[RTEMS Project] #4131: "fdisk DISK_NAME mount" in bdpart-mount.c uses non-existing file system type "msdos"

RTEMS trac trac at rtems.org
Wed Oct 7 14:27:18 UTC 2020

#4131: "fdisk DISK_NAME mount" in bdpart-mount.c uses non-existing file system
type "msdos"
  Reporter:  Frank       |      Owner:  (none)
  Kuehndel               |
      Type:  defect      |     Status:  assigned
  Priority:  normal      |  Milestone:  6.1
 Component:  shell       |    Version:
  Severity:  minor       |   Keywords:  fdisk shell bdpart mount bdpart-
                         |  mount.c msdos
Blocked By:              |   Blocking:
 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

   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
 #fdisk-format-disk 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)
 -    "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

   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):

 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).

Ticket URL: <http://devel.rtems.org/ticket/4131>
RTEMS Project <http://www.rtems.org/>
RTEMS Project

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