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[PATCH v2] Y2038: make __difftime compatible with 64-bit time
- From: "Albert ARIBAUD (3ADEV)" <albert dot aribaud at 3adev dot fr>
- To: libc-alpha at sourceware dot org
- Cc: "Albert ARIBAUD (3ADEV)" <albert dot aribaud at 3adev dot fr>
- Date: Wed, 26 Sep 2018 09:42:43 +0200
- Subject: [PATCH v2] Y2038: make __difftime compatible with 64-bit time
Provide a 64-bit-time version of __difftime (but do not assume
__time64_t is a signed int so that Gnulib can reuse the code)
and make the 32-bit version a wrapper of it.
Current difftime expects two time_t arguments and returns a
double. To preserve source-code compatibility, its 64-bit-time
equivalent expects two __time64_t arguments but still returns
a double.
* include/time.h (__difftime64): Add.
* time/difftime.c (subtract): convert to 64-bit time.
* time/difftime.c (__difftime64): Add.
* time/difftime.c (__difftime): Wrap around __difftime64.
---
include/time.h | 6 ++++++
time/difftime.c | 31 ++++++++++++++++++++++---------
2 files changed, 28 insertions(+), 9 deletions(-)
diff --git a/include/time.h b/include/time.h
index 68e1624f0c..0325772b8e 100644
--- a/include/time.h
+++ b/include/time.h
@@ -124,6 +124,12 @@ extern char * __strptime_internal (const char *rp, const char *fmt,
struct tm *tm, void *statep,
locale_t locparam) attribute_hidden;
+#if __TIMESIZE == 64
+# define __difftime64 __difftime
+#else
+extern double __difftime64 (__time64_t time1, __time64_t time0);
+#endif
+
extern double __difftime (time_t time1, time_t time0);
/* Use in the clock_* functions. Size of the field representing the
diff --git a/time/difftime.c b/time/difftime.c
index 7c5dd9898b..e3a4e57b44 100644
--- a/time/difftime.c
+++ b/time/difftime.c
@@ -31,9 +31,9 @@
time_t is known to be an integer type. */
static double
-subtract (time_t time1, time_t time0)
+subtract (__time64_t time1, __time64_t time0)
{
- if (! TYPE_SIGNED (time_t))
+ if (! TYPE_SIGNED (__time64_t))
return time1 - time0;
else
{
@@ -76,9 +76,9 @@ subtract (time_t time1, time_t time0)
1 is unsigned in C, so it need not be compared to zero. */
uintmax_t hdt = dt / 2;
- time_t ht1 = time1 / 2;
- time_t ht0 = time0 / 2;
- time_t dht = ht1 - ht0;
+ __time64_t ht1 = time1 / 2;
+ __time64_t ht0 = time0 / 2;
+ __time64_t dht = ht1 - ht0;
if (2 < dht - hdt + 1)
{
@@ -99,18 +99,18 @@ subtract (time_t time1, time_t time0)
/* Return the difference between TIME1 and TIME0. */
double
-__difftime (time_t time1, time_t time0)
+__difftime64 (__time64_t time1, __time64_t time0)
{
/* Convert to double and then subtract if no double-rounding error could
result. */
- if (TYPE_BITS (time_t) <= DBL_MANT_DIG
- || (TYPE_FLOATING (time_t) && sizeof (time_t) < sizeof (long double)))
+ if (TYPE_BITS (__time64_t) <= DBL_MANT_DIG
+ || (TYPE_FLOATING (__time64_t) && sizeof (__time64_t) < sizeof (long double)))
return (double) time1 - (double) time0;
/* Likewise for long double. */
- if (TYPE_BITS (time_t) <= LDBL_MANT_DIG || TYPE_FLOATING (time_t))
+ if (TYPE_BITS (__time64_t) <= LDBL_MANT_DIG || TYPE_FLOATING (__time64_t))
return (long double) time1 - (long double) time0;
/* Subtract the smaller integer from the larger, convert the difference to
@@ -118,4 +118,17 @@ __difftime (time_t time1, time_t time0)
return time1 < time0 ? - subtract (time0, time1) : subtract (time1, time0);
}
+
+/* Provide a 32-bit wrapper if needed */
+
+#if __TIMESIZE != 64
+
+double
+__difftime (time_t time1, time_t time0)
+{
+ return __difftime64 (time1, time0);
+}
+
+#endif
+
strong_alias (__difftime, difftime)
--
2.17.1