2009-06-10 Philip Blundell <philb@gnu.org>
[binutils.git] / bfd / bfdwin.c
blob3a35fc91c414845eb46bee330b1048fabc6e6e49
1 /* Support for memory-mapped windows into a BFD.
2 Copyright 1995, 1996, 2001, 2002, 2003, 2005, 2007, 2008
3 Free Software Foundation, Inc.
4 Written by Cygnus Support.
6 This file is part of BFD, the Binary File Descriptor library.
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 3 of the License, or
11 (at your option) any later version.
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.
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., 51 Franklin Street - Fifth Floor, Boston,
21 MA 02110-1301, USA. */
23 #include "sysdep.h"
25 #include "bfd.h"
26 #include "libbfd.h"
28 /* Currently, if USE_MMAP is undefined, none of the window stuff is
29 used. Enabled by --with-mmap. */
31 #ifdef USE_MMAP
33 #undef HAVE_MPROTECT /* code's not tested yet */
35 #if HAVE_MMAP || HAVE_MPROTECT || HAVE_MADVISE
36 #include <sys/mman.h>
37 #endif
39 #ifndef MAP_FILE
40 #define MAP_FILE 0
41 #endif
43 static int debug_windows;
45 /* The idea behind the next and refcount fields is that one mapped
46 region can suffice for multiple read-only windows or multiple
47 non-overlapping read-write windows. It's not implemented yet
48 though. */
51 INTERNAL_DEFINITION
53 .struct _bfd_window_internal {
54 . struct _bfd_window_internal *next;
55 . void *data;
56 . bfd_size_type size;
57 . int refcount : 31; {* should be enough... *}
58 . unsigned mapped : 1; {* 1 = mmap, 0 = malloc *}
59 .};
62 void
63 bfd_init_window (bfd_window *windowp)
65 windowp->data = 0;
66 windowp->i = 0;
67 windowp->size = 0;
70 void
71 bfd_free_window (bfd_window *windowp)
73 bfd_window_internal *i = windowp->i;
74 windowp->i = 0;
75 windowp->data = 0;
76 if (i == 0)
77 return;
78 i->refcount--;
79 if (debug_windows)
80 fprintf (stderr, "freeing window @%p<%p,%lx,%p>\n",
81 windowp, windowp->data, windowp->size, windowp->i);
82 if (i->refcount != 0)
83 return;
85 if (i->mapped)
87 #ifdef HAVE_MMAP
88 munmap (i->data, i->size);
89 goto no_free;
90 #else
91 abort ();
92 #endif
94 #ifdef HAVE_MPROTECT
95 mprotect (i->data, i->size, PROT_READ | PROT_WRITE);
96 #endif
97 free (i->data);
98 #ifdef HAVE_MMAP
99 no_free:
100 #endif
101 i->data = 0;
102 /* There should be no more references to i at this point. */
103 free (i);
106 static int ok_to_map = 1;
108 bfd_boolean
109 bfd_get_file_window (bfd *abfd,
110 file_ptr offset,
111 bfd_size_type size,
112 bfd_window *windowp,
113 bfd_boolean writable)
115 static size_t pagesize;
116 bfd_window_internal *i = windowp->i;
117 bfd_size_type size_to_alloc = size;
119 if (debug_windows)
120 fprintf (stderr, "bfd_get_file_window (%p, %6ld, %6ld, %p<%p,%lx,%p>, %d)",
121 abfd, (long) offset, (long) size,
122 windowp, windowp->data, (unsigned long) windowp->size,
123 windowp->i, writable);
125 /* Make sure we know the page size, so we can be friendly to mmap. */
126 if (pagesize == 0)
127 pagesize = getpagesize ();
128 if (pagesize == 0)
129 abort ();
131 if (i == 0)
133 i = bfd_zmalloc (sizeof (bfd_window_internal));
134 windowp->i = i;
135 if (i == 0)
136 return FALSE;
137 i->data = 0;
139 #ifdef HAVE_MMAP
140 if (ok_to_map
141 && (i->data == 0 || i->mapped == 1)
142 && (abfd->flags & BFD_IN_MEMORY) == 0)
144 file_ptr file_offset, offset2;
145 size_t real_size;
146 int fd;
148 /* Find the real file and the real offset into it. */
149 while (abfd->my_archive != NULL)
151 offset += abfd->origin;
152 abfd = abfd->my_archive;
155 /* Seek into the file, to ensure it is open if cacheable. */
156 if (abfd->iostream == NULL
157 && (abfd->iovec == NULL
158 || abfd->iovec->bseek (abfd, offset, SEEK_SET) != 0))
159 return FALSE;
160 fd = fileno ((FILE *) abfd->iostream);
162 /* Compute offsets and size for mmap and for the user's data. */
163 offset2 = offset % pagesize;
164 if (offset2 < 0)
165 abort ();
166 file_offset = offset - offset2;
167 real_size = offset + size - file_offset;
168 real_size = real_size + pagesize - 1;
169 real_size -= real_size % pagesize;
171 /* If we're re-using a memory region, make sure it's big enough. */
172 if (i->data && i->size < size)
174 munmap (i->data, i->size);
175 i->data = 0;
177 i->data = mmap (i->data, real_size,
178 writable ? PROT_WRITE | PROT_READ : PROT_READ,
179 (writable
180 ? MAP_FILE | MAP_PRIVATE
181 : MAP_FILE | MAP_SHARED),
182 fd, file_offset);
183 if (i->data == (void *) -1)
185 /* An error happened. Report it, or try using malloc, or
186 something. */
187 bfd_set_error (bfd_error_system_call);
188 i->data = 0;
189 windowp->data = 0;
190 if (debug_windows)
191 fprintf (stderr, "\t\tmmap failed!\n");
192 return FALSE;
194 if (debug_windows)
195 fprintf (stderr, "\n\tmapped %ld at %p, offset is %ld\n",
196 (long) real_size, i->data, (long) offset2);
197 i->size = real_size;
198 windowp->data = (bfd_byte *) i->data + offset2;
199 windowp->size = size;
200 i->mapped = 1;
201 return TRUE;
203 else if (debug_windows)
205 if (ok_to_map)
206 fprintf (stderr, _("not mapping: data=%lx mapped=%d\n"),
207 (unsigned long) i->data, (int) i->mapped);
208 else
209 fprintf (stderr, _("not mapping: env var not set\n"));
211 #else
212 ok_to_map = 0;
213 #endif
215 #ifdef HAVE_MPROTECT
216 if (!writable)
218 size_to_alloc += pagesize - 1;
219 size_to_alloc -= size_to_alloc % pagesize;
221 #endif
222 if (debug_windows)
223 fprintf (stderr, "\n\t%s(%6ld)",
224 i->data ? "realloc" : " malloc", (long) size_to_alloc);
225 i->data = bfd_realloc_or_free (i->data, size_to_alloc);
226 if (debug_windows)
227 fprintf (stderr, "\t-> %p\n", i->data);
228 if (i->data == NULL)
230 if (size_to_alloc == 0)
231 return TRUE;
232 return FALSE;
234 i->refcount = 1;
235 if (bfd_seek (abfd, offset, SEEK_SET) != 0)
236 return FALSE;
237 i->size = bfd_bread (i->data, size, abfd);
238 if (i->size != size)
239 return FALSE;
240 i->mapped = 0;
241 #ifdef HAVE_MPROTECT
242 if (!writable)
244 if (debug_windows)
245 fprintf (stderr, "\tmprotect (%p, %ld, PROT_READ)\n", i->data,
246 (long) i->size);
247 mprotect (i->data, i->size, PROT_READ);
249 #endif
250 windowp->data = i->data;
251 windowp->size = i->size;
252 return TRUE;
255 #endif /* USE_MMAP */