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[binutils.git] / bfd / bfdwin.c
blobfb7c967bff3b6f4f8349ac5103a6819a00a276c2
1 /* Support for memory-mapped windows into a BFD.
2 Copyright 1995, 1996, 2001, 2002, 2003 Free Software Foundation, Inc.
3 Written by Cygnus Support.
5 This file is part of BFD, the Binary File Descriptor library.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 #include "sysdep.h"
23 #include "bfd.h"
24 #include "libbfd.h"
26 /* Currently, if USE_MMAP is undefined, none if the window stuff is
27 used. Okay, so it's mis-named. At least the command-line option
28 "--without-mmap" is more obvious than "--without-windows" or some
29 such. */
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;
147 FILE *f;
149 /* Find the real file and the real offset into it. */
150 while (abfd->my_archive != NULL)
152 offset += abfd->origin;
153 abfd = abfd->my_archive;
155 f = bfd_cache_lookup (abfd);
156 fd = fileno (f);
158 /* Compute offsets and size for mmap and for the user's data. */
159 offset2 = offset % pagesize;
160 if (offset2 < 0)
161 abort ();
162 file_offset = offset - offset2;
163 real_size = offset + size - file_offset;
164 real_size = real_size + pagesize - 1;
165 real_size -= real_size % pagesize;
167 /* If we're re-using a memory region, make sure it's big enough. */
168 if (i->data && i->size < size)
170 munmap (i->data, i->size);
171 i->data = 0;
173 i->data = mmap (i->data, real_size,
174 writable ? PROT_WRITE | PROT_READ : PROT_READ,
175 (writable
176 ? MAP_FILE | MAP_PRIVATE
177 : MAP_FILE | MAP_SHARED),
178 fd, file_offset);
179 if (i->data == (void *) -1)
181 /* An error happened. Report it, or try using malloc, or
182 something. */
183 bfd_set_error (bfd_error_system_call);
184 i->data = 0;
185 windowp->data = 0;
186 if (debug_windows)
187 fprintf (stderr, "\t\tmmap failed!\n");
188 return FALSE;
190 if (debug_windows)
191 fprintf (stderr, "\n\tmapped %ld at %p, offset is %ld\n",
192 (long) real_size, i->data, (long) offset2);
193 i->size = real_size;
194 windowp->data = (bfd_byte *) i->data + offset2;
195 windowp->size = size;
196 i->mapped = 1;
197 return TRUE;
199 else if (debug_windows)
201 if (ok_to_map)
202 fprintf (stderr, _("not mapping: data=%lx mapped=%d\n"),
203 (unsigned long) i->data, (int) i->mapped);
204 else
205 fprintf (stderr, _("not mapping: env var not set\n"));
207 #else
208 ok_to_map = 0;
209 #endif
211 #ifdef HAVE_MPROTECT
212 if (!writable)
214 size_to_alloc += pagesize - 1;
215 size_to_alloc -= size_to_alloc % pagesize;
217 #endif
218 if (debug_windows)
219 fprintf (stderr, "\n\t%s(%6ld)",
220 i->data ? "realloc" : " malloc", (long) size_to_alloc);
221 i->data = bfd_realloc (i->data, size_to_alloc);
222 if (debug_windows)
223 fprintf (stderr, "\t-> %p\n", i->data);
224 i->refcount = 1;
225 if (i->data == NULL)
227 if (size_to_alloc == 0)
228 return TRUE;
229 return FALSE;
231 if (bfd_seek (abfd, offset, SEEK_SET) != 0)
232 return FALSE;
233 i->size = bfd_bread (i->data, size, abfd);
234 if (i->size != size)
235 return FALSE;
236 i->mapped = 0;
237 #ifdef HAVE_MPROTECT
238 if (!writable)
240 if (debug_windows)
241 fprintf (stderr, "\tmprotect (%p, %ld, PROT_READ)\n", i->data,
242 (long) i->size);
243 mprotect (i->data, i->size, PROT_READ);
245 #endif
246 windowp->data = i->data;
247 windowp->size = i->size;
248 return TRUE;
251 #endif /* USE_MMAP */