`Fatfsys`

DOS FAT12/16/32 filesystem manager (QNX)

Syntax:

Fatfsys [options]... [dos_drive=host_device]... &

Options:

-d

Name of the directory to hold the DOS drives. (Default: /dos)

-D

Enable the FAT32 volume to be marked "dirty" at mount, "clean" at unmount. This forces Windows to do a ScanDisk the next time it boots. (Default: disabled)

-f

Set the maximum number of concurrent open files. This option also sizes the internal caches based on this value. (Default: 128)

-F

Disable usage/update of the FAT32 FSInfo record, which contains the free cluster count and a hint of the next free cluster. By default Fatfsys loads and uses this information at mount, and writes back any changes at unmount. This option disables that usage.

-H

Specify how to display DOS hidden files:

ignore: Never display hidden files.
show: Always display hidden files.
dot: Display hidden files with a leading "." (useful with ls -a).

The default is show.

-i

Set the user/group IDs to apply as the owner of all DOS files. These may be specified as numeric values (in the form of num:num) or as a user ID from /etc/passwd or group ID from etc/group. (Default: 0:0)

-L

Specify how to treat long filenames:

ignore: Never show or create long filenames; use only the corresponding short name (e.g. PROGRA~1).
show: Display and create long filenames where appropriate (i.e. if the filename is longer than 8.3 or is mixed-case).
always: Always create long filenames to preserve case.

The default is show.

-m

Set mount options to apply to all subsequent DOS filesystem mountpoints. Valid options are:

ro: Mark file as read-only.
rw: Mark file as read-write.
noatime: Don't record the time the file was last accessed.
atime: Record the access time.
noexec: Don't allow executable files to load.
exec: Allow executable files to load.
nocreat: Don't allow files to be created.
creat: Allow files to be created.
async: Enable asynchronous writes.
sync: Enable synchronous writes.

The defaults are rw, noatime, exec, creat, async.

-P

Set POSIX-like emulation/checking level. Valid options are:

ignore: Don't do any emulation or checks.
emulate: Attempt to provide features not present in the DOS filesystem (e.g. link counts on directories, . and .. entries at the root).
strict: Use the emulate features, but also check for any attribute changes that DOS can't handle (e.g. a chown() to a user other than that specified in -i, or a utime() to a time before 1980, the DOS epoch). If you don't specify strict, such attribute changes are silently ignored.

The default is ignore.

-s

Toggle the automatic device scanning sequence (based on user-specified mounts).

If any user mounts are specified on the command line, then Fatfsys won't scan the /dev directory. Use -s to toggle scanning on.

If no user mounts are specified on the command line, then Fatfsys will scan the /dev directory. Use -s to toggle scanning off.

-S

Specify how to treat short (8.3) filenames (assuming -L ignore is specified):

lower: Use all lowercase.
upper: Use all uppercase.
windows: Try to behave like Windows -- use a leading uppercase letter and the rest lowercase, unless overridden by the case attribute in the directory entry.

The default is lower.

-t

Set the timeout for removable media. After the timeout, the media is assumed to be possibly stale and is auto-remounted. (Default: 2 seconds)

-T

Disable silent 8.3 name truncation. This option is valid only if long filenames are being ignored (via -L ignore). By default, DOS truncates filenames to fit into the 8.3 format, so the files FILENAME.C and FILENAMETWO.C are considered identical. The -T option will raise an ENAMETOOLONG error rather than truncate.

-u

Set a umask to apply to all DOS files. A umask specifies a set of permission bits that should be cleared for a file. You can specify the umask using a numeric form or a symbolic string (of the form u=rwx,g=rwx,o=rwx) as an inverse umask. (Default: 0)

-v

Increase level of verbosity for information/error messages.

-V

Specify how to treat the DOS volume label:

ignore: Never display the volume label.
show: Show the label unchanged.
equals: Display the label with a leading = in the name.

When not being ignored, the volume label (if present) will be a name-special file with no access permissions.

The default is equals.

-w

Specify how long to wait for devices to be set up. This is useful in sysinit or boot files. (Default: 10 seconds)

-X

Control the setting of the executable bit:

none: No files will be executable.
all: All files will be executable.
system: Use the DOS "system" attribute to indicate an executable file.
auto: Let the DOS filename extension (e.g. *.EXE, *.COM, *.BAT) dictate if a file should be executable.

The default is auto.

dos_drive

A DOS drive name (typically a letter from a to z).

host_device

The name of the QNX device or file to open (e.g. /dev/hd1t6).

Description:

Fatfsys provides transparent access to DOS disks, so you can treat DOS filesystems as though they were QNX filesystems.

If started with no arguments, Fatfsys will scan the /dev directory for DOS devices to adopt. Hard drive partitions of types 1, 4, 6, 11, 12, and 14 will be assumed to contain a DOS filesystem. And any removable device (floppy, LS-120, etc.) will be assumed to be capable of having media containing a DOS filesystem inserted into it.

You may also specify explicit mount devices on the command line, using the form dos_drive=host_device (e.g. c=/dev/hd1t6). Specifying any device in this way will suppress the default device scan, but you can re-enable scanning by using the -s option.

Using `mount` and `mount_dos`

You can also mount DOS filesystems at runtime using the mount utility:

mount -t dos /dev/fd0 /dos/a

or the mount_dos utility:

mount_dos /dev/fd0 /dos/a

Typically, mount_dos is invoked via the mount utility. But if this isn't possible (e.g. if the device is being mounted from within the boot image), then you may run the mount_dos utility directly.

Using `umount`

You can unmount a DOS filesystem at runtime using the standard umount utility (e.g. umount /dos/c). Note that when Fatfsys is terminated (with a SIGTERM or simple slay Fatfsys), all current DOS filesystems are implicitly unmounted (this will affect FAT32 volumes; see the -D and -F options).

Removable media

Fatfsys maintains an activity timeout on removable media. After 2 seconds (see -t) of inactivity, the next attempted access to that filesystem will force a relearn of the DOS filesystem.

Fatfsys relies on the volume-tracking details of a disk to detect changes, then uses a heuristic (any open valid FDs) to determine if the media represents the same or a different filesystem.

Caching

Fatfsys maintains no local physical data block cache. All reads and writes to the host device are passed immediately to Fsys, which has a data cache.

To force Fsys to flush its cache, you may use the fsync() routine or O_SYNC flag on a per-FD basis, or use the -m sync option to affect all files written to the host device.

Fatfsys does contain a number of logical data caches (names, attributes, and cluster mappings), which are invalidated for removable media as described above. The size of these caches is based on the -f value.

Examples:

Start Fatfsys, mounting the floppy drive as /dos/a:

Fatfsys a=/dev/fd0 &

Start Fatfsys, mounting the floppy drive as read-only and the hard disk as read-write:

Fatfsys -m ro a=/dev/fd0 -m rw c=/dev/hd1t6 &

Using mount and mount_dos

Using `mount` and `mount_dos`