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eff02e4f | 1 | /* mmapio.c -- File views using mmap. |
85ec4feb | 2 | Copyright (C) 2012-2018 Free Software Foundation, Inc. |
eff02e4f ILT |
3 | Written by Ian Lance Taylor, Google. |
4 | ||
5 | Redistribution and use in source and binary forms, with or without | |
6 | modification, are permitted provided that the following conditions are | |
7 | met: | |
8 | ||
9 | (1) Redistributions of source code must retain the above copyright | |
84ebf639 | 10 | notice, this list of conditions and the following disclaimer. |
eff02e4f ILT |
11 | |
12 | (2) Redistributions in binary form must reproduce the above copyright | |
13 | notice, this list of conditions and the following disclaimer in | |
14 | the documentation and/or other materials provided with the | |
84ebf639 CL |
15 | distribution. |
16 | ||
eff02e4f ILT |
17 | (3) The name of the author may not be used to |
18 | endorse or promote products derived from this software without | |
19 | specific prior written permission. | |
20 | ||
21 | THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
22 | IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | |
23 | WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
24 | DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, | |
25 | INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
26 | (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
27 | SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
28 | HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
29 | STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING | |
30 | IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
31 | POSSIBILITY OF SUCH DAMAGE. */ | |
32 | ||
eff02e4f ILT |
33 | #include "config.h" |
34 | ||
35 | #include <errno.h> | |
36 | #include <sys/types.h> | |
37 | #include <sys/mman.h> | |
38 | #include <unistd.h> | |
39 | ||
40 | #include "backtrace.h" | |
41 | #include "internal.h" | |
42 | ||
85619b6f JDA |
43 | #ifndef MAP_FAILED |
44 | #define MAP_FAILED ((void *)-1) | |
45 | #endif | |
46 | ||
eff02e4f ILT |
47 | /* This file implements file views and memory allocation when mmap is |
48 | available. */ | |
49 | ||
50 | /* Create a view of SIZE bytes from DESCRIPTOR at OFFSET. */ | |
51 | ||
52 | int | |
53 | backtrace_get_view (struct backtrace_state *state ATTRIBUTE_UNUSED, | |
54 | int descriptor, off_t offset, size_t size, | |
55 | backtrace_error_callback error_callback, | |
56 | void *data, struct backtrace_view *view) | |
57 | { | |
58 | size_t pagesize; | |
59 | unsigned int inpage; | |
60 | off_t pageoff; | |
61 | void *map; | |
62 | ||
63 | pagesize = getpagesize (); | |
64 | inpage = offset % pagesize; | |
65 | pageoff = offset - inpage; | |
66 | ||
67 | size += inpage; | |
68 | size = (size + (pagesize - 1)) & ~ (pagesize - 1); | |
69 | ||
70 | map = mmap (NULL, size, PROT_READ, MAP_PRIVATE, descriptor, pageoff); | |
71 | if (map == MAP_FAILED) | |
72 | { | |
73 | error_callback (data, "mmap", errno); | |
74 | return 0; | |
75 | } | |
76 | ||
77 | view->data = (char *) map + inpage; | |
78 | view->base = map; | |
79 | view->len = size; | |
80 | ||
81 | return 1; | |
82 | } | |
83 | ||
84 | /* Release a view read by backtrace_get_view. */ | |
85 | ||
86 | void | |
87 | backtrace_release_view (struct backtrace_state *state ATTRIBUTE_UNUSED, | |
88 | struct backtrace_view *view, | |
89 | backtrace_error_callback error_callback, | |
90 | void *data) | |
91 | { | |
92 | union { | |
93 | const void *cv; | |
94 | void *v; | |
95 | } const_cast; | |
96 | ||
97 | const_cast.cv = view->base; | |
98 | if (munmap (const_cast.v, view->len) < 0) | |
99 | error_callback (data, "munmap", errno); | |
100 | } |