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2f4f3bd4 | 1 | /* clock_getres -- Get the resolution of a POSIX clockid_t. |
dff8da6b | 2 | Copyright (C) 1999-2024 Free Software Foundation, Inc. |
13fa3676 UD |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
13fa3676 UD |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
13fa3676 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
13fa3676 UD |
18 | |
19 | #include <errno.h> | |
3b5c1b57 | 20 | #include <stdint.h> |
8be918b7 | 21 | #include <time.h> |
13fa3676 | 22 | #include <unistd.h> |
3b5c1b57 UD |
23 | #include <sys/param.h> |
24 | #include <libc-internal.h> | |
7b5af2d8 | 25 | #include <shlib-compat.h> |
13fa3676 | 26 | |
2f4f3bd4 RM |
27 | static inline int |
28 | realtime_getres (struct timespec *res) | |
29 | { | |
dba2bdbe | 30 | long int clk_tck = __sysconf (_SC_CLK_TCK); |
2f4f3bd4 | 31 | |
a1ffb40e | 32 | if (__glibc_likely (clk_tck != -1)) |
2f4f3bd4 RM |
33 | { |
34 | /* This implementation assumes that the realtime clock has a | |
35 | resolution higher than 1 second. This is the case for any | |
36 | reasonable implementation. */ | |
67ca1c55 ST |
37 | if (res) |
38 | { | |
39 | res->tv_sec = 0; | |
40 | res->tv_nsec = 1000000000 / clk_tck; | |
41 | } | |
2f4f3bd4 RM |
42 | return 0; |
43 | } | |
44 | ||
45 | return -1; | |
46 | } | |
47 | ||
3b5c1b57 | 48 | |
13fa3676 UD |
49 | /* Get resolution of clock. */ |
50 | int | |
89fb6835 | 51 | __clock_getres (clockid_t clock_id, struct timespec *res) |
13fa3676 | 52 | { |
4a199526 | 53 | int retval = -1; |
13fa3676 UD |
54 | |
55 | switch (clock_id) | |
56 | { | |
ad0e8eb0 | 57 | case CLOCK_REALTIME: |
2f4f3bd4 | 58 | retval = realtime_getres (res); |
13fa3676 UD |
59 | break; |
60 | ||
4165d44d | 61 | default: |
38cc11da | 62 | __set_errno (EINVAL); |
3b5c1b57 | 63 | break; |
13fa3676 UD |
64 | } |
65 | ||
66 | return retval; | |
67 | } | |
e5ac7bd6 | 68 | libc_hidden_def (__clock_getres) |
7b5af2d8 ZW |
69 | |
70 | versioned_symbol (libc, __clock_getres, clock_getres, GLIBC_2_17); | |
71 | /* clock_getres moved to libc in version 2.17; | |
72 | old binaries may expect the symbol version it had in librt. */ | |
73 | #if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17) | |
74 | strong_alias (__clock_getres, __clock_getres_2); | |
75 | compat_symbol (libc, __clock_getres_2, clock_getres, GLIBC_2_2); | |
76 | #endif |