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
   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 ((abfd->flags & BFD_IN_MEMORY) != 0)
 120     {
 121       struct bfd_in_memory *bim;
 122       bfd_size_type get;
 123
 124       bim = abfd->iostream;
 125       get = size;
 126       if (abfd->where + get > bim->size)
 127         {
 128           if (bim->size < (bfd_size_type) abfd->where)
 129             get = 0;
 130           else
 131             get = bim->size - abfd->where;
 132           bfd_set_error (bfd_error_file_truncated);
 133         }
 134       memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
 135       abfd->where += get;
 136       return get;
 137     }
 138
 139   if (abfd->iovec)
 140     nread = abfd->iovec->bread (abfd, ptr, size);
 141   else
 142     nread = 0;
 143   if (nread != (size_t) -1)
 144     abfd->where += nread;
 145
 146   return nread;
 147 }
 148
 149 bfd_size_type
 150 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 151 {
 152   size_t nwrote;
 153
 154   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 155     {
 156       struct bfd_in_memory *bim = abfd->iostream;
 157
 158       size = (size_t) size;
 159       if (abfd->where + size > bim->size)
 160         {
 161           bfd_size_type newsize, oldsize;
 162
 163           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 164           bim->size = abfd->where + size;
 165           /* Round up to cut down on memory fragmentation */
 166           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 167           if (newsize > oldsize)
 168             {
 169               bim->buffer = bfd_realloc (bim->buffer, newsize);
 170               if (bim->buffer == 0)
 171                 {
 172                   bim->size = 0;
 173                   return 0;
 174                 }
 175             }
 176         }
 177       memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 178       abfd->where += size;
 179       return size;
 180     }
 181
 182   if (abfd->iovec)
 183     nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 184   else
 185     nwrote = 0;
 186
 187   if (nwrote != (size_t) -1)
 188     abfd->where += nwrote;
 189   if (nwrote != size)
 190     {
 191 #ifdef ENOSPC
 192       errno = ENOSPC;
 193 #endif
 194       bfd_set_error (bfd_error_system_call);
 195     }
 196   return nwrote;
 197 }
 198
 199 file_ptr
 200 bfd_tell (bfd *abfd)
 201 {
 202   file_ptr ptr;
 203
 204   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 205     return abfd->where;
 206
 207   if (abfd->iovec)
 208     {
 209       ptr = abfd->iovec->btell (abfd);
 210
 211       if (abfd->my_archive)
 212         ptr -= abfd->origin;
 213     }
 214   else
 215     ptr = 0;
 216
 217   abfd->where = ptr;
 218   return ptr;
 219 }
 220
 221 int
 222 bfd_flush (bfd *abfd)
 223 {
 224   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 225     return 0;
 226
 227   if (abfd->iovec)
 228     return abfd->iovec->bflush (abfd);
 229   return 0;
 230 }
 231
 232 /* Returns 0 for success, negative value for failure (in which case
 233    bfd_get_error can retrieve the error code).  */
 234 int
 235 bfd_stat (bfd *abfd, struct stat *statbuf)
 236 {
 237   int result;
 238
 239   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 240     abort ();
 241
 242   if (abfd->iovec)
 243     result = abfd->iovec->bstat (abfd, statbuf);
 244   else
 245     result = -1;
 246
 247   if (result < 0)
 248     bfd_set_error (bfd_error_system_call);
 249   return result;
 250 }
 251
 252 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 253    can retrieve the error code).  */
 254
 255 int
 256 bfd_seek (bfd *abfd, file_ptr position, int direction)
 257 {
 258   int result;
 259   file_ptr file_position;
 260   /* For the time being, a BFD may not seek to it's end.  The problem
 261      is that we don't easily have a way to recognize the end of an
 262      element in an archive.  */
 263
 264   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 265
 266   if (direction == SEEK_CUR && position == 0)
 267     return 0;
 268
 269   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 270     {
 271       struct bfd_in_memory *bim;
 272
 273       bim = abfd->iostream;
 274
 275       if (direction == SEEK_SET)
 276         abfd->where = position;
 277       else
 278         abfd->where += position;
 279
 280       if (abfd->where > bim->size)
 281         {
 282           if ((abfd->direction == write_direction) ||
 283               (abfd->direction == both_direction))
 284             {
 285               bfd_size_type newsize, oldsize;
 286
 287               oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 288               bim->size = abfd->where;
 289               /* Round up to cut down on memory fragmentation */
 290               newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 291               if (newsize > oldsize)
 292                 {
 293                   bim->buffer = bfd_realloc (bim->buffer, newsize);
 294                   if (bim->buffer == 0)
 295                     {
 296                       bim->size = 0;
 297                       return -1;
 298                     }
 299                 }
 300             }
 301           else
 302             {
 303               abfd->where = bim->size;
 304               bfd_set_error (bfd_error_file_truncated);
 305               return -1;
 306             }
 307         }
 308       return 0;
 309     }
 310
 311   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 312     {
 313       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 314         return 0;
 315     }
 316   else
 317     {
 318       /* We need something smarter to optimize access to archives.
 319          Currently, anything inside an archive is read via the file
 320          handle for the archive.  Which means that a bfd_seek on one
 321          component affects the `current position' in the archive, as
 322          well as in any other component.
 323
 324          It might be sufficient to put a spike through the cache
 325          abstraction, and look to the archive for the file position,
 326          but I think we should try for something cleaner.
 327
 328          In the meantime, no optimization for archives.  */
 329     }
 330
 331   file_position = position;
 332   if (direction == SEEK_SET && abfd->my_archive != NULL)
 333     file_position += abfd->origin;
 334
 335   if (abfd->iovec)
 336     result = abfd->iovec->bseek (abfd, file_position, direction);
 337   else
 338     result = -1;
 339
 340   if (result != 0)
 341     {
 342       int hold_errno = errno;
 343
 344       /* Force redetermination of `where' field.  */
 345       bfd_tell (abfd);
 346
 347       /* An EINVAL error probably means that the file offset was
 348          absurd.  */
 349       if (hold_errno == EINVAL)
 350         bfd_set_error (bfd_error_file_truncated);
 351       else
 352         {
 353           bfd_set_error (bfd_error_system_call);
 354           errno = hold_errno;
 355         }
 356     }
 357   else
 358     {
 359       /* Adjust `where' field.  */
 360       if (direction == SEEK_SET)
 361         abfd->where = position;
 362       else
 363         abfd->where += position;
 364     }
 365   return result;
 366 }
 367
 368 /*
 369 FUNCTION
 370         bfd_get_mtime
 371
 372 SYNOPSIS
 373         long bfd_get_mtime (bfd *abfd);
 374
 375 DESCRIPTION
 376         Return the file modification time (as read from the file system, or
 377         from the archive header for archive members).
 378
 379 */
 380
 381 long
 382 bfd_get_mtime (bfd *abfd)
 383 {
 384   struct stat buf;
 385
 386   if (abfd->mtime_set)
 387     return abfd->mtime;
 388
 389   if (abfd->iovec == NULL)
 390     return 0;
 391
 392   if (abfd->iovec->bstat (abfd, &buf) != 0)
 393     return 0;
 394
 395   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 396   return buf.st_mtime;
 397 }
 398
 399 /*
 400 FUNCTION
 401         bfd_get_size
 402
 403 SYNOPSIS
 404         long bfd_get_size (bfd *abfd);
 405
 406 DESCRIPTION
 407         Return the file size (as read from file system) for the file
 408         associated with BFD @var{abfd}.
 409
 410         The initial motivation for, and use of, this routine is not
 411         so we can get the exact size of the object the BFD applies to, since
 412         that might not be generally possible (archive members for example).
 413         It would be ideal if someone could eventually modify
 414         it so that such results were guaranteed.
 415
 416         Instead, we want to ask questions like "is this NNN byte sized
 417         object I'm about to try read from file offset YYY reasonable?"
 418         As as example of where we might do this, some object formats
 419         use string tables for which the first <<sizeof (long)>> bytes of the
 420         table contain the size of the table itself, including the size bytes.
 421         If an application tries to read what it thinks is one of these
 422         string tables, without some way to validate the size, and for
 423         some reason the size is wrong (byte swapping error, wrong location
 424         for the string table, etc.), the only clue is likely to be a read
 425         error when it tries to read the table, or a "virtual memory
 426         exhausted" error when it tries to allocate 15 bazillon bytes
 427         of space for the 15 bazillon byte table it is about to read.
 428         This function at least allows us to answer the question, "is the
 429         size reasonable?".
 430 */
 431
 432 long
 433 bfd_get_size (bfd *abfd)
 434 {
 435   struct stat buf;
 436
 437   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 438     return ((struct bfd_in_memory *) abfd->iostream)->size;
 439
 440   if (abfd->iovec == NULL)
 441     return 0;
 442
 443   if (abfd->iovec->bstat (abfd, &buf) != 0)
 444     return 0;
 445
 446   return buf.st_size;
 447 }