1 /* Copyright (C) 2004, 2005 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
22 #include <stdio_ext.h>
25 #include "libio/libioP.h"
27 /* Return 1 if the whole area PTR .. PTR+SIZE is not writable.
28 Return -1 if it is writable. */
31 __readonly_area (const char *ptr, size_t size)
33 const void *ptr_end = ptr + size;
35 FILE *fp = fopen ("/proc/self/maps", "rc");
38 /* It is the system administrator's choice to not have /proc
39 available to this process (e.g., because it runs in a chroot
40 environment. Don't fail in this case. */
42 /* The kernel has a bug in that a process is denied access
43 to the /proc filesystem if it is set[ug]id. There has
44 been no willingness to change this in the kernel so
51 /* We need no locking. */
52 __fsetlocking (fp, FSETLOCKING_BYCALLER);
57 while (! feof_unlocked (fp))
59 if (_IO_getdelim (&line, &linelen, '\n', fp) <= 0)
63 uintptr_t from = strtoul (line, &p, 16);
65 if (p == line || *p++ != '-')
69 uintptr_t to = strtoul (p, &q, 16);
71 if (q == p || *q++ != ' ')
74 if (from < (uintptr_t) ptr_end && to > (uintptr_t) ptr)
76 /* Found an entry that at least partially covers the area. */
77 if (*q++ != 'r' || *q++ != '-')
80 if (from <= (uintptr_t) ptr && to >= (uintptr_t) ptr_end)
85 else if (from <= (uintptr_t) ptr)
86 size -= to - (uintptr_t) ptr;
87 else if (to >= (uintptr_t) ptr_end)
88 size -= (uintptr_t) ptr_end - from;
100 /* If the whole area between ptr and ptr_end is covered by read-only
101 VMAs, return 1. Otherwise return -1. */
102 return size == 0 ? 1 : -1;