2009-12-02 Rafael Avila de Espindola <espindola@google.com>
[binutils.git] / bfd / bfdio.c
blobe428b165b2f03c29b7df36a68ba50a324f6caf54
1 /* Low-level I/O routines for BFDs.
3 Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
4 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
5 Free Software Foundation, Inc.
7 Written by Cygnus Support.
9 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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. */
26 #include "sysdep.h"
27 #include <limits.h>
28 #include "bfd.h"
29 #include "libbfd.h"
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
41 #ifndef FD_CLOEXEC
42 #define FD_CLOEXEC 1
43 #endif
45 file_ptr
46 real_ftell (FILE *file)
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
57 int
58 real_fseek (FILE *file, file_ptr offset, int whence)
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
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)
74 #if defined (HAVE_FILENO) && defined (F_GETFD)
75 if (file)
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);
82 #endif
83 return file;
86 FILE *
87 real_fopen (const char *filename, const char *modes)
89 #ifdef VMS
90 char vms_modes[4];
91 char *vms_attr;
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)
100 /* No attributes. */
101 return close_on_exec (fopen (filename, modes));
103 else
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;
111 memcpy (attrs, modes, modes_len);
112 at[0] = attrs;
113 for (i = 0; i < 2; i++)
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. */
119 return close_on_exec (fopen (filename, at[0], at[1], at[2]));
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 */
131 INTERNAL_DEFINITION
132 struct bfd_iovec
134 DESCRIPTION
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).
141 .struct bfd_iovec
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 . {* Just like mmap: (void*)-1 on failure, mmapped address on success. *}
162 . void *(*bmmap) (struct bfd *abfd, void *addr, bfd_size_type len,
163 . int prot, int flags, file_ptr offset);
169 /* Return value is amount read. */
171 bfd_size_type
172 bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
174 size_t nread;
176 /* If this is an archive element, don't read past the end of
177 this element. */
178 if (abfd->arelt_data != NULL)
180 size_t maxbytes = ((struct areltdata *) abfd->arelt_data)->parsed_size;
181 if (size > maxbytes)
182 size = maxbytes;
185 if ((abfd->flags & BFD_IN_MEMORY) != 0)
187 struct bfd_in_memory *bim;
188 bfd_size_type get;
190 bim = (struct bfd_in_memory *) abfd->iostream;
191 get = size;
192 if (abfd->where + get > bim->size)
194 if (bim->size < (bfd_size_type) abfd->where)
195 get = 0;
196 else
197 get = bim->size - abfd->where;
198 bfd_set_error (bfd_error_file_truncated);
200 memcpy (ptr, bim->buffer + abfd->where, (size_t) get);
201 abfd->where += get;
202 return get;
205 if (abfd->iovec)
206 nread = abfd->iovec->bread (abfd, ptr, size);
207 else
208 nread = 0;
209 if (nread != (size_t) -1)
210 abfd->where += nread;
212 return nread;
215 bfd_size_type
216 bfd_bwrite (const void *ptr, bfd_size_type size, bfd *abfd)
218 size_t nwrote;
220 if ((abfd->flags & BFD_IN_MEMORY) != 0)
222 struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
224 size = (size_t) size;
225 if (abfd->where + size > bim->size)
227 bfd_size_type newsize, oldsize;
229 oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
230 bim->size = abfd->where + size;
231 /* Round up to cut down on memory fragmentation */
232 newsize = (bim->size + 127) & ~(bfd_size_type) 127;
233 if (newsize > oldsize)
235 bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer,
236 newsize);
237 if (bim->buffer == NULL)
239 bim->size = 0;
240 return 0;
242 if (newsize > bim->size)
243 memset (bim->buffer + bim->size, 0, newsize - bim->size);
246 memcpy (bim->buffer + abfd->where, ptr, (size_t) size);
247 abfd->where += size;
248 return size;
251 if (abfd->iovec)
252 nwrote = abfd->iovec->bwrite (abfd, ptr, size);
253 else
254 nwrote = 0;
256 if (nwrote != (size_t) -1)
257 abfd->where += nwrote;
258 if (nwrote != size)
260 #ifdef ENOSPC
261 errno = ENOSPC;
262 #endif
263 bfd_set_error (bfd_error_system_call);
265 return nwrote;
268 file_ptr
269 bfd_tell (bfd *abfd)
271 file_ptr ptr;
273 if ((abfd->flags & BFD_IN_MEMORY) != 0)
274 return abfd->where;
276 if (abfd->iovec)
278 ptr = abfd->iovec->btell (abfd);
280 if (abfd->my_archive)
281 ptr -= abfd->origin;
283 else
284 ptr = 0;
286 abfd->where = ptr;
287 return ptr;
291 bfd_flush (bfd *abfd)
293 if ((abfd->flags & BFD_IN_MEMORY) != 0)
294 return 0;
296 if (abfd->iovec)
297 return abfd->iovec->bflush (abfd);
298 return 0;
301 /* Returns 0 for success, negative value for failure (in which case
302 bfd_get_error can retrieve the error code). */
304 bfd_stat (bfd *abfd, struct stat *statbuf)
306 int result;
308 if ((abfd->flags & BFD_IN_MEMORY) != 0)
309 abort ();
311 if (abfd->iovec)
312 result = abfd->iovec->bstat (abfd, statbuf);
313 else
314 result = -1;
316 if (result < 0)
317 bfd_set_error (bfd_error_system_call);
318 return result;
321 /* Returns 0 for success, nonzero for failure (in which case bfd_get_error
322 can retrieve the error code). */
325 bfd_seek (bfd *abfd, file_ptr position, int direction)
327 int result;
328 file_ptr file_position;
329 /* For the time being, a BFD may not seek to it's end. The problem
330 is that we don't easily have a way to recognize the end of an
331 element in an archive. */
333 BFD_ASSERT (direction == SEEK_SET || direction == SEEK_CUR);
335 if (direction == SEEK_CUR && position == 0)
336 return 0;
338 if ((abfd->flags & BFD_IN_MEMORY) != 0)
340 struct bfd_in_memory *bim;
342 bim = (struct bfd_in_memory *) abfd->iostream;
344 if (direction == SEEK_SET)
345 abfd->where = position;
346 else
347 abfd->where += position;
349 if (abfd->where > bim->size)
351 if (abfd->direction == write_direction
352 || abfd->direction == both_direction)
354 bfd_size_type newsize, oldsize;
356 oldsize = (bim->size + 127) & ~(bfd_size_type) 127;
357 bim->size = abfd->where;
358 /* Round up to cut down on memory fragmentation */
359 newsize = (bim->size + 127) & ~(bfd_size_type) 127;
360 if (newsize > oldsize)
362 bim->buffer = (bfd_byte *) bfd_realloc_or_free (bim->buffer,
363 newsize);
364 if (bim->buffer == NULL)
366 bim->size = 0;
367 return -1;
369 memset (bim->buffer + oldsize, 0, newsize - oldsize);
372 else
374 abfd->where = bim->size;
375 bfd_set_error (bfd_error_file_truncated);
376 return -1;
379 return 0;
382 if (abfd->format != bfd_archive && abfd->my_archive == 0)
384 if (direction == SEEK_SET && (bfd_vma) position == abfd->where)
385 return 0;
387 else
389 /* We need something smarter to optimize access to archives.
390 Currently, anything inside an archive is read via the file
391 handle for the archive. Which means that a bfd_seek on one
392 component affects the `current position' in the archive, as
393 well as in any other component.
395 It might be sufficient to put a spike through the cache
396 abstraction, and look to the archive for the file position,
397 but I think we should try for something cleaner.
399 In the meantime, no optimization for archives. */
402 file_position = position;
403 if (direction == SEEK_SET && abfd->my_archive != NULL)
404 file_position += abfd->origin;
406 if (abfd->iovec)
407 result = abfd->iovec->bseek (abfd, file_position, direction);
408 else
409 result = -1;
411 if (result != 0)
413 int hold_errno = errno;
415 /* Force redetermination of `where' field. */
416 bfd_tell (abfd);
418 /* An EINVAL error probably means that the file offset was
419 absurd. */
420 if (hold_errno == EINVAL)
421 bfd_set_error (bfd_error_file_truncated);
422 else
424 bfd_set_error (bfd_error_system_call);
425 errno = hold_errno;
428 else
430 /* Adjust `where' field. */
431 if (direction == SEEK_SET)
432 abfd->where = position;
433 else
434 abfd->where += position;
436 return result;
440 FUNCTION
441 bfd_get_mtime
443 SYNOPSIS
444 long bfd_get_mtime (bfd *abfd);
446 DESCRIPTION
447 Return the file modification time (as read from the file system, or
448 from the archive header for archive members).
452 long
453 bfd_get_mtime (bfd *abfd)
455 struct stat buf;
457 if (abfd->mtime_set)
458 return abfd->mtime;
460 if (abfd->iovec == NULL)
461 return 0;
463 if (abfd->iovec->bstat (abfd, &buf) != 0)
464 return 0;
466 abfd->mtime = buf.st_mtime; /* Save value in case anyone wants it */
467 return buf.st_mtime;
471 FUNCTION
472 bfd_get_size
474 SYNOPSIS
475 file_ptr bfd_get_size (bfd *abfd);
477 DESCRIPTION
478 Return the file size (as read from file system) for the file
479 associated with BFD @var{abfd}.
481 The initial motivation for, and use of, this routine is not
482 so we can get the exact size of the object the BFD applies to, since
483 that might not be generally possible (archive members for example).
484 It would be ideal if someone could eventually modify
485 it so that such results were guaranteed.
487 Instead, we want to ask questions like "is this NNN byte sized
488 object I'm about to try read from file offset YYY reasonable?"
489 As as example of where we might do this, some object formats
490 use string tables for which the first <<sizeof (long)>> bytes of the
491 table contain the size of the table itself, including the size bytes.
492 If an application tries to read what it thinks is one of these
493 string tables, without some way to validate the size, and for
494 some reason the size is wrong (byte swapping error, wrong location
495 for the string table, etc.), the only clue is likely to be a read
496 error when it tries to read the table, or a "virtual memory
497 exhausted" error when it tries to allocate 15 bazillon bytes
498 of space for the 15 bazillon byte table it is about to read.
499 This function at least allows us to answer the question, "is the
500 size reasonable?".
503 file_ptr
504 bfd_get_size (bfd *abfd)
506 struct stat buf;
508 if ((abfd->flags & BFD_IN_MEMORY) != 0)
509 return ((struct bfd_in_memory *) abfd->iostream)->size;
511 if (abfd->iovec == NULL)
512 return 0;
514 if (abfd->iovec->bstat (abfd, &buf) != 0)
515 return 0;
517 return buf.st_size;
522 FUNCTION
523 bfd_mmap
525 SYNOPSIS
526 void *bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
527 int prot, int flags, file_ptr offset);
529 DESCRIPTION
530 Return mmap()ed region of the file, if possible and implemented.
534 void *
535 bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
536 int prot, int flags, file_ptr offset)
538 void *ret = (void *)-1;
539 if ((abfd->flags & BFD_IN_MEMORY) != 0)
540 return ret;
542 if (abfd->iovec == NULL)
543 return ret;
545 return abfd->iovec->bmmap (abfd, addr, len, prot, flags, offset);