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 .};
 162
 163 */
 164
 165
 166 /* Return value is amount read.  */
 167
 168 bfd_size_type
 169 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
 170 {
 171   size_t nread;
 172
 173   /* If this is an archive element, don't read past the end of
 174      this element.  */
 175   if (abfd->arelt_data != NULL)
 176     {
 177       size_t maxbytes = ((struct areltdata *) abfd->arelt_data)->parsed_size;
 178       if (size > maxbytes)
 179         size = maxbytes;
 180     }
 181
 182   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 183     {
 184       struct bfd_in_memory *bim;
 185       bfd_size_type get;
 186
 187       bim = abfd->iostream;
 188       get = size;
 189       if (abfd->where + get > bim->size)
 190         {
 191           if (bim->size < (bfd_size_type) abfd->where)
 192             get = 0;
 193           else
 194             get = bim->size - abfd->where;
 195           bfd_set_error (bfd_error_file_truncated);
 196         }
 197       memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
 198       abfd->where += get;
 199       return get;
 200     }
 201
 202   if (abfd->iovec)
 203     nread = abfd->iovec->bread (abfd, ptr, size);
 204   else
 205     nread = 0;
 206   if (nread != (size_t) -1)
 207     abfd->where += nread;
 208
 209   return nread;
 210 }
 211
 212 bfd_size_type
 213 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 214 {
 215   size_t nwrote;
 216
 217   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 218     {
 219       struct bfd_in_memory *bim = abfd->iostream;
 220
 221       size = (size_t) size;
 222       if (abfd->where + size > bim->size)
 223         {
 224           bfd_size_type newsize, oldsize;
 225
 226           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 227           bim->size = abfd->where + size;
 228           /* Round up to cut down on memory fragmentation */
 229           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 230           if (newsize > oldsize)
 231             {
 232               bim->buffer = bfd_realloc_or_free (bim->buffer, newsize);
 233               if (bim->buffer == NULL)
 234                 {
 235                   bim->size = 0;
 236                   return 0;
 237                 }
 238             }
 239         }
 240       memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 241       abfd->where += size;
 242       return size;
 243     }
 244
 245   if (abfd->iovec)
 246     nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 247   else
 248     nwrote = 0;
 249
 250   if (nwrote != (size_t) -1)
 251     abfd->where += nwrote;
 252   if (nwrote != size)
 253     {
 254 #ifdef ENOSPC
 255       errno = ENOSPC;
 256 #endif
 257       bfd_set_error (bfd_error_system_call);
 258     }
 259   return nwrote;
 260 }
 261
 262 file_ptr
 263 bfd_tell (bfd *abfd)
 264 {
 265   file_ptr ptr;
 266
 267   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 268     return abfd->where;
 269
 270   if (abfd->iovec)
 271     {
 272       ptr = abfd->iovec->btell (abfd);
 273
 274       if (abfd->my_archive)
 275         ptr -= abfd->origin;
 276     }
 277   else
 278     ptr = 0;
 279
 280   abfd->where = ptr;
 281   return ptr;
 282 }
 283
 284 int
 285 bfd_flush (bfd *abfd)
 286 {
 287   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 288     return 0;
 289
 290   if (abfd->iovec)
 291     return abfd->iovec->bflush (abfd);
 292   return 0;
 293 }
 294
 295 /* Returns 0 for success, negative value for failure (in which case
 296    bfd_get_error can retrieve the error code).  */
 297 int
 298 bfd_stat (bfd *abfd, struct stat *statbuf)
 299 {
 300   int result;
 301
 302   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 303     abort ();
 304
 305   if (abfd->iovec)
 306     result = abfd->iovec->bstat (abfd, statbuf);
 307   else
 308     result = -1;
 309
 310   if (result < 0)
 311     bfd_set_error (bfd_error_system_call);
 312   return result;
 313 }
 314
 315 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 316    can retrieve the error code).  */
 317
 318 int
 319 bfd_seek (bfd *abfd, file_ptr position, int direction)
 320 {
 321   int result;
 322   file_ptr file_position;
 323   /* For the time being, a BFD may not seek to it's end.  The problem
 324      is that we don't easily have a way to recognize the end of an
 325      element in an archive.  */
 326
 327   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 328
 329   if (direction == SEEK_CUR && position == 0)
 330     return 0;
 331
 332   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 333     {
 334       struct bfd_in_memory *bim;
 335
 336       bim = abfd->iostream;
 337
 338       if (direction == SEEK_SET)
 339         abfd->where = position;
 340       else
 341         abfd->where += position;
 342
 343       if (abfd->where > bim->size)
 344         {
 345           if ((abfd->direction == write_direction) ||
 346               (abfd->direction == both_direction))
 347             {
 348               bfd_size_type newsize, oldsize;
 349
 350               oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 351               bim->size = abfd->where;
 352               /* Round up to cut down on memory fragmentation */
 353               newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 354               if (newsize > oldsize)
 355                 {
 356                   bim->buffer = bfd_realloc_or_free (bim->buffer, newsize);
 357                   if (bim->buffer == NULL)
 358                     {
 359                       bim->size = 0;
 360                       return -1;
 361                     }
 362                 }
 363             }
 364           else
 365             {
 366               abfd->where = bim->size;
 367               bfd_set_error (bfd_error_file_truncated);
 368               return -1;
 369             }
 370         }
 371       return 0;
 372     }
 373
 374   if (abfd->format != bfd_archive && abfd->my_archive == 0)
 375     {
 376       if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
 377         return 0;
 378     }
 379   else
 380     {
 381       /* We need something smarter to optimize access to archives.
 382          Currently, anything inside an archive is read via the file
 383          handle for the archive.  Which means that a bfd_seek on one
 384          component affects the `current position' in the archive, as
 385          well as in any other component.
 386
 387          It might be sufficient to put a spike through the cache
 388          abstraction, and look to the archive for the file position,
 389          but I think we should try for something cleaner.
 390
 391          In the meantime, no optimization for archives.  */
 392     }
 393
 394   file_position = position;
 395   if (direction == SEEK_SET && abfd->my_archive != NULL)
 396     file_position += abfd->origin;
 397
 398   if (abfd->iovec)
 399     result = abfd->iovec->bseek (abfd, file_position, direction);
 400   else
 401     result = -1;
 402
 403   if (result != 0)
 404     {
 405       int hold_errno = errno;
 406
 407       /* Force redetermination of `where' field.  */
 408       bfd_tell (abfd);
 409
 410       /* An EINVAL error probably means that the file offset was
 411          absurd.  */
 412       if (hold_errno == EINVAL)
 413         bfd_set_error (bfd_error_file_truncated);
 414       else
 415         {
 416           bfd_set_error (bfd_error_system_call);
 417           errno = hold_errno;
 418         }
 419     }
 420   else
 421     {
 422       /* Adjust `where' field.  */
 423       if (direction == SEEK_SET)
 424         abfd->where = position;
 425       else
 426         abfd->where += position;
 427     }
 428   return result;
 429 }
 430
 431 /*
 432 FUNCTION
 433         bfd_get_mtime
 434
 435 SYNOPSIS
 436         long bfd_get_mtime (bfd *abfd);
 437
 438 DESCRIPTION
 439         Return the file modification time (as read from the file system, or
 440         from the archive header for archive members).
 441
 442 */
 443
 444 long
 445 bfd_get_mtime (bfd *abfd)
 446 {
 447   struct stat buf;
 448
 449   if (abfd->mtime_set)
 450     return abfd->mtime;
 451
 452   if (abfd->iovec == NULL)
 453     return 0;
 454
 455   if (abfd->iovec->bstat (abfd, &buf) != 0)
 456     return 0;
 457
 458   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 459   return buf.st_mtime;
 460 }
 461
 462 /*
 463 FUNCTION
 464         bfd_get_size
 465
 466 SYNOPSIS
 467         file_ptr bfd_get_size (bfd *abfd);
 468
 469 DESCRIPTION
 470         Return the file size (as read from file system) for the file
 471         associated with BFD @var{abfd}.
 472
 473         The initial motivation for, and use of, this routine is not
 474         so we can get the exact size of the object the BFD applies to, since
 475         that might not be generally possible (archive members for example).
 476         It would be ideal if someone could eventually modify
 477         it so that such results were guaranteed.
 478
 479         Instead, we want to ask questions like "is this NNN byte sized
 480         object I'm about to try read from file offset YYY reasonable?"
 481         As as example of where we might do this, some object formats
 482         use string tables for which the first <<sizeof (long)>> bytes of the
 483         table contain the size of the table itself, including the size bytes.
 484         If an application tries to read what it thinks is one of these
 485         string tables, without some way to validate the size, and for
 486         some reason the size is wrong (byte swapping error, wrong location
 487         for the string table, etc.), the only clue is likely to be a read
 488         error when it tries to read the table, or a "virtual memory
 489         exhausted" error when it tries to allocate 15 bazillon bytes
 490         of space for the 15 bazillon byte table it is about to read.
 491         This function at least allows us to answer the question, "is the
 492         size reasonable?".
 493 */
 494
 495 file_ptr
 496 bfd_get_size (bfd *abfd)
 497 {
 498   struct stat buf;
 499
 500   if ((abfd->flags & BFD_IN_MEMORY) != 0)
 501     return ((struct bfd_in_memory *) abfd->iostream)->size;
 502
 503   if (abfd->iovec == NULL)
 504     return 0;
 505
 506   if (abfd->iovec->bstat (abfd, &buf) != 0)
 507     return 0;
 508
 509   return buf.st_size;
 510 }