  Macintosh HFS Filesystem for Linux
  Paul H. Hargrove, hargrove@sccm.Stanford.EDU
  version 0.95, 28 Apr 1997

  This document describes version 0.95 of the Macintosh HFS filesystem
  for Linux.  The most current versions of this document and the
  software are kept at The HFS for Linux Page
  <http://www-sccm.Stanford.EDU/~hargrove/HFS/>.
  ______________________________________________________________________

  Table of Contents:

  1.      Introduction

  2.      Mounting HFS Filesystems

  2.1.    afpd

  2.2.    case={asis, lower}

  2.3.    conv={auto, binary, text}

  2.4.    creator=cccc

  2.5.    fork={cap, double, netatalk}

  2.6.    gid=n

  2.7.    names={7bit, 8bit, alpha, cap, latin, netatalk, trivial}

  2.8.    part=n

  2.9.    quiet

  2.10.   type=cccc

  2.11.   uid=n

  2.12.   umask=n

  3.      Writing to HFS Filesystems

  3.1.    Writing with fork=cap

  3.2.    Writing with fork=double

  3.3.    Writing with fork=netatalk

  4.      A Guide to Special File Formats

  4.1.    CAP .finderinfo Files

  4.2.    AppleDouble Header Files

  5.      Reporting Bugs

  5.1.    What Goes in a Bug Report

  5.2.    How to Report a Kernel Oops or GPF

  6.      Legal Notices

  6.1.    This Document

  6.2.    The Software

  6.2.1.  The Columbia AppleTalk Package for UNIX

  6.2.2.  Netatalk

  6.3.    Trademarks
  ______________________________________________________________________

  1.  Introduction

  This software implements the Macintosh HFS filesystem under Linux.  It
  allows you to read and write HFS filesystems on floppy disks, CDROMs,
  hard drives, ZIP drives, etc.  It is not an AppleShare client.

  If you use this software, please send me a note telling of your
  success or failure with it.  Your feedback lets me know that this
  project is not a waste of my time.

  This code is still experimental, so backup anything important before
  you start playing.  I'd like you to know that I've never lost any
  files while using this software, or I would not release it.  However,
  a ``better safe than sorry'' attitude is probably best.

  If, for instance, the buffer cache were to become corrupted you could
  start losing things on other disks.  Because of this, if you get a
  General Protection Fault, or a kernel Oops, I strongly recommend that
  you reboot before writing any files.

  2.  Mounting HFS Filesystems

  Once you have the HFS filesystem compiled into the kernel or installed
  as a loadable module, you will be able to use hfs as a filesystem type
  option to mount.  For instance, to mount a Macintosh floppy disk on
  the directory /mnt using the default mount options you would execute
  ``mount -t hfs /dev/fd0 /mnt''.

  The remainder of this section describes the several mount options
  available to control how the HFS filesystem is mapped onto a Linux
  filesystem structure.  The values for the multiple-choice options
  (case, conv, fork and names) can be abbreviated by their first
  character.

  2.1.  afpd

  If included in the options, then the behavior of the filesystem is
  changed to make it fully read-write compatible with Netatalk's afpd.
  In this mode you should not use normal user-level tools to modify the
  filesystem, though reading from it is acceptable.  This is because the
  return codes from some system calls are changed to fool afpd.  These
  changes will confuse many user-level tools.  In particular ``rm -r''
  will loop forever.

  This option implies fork=netatalk, which in turn implies
  names=netatalk.  If either of these options are explicitly set to
  something else they will take precedence and will confuse afpd.  The
  quiet option has no effect.  The case= option functions normally, but
  afpd usually does the same thing for you.  The conv= and part= options
  also function normally.

  You will probably want to use the uid=, gid= and umask= mount options.
  Note that because all the files on an HFS filesystem belong to a
  single user and group and have a single umask, the full AppleShare
  permission scheme will not work through Netatalk.

  One additional limitation is that the Desktop database on the disk is
  stored in afpd's format and is separate from any existing database
  maintained by the Finder when the volume is used on a Macintosh.
  Because of this mounting an HFS CDROM across the network to a
  Macintosh may result in applications and documents showing up with
  default application and document icons.  Additionally double clicking
  on a document will fail to start the correct application.  Both of
  these problems can be worked around by copying the application to a
  local disk on the Macintosh.

  This mode is known to be compatible with afpd from Netatalk versions
  1.4b1 and 1.4b2, and known to be incompatible with the afpd from
  version 1.3.3.  As of this writing Netatalk version 1.4 has not yet
  been released.  However, it is expected that this mode will be
  compatible with afpd from Netatalk version 1.4 when it is released.

  2.2.  case={asis, lower}

  default value: asis

  This option determines if Macintosh filenames are presented in their
  original case or in all lowercase.  Filename lookup is always case
  insensitive, so either way foo and Foo refer to the same file but ls
  will list Foo with case=asis, and foo with case=lower.  (Same as for
  the HPFS filesystem.)

     asis
        Filenames are reported in the case they were created with.

     lower
        Filenames are reported in lowercase.

  2.3.  conv={auto, binary, text}

  default value: binary

  This option controls CR<->NL conversion of Macintosh data forks.  Any
  translation takes place only for files accessed with the read() and
  write() system calls (either directly or through the stdio functions).
  Access through mmap() is unaffected.  (Similar to the conv= option for
  the MS-DOS filesystem.)

     auto
        If the Finder's type for a file is TEXT or ttro, then CR
        characters are converted to NL characters when read, and NL
        characters are converted to CR characters when written.

        Be warned that some Macintosh applications create files with
        type TEXT even though the contents is clearly binary.

     binary
        No CR<->NL conversion is done.

     text
        In all data forks, regardless of the Finder's type for the file,
        CR characters are converted to NL characters when read, and NL
        characters are converted to CR characters when written.

  2.4.  creator=cccc

  default value: ``????''

  Specifies the 4-character string specifying the Finder's Creator for
  new files.

  2.5.  fork={cap, double, netatalk}

  default value: cap

  This option determines how resource forks and the Finder's metadata
  are represented within the structure of the Linux filesystem.

     cap
        The scheme used by the Columbia AppleTalk Package's AUFS.

        Associated with each directory are two special directories and a
        metadata file.  The directory ./bar is represented by:

        ./bar
           The directory itself, containing subdirectories, the data
           forks of files, and the following two special directories.

        ./bar/.resource
           A special directory holding resource forks of the files in
           ./bar.

        ./bar/.finderinfo
           A special directory holding metadata files for the files and
           subdirectories in ./bar.

        ./.finderinfo/bar
           The metadata file for the directory ./bar.

        The files in a directory are represented as three files:

        ./foo
           The data fork of the file ./foo.

        ./.resource/foo
           The resource fork of the file ./foo.

        ./.finderinfo/foo
           The metadata file for the file ./foo.

        Additionally, the file .rootinfo in the root directory of the
        HFS filesystem is a metadata file for the root directory.

        Brief documentation on the format of file containing the
        Finder's metadata is included in the section ``A Guide to
        Special File Formats'' in this document.  More detailed
        information is available in the Columbia AppleTalk Package.

     double
        The ``AppleDouble'' format recommended by Apple.  (Apple's other
        recommended format, ``AppleSingle'', is not yet implemented.)

        Associated with each directory is an AppleDouble ``header
        file''.  The directory ./bar is represented by:

        ./bar
           The directory itself, containing subdirectories, the data
           forks for files, and the header files for files and
           subdirectories.

        ./%bar
           The header file for the directory ./bar, containing the
           Finder's metadata for the directory.

        The files in a directory are represented as two files:

        ./foo
           The data fork of the file ./foo.

        ./%foo
           The header file for the file ./foo, containing the resource
           fork and the Finder's metadata for the file.

        Additionally, the file %RootInfo in the root directory of the
        HFS filesystem is a header file for the root directory.  This is
        not quite the %RootInfo file referred to in the AppleDouble
        specification.

        The header files used in this scheme are version 2 AppleDouble
        header files.  Their format is described briefly in the section
        ``A Guide to Special File Formats'' in this document.  They are
        documented in detail in ``AppleSingle/AppleDouble Formats:
        Developer's Note (9/94)'', available from Apple's Developer
        Services Page <http://devworld.apple.com>.

        Note that the naming convention for the header file can cause
        name conflicts.  For instance, using Apple's 7-bit ASCII name
        conversion (see the names mount option) the name %Desktop could
        be interpreted either as the header file for the file Desktop or
        as the file with 0xDE as the hexadecimal representation of its
        first character, and "sktop" as the remaining 5 characters.  The
        problem arises when both files exist, since only one will be
        accessible.  The behavior of the HFS filesystem in the case of
        such a conflict is undefined, and may change in future releases.
        (If this causes problems for you, please don't report it as a
        bug; I didn't design this ``standard'', Apple did.)

     netatalk
        The scheme used by the Netatalk afpd.

        Associated with each directory is a special directory and a
        metadata file.  The directory ./bar is represented by:

        ./bar
           The directory itself, containing subdirectories, the data
           forks of files, and the following special directory.

        ./bar/.AppleDouble
           A special directory holding AppleDouble header files for
           ./bar and the files it contains, but not for the
           subdirectories it contains.

        ./bar/.AppleDouble/.Parent
           The header file for the directory ./bar, containing the
           Finder's metadata for the directory.

        The files in a directory are represented as two files:

        ./foo
           The data fork of the file ./foo.

        ./.AppleDouble/foo
           The header file for file ./foo, containing the resource fork
           and the Finder's metadata.

        The header files used in this scheme are version 1 AppleDouble
        header files.  They are described briefly in the section ``A
        Guide to Special File Formats'' in this document.  The format is
        documented in detail in the ``Apple II File Type Notes'' under
        the type ``$E0.0002/$E0.0003-AppleDouble'', and in Appendix B of
        the ``A/UX Toolbox: Macintosh ROM Interface'' manual.

  2.6.  gid=n

  default value: gid of the mounting process

  Specifies the group that owns all files and directories on the
  filesystem.  (Same as for the MS-DOS and HPFS filesystems.)

  2.7.  names={7bit, 8bit, alpha, cap, latin, netatalk, trivial}

  default value: varies as follows

  o  If the fork option is set to double, then names defaults to alpha.

  o  If the fork option is set to netatalk, then names defaults to
     netatalk.

  o  If the fork option is set to cap (or has taken that value by
     default), then names defaults to cap.

  This option determines how to convert between valid Macintosh
  filenames and valid Linux filenames.  The 7bit, 8bit and alpha options
  correspond to Apple's recommended conventions named ``7-bit ASCII'',
  ``8-bit'' and ``7-bit alphanumeric''.

     7bit
        When converting from Macintosh filenames to Linux filenames the
        NULL (0x00), slash (/) and percent (%) characters and the
        extended 8-bit characters (hexadecimal codes 0x80-0xff) are
        replaced by a percent character (%) followed by the two-digit
        hexadecimal code for the character.

        When converting from Linux filenames to Macintosh filenames the
        string "%YZ" is replaced by the character with hexadecimal code
        0xYZ.  If 0xYZ is not a valid hexadecimal number or is the code
        for NULL or colon (:) then the string "%YZ" is unchanged.  A
        colon (:) is replaced by a pipe character (|).

     8bit
        When converting from Macintosh filenames to Linux filenames the
        NULL (0x00), slash (/) and percent (%) characters are replaced
        by a percent character (%) followed by the two-digit hexadecimal
        code for the character.

        When converting from Linux filenames to Macintosh filenames the
        string "%YZ" is replaced by the character with hexadecimal code
        0xYZ.  If 0xYZ is not a valid hexadecimal number or is the code
        for NULL or colon (:) then the string "%YZ" is unchanged.  A
        colon (:) is replaced by a pipe character (|).

     alpha
        When converting from Macintosh filenames to Linux filenames only
        the alphanumeric characters (a-z, A-Z and 0-9), the underscore
        (_) and the last period (.) in the filename are unchanged.  The
        remaining characters are replaced by a percent character (%)
        followed by the two-digit hexadecimal code for the character.

        When converting from Linux filenames to Macintosh filenames the
        string "%YZ" is replaced by the character with hexadecimal code
        0xYZ.  If 0xYZ is not a valid hexadecimal number or is the code
        for NULL or colon (:) then the string "%YZ" is unchanged.  A
        colon (:) is replaced by a pipe character (|).

     cap
        The convention used by the Columbia AppleTalk Package's AUFS.

        When converting from Macintosh filenames to Linux filenames the
        characters from space ( ) through tilde (~) (ASCII 32-126) are
        unchanged, with the exception of slash (/).  The slash (/) and
        all characters outside the range 32-126 are replaced by a colon
        (:) followed by the two-digit hexadecimal code for the
        character.

        When converting from Linux filenames to Macintosh filenames the
        string ":YZ" is replaced by the character with hexadecimal code
        0xYZ.  If 0xYZ is not a valid hexadecimal number or is the code
        for NULL or colon (:) then the colon is replaced by a pipe
        character (|).

     latin
        When converting from Macintosh filenames to Linux filenames the
        characters from space ( ) through tilde (~) (ASCII 32-126) are
        unchanged, with the exception of slash (/) and percent (%).  The
        extended 8-bit Macintosh characters with equivalents in the
        Latin-1 character set are replaced by those equivalents.  The
        remaining characters are replaced by a percent character (%)
        followed by the two-digit hexadecimal code for the character.

        When converting from Linux filenames to Macintosh filenames the
        string "%YZ" is replaced by the character with hexadecimal code
        0xYZ.  If 0xYZ is not a valid hexadecimal number or is the code
        for NULL or colon (:) then the string "%YZ" is unchanged. The
        Latin-1 characters with equivalents in the extended 8-bit
        Macintosh character set are replaced by those equivalents.  A
        colon (:) is replaced by a pipe character (|).

        Thanks to Holger Schemel (aeglos@valinor.owl.de) for
        contributing this conversion mode.

     netatalk
        The convention used by the Netatalk afpd.

        When converting from Macintosh filenames to Linux filenames the
        characters from space ( ) through tilde (~) (ASCII 32-126) are
        unchanged, with the exception of slash (/) and any initial
        period (.).  The slash (/) and any initial period (.)  and all
        characters outside the range 32-126 are replaced by a colon (:)
        followed by the two-digit hexadecimal code for the character.

        When converting from Linux filenames to Macintosh filenames the
        string ":YZ" is replaced by the character with hexadecimal code
        0xYZ.  If 0xYZ is not a valid hexadecimal number or is the code
        for NULL or colon (:) then the colon is replaced by a pipe
        character (|).

     trivial
        When converting from Macintosh filenames to Linux filenames a
        slash character (/) is replaced by a colon (:).

        When converting from Linux filenames to Macintosh filenames a
        colon (:) is replaced by a slash character (/).

  2.8.  part=n

  default value: 0

  Specifies which HFS partition to mount from a Macintosh CDROM or hard
  drive.  Partitions are numbered from 0 and count only those identified
  in the partition table as containing HFS filesystems.  This option is
  only useful when the Linux platform doesn't fully support Macintosh
  partition tables.  In particular on MkLinux and Linux-Pmac this option
  is useless.

  Note that in versions before 0.8.3 partitions were numbered from 1.

  2.9.  quiet

  If included in the options, then chown and chmod operations will not
  return errors, but will instead fail silently.  (Same as for the MS-
  DOS and HPFS filesystems.)

  2.10.  type=cccc

  default value: ``????''

  Specifies the 4-character string specifying the Finder's Type for new
  files.

  2.11.  uid=n

  default value: uid of the mounting process

  Specifies the user that owns all files and directories on the
  filesystem.  (Same as for the MS-DOS and HPFS filesystems.)

  2.12.  umask=n

  default value: umask of the mounting process

  Specifies (in octal) the umask used for all files and directories.
  (Same as for the MS-DOS and HPFS filesystems.)

  3.  Writing to HFS Filesystems

  Each of the values of the fork mount option yields a different
  representation of the Macintosh-specific parts of a file within the
  structure of the Linux filesystem.  There are, therefore, slightly
  different steps involved in copying files if you want to preserve the
  resource forks and the Finder's metadata.

  It is important to remember not to use normal user-level tools to
  modify a filesystem mounted with the afpd mount option.

  Regardless of the value of the fork mount option you can do virtually
  everything to the data fork of a file that you can to a file on any
  other filesystem.  The limitations are essentially the same as those
  imposed by the MS-DOS filesystem:

  o  You can't change the uid or gid of files.

  o  You can't set the set-uid, set-gid or sticky permission bits.

  o  You can't clear the execute permission bits.

  Likewise you can do virtually everything to a directory that you can
  to a directory on another file system with the following exceptions:

  o  You can't create, delete or rename resource forks of files or the
     Finder's metadata.  Note, however, that they are created (with
     defaults values), deleted and renamed along with the corresponding
     data fork or directory.

  o  You can't change permissions on directories.

  o  You can't change the uid or gid of directories.

  o  You can't create multiple links to files.

  o  You can't create symlinks, device files, sockets or FIFOs.

  3.1.  Writing with fork=cap

  Unlike the other schemes for representing forked files, the CAP scheme
  presents the resource fork as an independent file; the resource fork
  of ./foo is ./.resource/foo.  Therefore, you can treat it as a normal
  file.  You can do anything to a resource fork that you can do to a
  data fork, except that you cannot enable execute permissions on a
  resource fork.  Therefore, resource forks are not suitable for holding
  Linux executables or shared libraries.

  If you plan to use the resource fork on a Macintosh then you must obey
  the format of a valid resource fork.  This format is documented in
  Chapter 1 of Apple's Inside Macintosh: More Macintosh Toolbox.  The
  filesystem knows nothing about this format and so does nothing to
  enforce it.

  The current support for reading and writing is sufficient to allow
  copying of entire directories with tar, as long as both the source and
  destination are mounted with fork=cap.  tar may complain about being
  unable to change the uid, gid or mode of files.  This is normal and is
  an unavoidable side effect of the having a single uid, gid and umask
  for the entire filesystem.

  It is impossible to create a resource fork or a Finder metadata file.
  However, they are created automatically when the data fork is created.
  Therefore, if you wish to copy a single file including both forks and
  the Finder's metadata then you must create the data fork first.  Then
  you can copy the resource fork and the Finder's metadata.  For
  instance to copy the file foo to dir/bar you should do the following:

  1. cp foo dir/bar

  2. cp .resource/foo dir/.resource/bar

  3. cp .finderinfo/foo dir/.finderinfo/bar

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.  This method will work even if the file dir/bar exists.

  If you wish to move foo to dir/bar and foo and dir are on the same
  filesystem then you only need to execute ``mv foo dir/bar'' and the
  resource fork and the Finder's metadata will move too.  However, if
  foo and dir are on different filesystem then this will lose the
  resource fork and metadata.  Therefore, it is safest to always move
  files as follows:

  1. cp foo dir/bar

  2. cp .resource/foo dir/.resource/bar

  3. cp .finderinfo/foo dir/.finderinfo/bar

  4. rm foo

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.  This method will work even if the file dir/bar exists.

  Directories have no resource fork but you may wish to create a
  directory which has the same location and view on the Finder's screen
  as an existing one.  This can be done by copying the Finder metadata
  file.  To give the directory bar the same location, layout, creation
  date and modify date as foo you simply execute ``cp .finderinfo/foo
  .finderinfo/bar''.

  When copying an entire directory with ``cp -R'' you may also wish to
  copy the metadata for the directory:

  1. cp -R foo bar

  2. cp .finderinfo/foo .finderinfo/bar

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.

  3.2.  Writing with fork=double

  The current support for reading and writing header files is sufficient
  to allow copying of entire directories with tar, as long as both the
  source and destination are mounted with fork=double.  tar may complain
  about being unable to change the uid, gid or mode of files.  This is
  normal and is an unavoidable side effect of the having a single uid,
  gid and umask for the entire filesystem.

  It is impossible to create a header file.  However, they are created
  automatically when the data fork is created.  Therefore, if you wish
  to copy a single file including both forks and the Finder's metadata
  then you must create the data fork first.  Then you can copy the
  header file.  instance to copy the file foo to dir/bar you should do
  the following:

  1. cp foo dir/bar

  2. cp %foo dir/%bar

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.  This method will work even if the file dir/bar exists.

  If you wish to move foo to dir/bar and foo and dir are on the same
  filesystem then you only need to execute ``mv foo dir/bar'' and the
  header file will move too.  However, if foo and dir are on different
  filesystem then this will lose the header file.  Therefore, it is
  safest to always move files as follows:

  1. cp foo dir/bar

  2. cp %foo dir/%bar

  3. rm foo

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.  This method will work even if the file dir/bar exists.

  Directories have no resource fork but you may wish to create a
  directory which has the same location and view on the Finder's screen
  as an existing one.  This can be done by copying the corresponding
  header file.  To give the directory bar the same location, layout,
  creation date and modify date as foo simply execute ``cp %foo %bar''.

  When copying an entire directory with ``cp -R'' you may also wish to
  copy the header file for the directory as well:

  1. cp -R foo bar

  2. cp %foo %bar

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.

  3.3.  Writing with fork=netatalk

  The current support for reading and writing header files is sufficient
  to allow copying of entire directories with tar, as long as both the
  source and destination are mounted fork=netatalk.  tar may complain
  about being unable to change the uid, gid or mode of files.  This is
  normal and is an unavoidable side effect of the having a single uid,
  gid and umask for the entire filesystem.

  It is impossible to create a header file.  However, they are created
  automatically when the data fork is created.  Therefore, if you wish
  to copy a single file including both forks and the Finder's metadata
  then you must create the data fork first.  Then you can copy the
  header file.  instance to copy the file foo to dir/bar you should do
  the following:

  1. cp foo dir/bar

  2. cp .AppleDouble/foo dir/.AppleDouble/bar

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.  This method will work even if the file dir/bar exists.

  If you wish to move foo to dir/bar and foo and dir are on the same
  filesystem then you only need to execute ``mv foo dir/bar'' and the
  header file will move too.  However, if foo and dir are on different
  filesystem then this will lose the header file.  Therefore, it is
  safest to always move files as follows:

  1. cp foo dir/bar

  2. cp .AppleDouble/foo dir/.AppleDouble/bar

  3. rm foo

  You may get ``Operation not permitted'' errors from cp when it tries
  to change the permissions on files.  These errors can safely be
  ignored.  This method will work even if the file dir/bar exists.

  Directories have no resource fork but you may wish to create a
  directory which has the same location and view on the Finder's screen
  as an existing one.  This can be done by copying the corresponding
  header file.  To give the directory bar the same location, layout,
  creation date and modify date as foo you simply execute ``cp
  foo/.AppleDouble/.Parent bar/.AppleDouble/.Parent''.

  Because the fork=netatalk scheme holds the header file for a directory
  within that directory, directories can safely be copied with ``cp -R
  foo bar'' with no loss of information.  However, you may get
  ``Operation not permitted'' errors from cp when it tries to change the
  permissions on files.  These errors can safely be ignored.

  4.  A Guide to Special File Formats

  Each of the values of the fork mount option yields different special
  files to represent the Macintosh-specific parts of a file within the
  structure of the Linux filesystem.  You can write to these special
  files to change things such as the Creator and Type of a file.
  However, to do so safely you must follow certain rules to avoid
  corrupting the data.  Additionally, there are certain fields in the
  special files that you can't change (writes to them will fail
  silently).

  4.1.  CAP .finderinfo Files

  The Finder's metadata for the file ./foo in held in the file
  ./.finderinfo/foo.  The file has a fixed format defined in hfs_fs.h as
  follows:

       ______________________________________________________________________
       struct hfs_cap_info {
               __u8    fi_fndr[32];            /* Finder's info */
               __u16   fi_attr;                /* AFP attributes */
               __u8    fi_magic1;              /* Magic number: */
       #define HFS_CAP_MAGIC1          0xFF
               __u8    fi_version;             /* Version of this structure: */
       #define HFS_CAP_VERSION         0x10
               __u8    fi_magic;               /* Another magic number: */
       #define HFS_CAP_MAGIC           0xDA
               __u8    fi_bitmap;              /* Bitmap of which names are valid: */
       #define HFS_CAP_SHORTNAME       0x01
       #define HFS_CAP_LONGNAME        0x02
               __u8    fi_shortfilename[12+1]; /* "short name" (unused) */
               __u8    fi_macfilename[32+1];   /* Original (Macintosh) name */
               __u8    fi_comln;               /* Length of comment (always 0) */
               __u8    fi_comnt[200];          /* Finder comment (unused) */
               /* optional:    used by aufs only if compiled with USE_MAC_DATES */
               __u8    fi_datemagic;           /* Magic number for dates extension: */
       #define HFS_CAP_DMAGIC          0xDA
               __u8    fi_datevalid;           /* Bitmap of which dates are valid: */
       #define HFS_CAP_MDATE           0x01
       #define HFS_CAP_CDATE           0x02
               __u8    fi_ctime[4];            /* Creation date (in AFP format) */
               __u8    fi_mtime[4];            /* Modify date (in AFP format) */
               __u8    fi_utime[4];            /* Un*x time of last mtime change */
       };
       ______________________________________________________________________

  The type __u8 is an unsigned character, and __u16 is an unsigned
  16-bit integer.

  Currently only the fields fi_fndr, fi_attr, fi_ctime and fi_mtime can
  be changed.  Writes to the other fields are silently ignored.
  However, you shouldn't write random bytes to the other fields, since
  they may be writable in the future.

  The fi_fndr field is the ``Finder info'' and ``Extended Finder info''
  for a file or directory.  These structures are described in various
  books on Macintosh programming.  The portion of the most interest is
  probably the first 8 bytes which, for a file, give the 4-byte Type
  followed by the 4-byte Creator.

  The fi_attr field is the AFP attributes of the file or directory.
  While you can write any value to this field, only the ``write-
  inhibit'' bit is significant.  Setting or clearing this bit will clear
  or set the write bits in the file's permissions.  When you read from
  this field anything you may have written is lost.  If the file has
  write permissions enabled then you will read zero from this field.
  With write permission disabled you will read back 0x01 0xA0, which
  corresponds to setting the ``write-inhibit'', ``rename-inhibit'' and
  ``delete-inhibit'' bits.

  The fi_ctime and fi_mtime are the Macintosh created and modified time
  for the file or directory, and are 32-bit signed integers in network
  byteorder giving seconds from 00:00 GMT Jan. 1, 2000.

  4.2.  AppleDouble Header Files

  Both the fork=double and fork=netatalk schemes for representing forked
  files use AppleDouble header files to contain the resource fork and
  the Finder's metadata together in a single file.

  The AppleDouble format specifies a fixed-format header which describes
  which fields are contained in the remainder of the file, where they
  are located in the file and how long they are.  A full description of
  the version 1 format used when fork=netatalk is available from ??????.
  The version 2 format used when fork=double is documented in ??????.
  The discussion that follows assumes you have read and understood these
  documents, which may be difficult until I've replaced the ``??????''s
  above with something more informative :-).

  Due to the variable structure of an AppleDouble header file you must
  not use buffered I/O when reading or writing them; you should only use
  the read() and write() system calls.  It is also important that you
  make some effort to coordinate processes that are reading and writing
  the same header file, since a reader will receive the wrong data if
  the location of a given entry has changed since it read the descriptor
  for the entry.  If a process tries to read the descriptor table while
  it is changing then it is possible to read totally meaningless data.

  When a header file is opened it is initially presented with a default
  header layout.  You may write to the header to change the layout, but
  when all file descriptors for the file or directory have been closed
  the change in format is lost and subsequent opens will yield the
  default layout.  Changes to supported entries are made directly to the
  filesystem and are thus preserved when the file is closed and
  reopened.

  The HFS filesystem currently uses a fixed-size table to hold the
  descriptors.  Therefore you are limited to HFS_HDR_MAX (currently 10)
  descriptors.  In the unlikely event that you try to write a header
  with more descriptors, a warning will be issued by the kernel, and
  extra descriptors will be ignored.  This should be considered a bug
  and will hopefully change sooner rather than later.

  The results of specifying overlapping entries is undefined and should
  not be relied upon to remain unchanged from one version of the HFS
  filesystem to the next.  There is no valid reason to define
  overlapping entries, so just don't do it!

  Changes to the magic number and version fields are preserved until all
  file descriptors are closed, however the only significance given to
  them internally is that the 16 bytes following the version changes
  meaning according to the version.  For version 1 header files these 16
  bytes contain the string ``Macintosh'' followed by 7 spaces.  For any
  other value of the version field these 16 bytes are all zeros.  In
  either case writes to these 16 bytes are silently ignored.

  Since the magic number and version are given no other significance
  internally, you are free to do many things that violate the official
  formats.  For instance you can create an entry for the data fork in a
  header file with an AppleDouble magic number or create ``File Info''
  (id=7) entries in version 2 header files and ``File Dates Info''
  (id=8) entries in version 1 header files.  However, future versions of
  the filesystem may enforce the format more strictly.

  Entry id 1 (``Data Fork'') is read-only.  You should use the data file
  to modify the data fork.  The data fork is, of course, not supported
  for directories.

  Entry ids 2, 7, 8, 9 and 10 (``Resource Fork'', ``File Info'', ``File
  Dates Info'', ``Finder Info'' and ``Macintosh File Info'') are fully
  supported, meaning that their contents may be read and written and
  that data written is preserved when the file is closed and reopened.
  The resource fork is, of course, not supported for directories.

  Entry id 7 specifies some of the same data given by ids 8 and 10.  If
  you create a header file with an entry for id 7 and for ids 8 or 10,
  then the behavior with respect to their interaction is undefined.  A
  header that contains an entry for id 7 and for ids 8 or 10 is not
  valid as either a version 1 or a version 2 header file, so there is no
  reason to do this and future versions may prevent it.

  Entry id 3 (``Real Name'') is read-only, since it will change
  automatically when a file is renamed.  Writes to the corresponding
  entry are silently ignored.

  All other entry ids are ignored.  You may create descriptors for them;
  in fact the default header layout when fork=netatalk includes a
  descriptor for id 4 (``Comment'').  However writes to the entries
  corresponding to the ignored ids fail silently and reads from the
  entries always return zeros.  However, you shouldn't write random
  bytes to unsupported entries, since they may be supported in the
  future.

  All of the supported entry types except the data and resource forks
  have a fixed length.  If you give them a smaller length in the
  descriptor then you are unable to access part of the corresponding
  entry.  If you give them a larger length in the descriptor, then the
  corresponding entry is padded with zeros and writes to the extra space
  are silently ignored.

  Writes to the length field of descriptors for the data and resource
  forks will cause the corresponding fork to grow (with zero padding) or
  shrink to the indicated length.

  If you have an entry for the data fork then the descriptor's length
  field does not change automatically to reflect any modification of the
  data fork directly (the data does change however).  If the data fork
  is longer than the descriptor indicates, then a portion of it is
  inaccessible.  If the data fork is shorter than the descriptor
  indicates then reads will be padded with zeros.

  Writes beyond the end of the resource fork that extend into empty
  space between entries or beyond the end of the file will extend the
  fork, automatically changing the length field of the corresponding
  descriptor.  Writes to any other space between entries are silently
  ignored and read of such spaces always return zeros.

  Calling truncate() on a header file can change the length of the
  resource fork and such a change will automatically be reflected in the
  length field of the corresponding descriptor.  If truncate() shortens
  the file so that the entry for the resource fork would extend beyond
  the new end of the file then the fork is shortened to fit in the space
  that remains, or to zero bytes if the entry is now entirely beyond the
  end of the file.  If the last entry in a header file is the resource
  fork then a call to truncate() that extends the header file will
  extend the fork with zeros.  Note that this happens even if there was
  previously space between the end of the fork and the end of the file.

  5.  Reporting Bugs

  If you'd like any problems you encounter fixed, you'll need to provide
  a detailed bug report.  However, you should check the FAQ (available
  from the HFS for Linux Page <http://www-sccm.Stanford.EDU/~hargrove/HFS/>)
  first to be certain that your problem is not a known limitation of the
  filesystem.  If your bug doesn't appear in the FAQ then you should e-mail
  me at hargrove@sccm.Stanford.EDU.

  5.1.  What Goes in a Bug Report

  When writing your bug report, include any facts you think might be
  relevant; I'd much rather have a bunch of extra facts than need to
  e-mail you to get the information.  At a minimum the following
  information should be included:

  o  The version of the HFS filesystem you are using (see
     linux/fs/hfs/version.h).

  o  The kernel version you are using.

  o  Any unofficial kernel patches or loadable modules you are using.

  o  If you are loading the HFS filesystem as a module, then version of
     the module utilities used to load hfs.o.

  o  The type of media you are working with (floppy, CDROM, ZIP Drive,
     etc.).

  o  The steps required to reproduce the bug, including mount options
     used.  (If you can't reproduce the bug tell me everything you did
     the one time it did occur, but be warned that non-reproducible bugs
     can only rarely be fixed.)

  5.2.  How to Report a Kernel Oops or GPF

  If you encounter a bug that causes a kernel Oops or a General
  Protection Fault then you'll need to collect some additional
  information for the bug report.  If you are loading the HFS filesystem
  as a module, then is important that you do this before rebooting,
  since the module is unlikely to be loaded at the same address after
  the reboot.

  You should include all the information that the kernel prints to the
  console or to the system logs.  However, the EIP and Stack Trace are
  addresses in your kernel and mean nothing to me without more
  information.  Using your System.map file (or either ksymoops or klogd)
  determine which functions the EIP and Stack Trace are in.  If you do
  this by hand using your System.map file then the correct symbol is the
  one of type t or T with the largest address less than or equal to the
  one you are resolving.

  If you are loading the HFS filesystem as a module and the Oops or GPF
  was in the HFS code then the EIP and the top levels of the Stack Trace
  will be in a loadable module, rather than in the kernel proper.  So,
  their symbols will not be in the file System.map.  Therefore, you will
  need to use /proc/ksyms, or a loadmap produced by passing the -m
  option to insmod, to locate those symbols.

  6.  Legal Notices

  6.1.  This Document

  This document is Copyright (c) 1996, 1997 by Paul H. Hargrove.

  Permission is granted to make and distribute verbatim copies of this
  document provided the copyright notice and this permission notice are
  preserved on all copies.

  Permission is granted to copy and distribute modified versions of this
  document under the conditions for verbatim copies above, provided a
  notice clearly stating that the document is a modified version is also
  included in the modified document.

  Permission is granted to copy and distribute translations of this
  document into another language, under the conditions specified above
  for modified versions.

  Permission is granted to convert this document into another media
  under the conditions specified above for modified versions provided
  the requirement to acknowledge the source document is fulfilled by
  inclusion of an obvious reference to the source document in the new
  media. Where there is any doubt as to what defines ``obvious'' the
  copyright owner reserves the right to decide.

  6.2.  The Software

  The HFS filesystem for Linux is Copyright (c) 1994-1997 by Paul H.
  Hargrove.

  This software is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2, or (at your option)
  any later version.

  This software is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this software in the file ``COPYING''; if not, write to the
  Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
  USA.

  6.2.1.  The Columbia AppleTalk Package for UNIX

  The source code distribution of the Columbia AppleTalk Package for
  UNIX, version 6.0, (CAP) was used as a specification of the location
  and format of files used by CAP's Aufs.  No code from CAP appears in
  the HFS filesystem. The HFS filesystem is not a work ``derived'' from
  CAP in the sense of intellectual property law.

  6.2.2.  Netatalk

  The source code distributions of Netatalk, versions 1.3.3b2 and 1.4b2,
  were used as a specification of the location and format of files used
  by Netatalk's afpd.  No code from Netatalk appears in the HFS
  filesystem.  The HFS filesystem is not a work ``derived'' from
  Netatalk in the sense of intellectual property law.

  6.3.  Trademarks

  o  ``Finder'' is a trademarks of Apple Computer, Inc.

  o  ``Apple'', ``AppleShare'', ``AppleTalk'' and ``Macintosh'' are
     registered trademarks of Apple Computer, Inc.

  o  ``Microsoft'' and ``MS-DOS'' are registered trademarks of Microsoft
     Corporation.

  o  All other trademarks are the property of their respective owners.

