bfd/
[binutils.git] / bfd / bfdwin.c
blob7236906e28bc3ddcd1711f14844af19079f62549
1 /* Support for memory-mapped windows into a BFD.
2 Copyright 1995, 1996, 2001, 2002, 2003, 2005
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 2 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, MA 02110-1301, USA. */
22 #include "sysdep.h"
24 #include "bfd.h"
25 #include "libbfd.h"
27 /* Currently, if USE_MMAP is undefined, none if the window stuff is
28 used. Okay, so it's mis-named. At least the command-line option
29 "--without-mmap" is more obvious than "--without-windows" or some
30 such. */
32 #ifdef USE_MMAP
34 #undef HAVE_MPROTECT /* code's not tested yet */
36 #if HAVE_MMAP || HAVE_MPROTECT || HAVE_MADVISE
37 #include <sys/mman.h>
38 #endif
40 #ifndef MAP_FILE
41 #define MAP_FILE 0
42 #endif
44 static int debug_windows;
46 /* The idea behind the next and refcount fields is that one mapped
47 region can suffice for multiple read-only windows or multiple
48 non-overlapping read-write windows. It's not implemented yet
49 though. */
52 INTERNAL_DEFINITION
54 .struct _bfd_window_internal {
55 . struct _bfd_window_internal *next;
56 . void *data;
57 . bfd_size_type size;
58 . int refcount : 31; {* should be enough... *}
59 . unsigned mapped : 1; {* 1 = mmap, 0 = malloc *}
60 .};
63 void
64 bfd_init_window (bfd_window *windowp)
66 windowp->data = 0;
67 windowp->i = 0;
68 windowp->size = 0;
71 void
72 bfd_free_window (bfd_window *windowp)
74 bfd_window_internal *i = windowp->i;
75 windowp->i = 0;
76 windowp->data = 0;
77 if (i == 0)
78 return;
79 i->refcount--;
80 if (debug_windows)
81 fprintf (stderr, "freeing window @%p<%p,%lx,%p>\n",
82 windowp, windowp->data, windowp->size, windowp->i);
83 if (i->refcount != 0)
84 return;
86 if (i->mapped)
88 #ifdef HAVE_MMAP
89 munmap (i->data, i->size);
90 goto no_free;
91 #else
92 abort ();
93 #endif
95 #ifdef HAVE_MPROTECT
96 mprotect (i->data, i->size, PROT_READ | PROT_WRITE);
97 #endif
98 free (i->data);
99 #ifdef HAVE_MMAP
100 no_free:
101 #endif
102 i->data = 0;
103 /* There should be no more references to i at this point. */
104 free (i);
107 static int ok_to_map = 1;
109 bfd_boolean
110 bfd_get_file_window (bfd *abfd,
111 file_ptr offset,
112 bfd_size_type size,
113 bfd_window *windowp,
114 bfd_boolean writable)
116 static size_t pagesize;
117 bfd_window_internal *i = windowp->i;
118 bfd_size_type size_to_alloc = size;
120 if (debug_windows)
121 fprintf (stderr, "bfd_get_file_window (%p, %6ld, %6ld, %p<%p,%lx,%p>, %d)",
122 abfd, (long) offset, (long) size,
123 windowp, windowp->data, (unsigned long) windowp->size,
124 windowp->i, writable);
126 /* Make sure we know the page size, so we can be friendly to mmap. */
127 if (pagesize == 0)
128 pagesize = getpagesize ();
129 if (pagesize == 0)
130 abort ();
132 if (i == 0)
134 i = bfd_zmalloc (sizeof (bfd_window_internal));
135 windowp->i = i;
136 if (i == 0)
137 return FALSE;
138 i->data = 0;
140 #ifdef HAVE_MMAP
141 if (ok_to_map
142 && (i->data == 0 || i->mapped == 1)
143 && (abfd->flags & BFD_IN_MEMORY) == 0)
145 file_ptr file_offset, offset2;
146 size_t real_size;
147 int fd;
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;
156 /* Seek into the file, to ensure it is open if cacheable. */
157 if (abfd->iostream == NULL
158 && (abfd->iovec == NULL
159 || abfd->iovec->bseek (abfd, offset, SEEK_SET) != 0))
160 return FALSE;
161 fd = fileno ((FILE *) abfd->iostream);
163 /* Compute offsets and size for mmap and for the user's data. */
164 offset2 = offset % pagesize;
165 if (offset2 < 0)
166 abort ();
167 file_offset = offset - offset2;
168 real_size = offset + size - file_offset;
169 real_size = real_size + pagesize - 1;
170 real_size -= real_size % pagesize;
172 /* If we're re-using a memory region, make sure it's big enough. */
173 if (i->data && i->size < size)
175 munmap (i->data, i->size);
176 i->data = 0;
178 i->data = mmap (i->data, real_size,
179 writable ? PROT_WRITE | PROT_READ : PROT_READ,
180 (writable
181 ? MAP_FILE | MAP_PRIVATE
182 : MAP_FILE | MAP_SHARED),
183 fd, file_offset);
184 if (i->data == (void *) -1)
186 /* An error happened. Report it, or try using malloc, or
187 something. */
188 bfd_set_error (bfd_error_system_call);
189 i->data = 0;
190 windowp->data = 0;
191 if (debug_windows)
192 fprintf (stderr, "\t\tmmap failed!\n");
193 return FALSE;
195 if (debug_windows)
196 fprintf (stderr, "\n\tmapped %ld at %p, offset is %ld\n",
197 (long) real_size, i->data, (long) offset2);
198 i->size = real_size;
199 windowp->data = (bfd_byte *) i->data + offset2;
200 windowp->size = size;
201 i->mapped = 1;
202 return TRUE;
204 else if (debug_windows)
206 if (ok_to_map)
207 fprintf (stderr, _("not mapping: data=%lx mapped=%d\n"),
208 (unsigned long) i->data, (int) i->mapped);
209 else
210 fprintf (stderr, _("not mapping: env var not set\n"));
212 #else
213 ok_to_map = 0;
214 #endif
216 #ifdef HAVE_MPROTECT
217 if (!writable)
219 size_to_alloc += pagesize - 1;
220 size_to_alloc -= size_to_alloc % pagesize;
222 #endif
223 if (debug_windows)
224 fprintf (stderr, "\n\t%s(%6ld)",
225 i->data ? "realloc" : " malloc", (long) size_to_alloc);
226 i->data = bfd_realloc (i->data, size_to_alloc);
227 if (debug_windows)
228 fprintf (stderr, "\t-> %p\n", i->data);
229 i->refcount = 1;
230 if (i->data == NULL)
232 if (size_to_alloc == 0)
233 return TRUE;
234 return FALSE;
236 if (bfd_seek (abfd, offset, SEEK_SET) != 0)
237 return FALSE;
238 i->size = bfd_bread (i->data, size, abfd);
239 if (i->size != size)
240 return FALSE;
241 i->mapped = 0;
242 #ifdef HAVE_MPROTECT
243 if (!writable)
245 if (debug_windows)
246 fprintf (stderr, "\tmprotect (%p, %ld, PROT_READ)\n", i->data,
247 (long) i->size);
248 mprotect (i->data, i->size, PROT_READ);
250 #endif
251 windowp->data = i->data;
252 windowp->size = i->size;
253 return TRUE;
256 #endif /* USE_MMAP */