (fopen (filename, modes));
 101     }
 102   else
 103     {
 104       /* Attributes found.  Split.  */
 105       size_t modes_len = strlen (modes) + 1;
 106       char attrs[modes_len + 1];
 107       char *at[3];
 108       int i;
 109
 110       memcpy (attrs, modes, modes_len);
 111       at[0] = attrs;
 112       for (i = 0; i < 2; i++)
 113         {
 114           at[i + 1] = strchr (at[i], ',');
 115           BFD_ASSERT (at[i + 1] != NULL);
 116           *(at[i + 1]++) = 0; /* Replace ',' with a nul, and skip it.  */
 117         }
 118       return close_on_exec (fopen (filename, at[0], at[1], at[2]));
 119     }
 120 #else /* !VMS */
 121 #if defined (HAVE_FOPEN64)
 122   return close_on_exec (fopen64 (filename, modes));
 123 #else
 124   return close_on_exec (fopen (filename, modes));
 125 #endif
 126 #endif /* !VMS */
 127 }
 128
 129 /*
 130 INTERNAL_DEFINITION
 131         struct bfd_iovec
 132
 133 DESCRIPTION
 134
 135         The <<struct bfd_iovec>> contains the internal file I/O class.
 136         Each <<BFD>> has an instance of this class and all file I/O is
 137         routed through it (it is assumed that the instance implements
 138         all methods listed below).
 139
 140 .struct bfd_iovec
 141 .{
 142 .  {* To avoid problems with macros, a "b" rather than "f"
 143 .     prefix is prepended to each method name.  *}
 144 .  {* Attempt to read/write NBYTES on ABFD's IOSTREAM storing/fetching
 145 .     bytes starting at PTR.  Return the number of bytes actually
 146 .     transfered (a read past end-of-file returns less than NBYTES),
 147 .     or -1 (setting <<bfd_error>>) if an error occurs.  *}
 148 .  file_ptr (*bread) (struct bfd *abfd, void *ptr, file_ptr nbytes);
 149 .  file_ptr (*bwrite) (struct bfd *abfd, const void *ptr,
 150 .                      file_ptr nbytes);
 151 .  {* Return the current IOSTREAM file offset, or -1 (setting <<bfd_error>>
 152 .     if an error occurs.  *}
 153 .  file_ptr (*btell) (struct bfd *abfd);
 154 .  {* For the following, on successful completion a value of 0 is returned.
 155 .     Otherwise, a value of -1 is returned (and  <<bfd_error>> is set).  *}
 156 .  int (*bseek) (struct bfd *abfd, file_ptr offset, int whence);
 157 .  int (*bclose) (struct bfd *abfd);
 158 .  int (*bflush) (struct bfd *abfd);
 159 .  int (*bstat) (struct bfd *abfd, struct stat *sb);
 160 .  {* Mmap a part of the files. ADDR, LEN, PROT, FLAGS and OFFSET are the usual
 161 .     mmap parameter, except that LEN and OFFSET do not need to be page
 162 .     aligned.  Returns (void *)-1 on failure, mmapped address on success.
 163 .     Also write in MAP_ADDR the address of the page aligned buffer and in
 164 .     MAP_LEN the size mapped (a page multiple).  Use unmap with MAP_ADDR and
 165 .     MAP_LEN to unmap.  *}
 166 .  void *(*bmmap) (struct bfd *abfd, void *addr, bfd_size_type len,
 167 .                  int prot, int flags, file_ptr offset,
 168 .                  void **map_addr, bfd_size_type *map_len);
 169 .};
 170
 171 .extern const struct bfd_iovec _bfd_memory_iovec;
 172
 173 */
 174
 175
 176 /* Return value is amount read.  */
 177
 178 bfd_size_type
 179 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
 180 {
 181   size_t nread;
 182
 183   /* If this is an archive element, don't read past the end of
 184      this element.  */
 185   if (abfd->arelt_data != NULL)
 186     {
 187       bfd_size_type maxbytes = arelt_size (abfd);
 188
 189       if (abfd->where + size > maxbytes)
 190         {
 191           if (abfd->where >= maxbytes)
 192             return 0;
 193           size = maxbytes - abfd->where;
 194         }
 195     }
 196
 197   if (abfd->iovec)
 198     nread = abfd->iovec->bread (abfd, ptr, size);
 199   else
 200     nread = 0;
 201   if (nread != (size_t) -1)
 202     abfd->where += nread;
 203
 204   return nread;
 205 }
 206
 207 bfd_size_type
 208 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 209 {
 210   size_t nwrote;
 211
 212   if (abfd->iovec)
 213     nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 214   else
 215     nwrote = 0;
 216
 217   if (nwrote != (size_t) -1)
 218     abfd->where += nwrote;
 219   if (nwrote != size)
 220     {
 221 #ifdef ENOSPC
 222       errno = ENOSPC;
 223 #endif
 224       bfd_set_error (bfd_error_system_call);
 225     }
 226   return nwrote;
 227 }
 228
 229 file_ptr
 230 bfd_tell (bfd *abfd)
 231 {
 232   file_ptr ptr;
 233
 234   if (abfd->iovec)
 235     {
 236       bfd *parent_bfd = abfd;
 237       ptr = abfd->iovec->btell (abfd);
 238
 239       while (parent_bfd->my_archive != NULL)
 240         {
 241           ptr -= parent_bfd->origin;
 242           parent_bfd = parent_bfd->my_archive;
 243         }
 244     }
 245   else
 246     ptr = 0;
 247
 248   abfd->where = ptr;
 249   return ptr;
 250 }
 251
 252 int
 253 bfd_flush (bfd *abfd)
 254 {
 255   if (abfd->iovec)
 256     return abfd->iovec->bflush (abfd);
 257   return 0;
 258 }
 259
 260 /* Returns 0 for success, negative value for failure (in which case
 261    bfd_get_error can retrieve the error code).  */
 262 int
 263 bfd_stat (bfd *abfd, struct stat *statbuf)
 264 {
 265   int result;
 266
 267   if (abfd->iovec)
 268     result = abfd->iovec->bstat (abfd, statbuf);
 269   else
 270     result = -1;
 271
 272   if (result < 0)
 273     bfd_set_error (bfd_error_system_call);
 274   return result;
 275 }
 276
 277 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 278    can retrieve the error code).  */
 279
 280 int
 281 bfd_seek (bfd *abfd, file_ptr position, int direction)
 282 {
 283   int result;
 284   file_ptr file_position;
 285   /* For the time being, a BFD may not seek to it's end.  The problem
 286      is that we don't easily have a way to recognize the end of an
 287      element in an archive.  */
 288
 289   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 290
 291   if (direction == SEEK_CUR && position == 0)
 292     return 0;
 293
 294   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 295     {
 296       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 297         return 0;
 298     }
 299   else
 300     {
 301       /* We need something smarter to optimize access to archives.
 302          Currently, anything inside an archive is read via the file
 303          handle for the archive.  Which means that a bfd_seek on one
 304          component affects the `current position' in the archive, as
 305          well as in any other component.
 306
 307          It might be sufficient to put a spike through the cache
 308          abstraction, and look to the archive for the file position,
 309          but I think we should try for something cleaner.
 310
 311          In the meantime, no optimization for archives.  */
 312     }
 313
 314   file_position = position;
 315   if (direction == SEEK_SET)
 316     {
 317       bfd *parent_bfd = abfd;
 318
 319       while (parent_bfd->my_archive != NULL)
 320         {
 321           file_position += parent_bfd->origin;
 322           parent_bfd = parent_bfd->my_archive;
 323         }
 324     }
 325
 326   if (abfd->iovec)
 327     result = abfd->iovec->bseek (abfd, file_position, direction);
 328   else
 329     result = -1;
 330
 331   if (result != 0)
 332     {
 333       int hold_errno = errno;
 334
 335       /* Force redetermination of `where' field.  */
 336       bfd_tell (abfd);
 337
 338       /* An EINVAL error probably means that the file offset was
 339          absurd.  */
 340       if (hold_errno == EINVAL)
 341         bfd_set_error (bfd_error_file_truncated);
 342       else
 343         {
 344           bfd_set_error (bfd_error_system_call);
 345           errno = hold_errno;
 346         }
 347     }
 348   else
 349     {
 350       /* Adjust `where' field.  */
 351       if (direction == SEEK_SET)
 352         abfd->where = position;
 353       else
 354         abfd->where += position;
 355     }
 356   return result;
 357 }
 358
 359 /*
 360 FUNCTION
 361         bfd_get_mtime
 362
 363 SYNOPSIS
 364         long bfd_get_mtime (bfd *abfd);
 365
 366 DESCRIPTION
 367         Return the file modification time (as read from the file system, or
 368         from the archive header for archive members).
 369
 370 */
 371
 372 long
 373 bfd_get_mtime (bfd *abfd)
 374 {
 375   struct stat buf;
 376
 377   if (abfd->mtime_set)
 378     return abfd->mtime;
 379
 380   if (abfd->iovec == NULL)
 381     return 0;
 382
 383   if (abfd->iovec->bstat (abfd, &buf) != 0)
 384     return 0;
 385
 386   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 387   return buf.st_mtime;
 388 }
 389
 390 /*
 391 FUNCTION
 392         bfd_get_size
 393
 394 SYNOPSIS
 395         file_ptr bfd_get_size (bfd *abfd);
 396
 397 DESCRIPTION
 398         Return the file size (as read from file system) for the file
 399         associated with BFD @var{abfd}.
 400
 401         The initial motivation for, and use of, this routine is not
 402         so we can get the exact size of the object the BFD applies to, since
 403         that might not be generally possible (archive members for example).
 404         It would be ideal if someone could eventually modify
 405         it so that such results were guaranteed.
 406
 407         Instead, we want to ask questions like "is this NNN byte sized
 408         object I'm about to try read from file offset YYY reasonable?"
 409         As as example of where we might do this, some object formats
 410         use string tables for which the first <<sizeof (long)>> bytes of the
 411         table contain the size of the table itself, including the size bytes.
 412         If an application tries to read what it thinks is one of these
 413         string tables, without some way to validate the size, and for
 414         some reason the size is wrong (byte swapping error, wrong location
 415         for the string table, etc.), the only clue is likely to be a read
 416         error when it tries to read the table, or a "virtual memory
 417         exhausted" error when it tries to allocate 15 bazillon bytes
 418         of space for the 15 bazillon byte table it is about to read.
 419         This function at least allows us to answer the question, "is the
 420         size reasonable?".
 421 */
 422
 423 file_ptr
 424 bfd_get_size (bfd *abfd)
 425 {
 426   struct stat buf;
 427
 428   if (abfd->iovec == NULL)
 429     return 0;
 430
 431   if (abfd->iovec->bstat (abfd, &buf) != 0)
 432     return 0;
 433
 434   return buf.st_size;
 435 }
 436
 437
 438 /*
 439 FUNCTION
 440         bfd_mmap
 441
 442 SYNOPSIS
 443         void *bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 444                         int prot, int flags, file_ptr offset,
 445                         void **map_addr, bfd_size_type *map_len);
 446
 447 DESCRIPTION
 448         Return mmap()ed region of the file, if possible and implemented.
 449         LEN and OFFSET do not need to be page aligned.  The page aligned
 450         address and length are written to MAP_ADDR and MAP_LEN.
 451
 452 */
 453
 454 void *
 455 bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 456           int prot, int flags, file_ptr offset,
 457           void **map_addr, bfd_size_type *map_len)
 458 {
 459   void *ret = (void *)-1;
 460
 461   if (abfd->iovec == NULL)
 462     return ret;
 463
 464   return abfd->iovec->bmmap (abfd, addr, len, prot, flags, offset,
 465                              map_addr, map_len);
 466 }
 467
 468 /* Memory file I/O operations.  */
 469
 470 static file_ptr
 471 memory_bread (bfd *abfd, void *ptr, file_ptr size)
 472 {
 473   struct bfd_in_memory *bim;
 474   bfd_size_type get;
 475
 476   bim = (struct bfd_in_memory *) abfd->iostream;
 477   get = size;
 478   if (abfd->where + get > bim->size)
 479     {
 480       if (bim->size < (bfd_size_type) abfd->where)
 481         get = 0;
 482       else
 483         get = bim->size - abfd->where;
 484       bfd_set_error (bfd_error_file_truncated);
 485     }
 486   memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
 487   return get;
 488 }
 489
 490 static file_ptr
 491 memory_bwrite (bfd *abfd, const void *ptr, file_ptr size)
 492 {
 493   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 494
 495   if (abfd->where + size > bim->size)
 496     {
 497       bfd_size_type newsize, oldsize;
 498
 499       oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 500       bim->size = abfd->where + size;
 501       /* Round up to cut down on memory fragmentation */
 502       newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 503       if (newsize > oldsize)
 504         {
 505           bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer, newsize);
 506           if (bim->buffer == NULL)
 507             {
 508               bim->size = 0;
 509               return 0;
 510             }
 511           if (newsize > bim->size)
 512             memset (bim->buffer + bim->size, 0, newsize - bim->size);
 513         }
 514     }
 515   memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 516   return size;
 517 }
 518
 519 static file_ptr
 520 memory_btell (bfd *abfd)
 521 {
 522   return abfd->where;
 523 }
 524
 525 static int
 526 memory_bseek (bfd *abfd, file_ptr position, int direction)
 527 {
 528   file_ptr nwhere;
 529   struct bfd_in_memory *bim;
 530
 531   bim = (struct bfd_in_memory *) abfd->iostream;
 532
 533   if (direction == SEEK_SET)
 534     nwhere = position;
 535   else
 536     nwhere = abfd->where + position;
 537
 538   if (nwhere < 0)
 539     {
 540       abfd->where = 0;
 541       errno = EINVAL;
 542       return -1;
 543     }
 544
 545   if ((bfd_size_type)nwhere > bim->size)
 546     {
 547       if (abfd->direction == write_direction
 548           || abfd->direction == both_direction)
 549         {
 550           bfd_size_type newsize, oldsize;
 551
 552           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 553           bim->size = nwhere;
 554           /* Round up to cut down on memory fragmentation */
 555           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 556           if (newsize > oldsize)
 557             {
 558               bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer, newsize);
 559               if (bim->buffer == NULL)
 560                 {
 561                   errno = EINVAL;
 562                   bim->size = 0;
 563                   return -1;
 564                 }
 565               memset (bim->buffer + oldsize, 0, newsize - oldsize);
 566             }
 567         }
 568       else
 569         {
 570           abfd->where = bim->size;
 571           errno = EINVAL;
 572           bfd_set_error (bfd_error_file_truncated);
 573           return -1;
 574         }
 575     }
 576   return 0;
 577 }
 578
 579 static int
 580 memory_bclose (struct bfd *abfd)
 581 {
 582   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 583
 584   if (bim->buffer != NULL)
 585     free (bim->buffer);
 586   free (bim);
 587   abfd->iostream = NULL;
 588
 589   return TRUE;
 590 }
 591
 592 static int
 593 memory_bflush (bfd *abfd ATTRIBUTE_UNUSED)
 594 {
 595   return 0;
 596 }
 597
 598 static int
 599 memory_bstat (bfd *abfd, struct stat *statbuf)
 600 {
 601   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 602
 603   memset (statbuf, 0, sizeof (*statbuf));
 604   statbuf->st_size = bim->size;
 605
 606   return 0;
 607 }
 608
 609 static void *
 610 memory_bmmap (bfd *abfd ATTRIBUTE_UNUSED, void *addr ATTRIBUTE_UNUSED,
 611               bfd_size_type len ATTRIBUTE_UNUSED, int prot ATTRIBUTE_UNUSED,
 612               int flags ATTRIBUTE_UNUSED, file_ptr offset ATTRIBUTE_UNUSED,
 613               void **map_addr ATTRIBUTE_UNUSED,
 614               bfd_size_type *map_len ATTRIBUTE_UNUSED)
 615 {
 616   return (void *)-1;
 617 }
 618
 619 const struct bfd_iovec _bfd_memory_iovec =
 620 {
 621   &memory_bread, &memory_bwrite, &memory_btell, &memory_bseek,
 622   &memory_bclose, &memory_bflush, &memory_bstat, &memory_bmmap
 623 };