y2038: Support for Y2038 safe time on 32 bit systems

The time_t type is now Y2038 safe, which means that it is aliased to
__time64_t when __USE_TIME_BITS64 is defined or __time_t otherwise.

On the contrary the __time_t for 32 bit systems is only 32 bit, so for
Y2038 safe system it must be 64 bit (as is time_t)

This patch introduces the Y2038 specific code to make clock_settime/
__clock_settime64 Y2038 safe on 32 bit systems.
This goal is achieved by using aliasing to clock_settime names when
__USE_TIME_BITS64 is defined.
As a result user programs call 64 bit versions of functions (i.e.
__clock_settime64 instead of __clock_settime), which must have been
globally visible for this purpose - for non Y2038 safe code those are
hidden in glibc.

Additionally this patch also converts following syscalls to be Y2038:
- clock_gettime64
- clock_settime64
- clock_getres64
- utimensat
- futimens
- clock_nanosleep_time64
- ppoll64
- timer_gettime
- timer_settime
- timerfd_gettime (WIP)
- timerfd_settime (WIP)
- sched_rr_get_interval (WIP)
- timespec_get (WIP)
- settimeofday (WIP)

---
Changes for vX:
- Adjust the code to the current master branch of glibc
- Add support for converting clock_getres to be Y2038 safe
- Extend struct timeval to be Y2038 safe

Changes for v3:
- Only support clock_settime conversion to be Y2038 (use it as an example
  conversion code)

Changes for v2:
- Introduce unnamed padding in the struct timespec exported by glibc
  (to the /usr/include)

include/features.h

@@ -380,6 +380,25 @@
 # define __USE_FILE_OFFSET64	1
 #endif
 
+/* We need to know the word size in order to check the time size.  */
+#include <bits/wordsize.h>
+
+#if defined _TIME_BITS
+# if _TIME_BITS == 64
+#  if ! defined (_FILE_OFFSET_BITS) || _FILE_OFFSET_BITS != 64
+#   error _TIME_BITS==64 is allowed only when _FILE_OFFSET_BITS==64
+#  elif __WORDSIZE == 32
+#   define __USE_TIME_BITS64	1
+#  endif
+# elif _TIME_BITS == 32
+#  if __WORDSIZE > 32
+#   error _TIME_BITS=32 is not compatible with __WORDSIZE > 32
+#  endif
+# else
+#  error Invalid _TIME_BITS value (can only be 32 or 64)
+# endif
+#endif
+
 #if defined _DEFAULT_SOURCE
 # define __USE_MISC	1
 #endif

include/sys/poll.h

@@ -16,7 +16,8 @@ libc_hidden_proto (ppoll)
 extern int __ppoll64 (struct pollfd *fds, nfds_t nfds,
                       const struct __timespec64 *timeout,
                       const sigset_t *sigmask);
-libc_hidden_proto (__ppoll64)
+/* For Y2038 safe system the __ppoll64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe ppoll.  */
 # endif
 #endif
 #endif

include/time.h

@@ -164,23 +164,26 @@ libc_hidden_proto (__timegm64)
 #else
 extern int __clock_settime64 (clockid_t clock_id,
                               const struct __timespec64 *tp);
-libc_hidden_proto (__clock_settime64)
+/* For Y2038 safe system the __clock_settime64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe clock_settime.  */
 #endif
 
 #if __TIMESIZE == 64
 # define __clock_getres64 __clock_getres
 #else
 extern int __clock_getres64 (clockid_t clock_id,
                              struct __timespec64 *tp);
-libc_hidden_proto (__clock_getres64);
+/* For Y2038 safe system the __clock_settime64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe clock_settime.  */
 #endif
 
 #if __TIMESIZE == 64
 # define __utimensat64 __utimensat
 #else
 extern int __utimensat64 (int fd, const char *file,
                           const struct __timespec64 tsp[2], int flags);
-libc_hidden_proto (__utimensat64);
+/* For Y2038 safe system the __utimensat64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe utimensat.  */
 #endif
 
 extern int __utimensat64_helper (int fd, const char *file,
@@ -191,7 +194,8 @@ libc_hidden_proto (__utimensat64_helper);
 # define __futimens64 __futimens
 #else
 extern int __futimens64 (int fd, const struct __timespec64 tsp[2]);
-libc_hidden_proto (__futimens64);
+/* For Y2038 safe system the __utimensat64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe utimensat.  */
 #endif
 
 #if __TIMESIZE == 64
@@ -200,7 +204,8 @@ libc_hidden_proto (__futimens64);
 #else
 extern int __timer_gettime64 (timer_t timerid, struct __itimerspec64 *value);
 extern int __timerfd_gettime64 (int fd, struct __itimerspec64 *value);
-libc_hidden_proto (__timer_gettime64);
+/* For Y2038 safe system the __timer_gettime64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe timer_gettime.  */
 libc_hidden_proto (__timerfd_gettime64);
 #endif
 
@@ -211,10 +216,11 @@ libc_hidden_proto (__timerfd_gettime64);
 extern int __timer_settime64 (timer_t timerid, int flags,
                               const struct __itimerspec64 *value,
                               struct __itimerspec64 *ovalue);
+/* For Y2038 safe system the __timer_settime64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe timer_settime.  */
 extern int __timerfd_settime64 (int fd, int flags,
                                 const struct __itimerspec64 *value,
                                 struct __itimerspec64 *ovalue);
-libc_hidden_proto (__timer_settime64);
 libc_hidden_proto (__timerfd_settime64);
 #endif
 
@@ -282,9 +288,11 @@ extern double __difftime (time_t time1, time_t time0);
 extern int __clock_nanosleep_time64 (clockid_t clock_id,
                                      int flags, const struct __timespec64 *req,
                                      struct __timespec64 *rem);
-libc_hidden_proto (__clock_nanosleep_time64)
 extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
-libc_hidden_proto (__clock_gettime64)
+/* For Y2038 safe system the __clock_nanosleep_time64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe clock_nanosleep.  */
+/* For Y2038 safe system the __clock_gettime64 needs to be a visible
+   symbol as a replacement for Y2038 unsafe clock_gettime64.  */
 extern int __timespec_get64 (struct __timespec64 *ts, int base);
 libc_hidden_proto (__timespec_get64)
 #endif

io/Versions

@@ -137,5 +137,6 @@ libc {
     __fcntl_nocancel;
     __open64_nocancel;
     __write_nocancel;
+    __ppoll64;
   }
 }

io/sys/poll.h

@@ -63,6 +63,17 @@ extern int poll (struct pollfd *__fds, nfds_t __nfds, int __timeout);
 extern int ppoll (struct pollfd *__fds, nfds_t __nfds,
 		  const struct timespec *__timeout,
 		  const __sigset_t *__ss);
+
+# ifdef __USE_TIME_BITS64
+#  if defined(__REDIRECT)
+extern int __REDIRECT (ppoll, (struct pollfd *__fds, nfds_t __nfds,
+                               const struct timespec *__timeout,
+                               const __sigset_t *__ss),
+                       __ppoll64);
+#  else
+#  define ppoll __ppoll64
+#  endif
+# endif
 #endif
 
 __END_DECLS

io/sys/stat.h

@@ -361,11 +361,31 @@ extern int utimensat (int __fd, const char *__path,
 		      const struct timespec __times[2],
 		      int __flags)
      __THROW __nonnull ((2));
+
+# ifdef __USE_TIME_BITS64
+#  if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (utimensat, (int fd, const char *__path,
+                                       const struct timespec __times[2],
+                                       int flags),
+                           __utimensat64) __nonnull ((2));
+#  else
+#  define utimensat __utimensat64
+#  endif
+# endif
 #endif
 
 #ifdef __USE_XOPEN2K8
 /* Set file access and modification times of the file associated with FD.  */
 extern int futimens (int __fd, const struct timespec __times[2]) __THROW;
+
+# ifdef __USE_TIME_BITS64
+#  if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (futimens, (int fd, const struct timespec __times[2]),
+                           __futimens64);
+#  else
+#  define futimens __futimens64
+#  endif
+# endif
 #endif
 
 /* To allow the `struct stat' structure and the file type `mode_t'

manual/creature.texi

@@ -165,6 +165,34 @@ This macro was introduced as part of the Large File Support extension
 (LFS).
 @end defvr
 
+@defvr Macro _TIME_BITS
+This macro determines the bit size of @code{time_t} (and therefore the
+bit size of all @code{time_t} derived types and the prototypes of all
+related functions). If @code{_TIME_BITS} is undefined, the bit size of
+time_t equals the bit size of the architecture.
+
+If @code{_TIME_BITS} is undefined, or if @code{_TIME_BITS} is defined
+to the value @code{32} and @code{__WORDSIZE} is defined to the value
+@code{32}, or or if @code{_TIME_BITS} is defined to the value @code{64}
+and @code{__WORDSIZE} is defined to the value @code{64}, nothing changes.
+
+If @code{_TIME_BITS} is defined to the value @code{64} and if
+@code{__WORDSIZE} is defined to the value @code{32}, then the @w{64 bit}
+time API and implementation are used even though the architecture word
+size is @code{32}. Also, if the kernel provides @w{64 bit} time support,
+it is used; otherwise, the @w{32 bit} kernel time support is used (with
+no provision to address kernel Y2038 shortcomings).
+
+If @code{_TIME_BITS} is defined to the value @code{32} and if
+@code{__WORDSIZE} is defined to the value @code{64}, then a compile-time
+error is emitted.
+
+If @code{_TIME_BITS} is defined to a value different from both @code{32}
+and @code{64}, then a compile-time error is emitted.
+
+This macro was introduced as part of the Y2038 support.
+@end defvr
+
 @defvr Macro _ISOC99_SOURCE
 @standards{GNU, (none)}
 If this macro is defined, features from ISO C99 are included.  Since

rt/Versions

@@ -1,4 +1,8 @@
 librt {
+  GLIBC_PRIVATE {
+    __timer_gettime64;
+    __timer_settime64;
+  }
   GLIBC_2.1 {
     # AIO functions.
     aio_cancel; aio_cancel64; aio_error; aio_error64; aio_fsync; aio_fsync64;

time/Versions

@@ -1,4 +1,14 @@
 libc {
+  GLIBC_PRIVATE {
+    __clock_gettime64;
+    __clock_settime64;
+    __clock_getres64;
+    __clock_nanosleep_time64;
+    __utimensat64;
+    __futimens64;
+    __timer_gettime64;
+    __timer_settime64;
+  }
   GLIBC_2.0 {
     # global variables
     __daylight; __timezone; __tzname;

time/bits/types/struct_timespec.h

@@ -4,25 +4,30 @@
 
 #include <bits/types.h>
 #include <bits/endian.h>
+#include <bits/types/time_t.h>
 
 /* POSIX.1b structure for a time value.  This is like a `struct timeval' but
    has nanoseconds instead of microseconds.  */
 struct timespec
 {
+# ifdef __USE_TIME_BITS64
+  __time64_t tv_sec;		/* Seconds.  */
+# else
   __time_t tv_sec;		/* Seconds.  */
-#if __WORDSIZE == 64 \
+# endif
+# if __WORDSIZE == 64 \
   || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64) \
-  || __TIMESIZE == 32
+	|| (__TIMESIZE == 32 && !defined __USE_TIME_BITS64)
   __syscall_slong_t tv_nsec;	/* Nanoseconds.  */
-#else
-# if __BYTE_ORDER == __BIG_ENDIAN
+# else
+#  if __BYTE_ORDER == __BIG_ENDIAN
   int: 32;           /* Padding.  */
   long int tv_nsec;  /* Nanoseconds.  */
-# else
+#  else
   long int tv_nsec;  /* Nanoseconds.  */
   int: 32;           /* Padding.  */
+#  endif
 # endif
-#endif
 };
 
 #endif

time/bits/types/struct_timeval.h

@@ -7,7 +7,11 @@
    microsecond but also has a range of years.  */
 struct timeval
 {
+# ifdef __USE_TIME_BITS64
+  __time64_t tv_sec;		/* Seconds.  */
+# else
   __time_t tv_sec;		/* Seconds.  */
+# endif
   __suseconds_t tv_usec;	/* Microseconds.  */
 };
 #endif

time/bits/types/time_t.h

@@ -4,6 +4,10 @@
 #include <bits/types.h>
 
 /* Returned by `time'.  */
+#ifdef __USE_TIME_BITS64
+typedef __time64_t time_t;
+#else
 typedef __time_t time_t;
+#endif
 
 #endif

time/time.h

@@ -209,13 +209,41 @@ extern int nanosleep (const struct timespec *__requested_time,
 /* Get resolution of clock CLOCK_ID.  */
 extern int clock_getres (clockid_t __clock_id, struct timespec *__res) __THROW;
 
+#ifdef __USE_TIME_BITS64
+# if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (clock_getres, (clockid_t __clock_id,
+                                          struct timespec *__res),
+                           __clock_getres64);
+# else
+# define clock_getres __clock_getres64
+# endif
+#endif
+
 /* Get current value of clock CLOCK_ID and store it in TP.  */
 extern int clock_gettime (clockid_t __clock_id, struct timespec *__tp) __THROW;
 
+#ifdef __USE_TIME_BITS64
+# if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (clock_gettime, (clockid_t __clock_id, struct
+                                           timespec *__tp), __clock_gettime64);
+# else
+# define clock_gettime __clock_gettime64
+# endif
+#endif
+
 /* Set clock CLOCK_ID to value TP.  */
 extern int clock_settime (clockid_t __clock_id, const struct timespec *__tp)
      __THROW;
 
+#ifdef __USE_TIME_BITS64
+# if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (clock_settime, (clockid_t __clock_id, const struct
+                                           timespec *__tp), __clock_settime64);
+# else
+# define clock_settime __clock_settime64
+# endif
+#endif
+
 # ifdef __USE_XOPEN2K
 /* High-resolution sleep with the specified clock.
 
@@ -225,6 +253,17 @@ extern int clock_nanosleep (clockid_t __clock_id, int __flags,
 			    const struct timespec *__req,
 			    struct timespec *__rem);
 
+#ifdef __USE_TIME_BITS64
+# if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (clock_nanosleep, (clockid_t __clock_id, int __flags,
+                                             const struct timespec *__req,
+                                             struct timespec *__rem),
+                           __clock_nanosleep_time64);
+# else
+# define clock_nanosleep __clock_nanosleep_time64
+# endif
+#endif
+
 /* Return clock ID for CPU-time clock.  */
 extern int clock_getcpuclockid (pid_t __pid, clockid_t *__clock_id) __THROW;
 # endif
@@ -243,10 +282,31 @@ extern int timer_settime (timer_t __timerid, int __flags,
 			  const struct itimerspec *__restrict __value,
 			  struct itimerspec *__restrict __ovalue) __THROW;
 
+#ifdef __USE_TIME_BITS64
+# if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (timer_settime, (timer_t __timerid, int __flags,
+     const struct itimerspec *__restrict __value,
+     struct itimerspec *__restrict __ovalue),
+                          __timer_settime64);
+# else
+# define timer_settime __timer_settime64
+# endif
+#endif
+
 /* Get current value of timer TIMERID and store it in VALUE.  */
 extern int timer_gettime (timer_t __timerid, struct itimerspec *__value)
      __THROW;
 
+#ifdef __USE_TIME_BITS64
+# if defined(__REDIRECT_NTH)
+extern int __REDIRECT_NTH (timer_gettime, (timer_t __timerid,
+                                           struct itimerspec *__value),
+                           __timer_gettime64) __nonnull ((1));
+# else
+# define timer_gettime __timer_gettime64
+# endif
+#endif
+
 /* Get expiration overrun for timer TIMERID.  */
 extern int timer_getoverrun (timer_t __timerid) __THROW;
 #endif