[RTEMS Project] #4131: "fdisk DISK_NAME mount" in bdpart-mount.c uses non-existing file system type "msdos"
trac at rtems.org
Mon Oct 12 11:19:08 UTC 2020
#4131: "fdisk DISK_NAME mount" in bdpart-mount.c uses non-existing file system
Reporter: Frank Kuehndel | Owner: Frank Kühndel
Type: defect | Status: closed
Priority: normal | Milestone: 6.1
Component: shell | Version:
Severity: minor | Resolution: fixed
Keywords: fdisk shell bdpart | Blocked By:
mount bdpart-mount.c msdos |
Changes (by Frank Kühndel <frank.kuehndel@…>):
* owner: (none) => Frank Kühndel <frank.kuehndel@…>
* status: assigned => closed
* resolution: => fixed
shell: Remove not functioning fdisk mount/unmount
The shell has an 'fdisk' command which has sub-commands 'mount' and
These two sub-commands have a bug which causes them to be not able
to mount anything. This proposed patch removes the buggy file
cpukit/libblock/src/bdpart-mount.c and the mount/unmount commands
from 'fdisk' as bug fix. The 'fdisk' command itself is not removed.
The reasons for removing the sub-commands (instead of fixing the issue)
1) The bug has been introduced on 2010-May-31 with commit
29e92b090c8bc35745aa5c89231ce806bcb11e57. Since ten years no one
can use this feature, nor has anybody complained about it.
2) Besides of the 'fdisk' 'mount' sub-command, the shell has the
usual 'mount' and 'unmount' commands which can serve as
3) There are additional minor issues (see further down) which needed to
be addressed when the file will be kept.
What follows below is the precise bug description.
The bug is in function rtems_bdpart_mount() which is only be used
by the 'fdisk' shell command to mount all partitions of a disk with a
> fdisk DISK_NAME mount
> mounts the file system of each partition of the disk
> fdisk DISK_NAME unmount
> unmounts the file system of each partition of the disk
The whole command does not work because in file
cpukit/libblock/src/bdpart-mount.c line 103 specifies the file system type
of each partition to be "msdos". Yet, "msdos" does not exist. The name
must be "dosfs".
Beside of this fundamental problem, there are more issues with the code
1) The function returns RTEMS_SUCCESSFUL despite the mount always fails.
2) The reason for errors is not written to the terminal.
3) The directory '/mnt' is created but not deleted later on (failure or
3) There is no documentation about this special 'fdisk' feature in the
RTEMS Shell Guide ('fdisk' is mentioned but its documentation is a
4) Only "msdos" formatted partitions can be mounted and all partitions
are mounted read-only. This is hard coded and cannot be changed by
options. Moreover, there is no information about this to the user of
the shell (i.e. using 'fdisk' mount requires insider knowledge).
How to reproduce:
1) For testing, I use the 'testsuites/samples/fileio.exe' sample with
> cd rtems
> env QEMU_AUDIO_DRV="none" qemu-system-arm -net none -nographic \
> -M realview-pbx-a9 -m 256M -kernel \
2) Type any key to stop the timer and enter the sample tool.
Type 's' to enter the shell, login as 'root' with the password
shown in the terminal.
3) Type the following shell commands (they create a RAM disk,
partition it, register it, format it and try to mount it):
> fdisk /dev/rda fat32 16 write mbr
> fdisk /dev/rda register
> mkdos /dev/rda1
> fdisk /dev/rda mount
4) The last line above is the command which fails - without an error
message. There exists a '/mnt' directory but no '/mnt/rda1' directory
as it should be:
> ls -la /mnt
5) If you change line 103 of 'cpukit/libblock/src/bdpart-mount.c'
from "msdos" to "dosfs", compile and build the executable and
re-run the above test, '/mnt/rda1' exists (but the file system
is mounted read-only).
Ticket URL: <http://devel.rtems.org/ticket/4131#comment:1>
RTEMS Project <http://www.rtems.org/>
More information about the bugs