linux/time.h: glibc time.h header file compatibility fixes

Fixes these userspace compile errors and warnings when glibc time.h
is included before linux/time.h:

linux/time.h:9:8: error: redefinition of ‘struct timespec’
linux/time.h:15:8: error: redefinition of ‘struct timeval’
linux/time.h:20:8: error: redefinition of ‘struct timezone’
linux/time.h:30:0: warning: "ITIMER_REAL" redefined
linux/time.h:31:0: warning: "ITIMER_VIRTUAL" redefined
linux/time.h:32:0: warning: "ITIMER_PROF" redefined
linux/time.h:34:8: error: redefinition of ‘struct itimerspec’
linux/time.h:39:8: error: redefinition of ‘struct itimerval’
linux/time.h:67:0: warning: "TIMER_ABSTIME" redefined

<linux/time.h> conflicts with glibc <time.h> is the root cause of several
compatibility problems in uapi headers.

Signed-off-by: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>

include/uapi/linux/libc-compat.h

@@ -230,13 +230,41 @@
 
 #endif /* defined(_NETROSE_ROSE_H) */
 
+/* Coordinate with glibc time.h */
+#if defined(_TIME_H)
+#define __UAPI_DEF_TIMESPEC		0
+#define __UAPI_DEF_TIMEVAL		0
+#define __UAPI_DEF_ITIMERSPEC		0
+#define __UAPI_DEF_TIMER_ABSTIME	0
+
+#else /* defined(_TIME_H) */
+#define __UAPI_DEF_TIMESPEC		1
+#define __UAPI_DEF_TIMEVAL		1
+#define __UAPI_DEF_ITIMERSPEC		1
+#define __UAPI_DEF_TIMER_ABSTIME	1
+
+#endif /* defined(_TIME_H) */
+
 /* Definitions for sys/uio.h */
 #if defined(_SYS_UIO_H)
 #define __UAPI_DEF_IOVEC		0
 #else /* defined(_SYS_UIO_H) */
 #define __UAPI_DEF_IOVEC		1
 #endif /* defined(_SYS_UIO_H) */
 
+/* Definitions for sys/time.h */
+#if defined(_SYS_TIME_H)
+#define __UAPI_DEF_TIMEZONE			0
+#define __UAPI_DEF_ITIMER_REAL_VIRTUAL_PROF	0
+#define __UAPI_DEF_ITIMERVAL			0
+
+#else /* defined(_SYS_TIME_H) */
+#define __UAPI_DEF_TIMEZONE			1
+#define __UAPI_DEF_ITIMER_REAL_VIRTUAL_PROF	1
+#define __UAPI_DEF_ITIMERVAL			1
+
+#endif /* defined(_SYS_TIME_H) */
+
 /* Definitions for xattr.h */
 #if defined(_SYS_XATTR_H)
 #define __UAPI_DEF_XATTR		0
@@ -313,6 +341,15 @@
 #define __UAPI_DEF_ROSE_CAUSE_STRUCT			1
 #define __UAPI_DEF_ROSE_FACILITIES_STRUCT		1
 
+/* Definitions for time.h */
+#define __UAPI_DEF_TIMESPEC			1
+#define __UAPI_DEF_TIMEVAL			1
+#define __UAPI_DEF_TIMEZONE			1
+#define __UAPI_DEF_ITIMER_REAL_VIRTUAL_PROF	1
+#define __UAPI_DEF_ITIMERSPEC			1
+#define __UAPI_DEF_ITIMERVAL			1
+#define __UAPI_DEF_TIMER_ABSTIME		1
+
 /* Definitions for uio.h */
 #define __UAPI_DEF_IOVEC		1
 

include/uapi/linux/time.h

@@ -1,45 +1,57 @@
 #ifndef _UAPI_LINUX_TIME_H
 #define _UAPI_LINUX_TIME_H
 
+#include <linux/libc-compat.h>
 #include <linux/types.h>
 
 
 #ifndef _STRUCT_TIMESPEC
 #define _STRUCT_TIMESPEC
+#if __UAPI_DEF_TIMESPEC
 struct timespec {
 	__kernel_time_t	tv_sec;			/* seconds */
 	long		tv_nsec;		/* nanoseconds */
 };
-#endif
+#endif /* __UAPI_DEF_TIMESPEC */
+#endif /* _STRUCT_TIMESPEC */
 
+#if __UAPI_DEF_TIMEVAL
 struct timeval {
 	__kernel_time_t		tv_sec;		/* seconds */
 	__kernel_suseconds_t	tv_usec;	/* microseconds */
 };
+#endif /* __UAPI_DEF_TIMEVAL */
 
+#if __UAPI_DEF_TIMEZONE
 struct timezone {
 	int	tz_minuteswest;	/* minutes west of Greenwich */
 	int	tz_dsttime;	/* type of dst correction */
 };
-
+#endif /* __UAPI_DEF_TIMEZONE */
 
 /*
  * Names of the interval timers, and structure
  * defining a timer setting:
  */
+#if __UAPI_DEF_ITIMER_REAL_VIRTUAL_PROF
 #define	ITIMER_REAL		0
 #define	ITIMER_VIRTUAL		1
 #define	ITIMER_PROF		2
+#endif /* __UAPI_DEF_ITIMER_REAL_VIRTUAL_PROF */
 
+#if __UAPI_DEF_ITIMERSPEC
 struct itimerspec {
 	struct timespec it_interval;	/* timer period */
 	struct timespec it_value;	/* timer expiration */
 };
+#endif /* __UAPI_DEF_ITIMERSPEC */
 
+#if __UAPI_DEF_ITIMERVAL
 struct itimerval {
 	struct timeval it_interval;	/* timer interval */
 	struct timeval it_value;	/* current value */
 };
+#endif /* __UAPI_DEF_ITIMERVAL */
 
 /*
  * The IDs of the various system clocks (for POSIX.1b interval timers):
@@ -68,6 +80,8 @@ struct itimerval {
 /*
  * The various flags for setting POSIX.1b interval timers:
  */
+#if __UAPI_DEF_TIMER_ABSTIME
 #define TIMER_ABSTIME			0x01
+#endif /* __UAPI_DEF_TIMER_ABSTIME */
 
 #endif /* _UAPI_LINUX_TIME_H */