266 lines
6.7 KiB
C
266 lines
6.7 KiB
C
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/* Support for memory-mapped windows into a BFD.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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Written by Cygnus Support.
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "sysdep.h"
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#include "bfd.h"
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#include "libbfd.h"
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/* Currently, if USE_MMAP is undefined, none of the window stuff is
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used. Enabled by --with-mmap. */
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#ifdef USE_MMAP
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#undef HAVE_MPROTECT /* code's not tested yet */
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#if HAVE_MMAP || HAVE_MPROTECT || HAVE_MADVISE
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#include <sys/mman.h>
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#endif
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#ifndef MAP_FILE
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#define MAP_FILE 0
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#endif
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static int debug_windows;
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/* The idea behind the next and refcount fields is that one mapped
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region can suffice for multiple read-only windows or multiple
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non-overlapping read-write windows. It's not implemented yet
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though. */
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/*
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INTERNAL_DEFINITION
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.struct _bfd_window_internal {
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. struct _bfd_window_internal *next;
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. void *data;
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. bfd_size_type size;
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. int refcount : 31; {* should be enough... *}
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. unsigned mapped : 1; {* 1 = mmap, 0 = malloc *}
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.};
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*/
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void
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bfd_init_window (bfd_window *windowp)
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{
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windowp->data = 0;
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windowp->i = 0;
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windowp->size = 0;
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}
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void
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bfd_free_window (bfd_window *windowp)
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{
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bfd_window_internal *i = windowp->i;
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windowp->i = 0;
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windowp->data = 0;
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if (i == 0)
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return;
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i->refcount--;
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if (debug_windows)
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fprintf (stderr, "freeing window @%p<%p,%lx,%p>\n",
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windowp, windowp->data, (unsigned long) windowp->size, windowp->i);
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if (i->refcount != 0)
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return;
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if (i->mapped)
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{
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#ifdef HAVE_MMAP
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munmap (i->data, i->size);
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goto no_free;
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#else
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abort ();
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#endif
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}
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#ifdef HAVE_MPROTECT
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mprotect (i->data, i->size, PROT_READ | PROT_WRITE);
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#endif
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free (i->data);
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#ifdef HAVE_MMAP
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no_free:
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#endif
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i->data = 0;
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/* There should be no more references to i at this point. */
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free (i);
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}
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static int ok_to_map = 1;
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bool
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bfd_get_file_window (bfd *abfd,
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file_ptr offset,
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bfd_size_type size,
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bfd_window *windowp,
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bool writable)
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{
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static size_t pagesize;
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bfd_window_internal *i = windowp->i;
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bfd_size_type size_to_alloc = size;
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if (debug_windows)
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fprintf (stderr, "bfd_get_file_window (%p, %6ld, %6ld, %p<%p,%lx,%p>, %d)",
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abfd, (long) offset, (long) size,
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windowp, windowp->data, (unsigned long) windowp->size,
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windowp->i, writable);
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/* Make sure we know the page size, so we can be friendly to mmap. */
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if (pagesize == 0)
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pagesize = getpagesize ();
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if (pagesize == 0)
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abort ();
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if (i == NULL)
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{
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i = bfd_zmalloc (sizeof (bfd_window_internal));
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if (i == NULL)
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return false;
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i->data = NULL;
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}
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#ifdef HAVE_MMAP
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if (ok_to_map
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&& (i->data == NULL || i->mapped == 1)
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&& (abfd->flags & BFD_IN_MEMORY) == 0)
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{
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file_ptr file_offset, offset2;
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size_t real_size;
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int fd;
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/* Find the real file and the real offset into it. */
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while (abfd->my_archive != NULL
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&& !bfd_is_thin_archive (abfd->my_archive))
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{
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offset += abfd->origin;
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abfd = abfd->my_archive;
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}
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offset += abfd->origin;
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/* Seek into the file, to ensure it is open if cacheable. */
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if (abfd->iostream == NULL
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&& (abfd->iovec == NULL
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|| abfd->iovec->bseek (abfd, offset, SEEK_SET) != 0))
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goto free_and_fail;
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fd = fileno ((FILE *) abfd->iostream);
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/* Compute offsets and size for mmap and for the user's data. */
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offset2 = offset % pagesize;
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if (offset2 < 0)
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abort ();
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file_offset = offset - offset2;
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real_size = offset + size - file_offset;
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real_size = real_size + pagesize - 1;
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real_size -= real_size % pagesize;
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/* If we're re-using a memory region, make sure it's big enough. */
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if (i->data != NULL && i->size < size)
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{
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munmap (i->data, i->size);
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i->data = NULL;
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}
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i->data = mmap (i->data, real_size,
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writable ? PROT_WRITE | PROT_READ : PROT_READ,
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(writable
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? MAP_FILE | MAP_PRIVATE
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: MAP_FILE | MAP_SHARED),
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fd, file_offset);
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if (i->data == (void *) -1)
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{
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/* An error happened. Report it, or try using malloc, or
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something. */
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bfd_set_error (bfd_error_system_call);
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windowp->data = 0;
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if (debug_windows)
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fprintf (stderr, "\t\tmmap failed!\n");
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goto free_and_fail;
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}
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if (debug_windows)
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fprintf (stderr, "\n\tmapped %ld at %p, offset is %ld\n",
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(long) real_size, i->data, (long) offset2);
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i->size = real_size;
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windowp->data = (bfd_byte *) i->data + offset2;
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windowp->size = size;
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i->mapped = 1;
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i->refcount = 1;
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windowp->i = i;
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return true;
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}
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else if (debug_windows)
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{
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if (ok_to_map)
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fprintf (stderr, _("not mapping: data=%lx mapped=%d\n"),
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(unsigned long) i->data, (int) i->mapped);
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else
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fprintf (stderr, _("not mapping: env var not set\n"));
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}
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#else
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ok_to_map = 0;
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#endif
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#ifdef HAVE_MPROTECT
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if (!writable)
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{
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size_to_alloc += pagesize - 1;
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size_to_alloc -= size_to_alloc % pagesize;
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}
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#endif
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if (debug_windows)
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fprintf (stderr, "\n\t%s(%6ld)",
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i->data ? "realloc" : " malloc", (long) size_to_alloc);
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i->data = bfd_realloc_or_free (i->data, size_to_alloc);
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if (debug_windows)
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fprintf (stderr, "\t-> %p\n", i->data);
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if (i->data == NULL)
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{
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if (size_to_alloc == 0)
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{
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windowp->i = i;
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return true;
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}
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goto free_and_fail;
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}
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i->refcount = 1;
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if (bfd_seek (abfd, offset, SEEK_SET) != 0)
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goto free_and_fail;
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i->size = bfd_bread (i->data, size, abfd);
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if (i->size != size)
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goto free_and_fail;
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i->mapped = 0;
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#ifdef HAVE_MPROTECT
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if (!writable)
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{
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if (debug_windows)
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fprintf (stderr, "\tmprotect (%p, %ld, PROT_READ)\n", i->data,
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(long) i->size);
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mprotect (i->data, i->size, PROT_READ);
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}
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#endif
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windowp->data = i->data;
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windowp->size = i->size;
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windowp->i = i;
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return true;
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free_and_fail:
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/* We have a bfd_window_internal, but an error occurred. Free it. */
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free (i);
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return false;
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}
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#endif /* USE_MMAP */
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