bfd/bfdio.c

   1 /* Low-level I/O routines for BFDs.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
   3    2000, 2001, 2002, 2003 Free Software Foundation, Inc.
   4    Written by Cygnus Support.
   5
   6 This file is part of BFD, the Binary File Descriptor library.
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or
  11 (at your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 #include "sysdep.h"
  23
  24 #include "bfd.h"
  25 #include "libbfd.h"
  26
  27 #include <limits.h>
  28
  29 #ifndef S_IXUSR
  30 #define S_IXUSR 0100    /* Execute by owner.  */
  31 #endif
  32 #ifndef S_IXGRP
  33 #define S_IXGRP 0010    /* Execute by group.  */
  34 #endif
  35 #ifndef S_IXOTH
  36 #define S_IXOTH 0001    /* Execute by others.  */
  37 #endif
  38
  39 /* Note that archive entries don't have streams; they share their parent's.
  40    This allows someone to play with the iostream behind BFD's back.
  41
  42    Also, note that the origin pointer points to the beginning of a file's
  43    contents (0 for non-archive elements).  For archive entries this is the
  44    first octet in the file, NOT the beginning of the archive header.  */
  45
  46 static size_t
  47 real_read (void *where, size_t a, size_t b, FILE *file)
  48 {
  49   /* FIXME - this looks like an optimization, but it's really to cover
  50      up for a feature of some OSs (not solaris - sigh) that
  51      ld/pe-dll.c takes advantage of (apparently) when it creates BFDs
  52      internally and tries to link against them.  BFD seems to be smart
  53      enough to realize there are no symbol records in the "file" that
  54      doesn't exist but attempts to read them anyway.  On Solaris,
  55      attempting to read zero bytes from a NULL file results in a core
  56      dump, but on other platforms it just returns zero bytes read.
  57      This makes it to something reasonable. - DJ */
  58   if (a == 0 || b == 0)
  59     return 0;
  60
  61
  62 #if defined (__VAX) && defined (VMS)
  63   /* Apparently fread on Vax VMS does not keep the record length
  64      information.  */
  65   return read (fileno (file), where, a * b);
  66 #else
  67   return fread (where, a, b, file);
  68 #endif
  69 }
  70
  71 /* Return value is amount read.  */
  72
  73 bfd_size_type
  74 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
  75 {
  76   size_t nread;
  77
  78   if ((abfd->flags & BFD_IN_MEMORY) != 0)
  79     {
  80       struct bfd_in_memory *bim;
  81       bfd_size_type get;
  82
  83       bim = abfd->iostream;
  84       get = size;
  85       if (abfd->where + get > bim->size)
  86         {
  87           if (bim->size < (bfd_size_type) abfd->where)
  88             get = 0;
  89           else
  90             get = bim->size - abfd->where;
  91           bfd_set_error (bfd_error_file_truncated);
  92         }
  93       memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
  94       abfd->where += get;
  95       return get;
  96     }
  97
  98   nread = real_read (ptr, 1, (size_t) size, bfd_cache_lookup (abfd));
  99   if (nread != (size_t) -1)
 100     abfd->where += nread;
 101
 102   /* Set bfd_error if we did not read as much data as we expected.
 103
 104      If the read failed due to an error set the bfd_error_system_call,
 105      else set bfd_error_file_truncated.
 106
 107      A BFD backend may wish to override bfd_error_file_truncated to
 108      provide something more useful (eg. no_symbols or wrong_format).  */
 109   if (nread != size)
 110     {
 111       if (ferror (bfd_cache_lookup (abfd)))
 112         bfd_set_error (bfd_error_system_call);
 113       else
 114         bfd_set_error (bfd_error_file_truncated);
 115     }
 116
 117   return nread;
 118 }
 119
 120 bfd_size_type
 121 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 122 {
 123   size_t nwrote;
 124
 125   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 126     {
 127       struct bfd_in_memory *bim = abfd->iostream;
 128       size = (size_t) size;
 129       if (abfd->where + size > bim->size)
 130         {
 131           bfd_size_type newsize, oldsize;
 132
 133           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 134           bim->size = abfd->where + size;
 135           /* Round up to cut down on memory fragmentation */
 136           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 137           if (newsize > oldsize)
 138             {
 139               bim->buffer = bfd_realloc (bim->buffer, newsize);
 140               if (bim->buffer == 0)
 141                 {
 142                   bim->size = 0;
 143                   return 0;
 144                 }
 145             }
 146         }
 147       memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 148       abfd->where += size;
 149       return size;
 150     }
 151
 152   nwrote = fwrite (ptr, 1, (size_t) size, bfd_cache_lookup (abfd));
 153   if (nwrote != (size_t) -1)
 154     abfd->where += nwrote;
 155   if (nwrote != size)
 156     {
 157 #ifdef ENOSPC
 158       errno = ENOSPC;
 159 #endif
 160       bfd_set_error (bfd_error_system_call);
 161     }
 162   return nwrote;
 163 }
 164
 165 bfd_vma
 166 bfd_tell (bfd *abfd)
 167 {
 168   file_ptr ptr;
 169
 170   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 171     return abfd->where;
 172
 173   ptr = ftell (bfd_cache_lookup (abfd));
 174
 175   if (abfd->my_archive)
 176     ptr -= abfd->origin;
 177   abfd->where = ptr;
 178   return ptr;
 179 }
 180
 181 int
 182 bfd_flush (bfd *abfd)
 183 {
 184   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 185     return 0;
 186   return fflush (bfd_cache_lookup(abfd));
 187 }
 188
 189 /* Returns 0 for success, negative value for failure (in which case
 190    bfd_get_error can retrieve the error code).  */
 191 int
 192 bfd_stat (bfd *abfd, struct stat *statbuf)
 193 {
 194   FILE *f;
 195   int result;
 196
 197   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 198     abort ();
 199
 200   f = bfd_cache_lookup (abfd);
 201   if (f == NULL)
 202     {
 203       bfd_set_error (bfd_error_system_call);
 204       return -1;
 205     }
 206   result = fstat (fileno (f), statbuf);
 207   if (result < 0)
 208     bfd_set_error (bfd_error_system_call);
 209   return result;
 210 }
 211
 212 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 213    can retrieve the error code).  */
 214
 215 int
 216 bfd_seek (bfd *abfd, file_ptr position, int direction)
 217 {
 218   int result;
 219   FILE *f;
 220   long file_position;
 221   /* For the time being, a BFD may not seek to it's end.  The problem
 222      is that we don't easily have a way to recognize the end of an
 223      element in an archive.  */
 224
 225   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 226
 227   if (direction == SEEK_CUR && position == 0)
 228     return 0;
 229
 230   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 231     {
 232       struct bfd_in_memory *bim;
 233
 234       bim = abfd->iostream;
 235
 236       if (direction == SEEK_SET)
 237         abfd->where = position;
 238       else
 239         abfd->where += position;
 240
 241       if (abfd->where > bim->size)
 242         {
 243           if ((abfd->direction == write_direction) ||
 244               (abfd->direction == both_direction))
 245             {
 246               bfd_size_type newsize, oldsize;
 247               oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 248               bim->size = abfd->where;
 249               /* Round up to cut down on memory fragmentation */
 250               newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 251               if (newsize > oldsize)
 252                 {
 253                   bim->buffer = bfd_realloc (bim->buffer, newsize);
 254                   if (bim->buffer == 0)
 255                     {
 256                       bim->size = 0;
 257                       return -1;
 258                     }
 259                 }
 260             }
 261           else
 262             {
 263               abfd->where = bim->size;
 264               bfd_set_error (bfd_error_file_truncated);
 265               return -1;
 266             }
 267         }
 268       return 0;
 269     }
 270
 271   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 272     {
 273 #if 0
 274       /* Explanation for this code: I'm only about 95+% sure that the above
 275          conditions are sufficient and that all i/o calls are properly
 276          adjusting the `where' field.  So this is sort of an `assert'
 277          that the `where' field is correct.  If we can go a while without
 278          tripping the abort, we can probably safely disable this code,
 279          so that the real optimizations happen.  */
 280       file_ptr where_am_i_now;
 281       where_am_i_now = ftell (bfd_cache_lookup (abfd));
 282       if (abfd->my_archive)
 283         where_am_i_now -= abfd->origin;
 284       if (where_am_i_now != abfd->where)
 285         abort ();
 286 #endif
 287       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 288         return 0;
 289     }
 290   else
 291     {
 292       /* We need something smarter to optimize access to archives.
 293          Currently, anything inside an archive is read via the file
 294          handle for the archive.  Which means that a bfd_seek on one
 295          component affects the `current position' in the archive, as
 296          well as in any other component.
 297
 298          It might be sufficient to put a spike through the cache
 299          abstraction, and look to the archive for the file position,
 300          but I think we should try for something cleaner.
 301
 302          In the meantime, no optimization for archives.  */
 303     }
 304
 305   f = bfd_cache_lookup (abfd);
 306   file_position = position;
 307   if (direction == SEEK_SET && abfd->my_archive != NULL)
 308     file_position += abfd->origin;
 309
 310   result = fseek (f, file_position, direction);
 311   if (result != 0)
 312     {
 313       int hold_errno = errno;
 314
 315       /* Force redetermination of `where' field.  */
 316       bfd_tell (abfd);
 317
 318       /* An EINVAL error probably means that the file offset was
 319          absurd.  */
 320       if (hold_errno == EINVAL)
 321         bfd_set_error (bfd_error_file_truncated);
 322       else
 323         {
 324           bfd_set_error (bfd_error_system_call);
 325           errno = hold_errno;
 326         }
 327     }
 328   else
 329     {
 330       /* Adjust `where' field.  */
 331       if (direction == SEEK_SET)
 332         abfd->where = position;
 333       else
 334         abfd->where += position;
 335     }
 336   return result;
 337 }
 338
 339 /*
 340 FUNCTION
 341         bfd_get_mtime
 342
 343 SYNOPSIS
 344         long bfd_get_mtime (bfd *abfd);
 345
 346 DESCRIPTION
 347         Return the file modification time (as read from the file system, or
 348         from the archive header for archive members).
 349
 350 */
 351
 352 long
 353 bfd_get_mtime (bfd *abfd)
 354 {
 355   FILE *fp;
 356   struct stat buf;
 357
 358   if (abfd->mtime_set)
 359     return abfd->mtime;
 360
 361   fp = bfd_cache_lookup (abfd);
 362   if (0 != fstat (fileno (fp), &buf))
 363     return 0;
 364
 365   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 366   return buf.st_mtime;
 367 }
 368
 369 /*
 370 FUNCTION
 371         bfd_get_size
 372
 373 SYNOPSIS
 374         long bfd_get_size (bfd *abfd);
 375
 376 DESCRIPTION
 377         Return the file size (as read from file system) for the file
 378         associated with BFD @var{abfd}.
 379
 380         The initial motivation for, and use of, this routine is not
 381         so we can get the exact size of the object the BFD applies to, since
 382         that might not be generally possible (archive members for example).
 383         It would be ideal if someone could eventually modify
 384         it so that such results were guaranteed.
 385
 386         Instead, we want to ask questions like "is this NNN byte sized
 387         object I'm about to try read from file offset YYY reasonable?"
 388         As as example of where we might do this, some object formats
 389         use string tables for which the first <<sizeof (long)>> bytes of the
 390         table contain the size of the table itself, including the size bytes.
 391         If an application tries to read what it thinks is one of these
 392         string tables, without some way to validate the size, and for
 393         some reason the size is wrong (byte swapping error, wrong location
 394         for the string table, etc.), the only clue is likely to be a read
 395         error when it tries to read the table, or a "virtual memory
 396         exhausted" error when it tries to allocate 15 bazillon bytes
 397         of space for the 15 bazillon byte table it is about to read.
 398         This function at least allows us to answer the question, "is the
 399         size reasonable?".
 400 */
 401
 402 long
 403 bfd_get_size (bfd *abfd)
 404 {
 405   FILE *fp;
 406   struct stat buf;
 407
 408   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 409     return ((struct bfd_in_memory *) abfd->iostream)->size;
 410
 411   fp = bfd_cache_lookup (abfd);
 412   if (0 != fstat (fileno (fp), & buf))
 413     return 0;
 414
 415   return buf.st_size;
 416 }