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b168057a | 1 | /* Copyright (C) 2004-2015 Free Software Foundation, Inc. |
b5cc329c UD |
2 | This file is part of the GNU C Library. |
3 | ||
4 | The GNU C Library is free software; you can redistribute it and/or | |
5 | modify it under the terms of the GNU Lesser General Public | |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
8 | ||
9 | The GNU C Library is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 PE |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ | |
b5cc329c | 17 | |
31d12f6c | 18 | #include <errno.h> |
b5cc329c UD |
19 | #include <stdint.h> |
20 | #include <stdio.h> | |
21 | #include <stdio_ext.h> | |
22 | #include <stdlib.h> | |
23 | #include <string.h> | |
24 | #include "libio/libioP.h" | |
25 | ||
26 | /* Return 1 if the whole area PTR .. PTR+SIZE is not writable. | |
27 | Return -1 if it is writable. */ | |
28 | ||
29 | int | |
30 | __readonly_area (const char *ptr, size_t size) | |
31 | { | |
32 | const void *ptr_end = ptr + size; | |
33 | ||
312be3f9 | 34 | FILE *fp = fopen ("/proc/self/maps", "rce"); |
b5cc329c | 35 | if (fp == NULL) |
31d12f6c | 36 | { |
5d1d7adb UD |
37 | /* It is the system administrator's choice to not have /proc |
38 | available to this process (e.g., because it runs in a chroot | |
39 | environment. Don't fail in this case. */ | |
40 | if (errno == ENOENT | |
41 | /* The kernel has a bug in that a process is denied access | |
42 | to the /proc filesystem if it is set[ug]id. There has | |
43 | been no willingness to change this in the kernel so | |
44 | far. */ | |
45 | || errno == EACCES) | |
31d12f6c UD |
46 | return 1; |
47 | return -1; | |
48 | } | |
b5cc329c UD |
49 | |
50 | /* We need no locking. */ | |
51 | __fsetlocking (fp, FSETLOCKING_BYCALLER); | |
52 | ||
53 | char *line = NULL; | |
54 | size_t linelen = 0; | |
55 | ||
56 | while (! feof_unlocked (fp)) | |
57 | { | |
58 | if (_IO_getdelim (&line, &linelen, '\n', fp) <= 0) | |
59 | break; | |
60 | ||
61 | char *p; | |
62 | uintptr_t from = strtoul (line, &p, 16); | |
63 | ||
64 | if (p == line || *p++ != '-') | |
65 | break; | |
66 | ||
67 | char *q; | |
68 | uintptr_t to = strtoul (p, &q, 16); | |
69 | ||
70 | if (q == p || *q++ != ' ') | |
71 | break; | |
72 | ||
73 | if (from < (uintptr_t) ptr_end && to > (uintptr_t) ptr) | |
74 | { | |
75 | /* Found an entry that at least partially covers the area. */ | |
76 | if (*q++ != 'r' || *q++ != '-') | |
77 | break; | |
78 | ||
79 | if (from <= (uintptr_t) ptr && to >= (uintptr_t) ptr_end) | |
80 | { | |
81 | size = 0; | |
82 | break; | |
83 | } | |
84 | else if (from <= (uintptr_t) ptr) | |
85 | size -= to - (uintptr_t) ptr; | |
86 | else if (to >= (uintptr_t) ptr_end) | |
87 | size -= (uintptr_t) ptr_end - from; | |
88 | else | |
89 | size -= to - from; | |
90 | ||
91 | if (!size) | |
92 | break; | |
93 | } | |
94 | } | |
95 | ||
96 | fclose (fp); | |
97 | free (line); | |
98 | ||
99 | /* If the whole area between ptr and ptr_end is covered by read-only | |
100 | VMAs, return 1. Otherwise return -1. */ | |
101 | return size == 0 ? 1 : -1; | |
102 | } |