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 <stuart.swales.croftnuisk@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 2 deletions

diff --git a/fs/adfs/adfs.h b/fs/adfs/adfs.h
index 58588ddb178c..a8a58d864f96 100644
--- a/fs/adfs/adfs.h
+++ b/fs/adfs/adfs.h
@@ -50,6 +50,7 @@ struct adfs_sb_info {
         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                   */
@@ -93,7 +94,7 @@ struct adfs_dir {
 /*
  * 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            */
@@ -101,10 +102,26 @@ struct object_info {
         __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);
         int     (*setpos)(struct adfs_dir *dir, unsigned int fpos);