On Fri, Dec 05, 2014 at 03:28:58PM -0800, Robert White wrote:
> Ah...
>
> I've been thinking "ctime" is/was (still) "create time". It seems
> that somewhere in the last couple decades it became "change time";
> Or that I picked up that incorrect "create time" idea back in the
> UNIX Sys V R 3 days and just never had cause to think about it
> again...
v7 is the point where the third timestamp has first appeared (v6 has
only two - access and update). And their stat(2) says this:
st_atime is the file was last read. For reasons of efficiency, it is
not set when a directory is searched, although this would be more logi‐
cal. st_mtime is the time the file was last written or created. It is
not set by changes of owner, group, link count, or mode. st_ctime is
set both both by writing and changing the i-node.
FWIW, their /usr/sys/sys/sys4.c has
chmod()
{
register struct inode *ip;
register struct a {
char *fname;
int fmode;
} *uap;
uap = (struct a *)u.u_ap;
if ((ip = owner()) == NULL)
return;
ip->i_mode &= ~07777;
if (u.u_uid)
uap->fmode &= ~ISVTX;
ip->i_mode |= uap->fmode&07777;
ip->i_flag |= ICHG;
if (ip->i_flag&ITEXT && (ip->i_mode&ISVTX)==0)
xrele(ip);
iput(ip);
}
and /usr/sys/sys/iget.c has, in the end of iupdat() (called on the final
iput(), as well as on stat(2) and several other paths), this:
if(ip->i_flag&IACC)
dp->di_atime = *ta;
if(ip->i_flag&IUPD)
dp->di_mtime = *tm;
if(ip->i_flag&ICHG)
dp->di_ctime = time;
ip->i_flag &= ~(IUPD|IACC|ICHG);
(ta and tm are both equal to &time in that call chain). IOW, chmod(2)
definitely sets ctime.
IOW, ctime has never been "create time"; it's "change time" and it had been
that way since its introduction.
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