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Path: utzoo!linus!decvax!harpo!seismo!rlgvax!cvl!umcp-cs!eneevax!chris
From: chris@eneevax.UUCP
Newsgroups: net.unix-wizards
Subject: Strange time() vs. stat() bug
Message-ID: <34@eneevax.UUCP>
Date: Sat, 3-Dec-83 05:22:48 EST
Article-I.D.: eneevax.34
Posted: Sat Dec  3 05:22:48 1983
Date-Received: Tue, 6-Dec-83 23:33:31 EST
Organization: Univ. of Maryland, EE Dept.
Lines: 36

I think this is a bug, but maybe someone can claim a "reasonable" reason
for it:

If I write to a tty device and then close it, a stat 10 seconds later
usually does not show it to have been modified when I did the write+close,
but instead, 5 to 10 seconds later!  If I use stat() instead of time() I
get the "right" value (which then remains consistent).  Using sync() will
also make the value remain consistent (thus "time()" will be OK in the
program below).

I suspect there's something odd going on with the delayed I/O system here.

---------------------------- BUG DEMONSTRATER ----------------------------
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>

main () {
	FILE *fp;
	time_t shouldbe;
	struct stat was;
	char *tty, *ttyname ();

	tty = ttyname (0);
	fp = fopen (tty, "w");
	fprintf (fp, "testing\n");
	fclose (fp);
	time (&shouldbe);
	sleep (10);
	stat (tty, &was);
	printf ("was %d should be <= %d\n", was.st_mtime, shouldbe);
}
--
Chris Torek, UMCP, CSD
UUCP: {allegra,seismo,brl-bmd}!umcp-cs!chris
ARPA: chris@maryland		CSNet: chris@umcp-cs