DOSSRV(4) DOSSRV(4)
NAME
dossrv, 9660srv, a:, b:, c:, d:, 9fat:, dosmnt, eject - DOS
and ISO9660 file systems
SYNOPSIS
dossrv [ -rsv ] [ -f file ] [ service ]
9660srv [ -9Jsv ] [ -c clusters ] [ -f file ] [ service ]
a:
b:
c:
9fat:
dosmnt n mtpt
eject [ n ]
DESCRIPTION
Dossrv is a file server that interprets DOS file systems. A
single instance of dossrv can provide access to multiple DOS
disks simultaneously.
Dossrv posts a file descriptor named service (default dos)
in the /srv directory. To access the DOS file system on a
device, use mount with the spec argument (see bind(1)) the
name of the file holding raw DOS file system, typically the
disk. If spec is undefined in the mount, dossrv will use
file as the default name for the device holding the DOS sys-
tem.
Normally dossrv creates a pipe to act as the communications
channel between itself and its clients. The -s flag
instructs dossrv to use its standard input and output
instead. The kernels use this option if they are booting
from a DOS disk. This flag also prevents the creation of an
explicit service file in /srv.
The -v flag causes verbose output for debugging, while the
-r flag makes the file system read-only.
The shell script a: contains
unmount /n/a: >[2] /dev/null
mount -c /srv/dos /n/a: /dev/fd0disk
and is therefore a shorthand for mounting a floppy disk in
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DOSSRV(4) DOSSRV(4)
drive A. The scripts b: and dosmnt are similar, mounting
the second floppy disk and the nth non-floppy DOS partition,
respectively. C: and d: call dosmnt in an attempt to name
the drives in the same order that Microsoft operating sys-
tems do. 9fat: provides access to the FAT component of the
Plan 9 partition (see prep(8)).
The file attribute flags used by the DOS file system do not
map directly to those used by Plan 9. Since there is no
concept of user or group, permission changes via wstat (see
stat(2)) will fail unless the same (read, write, execute)
permissions are specified for user, group, and other. For
example, removing write permission in Plan 9 corresponds to
setting the read-only attribute in the DOS file system.
Most of the other DOS attributes are not accessible.
Setting the exclusive use flag (DMEXCL) in Plan 9 corre-
sponds to setting the system use attribute in the DOS file
system. Such files are not actually restricted to exclusive
use, but do merit special treatment that helps in the cre-
ation of boot disks: when dossrv allocates a new block for
such a file (caused, say, by a write that fills the file's
last allocated block), it succeeds only if it can arrange
for the file to be stored contiguously on disk.
Since other operating systems do not guarantee that system
files are laid out contiguously, the DMAPPEND mode bit is
set in file stat information only when the file is currently
contiguous. Attempts to set the DMAPPEND mode bit explic-
itly will cause dossrv to try to make the file contiguous,
succeeding only if this is possible.
9660srv is similar to dossrv in specification, except that
it interprets ISO9660 CD-ROM file systems instead of DOS
file systems. Some CDs contain multiple directory trees
describing the same set of files. 9660srv's first choice in
such a case is a standard ISO9660 tree with Plan 9 system
use fields; the second choice is a Microsoft ``Joliet''
tree, which allows long file names and Unicode characters;
the third choice is a standard ISO9660 or High Sierra tree.
The -9 flag causes 9660srv to ignore the Plan 9 system use
fields, while the -J flag causes it to ignore the Joliet
tree. The -c option sets the size of the RAM cache to
clusters clusters of 128KB. The default clusters is 16, but
a value of 5600 will cache an entire CD incrementally.
If the floppy drive has an ejection motor, eject will spit
out the floppy from drive n, default 0.
EXAMPLE
Mount a floppy disk with a DOS file system on it.
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DOSSRV(4) DOSSRV(4)
a:
SEE ALSO
kfs(4)
SOURCE
/sys/src/cmd/dossrv
/sys/src/cmd/9660srv
/rc/bin/eject
BUGS
The overloading of the semantics of the DMEXCL and DMAPPEND
bits can be confusing.
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