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
   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 2 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, MA 02110-1301, USA.  */
  24
  25 #include "sysdep.h"
  26
  27 #include "bfd.h"
  28 #include "libbfd.h"
  29
  30 #include <limits.h>
  31
  32 #ifndef S_IXUSR
  33 #define S_IXUSR 0100    /* Execute by owner.  */
  34 #endif
  35 #ifndef S_IXGRP
  36 #define S_IXGRP 0010    /* Execute by group.  */
  37 #endif
  38 #ifndef S_IXOTH
  39 #define S_IXOTH 0001    /* Execute by others.  */
  40 #endif
  41
  42 file_ptr
  43 real_ftell (FILE *file)
  44 {
  45 #if defined (HAVE_FTELLO64)
  46   return ftello64 (file);
  47 #elif defined (HAVE_FTELLO)
  48   return ftello (file);
  49 #else
  50   return ftell (file);
  51 #endif
  52 }
  53
  54 int
  55 real_fseek (FILE *file, file_ptr offset, int whence)
  56 {
  57 #if defined (HAVE_FSEEKO64)
  58   return fseeko64 (file, offset, whence);
  59 #elif defined (HAVE_FSEEKO)
  60   return fseeko (file, offset, whence);
  61 #else
  62   return fseek (file, offset, whence);
  63 #endif
  64 }
  65
  66 FILE *
  67 real_fopen (const char *filename, const char *modes)
  68 {
  69 #if defined (HAVE_FOPEN64)
  70   return fopen64 (filename, modes);
  71 #else
  72   return fopen (filename, modes);
  73 #endif
  74 }
  75
  76 /*
  77 INTERNAL_DEFINITION
  78         struct bfd_iovec
  79
  80 DESCRIPTION
  81
  82         The <<struct bfd_iovec>> contains the internal file I/O class.
  83         Each <<BFD>> has an instance of this class and all file I/O is
  84         routed through it (it is assumed that the instance implements
  85         all methods listed below).
  86
  87 .struct bfd_iovec
  88 .{
  89 .  {* To avoid problems with macros, a "b" rather than "f"
  90 .     prefix is prepended to each method name.  *}
  91 .  {* Attempt to read/write NBYTES on ABFD's IOSTREAM storing/fetching
  92 .     bytes starting at PTR.  Return the number of bytes actually
  93 .     transfered (a read past end-of-file returns less than NBYTES),
  94 .     or -1 (setting <<bfd_error>>) if an error occurs.  *}
  95 .  file_ptr (*bread) (struct bfd *abfd, void *ptr, file_ptr nbytes);
  96 .  file_ptr (*bwrite) (struct bfd *abfd, const void *ptr,
  97 .                      file_ptr nbytes);
  98 .  {* Return the current IOSTREAM file offset, or -1 (setting <<bfd_error>>
  99 .     if an error occurs.  *}
 100 .  file_ptr (*btell) (struct bfd *abfd);
 101 .  {* For the following, on successful completion a value of 0 is returned.
 102 .     Otherwise, a value of -1 is returned (and  <<bfd_error>> is set).  *}
 103 .  int (*bseek) (struct bfd *abfd, file_ptr offset, int whence);
 104 .  int (*bclose) (struct bfd *abfd);
 105 .  int (*bflush) (struct bfd *abfd);
 106 .  int (*bstat) (struct bfd *abfd, struct stat *sb);
 107 .};
 108
 109 */
 110
 111
 112 /* Return value is amount read.  */
 113
 114 bfd_size_type
 115 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
 116 {
 117   size_t nread;
 118
 119   /* If this is an archive element, don't read past the end of
 120      this element.  */
 121   if (abfd->arelt_data != NULL)
 122     {
 123       size_t maxbytes = ((struct areltdata *) abfd->arelt_data)->parsed_size;
 124       if (size > maxbytes)
 125         size = maxbytes;
 126     }
 127
 128   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 129     {
 130       struct bfd_in_memory *bim;
 131       bfd_size_type get;
 132
 133       bim = abfd->iostream;
 134       get = size;
 135       if (abfd->where + get > bim->size)
 136         {
 137           if (bim->size < (bfd_size_type) abfd->where)
 138             get = 0;
 139           else
 140             get = bim->size - abfd->where;
 141           bfd_set_error (bfd_error_file_truncated);
 142         }
 143       memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
 144       abfd->where += get;
 145       return get;
 146     }
 147
 148   if (abfd->iovec)
 149     nread = abfd->iovec->bread (abfd, ptr, size);
 150   else
 151     nread = 0;
 152   if (nread != (size_t) -1)
 153     abfd->where += nread;
 154
 155   return nread;
 156 }
 157
 158 bfd_size_type
 159 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 160 {
 161   size_t nwrote;
 162
 163   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 164     {
 165       struct bfd_in_memory *bim = abfd->iostream;
 166
 167       size = (size_t) size;
 168       if (abfd->where + size > bim->size)
 169         {
 170           bfd_size_type newsize, oldsize;
 171
 172           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 173           bim->size = abfd->where + size;
 174           /* Round up to cut down on memory fragmentation */
 175           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 176           if (newsize > oldsize)
 177             {
 178               bim->buffer = bfd_realloc (bim->buffer, newsize);
 179               if (bim->buffer == 0)
 180                 {
 181                   bim->size = 0;
 182                   return 0;
 183                 }
 184             }
 185         }
 186       memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 187       abfd->where += size;
 188       return size;
 189     }
 190
 191   if (abfd->iovec)
 192     nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 193   else
 194     nwrote = 0;
 195
 196   if (nwrote != (size_t) -1)
 197     abfd->where += nwrote;
 198   if (nwrote != size)
 199     {
 200 #ifdef ENOSPC
 201       errno = ENOSPC;
 202 #endif
 203       bfd_set_error (bfd_error_system_call);
 204     }
 205   return nwrote;
 206 }
 207
 208 file_ptr
 209 bfd_tell (bfd *abfd)
 210 {
 211   file_ptr ptr;
 212
 213   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 214     return abfd->where;
 215
 216   if (abfd->iovec)
 217     {
 218       ptr = abfd->iovec->btell (abfd);
 219
 220       if (abfd->my_archive)
 221         ptr -= abfd->origin;
 222     }
 223   else
 224     ptr = 0;
 225
 226   abfd->where = ptr;
 227   return ptr;
 228 }
 229
 230 int
 231 bfd_flush (bfd *abfd)
 232 {
 233   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 234     return 0;
 235
 236   if (abfd->iovec)
 237     return abfd->iovec->bflush (abfd);
 238   return 0;
 239 }
 240
 241 /* Returns 0 for success, negative value for failure (in which case
 242    bfd_get_error can retrieve the error code).  */
 243 int
 244 bfd_stat (bfd *abfd, struct stat *statbuf)
 245 {
 246   int result;
 247
 248   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 249     abort ();
 250
 251   if (abfd->iovec)
 252     result = abfd->iovec->bstat (abfd, statbuf);
 253   else
 254     result = -1;
 255
 256   if (result < 0)
 257     bfd_set_error (bfd_error_system_call);
 258   return result;
 259 }
 260
 261 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 262    can retrieve the error code).  */
 263
 264 int
 265 bfd_seek (bfd *abfd, file_ptr position, int direction)
 266 {
 267   int result;
 268   file_ptr file_position;
 269   /* For the time being, a BFD may not seek to it's end.  The problem
 270      is that we don't easily have a way to recognize the end of an
 271      element in an archive.  */
 272
 273   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 274
 275   if (direction == SEEK_CUR && position == 0)
 276     return 0;
 277
 278   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 279     {
 280       struct bfd_in_memory *bim;
 281
 282       bim = abfd->iostream;
 283
 284       if (direction == SEEK_SET)
 285         abfd->where = position;
 286       else
 287         abfd->where += position;
 288
 289       if (abfd->where > bim->size)
 290         {
 291           if ((abfd->direction == write_direction) ||
 292               (abfd->direction == both_direction))
 293             {
 294               bfd_size_type newsize, oldsize;
 295
 296               oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 297               bim->size = abfd->where;
 298               /* Round up to cut down on memory fragmentation */
 299               newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 300               if (newsize > oldsize)
 301                 {
 302                   bim->buffer = bfd_realloc (bim->buffer, newsize);
 303                   if (bim->buffer == 0)
 304                     {
 305                       bim->size = 0;
 306                       return -1;
 307                     }
 308                 }
 309             }
 310           else
 311             {
 312               abfd->where = bim->size;
 313               bfd_set_error (bfd_error_file_truncated);
 314               return -1;
 315             }
 316         }
 317       return 0;
 318     }
 319
 320   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 321     {
 322       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 323         return 0;
 324     }
 325   else
 326     {
 327       /* We need something smarter to optimize access to archives.
 328          Currently, anything inside an archive is read via the file
 329          handle for the archive.  Which means that a bfd_seek on one
 330          component affects the `current position' in the archive, as
 331          well as in any other component.
 332
 333          It might be sufficient to put a spike through the cache
 334          abstraction, and look to the archive for the file position,
 335          but I think we should try for something cleaner.
 336
 337          In the meantime, no optimization for archives.  */
 338     }
 339
 340   file_position = position;
 341   if (direction == SEEK_SET && abfd->my_archive != NULL)
 342     file_position += abfd->origin;
 343
 344   if (abfd->iovec)
 345     result = abfd->iovec->bseek (abfd, file_position, direction);
 346   else
 347     result = -1;
 348
 349   if (result != 0)
 350     {
 351       int hold_errno = errno;
 352
 353       /* Force redetermination of `where' field.  */
 354       bfd_tell (abfd);
 355
 356       /* An EINVAL error probably means that the file offset was
 357          absurd.  */
 358       if (hold_errno == EINVAL)
 359         bfd_set_error (bfd_error_file_truncated);
 360       else
 361         {
 362           bfd_set_error (bfd_error_system_call);
 363           errno = hold_errno;
 364         }
 365     }
 366   else
 367     {
 368       /* Adjust `where' field.  */
 369       if (direction == SEEK_SET)
 370         abfd->where = position;
 371       else
 372         abfd->where += position;
 373     }
 374   return result;
 375 }
 376
 377 /*
 378 FUNCTION
 379         bfd_get_mtime
 380
 381 SYNOPSIS
 382         long bfd_get_mtime (bfd *abfd);
 383
 384 DESCRIPTION
 385         Return the file modification time (as read from the file system, or
 386         from the archive header for archive members).
 387
 388 */
 389
 390 long
 391 bfd_get_mtime (bfd *abfd)
 392 {
 393   struct stat buf;
 394
 395   if (abfd->mtime_set)
 396     return abfd->mtime;
 397
 398   if (abfd->iovec == NULL)
 399     return 0;
 400
 401   if (abfd->iovec->bstat (abfd, &buf) != 0)
 402     return 0;
 403
 404   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 405   return buf.st_mtime;
 406 }
 407
 408 /*
 409 FUNCTION
 410         bfd_get_size
 411
 412 SYNOPSIS
 413         file_ptr bfd_get_size (bfd *abfd);
 414
 415 DESCRIPTION
 416         Return the file size (as read from file system) for the file
 417         associated with BFD @var{abfd}.
 418
 419         The initial motivation for, and use of, this routine is not
 420         so we can get the exact size of the object the BFD applies to, since
 421         that might not be generally possible (archive members for example).
 422         It would be ideal if someone could eventually modify
 423         it so that such results were guaranteed.
 424
 425         Instead, we want to ask questions like "is this NNN byte sized
 426         object I'm about to try read from file offset YYY reasonable?"
 427         As as example of where we might do this, some object formats
 428         use string tables for which the first <<sizeof (long)>> bytes of the
 429         table contain the size of the table itself, including the size bytes.
 430         If an application tries to read what it thinks is one of these
 431         string tables, without some way to validate the size, and for
 432         some reason the size is wrong (byte swapping error, wrong location
 433         for the string table, etc.), the only clue is likely to be a read
 434         error when it tries to read the table, or a "virtual memory
 435         exhausted" error when it tries to allocate 15 bazillon bytes
 436         of space for the 15 bazillon byte table it is about to read.
 437         This function at least allows us to answer the question, "is the
 438         size reasonable?".
 439 */
 440
 441 file_ptr
 442 bfd_get_size (bfd *abfd)
 443 {
 444   struct stat buf;
 445
 446   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 447     return ((struct bfd_in_memory *) abfd->iostream)->size;
 448
 449   if (abfd->iovec == NULL)
 450     return 0;
 451
 452   if (abfd->iovec->bstat (abfd, &buf) != 0)
 453     return 0;
 454
 455   return buf.st_size;
 456 }