bfd/bfdio.c

   1 /* Low-level I/O routines for BFDs.
   2
   3    Copyright (C) 1990-2020 Free Software Foundation, Inc.
   4
   5    Written by Cygnus Support.
   6
   7    This file is part of BFD, the Binary File Descriptor library.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  22    MA 02110-1301, USA.  */
  23
  24 #include "sysdep.h"
  25 #include <limits.h>
  26 #include "bfd.h"
  27 #include "libbfd.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 #ifndef FD_CLOEXEC
  40 #define FD_CLOEXEC 1
  41 #endif
  42
  43 file_ptr
  44 _bfd_real_ftell (FILE *file)
  45 {
  46 #if defined (HAVE_FTELLO64)
  47   return ftello64 (file);
  48 #elif defined (HAVE_FTELLO)
  49   return ftello (file);
  50 #else
  51   return ftell (file);
  52 #endif
  53 }
  54
  55 int
  56 _bfd_real_fseek (FILE *file, file_ptr offset, int whence)
  57 {
  58 #if defined (HAVE_FSEEKO64)
  59   return fseeko64 (file, offset, whence);
  60 #elif defined (HAVE_FSEEKO)
  61   return fseeko (file, offset, whence);
  62 #else
  63   return fseek (file, offset, whence);
  64 #endif
  65 }
  66
  67 /* Mark FILE as close-on-exec.  Return FILE.  FILE may be NULL, in
  68    which case nothing is done.  */
  69 static FILE *
  70 close_on_exec (FILE *file)
  71 {
  72 #if defined (HAVE_FILENO) && defined (F_GETFD)
  73   if (file)
  74     {
  75       int fd = fileno (file);
  76       int old = fcntl (fd, F_GETFD, 0);
  77       if (old >= 0)
  78         fcntl (fd, F_SETFD, old | FD_CLOEXEC);
  79     }
  80 #endif
  81   return file;
  82 }
  83
  84 FILE *
  85 _bfd_real_fopen (const char *filename, const char *modes)
  86 {
  87 #ifdef VMS
  88   char *vms_attr;
  89
  90   /* On VMS, fopen allows file attributes as optional arguments.
  91      We need to use them but we'd better to use the common prototype.
  92      In fopen-vms.h, they are separated from the mode with a comma.
  93      Split here.  */
  94   vms_attr = strchr (modes, ',');
  95   if (vms_attr == NULL)
  96     {
  97       /* No attributes.  */
  98       return close_on_exec (fopen (filename, modes));
  99     }
 100   else
 101     {
 102       /* Attributes found.  Split.  */
 103       size_t modes_len = strlen (modes) + 1;
 104       char attrs[modes_len + 1];
 105       char *at[3];
 106       int i;
 107
 108       memcpy (attrs, modes, modes_len);
 109       at[0] = attrs;
 110       for (i = 0; i < 2; i++)
 111         {
 112           at[i + 1] = strchr (at[i], ',');
 113           BFD_ASSERT (at[i + 1] != NULL);
 114           *(at[i + 1]++) = 0; /* Replace ',' with a nul, and skip it.  */
 115         }
 116       return close_on_exec (fopen (filename, at[0], at[1], at[2]));
 117     }
 118 #else /* !VMS */
 119 #if defined (HAVE_FOPEN64)
 120   return close_on_exec (fopen64 (filename, modes));
 121 #else
 122   return close_on_exec (fopen (filename, modes));
 123 #endif
 124 #endif /* !VMS */
 125 }
 126
 127 /*
 128 INTERNAL_DEFINITION
 129         struct bfd_iovec
 130
 131 DESCRIPTION
 132
 133         The <<struct bfd_iovec>> contains the internal file I/O class.
 134         Each <<BFD>> has an instance of this class and all file I/O is
 135         routed through it (it is assumed that the instance implements
 136         all methods listed below).
 137
 138 .struct bfd_iovec
 139 .{
 140 .  {* To avoid problems with macros, a "b" rather than "f"
 141 .     prefix is prepended to each method name.  *}
 142 .  {* Attempt to read/write NBYTES on ABFD's IOSTREAM storing/fetching
 143 .     bytes starting at PTR.  Return the number of bytes actually
 144 .     transfered (a read past end-of-file returns less than NBYTES),
 145 .     or -1 (setting <<bfd_error>>) if an error occurs.  *}
 146 .  file_ptr (*bread) (struct bfd *abfd, void *ptr, file_ptr nbytes);
 147 .  file_ptr (*bwrite) (struct bfd *abfd, const void *ptr,
 148 .                      file_ptr nbytes);
 149 .  {* Return the current IOSTREAM file offset, or -1 (setting <<bfd_error>>
 150 .     if an error occurs.  *}
 151 .  file_ptr (*btell) (struct bfd *abfd);
 152 .  {* For the following, on successful completion a value of 0 is returned.
 153 .     Otherwise, a value of -1 is returned (and <<bfd_error>> is set).  *}
 154 .  int (*bseek) (struct bfd *abfd, file_ptr offset, int whence);
 155 .  int (*bclose) (struct bfd *abfd);
 156 .  int (*bflush) (struct bfd *abfd);
 157 .  int (*bstat) (struct bfd *abfd, struct stat *sb);
 158 .  {* Mmap a part of the files. ADDR, LEN, PROT, FLAGS and OFFSET are the usual
 159 .     mmap parameter, except that LEN and OFFSET do not need to be page
 160 .     aligned.  Returns (void *)-1 on failure, mmapped address on success.
 161 .     Also write in MAP_ADDR the address of the page aligned buffer and in
 162 .     MAP_LEN the size mapped (a page multiple).  Use unmap with MAP_ADDR and
 163 .     MAP_LEN to unmap.  *}
 164 .  void *(*bmmap) (struct bfd *abfd, void *addr, bfd_size_type len,
 165 .                  int prot, int flags, file_ptr offset,
 166 .                  void **map_addr, bfd_size_type *map_len);
 167 .};
 168
 169 .extern const struct bfd_iovec _bfd_memory_iovec;
 170
 171 */
 172
 173
 174 /* Return value is amount read.  */
 175
 176 bfd_size_type
 177 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
 178 {
 179   file_ptr nread;
 180   bfd *element_bfd = abfd;
 181   ufile_ptr offset = 0;
 182
 183   while (abfd->my_archive != NULL
 184          && !bfd_is_thin_archive (abfd->my_archive))
 185     {
 186       offset += abfd->origin;
 187       abfd = abfd->my_archive;
 188     }
 189
 190   /* If this is an archive element, don't read past the end of
 191      this element.  */
 192   if (element_bfd->arelt_data != NULL)
 193     {
 194       bfd_size_type maxbytes = arelt_size (element_bfd);
 195
 196       if (abfd->where < offset || abfd->where - offset >= maxbytes)
 197         {
 198           bfd_set_error (bfd_error_invalid_operation);
 199           return -1;
 200         }
 201       if (abfd->where - offset + size > maxbytes)
 202         size = maxbytes - (abfd->where - offset);
 203     }
 204
 205   if (abfd->iovec == NULL)
 206     {
 207       bfd_set_error (bfd_error_invalid_operation);
 208       return -1;
 209     }
 210
 211   nread = abfd->iovec->bread (abfd, ptr, size);
 212   if (nread != -1)
 213     abfd->where += nread;
 214
 215   return nread;
 216 }
 217
 218 bfd_size_type
 219 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
 220 {
 221   file_ptr nwrote;
 222
 223   while (abfd->my_archive != NULL
 224          && !bfd_is_thin_archive (abfd->my_archive))
 225     abfd = abfd->my_archive;
 226
 227   if (abfd->iovec == NULL)
 228     {
 229       bfd_set_error (bfd_error_invalid_operation);
 230       return -1;
 231     }
 232
 233   nwrote = abfd->iovec->bwrite (abfd, ptr, size);
 234   if (nwrote != -1)
 235     abfd->where += nwrote;
 236   if ((bfd_size_type) nwrote != size)
 237     {
 238 #ifdef ENOSPC
 239       errno = ENOSPC;
 240 #endif
 241       bfd_set_error (bfd_error_system_call);
 242     }
 243   return nwrote;
 244 }
 245
 246 file_ptr
 247 bfd_tell (bfd *abfd)
 248 {
 249   ufile_ptr offset = 0;
 250   file_ptr ptr;
 251
 252   while (abfd->my_archive != NULL
 253          && !bfd_is_thin_archive (abfd->my_archive))
 254     {
 255       offset += abfd->origin;
 256       abfd = abfd->my_archive;
 257     }
 258
 259   if (abfd->iovec == NULL)
 260     return 0;
 261
 262   ptr = abfd->iovec->btell (abfd);
 263   abfd->where = ptr;
 264   return ptr - offset;
 265 }
 266
 267 int
 268 bfd_flush (bfd *abfd)
 269 {
 270   while (abfd->my_archive != NULL
 271          && !bfd_is_thin_archive (abfd->my_archive))
 272     abfd = abfd->my_archive;
 273
 274   if (abfd->iovec == NULL)
 275     return 0;
 276
 277   return abfd->iovec->bflush (abfd);
 278 }
 279
 280 /* Returns 0 for success, negative value for failure (in which case
 281    bfd_get_error can retrieve the error code).  */
 282 int
 283 bfd_stat (bfd *abfd, struct stat *statbuf)
 284 {
 285   int result;
 286
 287   while (abfd->my_archive != NULL
 288          && !bfd_is_thin_archive (abfd->my_archive))
 289     abfd = abfd->my_archive;
 290
 291   if (abfd->iovec == NULL)
 292     {
 293       bfd_set_error (bfd_error_invalid_operation);
 294       return -1;
 295     }
 296
 297   result = abfd->iovec->bstat (abfd, statbuf);
 298   if (result < 0)
 299     bfd_set_error (bfd_error_system_call);
 300   return result;
 301 }
 302
 303 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
 304    can retrieve the error code).  */
 305
 306 int
 307 bfd_seek (bfd *abfd, file_ptr position, int direction)
 308 {
 309   int result;
 310   ufile_ptr offset = 0;
 311
 312   while (abfd->my_archive != NULL
 313          && !bfd_is_thin_archive (abfd->my_archive))
 314     {
 315       offset += abfd->origin;
 316       abfd = abfd->my_archive;
 317     }
 318
 319   if (abfd->iovec == NULL)
 320     {
 321       bfd_set_error (bfd_error_invalid_operation);
 322       return -1;
 323     }
 324
 325   /* For the time being, a BFD may not seek to it's end.  The problem
 326      is that we don't easily have a way to recognize the end of an
 327      element in an archive.  */
 328   BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
 329
 330   if (direction != SEEK_CUR)
 331     position += offset;
 332
 333   if ((direction == SEEK_CUR && position == 0)
 334       || (direction == SEEK_SET && (ufile_ptr) position == abfd->where))
 335     return 0;
 336
 337   result = abfd->iovec->bseek (abfd, position, direction);
 338   if (result != 0)
 339     {
 340       /* An EINVAL error probably means that the file offset was
 341          absurd.  */
 342       if (errno == EINVAL)
 343         bfd_set_error (bfd_error_file_truncated);
 344       else
 345         bfd_set_error (bfd_error_system_call);
 346     }
 347   else
 348     {
 349       /* Adjust `where' field.  */
 350       if (direction == SEEK_CUR)
 351         abfd->where += position;
 352       else
 353         abfd->where = position;
 354     }
 355
 356   return result;
 357 }
 358
 359 /*
 360 FUNCTION
 361         bfd_get_mtime
 362
 363 SYNOPSIS
 364         long bfd_get_mtime (bfd *abfd);
 365
 366 DESCRIPTION
 367         Return the file modification time (as read from the file system, or
 368         from the archive header for archive members).
 369
 370 */
 371
 372 long
 373 bfd_get_mtime (bfd *abfd)
 374 {
 375   struct stat buf;
 376
 377   if (abfd->mtime_set)
 378     return abfd->mtime;
 379
 380   if (bfd_stat (abfd, &buf) != 0)
 381     return 0;
 382
 383   abfd->mtime = buf.st_mtime;           /* Save value in case anyone wants it */
 384   return buf.st_mtime;
 385 }
 386
 387 /*
 388 FUNCTION
 389         bfd_get_size
 390
 391 SYNOPSIS
 392         ufile_ptr bfd_get_size (bfd *abfd);
 393
 394 DESCRIPTION
 395         Return the file size (as read from file system) for the file
 396         associated with BFD @var{abfd}.
 397
 398         The initial motivation for, and use of, this routine is not
 399         so we can get the exact size of the object the BFD applies to, since
 400         that might not be generally possible (archive members for example).
 401         It would be ideal if someone could eventually modify
 402         it so that such results were guaranteed.
 403
 404         Instead, we want to ask questions like "is this NNN byte sized
 405         object I'm about to try read from file offset YYY reasonable?"
 406         As as example of where we might do this, some object formats
 407         use string tables for which the first <<sizeof (long)>> bytes of the
 408         table contain the size of the table itself, including the size bytes.
 409         If an application tries to read what it thinks is one of these
 410         string tables, without some way to validate the size, and for
 411         some reason the size is wrong (byte swapping error, wrong location
 412         for the string table, etc.), the only clue is likely to be a read
 413         error when it tries to read the table, or a "virtual memory
 414         exhausted" error when it tries to allocate 15 bazillon bytes
 415         of space for the 15 bazillon byte table it is about to read.
 416         This function at least allows us to answer the question, "is the
 417         size reasonable?".
 418 */
 419
 420 ufile_ptr
 421 bfd_get_size (bfd *abfd)
 422 {
 423   struct stat buf;
 424
 425   if (bfd_stat (abfd, &buf) != 0)
 426     return 0;
 427
 428   return buf.st_size;
 429 }
 430
 431 /*
 432 FUNCTION
 433         bfd_get_file_size
 434
 435 SYNOPSIS
 436         ufile_ptr bfd_get_file_size (bfd *abfd);
 437
 438 DESCRIPTION
 439         Return the file size (as read from file system) for the file
 440         associated with BFD @var{abfd}.  It supports both normal files
 441         and archive elements.
 442
 443 */
 444
 445 ufile_ptr
 446 bfd_get_file_size (bfd *abfd)
 447 {
 448   if (abfd->my_archive != NULL
 449       && !bfd_is_thin_archive (abfd->my_archive))
 450     return arelt_size (abfd);
 451
 452   return bfd_get_size (abfd);
 453 }
 454
 455 /*
 456 FUNCTION
 457         bfd_mmap
 458
 459 SYNOPSIS
 460         void *bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 461                         int prot, int flags, file_ptr offset,
 462                         void **map_addr, bfd_size_type *map_len);
 463
 464 DESCRIPTION
 465         Return mmap()ed region of the file, if possible and implemented.
 466         LEN and OFFSET do not need to be page aligned.  The page aligned
 467         address and length are written to MAP_ADDR and MAP_LEN.
 468
 469 */
 470
 471 void *
 472 bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
 473           int prot, int flags, file_ptr offset,
 474           void **map_addr, bfd_size_type *map_len)
 475 {
 476   while (abfd->my_archive != NULL
 477          && !bfd_is_thin_archive (abfd->my_archive))
 478     {
 479       offset += abfd->origin;
 480       abfd = abfd->my_archive;
 481     }
 482
 483   if (abfd->iovec == NULL)
 484     {
 485       bfd_set_error (bfd_error_invalid_operation);
 486       return (void *) -1;
 487     }
 488
 489   return abfd->iovec->bmmap (abfd, addr, len, prot, flags, offset,
 490                              map_addr, map_len);
 491 }
 492
 493 /* Memory file I/O operations.  */
 494
 495 static file_ptr
 496 memory_bread (bfd *abfd, void *ptr, file_ptr size)
 497 {
 498   struct bfd_in_memory *bim;
 499   bfd_size_type get;
 500
 501   bim = (struct bfd_in_memory *) abfd->iostream;
 502   get = size;
 503   if (abfd->where + get > bim->size)
 504     {
 505       if (bim->size < (bfd_size_type) abfd->where)
 506         get = 0;
 507       else
 508         get = bim->size - abfd->where;
 509       bfd_set_error (bfd_error_file_truncated);
 510     }
 511   memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
 512   return get;
 513 }
 514
 515 static file_ptr
 516 memory_bwrite (bfd *abfd, const void *ptr, file_ptr size)
 517 {
 518   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 519
 520   if (abfd->where + size > bim->size)
 521     {
 522       bfd_size_type newsize, oldsize;
 523
 524       oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 525       bim->size = abfd->where + size;
 526       /* Round up to cut down on memory fragmentation */
 527       newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 528       if (newsize > oldsize)
 529         {
 530           bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer, newsize);
 531           if (bim->buffer == NULL)
 532             {
 533               bim->size = 0;
 534               return 0;
 535             }
 536           if (newsize > bim->size)
 537             memset (bim->buffer + bim->size, 0, newsize - bim->size);
 538         }
 539     }
 540   memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
 541   return size;
 542 }
 543
 544 static file_ptr
 545 memory_btell (bfd *abfd)
 546 {
 547   return abfd->where;
 548 }
 549
 550 static int
 551 memory_bseek (bfd *abfd, file_ptr position, int direction)
 552 {
 553   file_ptr nwhere;
 554   struct bfd_in_memory *bim;
 555
 556   bim = (struct bfd_in_memory *) abfd->iostream;
 557
 558   if (direction == SEEK_SET)
 559     nwhere = position;
 560   else
 561     nwhere = abfd->where + position;
 562
 563   if (nwhere < 0)
 564     {
 565       abfd->where = 0;
 566       errno = EINVAL;
 567       return -1;
 568     }
 569
 570   if ((bfd_size_type)nwhere > bim->size)
 571     {
 572       if (abfd->direction == write_direction
 573           || abfd->direction == both_direction)
 574         {
 575           bfd_size_type newsize, oldsize;
 576
 577           oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
 578           bim->size = nwhere;
 579           /* Round up to cut down on memory fragmentation */
 580           newsize = (bim->size + 127) & ~(bfd_size_type) 127;
 581           if (newsize > oldsize)
 582             {
 583               bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer, newsize);
 584               if (bim->buffer == NULL)
 585                 {
 586                   errno = EINVAL;
 587                   bim->size = 0;
 588                   return -1;
 589                 }
 590               memset (bim->buffer + oldsize, 0, newsize - oldsize);
 591             }
 592         }
 593       else
 594         {
 595           abfd->where = bim->size;
 596           errno = EINVAL;
 597           bfd_set_error (bfd_error_file_truncated);
 598           return -1;
 599         }
 600     }
 601   return 0;
 602 }
 603
 604 static int
 605 memory_bclose (struct bfd *abfd)
 606 {
 607   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 608
 609   if (bim->buffer != NULL)
 610     free (bim->buffer);
 611   free (bim);
 612   abfd->iostream = NULL;
 613
 614   return 0;
 615 }
 616
 617 static int
 618 memory_bflush (bfd *abfd ATTRIBUTE_UNUSED)
 619 {
 620   return 0;
 621 }
 622
 623 static int
 624 memory_bstat (bfd *abfd, struct stat *statbuf)
 625 {
 626   struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
 627
 628   memset (statbuf, 0, sizeof (*statbuf));
 629   statbuf->st_size = bim->size;
 630
 631   return 0;
 632 }
 633
 634 static void *
 635 memory_bmmap (bfd *abfd ATTRIBUTE_UNUSED, void *addr ATTRIBUTE_UNUSED,
 636               bfd_size_type len ATTRIBUTE_UNUSED, int prot ATTRIBUTE_UNUSED,
 637               int flags ATTRIBUTE_UNUSED, file_ptr offset ATTRIBUTE_UNUSED,
 638               void **map_addr ATTRIBUTE_UNUSED,
 639               bfd_size_type *map_len ATTRIBUTE_UNUSED)
 640 {
 641   return (void *)-1;
 642 }
 643
 644 const struct bfd_iovec _bfd_memory_iovec =
 645 {
 646   &memory_bread, &memory_bwrite, &memory_btell, &memory_bseek,
 647   &memory_bclose, &memory_bflush, &memory_bstat, &memory_bmmap
 648 };