| /* Copyright (C) 2004-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <errno.h> |
| #include <stdint.h> |
| #include <stdio.h> |
| #include <stdio_ext.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include "libio/libioP.h" |
| |
| /* Return 1 if the whole area PTR .. PTR+SIZE is not writable. |
| Return -1 if it is writable. */ |
| |
| int |
| __readonly_area (const char *ptr, size_t size) |
| { |
| const void *ptr_end = ptr + size; |
| |
| FILE *fp = fopen ("/proc/self/maps", "rce"); |
| if (fp == NULL) |
| { |
| /* It is the system administrator's choice to not have /proc |
| available to this process (e.g., because it runs in a chroot |
| environment. Don't fail in this case. */ |
| if (errno == ENOENT |
| /* The kernel has a bug in that a process is denied access |
| to the /proc filesystem if it is set[ug]id. There has |
| been no willingness to change this in the kernel so |
| far. */ |
| || errno == EACCES) |
| return 1; |
| return -1; |
| } |
| |
| /* We need no locking. */ |
| __fsetlocking (fp, FSETLOCKING_BYCALLER); |
| |
| char *line = NULL; |
| size_t linelen = 0; |
| |
| while (! feof_unlocked (fp)) |
| { |
| if (_IO_getdelim (&line, &linelen, '\n', fp) <= 0) |
| break; |
| |
| char *p; |
| uintptr_t from = strtoul (line, &p, 16); |
| |
| if (p == line || *p++ != '-') |
| break; |
| |
| char *q; |
| uintptr_t to = strtoul (p, &q, 16); |
| |
| if (q == p || *q++ != ' ') |
| break; |
| |
| if (from < (uintptr_t) ptr_end && to > (uintptr_t) ptr) |
| { |
| /* Found an entry that at least partially covers the area. */ |
| if (*q++ != 'r' || *q++ != '-') |
| break; |
| |
| if (from <= (uintptr_t) ptr && to >= (uintptr_t) ptr_end) |
| { |
| size = 0; |
| break; |
| } |
| else if (from <= (uintptr_t) ptr) |
| size -= to - (uintptr_t) ptr; |
| else if (to >= (uintptr_t) ptr_end) |
| size -= (uintptr_t) ptr_end - from; |
| else |
| size -= to - from; |
| |
| if (!size) |
| break; |
| } |
| } |
| |
| fclose (fp); |
| free (line); |
| |
| /* If the whole area between ptr and ptr_end is covered by read-only |
| VMAs, return 1. Otherwise return -1. */ |
| return size == 0 ? 1 : -1; |
| } |