Re: nanosecond support for stat

[Corinna Vinschen <vinschen at redhat dot com>]

On Jan 12 16:12, Mike Stump wrote:
> On Jan 12, 2012, at 3:07 PM, Eric Blake wrote:
> > Actually, it would be better to go with the definitions given by POSIX:
> > 
> > struct timespec st_atim Last data access timestamp.
> 
> That would make a nice follow-on patch.
> 
> Linux does:
> 
> #ifdef __USE_MISC
>     /* Nanosecond resolution timestamps are stored in a format                                 
>        equivalent to 'struct timespec'.  This is the type used                                 
>        whenever possible but the Unix namespace rules do not allow the                         
>        identifier 'timespec' to appear in the <sys/stat.h> header.                             
>        Therefore we have to handle the use of this header in strictly                          
>        standard-compliant sources special.  */
>     struct timespec st_atim;            /* Time of last access.  */
>     struct timespec st_mtim;            /* Time of last modification.  */
>     struct timespec st_ctim;            /* Time of last status change.  */
> # define st_atime st_atim.tv_sec        /* Backward compatibility.  */
> # define st_mtime st_mtim.tv_sec
> # define st_ctime st_ctim.tv_sec
> #else
>     __time_t st_atime;                  /* Time of last access.  */
>     unsigned long int st_atimensec;     /* Nscecs of last access.  */
>     __time_t st_mtime;                  /* Time of last modification.  */
>     unsigned long int st_mtimensec;     /* Nsecs of last modification.  */
>     __time_t st_ctime;                  /* Time of last status change.  */
>     unsigned long int st_ctimensec;     /* Nsecs of last status change.  */
> #endif
> 
> 
> :-)  Which is why I didn't do anymore.  We've merely implemented the
> second case of the #ifdef.  I've left the first case for someone that
> wants to do the additional work.

The definition right now already contains the struct timespec stuff in
sys/stat.h if __rtems__ is defined.  Also, struct timespec is always
available in sys/stat.h.  Therefore, is there a good reason not to
extend that to all targets?  Like this:

Index: libc/include/sys/stat.h
===================================================================
RCS file: /cvs/src/src/newlib/libc/include/sys/stat.h,v
retrieving revision 1.23
diff -u -p -r1.23 stat.h
--- libc/include/sys/stat.h	6 Aug 2010 18:26:21 -0000	1.23
+++ libc/include/sys/stat.h	13 Jan 2012 09:35:52 -0000
@@ -32,38 +32,29 @@ struct	stat 
   gid_t		st_gid;
   dev_t		st_rdev;
   off_t		st_size;
-#if defined(__rtems__)
-  struct timespec st_atim;
-  struct timespec st_mtim;
-  struct timespec st_ctim;
-  blksize_t     st_blksize;
-  blkcnt_t	st_blocks;
-#else
   /* SysV/sco doesn't have the rest... But Solaris, eabi does.  */
 #if defined(__svr4__) && !defined(__PPC__) && !defined(__sun__)
   time_t	st_atime;
   time_t	st_mtime;
   time_t	st_ctime;
 #else
-  time_t	st_atime;
-  long		st_spare1;
-  time_t	st_mtime;
-  long		st_spare2;
-  time_t	st_ctime;
-  long		st_spare3;
+  struct timespec st_atim;
+  struct timespec st_mtim;
+  struct timespec st_ctim;
+#define st_atime st_atim.tv_sec
+#define st_ctime st_ctim.tv_sec
+#define st_mtime st_mtim.tv_sec
+#if defined(__rtems__)
+  blksize_t     st_blksize;
+  blkcnt_t	st_blocks;
+#else
   long		st_blksize;
   long		st_blocks;
-  long	st_spare4[2];
+  long		st_spare4[2];
 #endif
 #endif
 };
 
-#if defined(__rtems__)
-#define st_atime st_atim.tv_sec
-#define st_ctime st_ctim.tv_sec
-#define st_mtime st_mtim.tv_sec
-#endif
-
 #endif
 
 #define	_IFMT		0170000	/* type of file */


Corinna

-- 
Corinna Vinschen
Cygwin Project Co-Leader
Red Hat