"fdisk DISK_NAME mount" in bdpart-mount.c uses non-existing file system type "msdos"

[Frank Kuehndel]

The function rtems_bdpart_mount() seems to be only used by the 'fdisk' shell command to mount all partitions of a disk with a single command:

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 in bdpart-mount.c:

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 not).

3) There is no documentation about this special 'fdisk' feature in the ​RTEMS Shell Guide. ('fdisk' is mentioned but its documentation is a bit short).

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/init.c' sample and since I do not know the 'root' password, the password must be removed from that file to login as 'root' without password:

index 86b34b99dd..51507f9a53 100644
--- a/testsuites/samples/fileio/init.c
+++ b/testsuites/samples/fileio/init.c
@@ -563,8 +563,7 @@ static void fileio_start_shell(void)
   writeFile(
     "/etc/passwd",
     0644,
-    "root:$6$$FuPOhnllx6lhW2qqlnmWvZQLJ8Thr/09I7ESTdb9VbnTOn5.65"
-      "/Vh2Mqa6FoKXwT0nHS/O7F0KfrDc6Svb/sH.:0:0:root::/:/bin/sh\n"
+    "root::0:0:root::/:/bin/sh\n"
     "rtems::1:1:RTEMS Application::/:/bin/sh\n"
     "test:$1$$oPu1Xt2Pw0ngIc7LyDHqu1:2:2:test account::/:/bin/sh\n"
     "tty:*:3:3:tty owner::/:/bin/false\n"

2) I run the fileio sample using qemu:

cd rtems
env QEMU_AUDIO_DRV="none" qemu-system-arm -net none -nographic -M realview-pbx-a9 -m 256M -kernel build/arm/realview_pbx_a9_qemu/testsuites/samples/fileio.exe

3) Type any key to stop the timer and enter the sample tool. Type 's' to enter the shell, login as 'root' with empty password.

4) Type the following shell commands (they create a RAM disk, partition it, regsiter it, format it and try to mount it):

mkrd
fdisk /dev/rda fat32 16 write mbr
fdisk /dev/rda register
mkdos /dev/rda1
fdisk /dev/rda mount

5) 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 shoud be:

ls -la /mnt

6) 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).

[Frank Kühndel <frank.kuehndel@…>]

In a479686/rtems:

shell: Remove not functioning fdisk mount/unmount

The shell has an 'fdisk' command which has sub-commands 'mount' and 'unmount'.
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) are:

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
substitutes.

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
single command:

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
in bdpart-mount.c:

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 not).

3) There is no documentation about this special 'fdisk' feature in the

RTEMS Shell Guide ('fdisk' is mentioned but its documentation is a
bit short):
​https://docs.rtems.org/branches/master/shell/
file_and_directory.html#fdisk-format-disk

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 qemu:

cd rtems
env QEMU_AUDIO_DRV="none" qemu-system-arm -net none -nographic \
-M realview-pbx-a9 -m 256M -kernel \
build/arm/realview_pbx_a9_qemu/testsuites/samples/fileio.exe

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):

mkrd
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).

Close #4131