[GitHub/mt8127/android_kernel_alcatel_ttab.git] / Documentation / filesystems / adfs.txt

Mount options for ADFS
----------------------

  uid=nnn	All files in the partition will be owned by
		user id nnn.  Default 0 (root).
  gid=nnn	All files in the partition will be in group
		nnn.  Default 0 (root).
  ownmask=nnn	The permission mask for ADFS 'owner' permissions
		will be nnn.  Default 0700.
  othmask=nnn	The permission mask for ADFS 'other' permissions
		will be nnn.  Default 0077.
  ftsuffix=n	When ftsuffix=0, no file type suffix will be applied.
		When ftsuffix=1, a hexadecimal suffix corresponding to
		the RISC OS file type will be added.  Default 0.

Mapping of ADFS permissions to Linux permissions
------------------------------------------------

  ADFS permissions consist of the following:

	Owner read
	Owner write
	Other read
	Other write

  (In older versions, an 'execute' permission did exist, but this
   does not hold the same meaning as the Linux 'execute' permission
   and is now obsolete).

  The mapping is performed as follows:

	Owner read				-> -r--r--r--
	Owner write				-> --w--w---w
	Owner read and filetype UnixExec	-> ---x--x--x
    These are then masked by ownmask, eg 700	-> -rwx------
	Possible owner mode permissions		-> -rwx------

	Other read				-> -r--r--r--
	Other write				-> --w--w--w-
	Other read and filetype UnixExec	-> ---x--x--x
    These are then masked by othmask, eg 077	-> ----rwxrwx
	Possible other mode permissions		-> ----rwxrwx

  Hence, with the default masks, if a file is owner read/write, and
  not a UnixExec filetype, then the permissions will be:

			-rw-------

  However, if the masks were ownmask=0770,othmask=0007, then this would
  be modified to:
			-rw-rw----

  There is no restriction on what you can do with these masks.  You may
  wish that either read bits give read access to the file for all, but
  keep the default write protection (ownmask=0755,othmask=0577):

			-rw-r--r--

  You can therefore tailor the permission translation to whatever you
  desire the permissions should be under Linux.

RISC OS file type suffix
------------------------

  RISC OS file types are stored in bits 19..8 of the file load address.

  To enable non-RISC OS systems to be used to store files without losing
  file type information, a file naming convention was devised (initially
  for use with NFS) such that a hexadecimal suffix of the form ,xyz
  denoted the file type: e.g. BasicFile,ffb is a BASIC (0xffb) file.  This
  naming convention is now also used by RISC OS emulators such as RPCEmu.

  Mounting an ADFS disc with option ftsuffix=1 will cause appropriate file
  type suffixes to be appended to file names read from a directory.  If the
  ftsuffix option is zero or omitted, no file type suffixes will be added.
Commit	Line	Data
1da177e4 LT	1	Mount options for ADFS
	2	----------------------
	3
	4	uid=nnn All files in the partition will be owned by
	5	user id nnn. Default 0 (root).
4ae0edc2	6	gid=nnn All files in the partition will be in group
1da177e4 LT	7	nnn. Default 0 (root).
	8	ownmask=nnn The permission mask for ADFS 'owner' permissions
	9	will be nnn. Default 0700.
	10	othmask=nnn The permission mask for ADFS 'other' permissions
	11	will be nnn. Default 0077.
da23ef05 SS	12	ftsuffix=n When ftsuffix=0, no file type suffix will be applied.
	13	When ftsuffix=1, a hexadecimal suffix corresponding to
	14	the RISC OS file type will be added. Default 0.
1da177e4 LT	15
	16	Mapping of ADFS permissions to Linux permissions
	17	------------------------------------------------
	18
	19	ADFS permissions consist of the following:
	20
	21	Owner read
	22	Owner write
	23	Other read
	24	Other write
	25
	26	(In older versions, an 'execute' permission did exist, but this
	27	does not hold the same meaning as the Linux 'execute' permission
	28	and is now obsolete).
	29
	30	The mapping is performed as follows:
	31
	32	Owner read -> -r--r--r--
	33	Owner write -> --w--w---w
	34	Owner read and filetype UnixExec -> ---x--x--x
	35	These are then masked by ownmask, eg 700 -> -rwx------
	36	Possible owner mode permissions -> -rwx------
	37
	38	Other read -> -r--r--r--
	39	Other write -> --w--w--w-
	40	Other read and filetype UnixExec -> ---x--x--x
	41	These are then masked by othmask, eg 077 -> ----rwxrwx
	42	Possible other mode permissions -> ----rwxrwx
	43
	44	Hence, with the default masks, if a file is owner read/write, and
	45	not a UnixExec filetype, then the permissions will be:
	46
	47	-rw-------
	48
	49	However, if the masks were ownmask=0770,othmask=0007, then this would
	50	be modified to:
	51	-rw-rw----
	52
	53	There is no restriction on what you can do with these masks. You may
	54	wish that either read bits give read access to the file for all, but
	55	keep the default write protection (ownmask=0755,othmask=0577):
	56
	57	-rw-r--r--
	58
	59	You can therefore tailor the permission translation to whatever you
	60	desire the permissions should be under Linux.
da23ef05 SS	61
	62	RISC OS file type suffix
	63	------------------------
	64
	65	RISC OS file types are stored in bits 19..8 of the file load address.
	66
	67	To enable non-RISC OS systems to be used to store files without losing
	68	file type information, a file naming convention was devised (initially
	69	for use with NFS) such that a hexadecimal suffix of the form ,xyz
	70	denoted the file type: e.g. BasicFile,ffb is a BASIC (0xffb) file. This
	71	naming convention is now also used by RISC OS emulators such as RPCEmu.
	72
	73	Mounting an ADFS disc with option ftsuffix=1 will cause appropriate file
	74	type suffixes to be appended to file names read from a directory. If the
	75	ftsuffix option is zero or omitted, no file type suffixes will be added.