1*38fd1498Szrj /* mmapio.c -- File views using mmap.
2*38fd1498Szrj Copyright (C) 2012-2018 Free Software Foundation, Inc.
3*38fd1498Szrj Written by Ian Lance Taylor, Google.
4*38fd1498Szrj
5*38fd1498Szrj Redistribution and use in source and binary forms, with or without
6*38fd1498Szrj modification, are permitted provided that the following conditions are
7*38fd1498Szrj met:
8*38fd1498Szrj
9*38fd1498Szrj (1) Redistributions of source code must retain the above copyright
10*38fd1498Szrj notice, this list of conditions and the following disclaimer.
11*38fd1498Szrj
12*38fd1498Szrj (2) Redistributions in binary form must reproduce the above copyright
13*38fd1498Szrj notice, this list of conditions and the following disclaimer in
14*38fd1498Szrj the documentation and/or other materials provided with the
15*38fd1498Szrj distribution.
16*38fd1498Szrj
17*38fd1498Szrj (3) The name of the author may not be used to
18*38fd1498Szrj endorse or promote products derived from this software without
19*38fd1498Szrj specific prior written permission.
20*38fd1498Szrj
21*38fd1498Szrj THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22*38fd1498Szrj IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23*38fd1498Szrj WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24*38fd1498Szrj DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
25*38fd1498Szrj INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
26*38fd1498Szrj (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
27*38fd1498Szrj SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28*38fd1498Szrj HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
29*38fd1498Szrj STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30*38fd1498Szrj IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31*38fd1498Szrj POSSIBILITY OF SUCH DAMAGE. */
32*38fd1498Szrj
33*38fd1498Szrj #include "config.h"
34*38fd1498Szrj
35*38fd1498Szrj #include <errno.h>
36*38fd1498Szrj #include <sys/types.h>
37*38fd1498Szrj #include <sys/mman.h>
38*38fd1498Szrj #include <unistd.h>
39*38fd1498Szrj
40*38fd1498Szrj #include "backtrace.h"
41*38fd1498Szrj #include "internal.h"
42*38fd1498Szrj
43*38fd1498Szrj #ifndef MAP_FAILED
44*38fd1498Szrj #define MAP_FAILED ((void *)-1)
45*38fd1498Szrj #endif
46*38fd1498Szrj
47*38fd1498Szrj /* This file implements file views and memory allocation when mmap is
48*38fd1498Szrj available. */
49*38fd1498Szrj
50*38fd1498Szrj /* Create a view of SIZE bytes from DESCRIPTOR at OFFSET. */
51*38fd1498Szrj
52*38fd1498Szrj int
backtrace_get_view(struct backtrace_state * state ATTRIBUTE_UNUSED,int descriptor,off_t offset,size_t size,backtrace_error_callback error_callback,void * data,struct backtrace_view * view)53*38fd1498Szrj backtrace_get_view (struct backtrace_state *state ATTRIBUTE_UNUSED,
54*38fd1498Szrj int descriptor, off_t offset, size_t size,
55*38fd1498Szrj backtrace_error_callback error_callback,
56*38fd1498Szrj void *data, struct backtrace_view *view)
57*38fd1498Szrj {
58*38fd1498Szrj size_t pagesize;
59*38fd1498Szrj unsigned int inpage;
60*38fd1498Szrj off_t pageoff;
61*38fd1498Szrj void *map;
62*38fd1498Szrj
63*38fd1498Szrj pagesize = getpagesize ();
64*38fd1498Szrj inpage = offset % pagesize;
65*38fd1498Szrj pageoff = offset - inpage;
66*38fd1498Szrj
67*38fd1498Szrj size += inpage;
68*38fd1498Szrj size = (size + (pagesize - 1)) & ~ (pagesize - 1);
69*38fd1498Szrj
70*38fd1498Szrj map = mmap (NULL, size, PROT_READ, MAP_PRIVATE, descriptor, pageoff);
71*38fd1498Szrj if (map == MAP_FAILED)
72*38fd1498Szrj {
73*38fd1498Szrj error_callback (data, "mmap", errno);
74*38fd1498Szrj return 0;
75*38fd1498Szrj }
76*38fd1498Szrj
77*38fd1498Szrj view->data = (char *) map + inpage;
78*38fd1498Szrj view->base = map;
79*38fd1498Szrj view->len = size;
80*38fd1498Szrj
81*38fd1498Szrj return 1;
82*38fd1498Szrj }
83*38fd1498Szrj
84*38fd1498Szrj /* Release a view read by backtrace_get_view. */
85*38fd1498Szrj
86*38fd1498Szrj void
backtrace_release_view(struct backtrace_state * state ATTRIBUTE_UNUSED,struct backtrace_view * view,backtrace_error_callback error_callback,void * data)87*38fd1498Szrj backtrace_release_view (struct backtrace_state *state ATTRIBUTE_UNUSED,
88*38fd1498Szrj struct backtrace_view *view,
89*38fd1498Szrj backtrace_error_callback error_callback,
90*38fd1498Szrj void *data)
91*38fd1498Szrj {
92*38fd1498Szrj union {
93*38fd1498Szrj const void *cv;
94*38fd1498Szrj void *v;
95*38fd1498Szrj } const_cast;
96*38fd1498Szrj
97*38fd1498Szrj const_cast.cv = view->base;
98*38fd1498Szrj if (munmap (const_cast.v, view->len) < 0)
99*38fd1498Szrj error_callback (data, "munmap", errno);
100*38fd1498Szrj }
101