clock_gettime implementation for Linux.
[kopensolaris-gnu/glibc.git] / sysdeps / unix / sysv / linux / clock_gettime.c
1 /* Copyright (C) 2003 Free Software Foundation, Inc.
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
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
17    02111-1307 USA.  */
18
19 #include <sysdep.h>
20
21 #include "kernel-features.h"
22
23
24 #ifdef __ASSUME_POSIX_TIMERS
25 /* This means the REALTIME and MONOTONIC clock are definitely
26    supported in the kernel.  */
27 # define SYSDEP_GETTIME \
28   case CLOCK_REALTIME:                                                        \
29   case CLOCK_MONOTONIC:                                                       \
30     retval = INLINE_SYSCALL (clock_gettime, 2, clock_id, tp);                 \
31     break
32 #elif defined __NR_clock_gettime
33 /* Is the syscall known to exist?  */
34 int __libc_missing_posix_timers attribute_hidden;
35
36 /* The REALTIME and MONOTONIC clock might be available.  Try the
37    syscall first.  */
38 # define SYSDEP_GETTIME \
39   case CLOCK_REALTIME:                                                        \
40   case CLOCK_MONOTONIC:                                                       \
41     {                                                                         \
42       int e = EINVAL;                                                         \
43                                                                               \
44       if (!__libc_missing_posix_timers)                                       \
45         {                                                                     \
46           INTERNAL_SYSCALL_DECL (err);                                        \
47           int r = INTERNAL_SYSCALL (clock_gettime, err, 2, clock_id, tp);     \
48           if (!INTERNAL_SYSCALL_ERROR_P (r, err))                             \
49             {                                                                 \
50               retval = 0;                                                     \
51               break;                                                          \
52             }                                                                 \
53                                                                               \
54           e = INTERNAL_SYSCALL_ERRNO (r, err);                                \
55           if (e == ENOSYS)                                                    \
56             {                                                                 \
57               __libc_missing_posix_timers = 1;                                \
58               e = EINVAL;                                                     \
59             }                                                                 \
60         }                                                                     \
61                                                                               \
62       /* Fallback code.  */                                                   \
63       if (e == EINVAL && clock_id == CLOCK_REALTIME)                          \
64         HANDLE_REALTIME;                                                      \
65       else                                                                    \
66         __set_errno (e);                                                      \
67     }                                                                         \
68     break
69 #endif
70
71 #ifdef __NR_clock_gettime
72 /* We handled the REALTIME clock here.  */
73 # define HANDLED_REALTIME       1
74 #endif
75
76 #include <sysdeps/unix/clock_gettime.c>