[RFC,02/52] Y2038: add function __difftime64
Commit Message
Note: the implementation 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
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.
Signed-off-by: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>
---
sysdeps/unix/sysv/linux/arm/Versions | 7 +++++++
time/difftime.c | 9 +++++++++
2 files changed, 16 insertions(+)
@@ -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;
+ }
}
@@ -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);
+}