From: kstailey@yahoo.com (Kenneth Stailey)
Subject: [TUHS] question about mkfs(8) and stdio
Date: Sun, 14 Dec 2003 11:11:20 -0800 (PST) [thread overview]
Message-ID: <20031214191120.7737.qmail@web60506.mail.yahoo.com> (raw)
Did stdio buffering change over time?
If you look at an old BSD mkfs for cylinder-group style file systems (not 7th
Ed filesystems) you will see the super block backup loop does not fflush(stdio)
between printf()s
printf("super-block backups (for fsck -b#) at:");
for (cylno = 0; cylno < sblock.fs_ncg; cylno++) {
initcg(cylno);
if (cylno % 10 == 0)
printf("\n");
printf(" %d,", fsbtodb(&sblock, cgsblock(&sblock, cylno)));
}
but I have memories that the superblocks were printed out one at a time as if
fflush(stdout) was called between them rather than one line at a time with
line-buffered stdio.
At some point I thought "SysV must have broke this" since newfs would print out
a complete row of superblock numbers at once with a big delay between the rows
rather than each superblock number with a short delay between each number.
But when I go searching the oldest BSD code has no fflush(stdout) the way
modern FreeBSD does:
for (cylno = 0; cylno < sblock.fs_ncg; cylno++) {
initcg(cylno, utime);
if (mfs)
continue;
j = snprintf(tmpbuf, sizeof(tmpbuf), " %ld%s",
fsbtodb(&sblock, cgsblock(&sblock, cylno)),
cylno < (sblock.fs_ncg-1) ? "," : "" );
if (i + j >= width) {
printf("\n");
i = 0;
}
i += j;
printf("%s", tmpbuf);
fflush(stdout);
}
Did stdio buffering change over time so that line buffering became the default?
Thanks,
Ken
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next reply other threads:[~2003-12-14 19:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-14 19:11 Kenneth Stailey [this message]
2003-12-15 0:48 John Holden
2003-12-15 1:22 Michael Sokolov
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