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.de EX		\" start example
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.PP
.RS 
.PD 0
.ft 5
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.RE
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.TH TM 3
.SH NAME
tv \- high resolution time support
.SH SYNOPSIS
.L "#include <tv.h>"
.SH DESCRIPTION
The
.I tv
library supports high resolution
.B Tv_t
time specifications.
.SS Tv_t
contains these elements:
.TP
.L unsigned
.L _ast_int4_t
.L tv_sec
Seconds since the epoch.
.TP
.L unsigned
.L _ast_int4_t
.L tv_nsec
Nanosecond resolution.
.PP
In practice resolution is much coarser than 1 nanosecond.
Systems that only support 1 second resolution always set
.L tv_nsec
to 0.
.SS "int tvgettime(Tv_t* tv)"
Sets
.L tv
to the current time.
.L 0
is returned on success,
.L -1
on error.
.SS "int tvsettime(const Tv_t* tv)"
Sets the system time to
.LR tv .
The caller must have sufficient privilege.
.L 0
is returned on success,
.L -1
on error.
.SS "int tvcmp(const Tv_t* av, const Tv_t* bv)"
Compares the times
.L av
and
.L bv
and returns
.L -1
if
.L av
is less than
.LR bv ,
.L 0
if
.L av
is equal to
.LR bv ,
and
.L 1
if
.L av
is greater than
.LR bv .
.SS "time_t tvgetatime(const struct stat* st, Tv_t* tv)"
.SS "time_t tvgetmtime(const struct stat* st, Tv_t* tv)"
.SS "time_t tvgetctime(const struct stat* st, Tv_t* tv)"
These macros set
.L tv
to the
.L st
the access, modify, or change time, respectively.
The seconds portion of
.L tv
is returned.
.SS "time_t tvsetatime(struct stat* st, const Tv_t* tv)"
.SS "time_t tvsetmtime(struct stat* st, const Tv_t* tv)"
.SS "time_t tvsetctime(struct stat* st, const Tv_t* tv)"
These macros set the
.L st
access, modify, or change time, respectively, to
.LR tv .
The seconds portion of
.L tv
is returned.
.SS "int tvtouch(const char* path, const Tv_t* av, const Tv_t* mv, const Tv_t* cv, int copy)"
Sets the file
.L path
access time from
.LR av ,
modify time from
.LR mv ,
and change time from
.LR cv .
Any of
.LR av ,
.LR mv ,
and
.L cv
may be 0; the corresponding file time will retain the previous value if
.L path
exists and
.L copy
is
.L 1 ;
otherwise the corresponding file time will be set to the current time.
.L 0
is returned on success,
.L -1
on error.
.SS "int tvsleep(const Tv_t* tv, Tv_t* rv)"
Pauses execution for
.L tv
time.
.L 0
is returned if the full
.L tv
amount has expired.
Otherwise
.L -1
is returned and
.LR rv ,
if not 0, is set to the sleep time remaining.
.SH "RETURN VALUE"
Except for
.LR tvcmp() ,
an error return of
.L -1
also sets
.L errno
to the corresponding error code.
.SH "SEE ALSO"
tm(3)