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1 /* mmapio.c -- File views using mmap.
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2 Copyright (C) 2012-2020 Free Software Foundation, Inc.
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3 Written by Ian Lance Taylor, Google.
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4
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5 Redistribution and use in source and binary forms, with or without
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6 modification, are permitted provided that the following conditions are
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7 met:
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8
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9 (1) Redistributions of source code must retain the above copyright
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10 notice, this list of conditions and the following disclaimer.
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11
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12 (2) Redistributions in binary form must reproduce the above copyright
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13 notice, this list of conditions and the following disclaimer in
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14 the documentation and/or other materials provided with the
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15 distribution.
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16
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17 (3) The name of the author may not be used to
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18 endorse or promote products derived from this software without
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19 specific prior written permission.
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20
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21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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24 DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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25 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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26 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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27 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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28 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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29 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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30 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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31 POSSIBILITY OF SUCH DAMAGE. */
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32
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33 #include "config.h"
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34
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35 #include <errno.h>
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36 #include <sys/types.h>
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37 #include <sys/mman.h>
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38 #include <unistd.h>
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39
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40 #include "backtrace.h"
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41 #include "internal.h"
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42
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43 #ifndef MAP_FAILED
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44 #define MAP_FAILED ((void *)-1)
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45 #endif
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46
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47 /* This file implements file views and memory allocation when mmap is
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48 available. */
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49
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50 /* Create a view of SIZE bytes from DESCRIPTOR at OFFSET. */
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51
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52 int
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53 backtrace_get_view (struct backtrace_state *state ATTRIBUTE_UNUSED,
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54 int descriptor, off_t offset, uint64_t size,
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55 backtrace_error_callback error_callback,
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56 void *data, struct backtrace_view *view)
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57 {
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58 size_t pagesize;
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59 unsigned int inpage;
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60 off_t pageoff;
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61 void *map;
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62
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63 if ((uint64_t) (size_t) size != size)
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64 {
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65 error_callback (data, "file size too large", 0);
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66 return 0;
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67 }
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68
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69 pagesize = getpagesize ();
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70 inpage = offset % pagesize;
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71 pageoff = offset - inpage;
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72
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73 size += inpage;
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74 size = (size + (pagesize - 1)) & ~ (pagesize - 1);
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75
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76 map = mmap (NULL, size, PROT_READ, MAP_PRIVATE, descriptor, pageoff);
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77 if (map == MAP_FAILED)
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78 {
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79 error_callback (data, "mmap", errno);
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80 return 0;
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81 }
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82
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83 view->data = (char *) map + inpage;
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84 view->base = map;
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85 view->len = size;
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86
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87 return 1;
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88 }
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89
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90 /* Release a view read by backtrace_get_view. */
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91
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92 void
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93 backtrace_release_view (struct backtrace_state *state ATTRIBUTE_UNUSED,
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94 struct backtrace_view *view,
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95 backtrace_error_callback error_callback,
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96 void *data)
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97 {
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98 union {
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99 const void *cv;
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100 void *v;
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101 } const_cast;
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102
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103 const_cast.cv = view->base;
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104 if (munmap (const_cast.v, view->len) < 0)
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105 error_callback (data, "munmap", errno);
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106 }
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