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Date: Sun, 12 Aug 2001 14:04:06 +0200
From: Bernd Walter <ticso@mail.cicely.de>
To: freebsd-hackers@freebsd.org
Subject: mtio questions
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Asume the following code examples:

int fd;
struct mtop mo;
char buf[10240];

fd = open("/dev/nsa0", O_RDWR | O_EXLOCK);
mo.mt_op = MTREW;
mo.mt_count = 0;
ioctl(fd, MTIOCTOP, &mo);
write(fd, buf, 10240);
close(fd);

and:

int fd;
struct mtop mo;
char buf[10240];

fd = open("/dev/nsa0", O_RDWR | O_EXLOCK);
mo.mt_op = MTREW;
mo.mt_count = 0;
ioctl(fd, MTIOCTOP, &mo);
write(fd, buf, 10240);
mo.mt_op = MTWEOF;
mo.mt_count = 1;
ioctl(fd, MTIOCTOP, &mo);
close(fd);

and:

int fd;
struct mtop mo;
char buf[10240];

fd = open("/dev/nsa0", O_RDWR | O_EXLOCK);
mo.mt_op = MTREW;
mo.mt_count = 0;
ioctl(fd, MTIOCTOP, &mo);
write(fd, buf, 10240);
mo.mt_op = MTWEOF;
mo.mt_count = 1;
ioctl(fd, MTIOCTOP, &mo);
mo.mt_op = MTREW;
mo.mt_count = 0;
ioctl(fd, MTIOCTOP, &mo);
close(fd);

The question is what filemark layout will I have on the tape?

If I MTEOD on the tape and write - will I have the same result with
all examples?

May I get into trouble with some tape types that use 2 filemarks EOD
detection?

Ist the result OS dependend?

Another point:
Can we '#define MTEOM MTEOD' as MTEOM is used on NetBSD and Solaris?

-- 
B.Walter              COSMO-Project         http://www.cosmo-project.de
ticso@cicely.de         Usergroup           info@cosmo-project.de


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