HFS.txt
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- 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
- ______________________________________________________________________
- 11.. IInnttrroodduuccttiioonn
- 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 _n_o_t 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 _s_t_r_o_n_g_l_y recommend that
- you reboot before writing any files.
- 22.. MMoouunnttiinngg HHFFSS FFiilleessyysstteemmss
- 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.
- 22..11.. aaffppdd
- 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.
- 22..22.. ccaassee=={{aassiiss,, lloowweerr}}
- 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.)
- aassiiss
- Filenames are reported in the case they were created with.
- lloowweerr
- Filenames are reported in lowercase.
- 22..33.. ccoonnvv=={{aauuttoo,, bbiinnaarryy,, tteexxtt}}
- default value: binary
- This option controls CR<->NL conversion of Macintosh _d_a_t_a _f_o_r_k_s. 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.)
- aauuttoo
- 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.
- bbiinnaarryy
- No CR<->NL conversion is done.
- tteexxtt
- 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.
- 22..44.. ccrreeaattoorr==cccccccc
- default value: ``????''
- Specifies the 4-character string specifying the Finder's Creator for
- new files.
- 22..55.. ffoorrkk=={{ccaapp,, ddoouubbllee,, nneettaattaallkk}}
- default value: cap
- This option determines how resource forks and the Finder's metadata
- are represented within the structure of the Linux filesystem.
- ccaapp
- 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:
- ..//bbaarr
- The directory itself, containing subdirectories, the data
- forks of files, and the following two special directories.
- ..//bbaarr//..rreessoouurrccee
- A special directory holding resource forks of the files in
- ./bar.
- ..//bbaarr//..ffiinnddeerriinnffoo
- A special directory holding metadata files for the files and
- subdirectories in ./bar.
- ..//..ffiinnddeerriinnffoo//bbaarr
- The metadata file for the directory ./bar.
- The files in a directory are represented as three files:
- ..//ffoooo
- The data fork of the file ./foo.
- ..//..rreessoouurrccee//ffoooo
- The resource fork of the file ./foo.
- ..//..ffiinnddeerriinnffoo//ffoooo
- 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.
- ddoouubbllee
- 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:
- ..//bbaarr
- The directory itself, containing subdirectories, the data
- forks for files, and the header files for files and
- subdirectories.
- ..//%%bbaarr
- 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:
- ..//ffoooo
- The data fork of the file ./foo.
- ..//%%ffoooo
- 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.)
- nneettaattaallkk
- 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:
- ..//bbaarr
- The directory itself, containing subdirectories, the data
- forks of files, and the following special directory.
- ..//bbaarr//..AApppplleeDDoouubbllee
- A special directory holding AppleDouble header files for
- ./bar and the files it contains, but not for the
- subdirectories it contains.
- ..//bbaarr//..AApppplleeDDoouubbllee//..PPaarreenntt
- 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:
- ..//ffoooo
- The data fork of the file ./foo.
- ..//..AApppplleeDDoouubbllee//ffoooo
- 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.
- 22..66.. ggiidd==nn
- 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.)
- 22..77.. nnaammeess=={{77bbiitt,, 88bbiitt,, aallpphhaa,, ccaapp,, llaattiinn,, nneettaattaallkk,, ttrriivviiaall}}
- 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''.
- 77bbiitt
- 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 (|).
- 88bbiitt
- 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 (|).
- aallpphhaa
- 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 (|).
- ccaapp
- 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 (|).
- llaattiinn
- 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.
- nneettaattaallkk
- 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 (|).
- ttrriivviiaall
- 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 (/).
- 22..88.. ppaarrtt==nn
- 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.
- 22..99.. qquuiieett
- 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.)
- 22..1100.. ttyyppee==cccccccc
- default value: ``????''
- Specifies the 4-character string specifying the Finder's Type for new
- files.
- 22..1111.. uuiidd==nn
- 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.)
- 22..1122.. uummaasskk==nn
- 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.)
- 33.. WWrriittiinngg ttoo HHFFSS FFiilleessyysstteemmss
- 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.
- 33..11.. WWrriittiinngg wwiitthh ffoorrkk==ccaapp
- 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 _I_n_s_i_d_e _M_a_c_i_n_t_o_s_h_: _M_o_r_e _M_a_c_i_n_t_o_s_h _T_o_o_l_b_o_x. 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.
- 33..22.. WWrriittiinngg wwiitthh ffoorrkk==ddoouubbllee
- 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.
- 33..33.. WWrriittiinngg wwiitthh ffoorrkk==nneettaattaallkk
- 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.
- 44.. AA GGuuiiddee ttoo SSppeecciiaall FFiillee FFoorrmmaattss
- 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).
- 44..11.. CCAAPP ..ffiinnddeerriinnffoo FFiilleess
- 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.
- 44..22.. AApppplleeDDoouubbllee HHeeaaddeerr FFiilleess
- 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.
- 55.. RReeppoorrttiinngg BBuuggss
- 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.
- 55..11.. WWhhaatt GGooeess iinn aa BBuugg RReeppoorrtt
- 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.)
- 55..22.. HHooww ttoo RReeppoorrtt aa KKeerrnneell OOooppss oorr GGPPFF
- 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 _y_o_u_r 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.
- 66.. LLeeggaall NNoottiicceess
- 66..11.. TThhiiss DDooccuummeenntt
- 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.
- 66..22.. TThhee SSooffttwwaarree
- 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.
- 66..22..11.. TThhee CCoolluummbbiiaa AApppplleeTTaallkk PPaacckkaaggee ffoorr UUNNIIXX
- The source code distribution of the Columbia AppleTalk Package for
- UNIX, version 6.0, (CAP) was used as a _s_p_e_c_i_f_i_c_a_t_i_o_n 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.
- 66..22..22.. NNeettaattaallkk
- The source code distributions of Netatalk, versions 1.3.3b2 and 1.4b2,
- were used as a _s_p_e_c_i_f_i_c_a_t_i_o_n 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.
- 66..33.. TTrraaddeemmaarrkkss
- +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.