| /* Copyright (C) 2000-2014 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 <fcntl.h> |
| #include <unistd.h> |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| #include <not-cancel.h> |
| |
| static int itc_usable; |
| |
| static int |
| has_cpuclock (void) |
| { |
| if (__builtin_expect (itc_usable == 0, 0)) |
| { |
| int newval = 1; |
| int fd = open_not_cancel_2 ("/proc/sal/itc_drift", O_RDONLY); |
| if (__builtin_expect (fd != -1, 1)) |
| { |
| char buf[16]; |
| /* We expect the file to contain a single digit followed by |
| a newline. If the format changes we better not rely on |
| the file content. */ |
| if (read_not_cancel (fd, buf, sizeof buf) != 2 |
| || buf[0] != '0' || buf[1] != '\n') |
| newval = -1; |
| |
| close_not_cancel_no_status (fd); |
| } |
| |
| itc_usable = newval; |
| } |
| |
| return itc_usable; |
| } |
