adfs: add hexadecimal filetype suffix option

ADFS (FileCore) storage complies with the RISC OS filetype specification
(12 bits of file type information is stored in the file load address,
rather than using a file extension). The existing driver largely ignores
this information and does not present it to the end user.

It is desirable that stored filetypes be made visible to the end user to
facilitate a precise copy of data and metadata from a hard disc (or image
thereof) into a RISC OS emulator (such as RPCEmu) or to a network share
which can be accessed by real Acorn systems.

This patch implements a per-mount filetype suffix option (use -o
ftsuffix=1) to present any filetype as a ,xyz hexadecimal suffix on each
file. This type suffix is compatible with that used by RISC OS systems
that access network servers using NFS client software and by RPCemu's host
filing system.

Signed-off-by: Stuart Swales <[e-mail]>
Cc: Russell King <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/filesystems/adfs.txt

···
 		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
 ------------------------------------------------
···
 
   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.

fs/adfs/adfs.h

···
 	gid_t		s_gid;		/* owner gid				 */
 	umode_t		s_owner_mask;	/* ADFS owner perm -> unix perm		 */
 	umode_t		s_other_mask;	/* ADFS other perm -> unix perm		 */
+	int		s_ftsuffix;	/* ,xyz hex filetype suffix option */
 
 	__u32		s_ids_per_zone;	/* max. no ids in one zone		 */
 	__u32		s_idlen;	/* length of ID in map			 */
···
 /*
  * This is the overall maximum name length
  */
-#define ADFS_MAX_NAME_LEN	256
+#define ADFS_MAX_NAME_LEN	(256 + 4) /* +4 for ,xyz hex filetype suffix */
 struct object_info {
 	__u32		parent_id;		/* parent object id	*/
 	__u32		file_id;		/* object id		*/
···
 	__u32		execaddr;		/* execution address	*/
 	__u32		size;			/* size			*/
 	__u8		attr;			/* RISC OS attributes	*/
-	unsigned char	name_len;		/* name length		*/
+	unsigned int	name_len;		/* name length		*/
 	char		name[ADFS_MAX_NAME_LEN];/* file name		*/
+
+	/* RISC OS file type (12-bit: derived from loadaddr) */
+	__u16		filetype;
 };
+
+/* RISC OS 12-bit filetype converts to ,xyz hex filename suffix */
+static inline int append_filetype_suffix(char *buf, __u16 filetype)
+{
+	if (filetype == -1)
+		return 0;
+
+	*buf++ = ',';
+	*buf++ = hex_asc_lo(filetype >> 8);
+	*buf++ = hex_asc_lo(filetype >> 4);
+	*buf++ = hex_asc_lo(filetype >> 0);
+	return 4;
+}
 
 struct adfs_dir_ops {
 	int	(*read)(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir);

fs/adfs/dir_f.c

···
 			*buf++ = *ptr;
 		ptr++;
 	}
-	*buf = '\0';
 
 	return buf - old_buf;
 }
···
  * convert a disk-based directory entry to a Linux ADFS directory entry
  */
 static inline void
-adfs_dir2obj(struct object_info *obj, struct adfs_direntry *de)
+adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
+	struct adfs_direntry *de)
 {
 	obj->name_len =	adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
 	obj->file_id  = adfs_readval(de->dirinddiscadd, 3);
···
 	obj->execaddr = adfs_readval(de->direxec, 4);
 	obj->size     = adfs_readval(de->dirlen,  4);
 	obj->attr     = de->newdiratts;
+	obj->filetype = -1;
+
+	/*
+	 * object is a file and is filetyped and timestamped?
+	 * RISC OS 12-bit filetype is stored in load_address[19:8]
+	 */
+	if ((0 == (obj->attr & ADFS_NDA_DIRECTORY)) &&
+		(0xfff00000 == (0xfff00000 & obj->loadaddr))) {
+		obj->filetype = (__u16) ((0x000fff00 & obj->loadaddr) >> 8);
+
+		/* optionally append the ,xyz hex filetype suffix */
+		if (ADFS_SB(dir->sb)->s_ftsuffix)
+			obj->name_len +=
+				append_filetype_suffix(
+					&obj->name[obj->name_len],
+					obj->filetype);
+	}
 }
 
 /*
···
 	if (!de.dirobname[0])
 		return -ENOENT;
 
-	adfs_dir2obj(obj, &de);
+	adfs_dir2obj(dir, obj, &de);
 
 	return 0;
 }

fs/adfs/dir_fplus.c

···
 		if (obj->name[i] == '/')
 			obj->name[i] = '.';
 
+	obj->filetype = -1;
+
+	/*
+	 * object is a file and is filetyped and timestamped?
+	 * RISC OS 12-bit filetype is stored in load_address[19:8]
+	 */
+	if ((0 == (obj->attr & ADFS_NDA_DIRECTORY)) &&
+		(0xfff00000 == (0xfff00000 & obj->loadaddr))) {
+		obj->filetype = (__u16) ((0x000fff00 & obj->loadaddr) >> 8);
+
+		/* optionally append the ,xyz hex filetype suffix */
+		if (ADFS_SB(dir->sb)->s_ftsuffix)
+			obj->name_len +=
+				append_filetype_suffix(
+					&obj->name[obj->name_len],
+					obj->filetype);
+	}
+
 	dir->pos += 1;
 	ret = 0;
 out:

fs/adfs/inode.c

···
 	.bmap		= _adfs_bmap
 };
 
-static inline unsigned int
-adfs_filetype(struct inode *inode)
-{
-	unsigned int type;
-
-	if (ADFS_I(inode)->stamped)
-		type = (ADFS_I(inode)->loadaddr >> 8) & 0xfff;
-	else
-		type = (unsigned int) -1;
-
-	return type;
-}
-
 /*
  * Convert ADFS attributes and filetype to Linux permission.
  */
 static umode_t
 adfs_atts2mode(struct super_block *sb, struct inode *inode)
 {
-	unsigned int filetype, attr = ADFS_I(inode)->attr;
+	unsigned int attr = ADFS_I(inode)->attr;
 	umode_t mode, rmask;
 	struct adfs_sb_info *asb = ADFS_SB(sb);
 
···
 		return S_IFDIR | S_IXUGO | mode;
 	}
 
-	filetype = adfs_filetype(inode);
-
-	switch (filetype) {
+	switch (ADFS_I(inode)->filetype) {
 	case 0xfc0:	/* LinkFS */
 		return S_IFLNK|S_IRWXUGO;
 
···
 	ADFS_I(inode)->loadaddr  = obj->loadaddr;
 	ADFS_I(inode)->execaddr  = obj->execaddr;
 	ADFS_I(inode)->attr      = obj->attr;
-	ADFS_I(inode)->stamped	  = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
+	ADFS_I(inode)->filetype  = obj->filetype;
+	ADFS_I(inode)->stamped   = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
 
 	inode->i_mode	 = adfs_atts2mode(sb, inode);
 	adfs_adfs2unix_time(&inode->i_mtime, inode);

fs/adfs/super.c

···
 		seq_printf(seq, ",ownmask=%o", asb->s_owner_mask);
 	if (asb->s_other_mask != ADFS_DEFAULT_OTHER_MASK)
 		seq_printf(seq, ",othmask=%o", asb->s_other_mask);
+	if (asb->s_ftsuffix != 0)
+		seq_printf(seq, ",ftsuffix=%u", asb->s_ftsuffix);
 
 	return 0;
 }
 
-enum {Opt_uid, Opt_gid, Opt_ownmask, Opt_othmask, Opt_err};
+enum {Opt_uid, Opt_gid, Opt_ownmask, Opt_othmask, Opt_ftsuffix, Opt_err};
 
 static const match_table_t tokens = {
 	{Opt_uid, "uid=%u"},
 	{Opt_gid, "gid=%u"},
 	{Opt_ownmask, "ownmask=%o"},
 	{Opt_othmask, "othmask=%o"},
+	{Opt_ftsuffix, "ftsuffix=%u"},
 	{Opt_err, NULL}
 };
 
···
 			if (match_octal(args, &option))
 				return -EINVAL;
 			asb->s_other_mask = option;
+			break;
+		case Opt_ftsuffix:
+			if (match_int(args, &option))
+				return -EINVAL;
+			asb->s_ftsuffix = option;
 			break;
 		default:
 			printk("ADFS-fs: unrecognised mount option \"%s\" "
···
 	asb->s_gid = 0;
 	asb->s_owner_mask = ADFS_DEFAULT_OWNER_MASK;
 	asb->s_other_mask = ADFS_DEFAULT_OTHER_MASK;
+	asb->s_ftsuffix = 0;
 
 	if (parse_options(sb, data))
 		goto error;
···
 
 	root_obj.parent_id = root_obj.file_id = le32_to_cpu(dr->root);
 	root_obj.name_len  = 0;
-	root_obj.loadaddr  = 0;
-	root_obj.execaddr  = 0;
+	/* Set root object date as 01 Jan 1987 00:00:00 */
+	root_obj.loadaddr  = 0xfff0003f;
+	root_obj.execaddr  = 0xec22c000;
 	root_obj.size	   = ADFS_NEWDIR_SIZE;
 	root_obj.attr	   = ADFS_NDA_DIRECTORY   | ADFS_NDA_OWNER_READ |
 			     ADFS_NDA_OWNER_WRITE | ADFS_NDA_PUBLIC_READ;
+	root_obj.filetype  = -1;
 
 	/*
 	 * If this is a F+ disk with variable length directories,
···
 		asb->s_dir     = &adfs_f_dir_ops;
 		asb->s_namelen = ADFS_F_NAME_LEN;
 	}
+	/*
+	 * ,xyz hex filetype suffix may be added by driver
+	 * to files that have valid RISC OS filetype
+	 */
+	if (asb->s_ftsuffix)
+		asb->s_namelen += 4;
 
 	sb->s_d_op = &adfs_dentry_operations;
 	root = adfs_iget(sb, &root_obj);