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| author | Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr> | 2017-03-29 11:57:53 +0200 |
|---|---|---|
| committer | Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr> | 2017-06-28 07:29:04 +0200 |
| commit | c105c7d64bec61acc38a8f2dbabc657f12319e34 (patch) | |
| tree | 50ac73071eff9e934111e5aa745cf54cd7ffc1f6 | |
| parent | 419246d155840ce465210febf0a5109667fe55e8 (diff) | |
| download | glibc-c105c7d64bec61acc38a8f2dbabc657f12319e34.tar.gz | |
Y2038: implement Y2038-proof difftime
With -D_TIME_BITS=64, the 'difftime' API is implemented by
function '__difftime64'.
The API expects __time64_t arguments but returns a double like its
32-bit-time counterpart, in order to remain as source-code-compatible
as possible, even though the precision of a a double is only about 55
bits.
The implementation is simpler than its 32-bit counterpart, as it
assumes that all __time64_t implementations are just 64-bit integers.
Also, the implementation does not require a Y2038-proof kernel.
| -rw-r--r-- | sysdeps/unix/sysv/linux/arm/Versions | 7 | ||||
| -rw-r--r-- | time/difftime.c | 9 | ||||
| -rw-r--r-- | time/time.h | 8 |
3 files changed, 24 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/arm/Versions b/sysdeps/unix/sysv/linux/arm/Versions index 7e5ba53455..d3655768c8 100644 --- a/sysdeps/unix/sysv/linux/arm/Versions +++ b/sysdeps/unix/sysv/linux/arm/Versions @@ -16,4 +16,11 @@ libc { # nptl/pthread_cond_timedwait.c uses INTERNAL_VSYSCALL(clock_gettime). __vdso_clock_gettime; } + + # Y2038 symbols are given their own version until they can be put in + # the right place + + GLIBC_Y2038 { + __difftime64; + } } diff --git a/time/difftime.c b/time/difftime.c index e5e3311744..1b2494c727 100644 --- a/time/difftime.c +++ b/time/difftime.c @@ -119,3 +119,12 @@ __difftime (time_t time1, time_t time0) return time1 < time0 ? - subtract (time0, time1) : subtract (time1, time0); } strong_alias (__difftime, difftime) + +/* Return the difference between 64-bit TIME1 and TIME0. */ +double +__difftime64 (__time64_t time1, __time64_t time0) +{ + /* Subtract the smaller integer from the larger, convert the difference to + double, and then negate if needed. */ + return time1 < time0 ? - (time0 - time1) : (time1 - time0); +} diff --git a/time/time.h b/time/time.h index 7f98338abe..0fb1416aad 100644 --- a/time/time.h +++ b/time/time.h @@ -76,6 +76,14 @@ extern clock_t clock (void) __THROW; extern time_t time (time_t *__timer) __THROW; /* Return the difference between TIME1 and TIME0. */ +#ifdef __USE_TIME_BITS64 +# if defined(__REDIRECT) +extern double __REDIRECT (difftime, (time_t __time1, time_t __time0), + __difftime64) __THROW; +# else +# define difftime __difftime64 +# endif +#endif extern double difftime (time_t __time1, time_t __time0) __THROW __attribute__ ((__const__)); |