Is there an existing linux userspace interface for accessing the
microsecond or nanosecond level (a|m|c)times of filesystems that support
them (e.g. ext4, xfs)? and possibly also the generation counters used by
NFS.
I notice sys_utimes is able to set microsecond (c|a|m)times but I can't
find an associated interface to read them (I've googled to no avail).
(also noticing freebsd and darwin's struct stat contains struct timespec
for these as well as an st_gen field - although I do realise how
incredibly difficult it would be to add these to linux's struct stat).
~mc
On Sun, 20 Jan 2008 21:09:52 +0800
Michael Clark <[email protected]> wrote:
> Is there an existing linux userspace interface for accessing the
> microsecond or nanosecond level (a|m|c)times of filesystems that support
> them (e.g. ext4, xfs)? and possibly also the generation counters used by
> NFS.
>
> I notice sys_utimes is able to set microsecond (c|a|m)times but I can't
> find an associated interface to read them (I've googled to no avail).
>
> (also noticing freebsd and darwin's struct stat contains struct timespec
> for these as well as an st_gen field - although I do realise how
> incredibly difficult it would be to add these to linux's struct stat).
>
Look at stat.
In /usr/include/bits/stat.h:
struct stat
{
__dev_t st_dev; /* Device. */
...
#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
--
Stephen Hemminger <[email protected]>
Stephen Hemminger wrote:
> Look at stat.
>
Thanks. OK that was what I wanted. I hadn't looked further than man 2
stat - I think the stat man page needs an update.
> In /usr/include/bits/stat.h:
> struct stat
> {
> __dev_t st_dev; /* Device. */
> ...
> #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
>