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[PATCH v4 1/3] y2038: Introduce internal for glibc struct __timespec64
- From: Lukasz Majewski <lukma at denx dot de>
- To: libc-alpha at sourceware dot org
- Cc: Stepan Golosunov <stepan at golosunov dot pp dot ru>, Arnd Bergmann <arnd at arndb dot de>, Paul Eggert <eggert at cs dot ucla dot edu>, Joseph Myers <joseph at codesourcery dot com>, Lukasz Majewski <lukma at denx dot de>
- Date: Mon, 20 May 2019 12:27:21 +0200
- Subject: [PATCH v4 1/3] y2038: Introduce internal for glibc struct __timespec64
- References: <20190414220841.20243-1-lukma@denx.de> <20190520102723.5380-1-lukma@denx.de>
This type is a glibc's type similar to struct timespec
but whose tv_sec field is a __time64_t rather than a time_t,
which makes it Y2038-proof and usable to pass between user
code and Y2038-proof kernel syscalls (e.g. clock_gettime()).
To support passing this structure to the kernel - the tv_pad,
32 bit int, has been introduced. The placement of it depends on
endianness of the SoC.
Tested on x86_64 and ARM.
* include/time.h: Add struct __timespec64 definition
---
Changes for v4:
- Change tv_pad's type from named bitfield to 32 bit int
Changes for v3:
- Replace __TIMESIZE with __WORDSIZE (as architectures with __TIMESIZE==64
will need to use this struct with 32 bit tv_nsec field).
- Update in-code comment
Changes for v2:
- None
---
include/time.h | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/include/time.h b/include/time.h
index ac3163c2a5..7dabb7a568 100644
--- a/include/time.h
+++ b/include/time.h
@@ -5,6 +5,7 @@
# include <bits/types/locale_t.h>
# include <stdbool.h>
# include <time/mktime-internal.h>
+# include <endian.h>
extern __typeof (strftime_l) __strftime_l;
libc_hidden_proto (__strftime_l)
@@ -51,6 +52,30 @@ extern void __tzset_parse_tz (const char *tz) attribute_hidden;
extern void __tz_compute (__time64_t timer, struct tm *tm, int use_localtime)
__THROW attribute_hidden;
+#if __WORDSIZE == 64
+# define __timespec64 timespec
+#else
+/* The glibc Y2038-proof struct __timespec64 structure for a time value.
+ To keep things Posix-ish, we keep the nanoseconds field a 32-bit
+ signed long, but since the Linux field is a 64-bit signed int, we
+ pad our tv_nsec with a 32-bit int.
+
+ As a general rule the Linux kernel is ignoring upper 32 bits of
+ tv_nsec field. However, there are architectures with potential need
+ for clearing the padding (i.e. 'x32'). */
+struct __timespec64
+{
+ __time64_t tv_sec; /* Seconds */
+# if BYTE_ORDER == BIG_ENDIAN
+ __int32_t tv_pad; /* Padding */
+ __int32_t tv_nsec; /* Nanoseconds */
+# else
+ __int32_t tv_nsec; /* Nanoseconds */
+ __int32_t tv_pad; /* Padding */
+# endif
+};
+#endif
+
#if __TIMESIZE == 64
# define __ctime64 ctime
#else
--
2.11.0