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
   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 = 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 = 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_realloc_or_free (bim->buffer, newsize);
 236               if (bim->buffer == NULL)
 237                 {
 238                   bim->size = 0;
 239                   return 0;
 240                 }
 241               if (newsize > bim->size)
 242                 memset (bim->buffer + bim->size, 0, newsize - bim->size);
 243             }
 244         }
 245       memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 246       abfd->where += size;
 247       return size;
 248     }
 249
 250   if (abfd->iovec)
 251     nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 252   else
 253     nwrote = 0;
 254
 255   if (nwrote != (size_t) -1)
 256     abfd->where += nwrote;
 257   if (nwrote != size)
 258     {
 259 #ifdef ENOSPC
 260       errno = ENOSPC;
 261 #endif
 262       bfd_set_error (bfd_error_system_call);
 263     }
 264   return nwrote;
 265 }
 266
 267 file_ptr
 268 bfd_tell (bfd *abfd)
 269 {
 270   file_ptr ptr;
 271
 272   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 273     return abfd->where;
 274
 275   if (abfd->iovec)
 276     {
 277       ptr = abfd->iovec->btell (abfd);
 278
 279       if (abfd->my_archive)
 280         ptr -= abfd->origin;
 281     }
 282   else
 283     ptr = 0;
 284
 285   abfd->where = ptr;
 286   return ptr;
 287 }
 288
 289 int
 290 bfd_flush (bfd *abfd)
 291 {
 292   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 293     return 0;
 294
 295   if (abfd->iovec)
 296     return abfd->iovec->bflush (abfd);
 297   return 0;
 298 }
 299
 300 /* Returns 0 for success, negative value for failure (in which case
 301    bfd_get_error can retrieve the error code).  */
 302 int
 303 bfd_stat (bfd *abfd, struct stat *statbuf)
 304 {
 305   int result;
 306
 307   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 308     abort ();
 309
 310   if (abfd->iovec)
 311     result = abfd->iovec->bstat (abfd, statbuf);
 312   else
 313     result = -1;
 314
 315   if (result < 0)
 316     bfd_set_error (bfd_error_system_call);
 317   return result;
 318 }
 319
 320 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 321    can retrieve the error code).  */
 322
 323 int
 324 bfd_seek (bfd *abfd, file_ptr position, int direction)
 325 {
 326   int result;
 327   file_ptr file_position;
 328   /* For the time being, a BFD may not seek to it's end.  The problem
 329      is that we don't easily have a way to recognize the end of an
 330      element in an archive.  */
 331
 332   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 333
 334   if (direction == SEEK_CUR && position == 0)
 335     return 0;
 336
 337   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 338     {
 339       struct bfd_in_memory *bim;
 340
 341       bim = abfd->iostream;
 342
 343       if (direction == SEEK_SET)
 344         abfd->where = position;
 345       else
 346         abfd->where += position;
 347
 348       if (abfd->where > bim->size)
 349         {
 350           if (abfd->direction == write_direction
 351               || abfd->direction == both_direction)
 352             {
 353               bfd_size_type newsize, oldsize;
 354
 355               oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 356               bim->size = abfd->where;
 357               /* Round up to cut down on memory fragmentation */
 358               newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 359               if (newsize > oldsize)
 360                 {
 361                   bim->buffer = bfd_realloc_or_free (bim->buffer, newsize);
 362                   if (bim->buffer == NULL)
 363                     {
 364                       bim->size = 0;
 365                       return -1;
 366                     }
 367                   memset (bim->buffer + oldsize, 0, newsize - oldsize);
 368                 }
 369             }
 370           else
 371             {
 372               abfd->where = bim->size;
 373               bfd_set_error (bfd_error_file_truncated);
 374               return -1;
 375             }
 376         }
 377       return 0;
 378     }
 379
 380   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 381     {
 382       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 383         return 0;
 384     }
 385   else
 386     {
 387       /* We need something smarter to optimize access to archives.
 388          Currently, anything inside an archive is read via the file
 389          handle for the archive.  Which means that a bfd_seek on one
 390          component affects the `current position' in the archive, as
 391          well as in any other component.
 392
 393          It might be sufficient to put a spike through the cache
 394          abstraction, and look to the archive for the file position,
 395          but I think we should try for something cleaner.
 396
 397          In the meantime, no optimization for archives.  */
 398     }
 399
 400   file_position = position;
 401   if (direction == SEEK_SET && abfd->my_archive != NULL)
 402     file_position += abfd->origin;
 403
 404   if (abfd->iovec)
 405     result = abfd->iovec->bseek (abfd, file_position, direction);
 406   else
 407     result = -1;
 408
 409   if (result != 0)
 410     {
 411       int hold_errno = errno;
 412
 413       /* Force redetermination of `where' field.  */
 414       bfd_tell (abfd);
 415
 416       /* An EINVAL error probably means that the file offset was
 417          absurd.  */
 418       if (hold_errno == EINVAL)
 419         bfd_set_error (bfd_error_file_truncated);
 420       else
 421         {
 422           bfd_set_error (bfd_error_system_call);
 423           errno = hold_errno;
 424         }
 425     }
 426   else
 427     {
 428       /* Adjust `where' field.  */
 429       if (direction == SEEK_SET)
 430         abfd->where = position;
 431       else
 432         abfd->where += position;
 433     }
 434   return result;
 435 }
 436
 437 /*
 438 FUNCTION
 439         bfd_get_mtime
 440
 441 SYNOPSIS
 442         long bfd_get_mtime (bfd *abfd);
 443
 444 DESCRIPTION
 445         Return the file modification time (as read from the file system, or
 446         from the archive header for archive members).
 447
 448 */
 449
 450 long
 451 bfd_get_mtime (bfd *abfd)
 452 {
 453   struct stat buf;
 454
 455   if (abfd->mtime_set)
 456     return abfd->mtime;
 457
 458   if (abfd->iovec == NULL)
 459     return 0;
 460
 461   if (abfd->iovec->bstat (abfd, &buf) != 0)
 462     return 0;
 463
 464   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 465   return buf.st_mtime;
 466 }
 467
 468 /*
 469 FUNCTION
 470         bfd_get_size
 471
 472 SYNOPSIS
 473         file_ptr bfd_get_size (bfd *abfd);
 474
 475 DESCRIPTION
 476         Return the file size (as read from file system) for the file
 477         associated with BFD @var{abfd}.
 478
 479         The initial motivation for, and use of, this routine is not
 480         so we can get the exact size of the object the BFD applies to, since
 481         that might not be generally possible (archive members for example).
 482         It would be ideal if someone could eventually modify
 483         it so that such results were guaranteed.
 484
 485         Instead, we want to ask questions like "is this NNN byte sized
 486         object I'm about to try read from file offset YYY reasonable?"
 487         As as example of where we might do this, some object formats
 488         use string tables for which the first <<sizeof (long)>> bytes of the
 489         table contain the size of the table itself, including the size bytes.
 490         If an application tries to read what it thinks is one of these
 491         string tables, without some way to validate the size, and for
 492         some reason the size is wrong (byte swapping error, wrong location
 493         for the string table, etc.), the only clue is likely to be a read
 494         error when it tries to read the table, or a "virtual memory
 495         exhausted" error when it tries to allocate 15 bazillon bytes
 496         of space for the 15 bazillon byte table it is about to read.
 497         This function at least allows us to answer the question, "is the
 498         size reasonable?".
 499 */
 500
 501 file_ptr
 502 bfd_get_size (bfd *abfd)
 503 {
 504   struct stat buf;
 505
 506   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 507     return ((struct bfd_in_memory *) abfd->iostream)->size;
 508
 509   if (abfd->iovec == NULL)
 510     return 0;
 511
 512   if (abfd->iovec->bstat (abfd, &buf) != 0)
 513     return 0;
 514
 515   return buf.st_size;
 516 }
 517
 518
 519 /*
 520 FUNCTION
 521         bfd_mmap
 522
 523 SYNOPSIS
 524         void *bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 525                         int prot, int flags, file_ptr offset);
 526
 527 DESCRIPTION
 528         Return mmap()ed region of the file, if possible and implemented.
 529
 530 */
 531
 532 void *
 533 bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 534           int prot, int flags, file_ptr offset)
 535 {
 536   void *ret = (void *)-1;
 537   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 538     return ret;
 539
 540   if (abfd->iovec == NULL)
 541     return ret;
 542
 543   return abfd->iovec->bmmap (abfd, addr, len, prot, flags, offset);
 544 }