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