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353 lines
15 KiB
353 lines
15 KiB
.. SPDX-License-Identifier: GPL-2.0 |
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==================== |
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Read/Write HPFS 2.09 |
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==================== |
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1998-2004, Mikulas Patocka |
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:email: [email protected] |
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:homepage: https://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/index-e.cgi |
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Credits |
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======= |
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Chris Smith, 1993, original read-only HPFS, some code and hpfs structures file |
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is taken from it |
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Jacques Gelinas, MSDos mmap, Inspired by fs/nfs/mmap.c (Jon Tombs 15 Aug 1993) |
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Werner Almesberger, 1992, 1993, MSDos option parser & CR/LF conversion |
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Mount options |
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uid=xxx,gid=xxx,umask=xxx (default uid=gid=0 umask=default_system_umask) |
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Set owner/group/mode for files that do not have it specified in extended |
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attributes. Mode is inverted umask - for example umask 027 gives owner |
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all permission, group read permission and anybody else no access. Note |
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that for files mode is anded with 0666. If you want files to have 'x' |
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rights, you must use extended attributes. |
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case=lower,asis (default asis) |
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File name lowercasing in readdir. |
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conv=binary,text,auto (default binary) |
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CR/LF -> LF conversion, if auto, decision is made according to extension |
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- there is a list of text extensions (I thing it's better to not convert |
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text file than to damage binary file). If you want to change that list, |
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change it in the source. Original readonly HPFS contained some strange |
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heuristic algorithm that I removed. I thing it's danger to let the |
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computer decide whether file is text or binary. For example, DJGPP |
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binaries contain small text message at the beginning and they could be |
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misidentified and damaged under some circumstances. |
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check=none,normal,strict (default normal) |
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Check level. Selecting none will cause only little speedup and big |
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danger. I tried to write it so that it won't crash if check=normal on |
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corrupted filesystems. check=strict means many superfluous checks - |
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used for debugging (for example it checks if file is allocated in |
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bitmaps when accessing it). |
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errors=continue,remount-ro,panic (default remount-ro) |
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Behaviour when filesystem errors found. |
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chkdsk=no,errors,always (default errors) |
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When to mark filesystem dirty so that OS/2 checks it. |
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eas=no,ro,rw (default rw) |
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What to do with extended attributes. 'no' - ignore them and use always |
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values specified in uid/gid/mode options. 'ro' - read extended |
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attributes but do not create them. 'rw' - create extended attributes |
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when you use chmod/chown/chgrp/mknod/ln -s on the filesystem. |
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timeshift=(-)nnn (default 0) |
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Shifts the time by nnn seconds. For example, if you see under linux |
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one hour more, than under os/2, use timeshift=-3600. |
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File names |
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========== |
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As in OS/2, filenames are case insensitive. However, shell thinks that names |
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are case sensitive, so for example when you create a file FOO, you can use |
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'cat FOO', 'cat Foo', 'cat foo' or 'cat F*' but not 'cat f*'. Note, that you |
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also won't be able to compile linux kernel (and maybe other things) on HPFS |
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because kernel creates different files with names like bootsect.S and |
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bootsect.s. When searching for file thats name has characters >= 128, codepages |
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are used - see below. |
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OS/2 ignores dots and spaces at the end of file name, so this driver does as |
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well. If you create 'a. ...', the file 'a' will be created, but you can still |
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access it under names 'a.', 'a..', 'a . . . ' etc. |
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Extended attributes |
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=================== |
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On HPFS partitions, OS/2 can associate to each file a special information called |
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extended attributes. Extended attributes are pairs of (key,value) where key is |
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an ascii string identifying that attribute and value is any string of bytes of |
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variable length. OS/2 stores window and icon positions and file types there. So |
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why not use it for unix-specific info like file owner or access rights? This |
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driver can do it. If you chown/chgrp/chmod on a hpfs partition, extended |
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attributes with keys "UID", "GID" or "MODE" and 2-byte values are created. Only |
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that extended attributes those value differs from defaults specified in mount |
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options are created. Once created, the extended attributes are never deleted, |
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they're just changed. It means that when your default uid=0 and you type |
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something like 'chown luser file; chown root file' the file will contain |
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extended attribute UID=0. And when you umount the fs and mount it again with |
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uid=luser_uid, the file will be still owned by root! If you chmod file to 444, |
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extended attribute "MODE" will not be set, this special case is done by setting |
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read-only flag. When you mknod a block or char device, besides "MODE", the |
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special 4-byte extended attribute "DEV" will be created containing the device |
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number. Currently this driver cannot resize extended attributes - it means |
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that if somebody (I don't know who?) has set "UID", "GID", "MODE" or "DEV" |
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attributes with different sizes, they won't be rewritten and changing these |
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values doesn't work. |
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Symlinks |
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======== |
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You can do symlinks on HPFS partition, symlinks are achieved by setting extended |
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attribute named "SYMLINK" with symlink value. Like on ext2, you can chown and |
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chgrp symlinks but I don't know what is it good for. chmoding symlink results |
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in chmoding file where symlink points. These symlinks are just for Linux use and |
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incompatible with OS/2. OS/2 PmShell symlinks are not supported because they are |
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stored in very crazy way. They tried to do it so that link changes when file is |
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moved ... sometimes it works. But the link is partly stored in directory |
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extended attributes and partly in OS2SYS.INI. I don't want (and don't know how) |
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to analyze or change OS2SYS.INI. |
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Codepages |
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========= |
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HPFS can contain several uppercasing tables for several codepages and each |
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file has a pointer to codepage its name is in. However OS/2 was created in |
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America where people don't care much about codepages and so multiple codepages |
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support is quite buggy. I have Czech OS/2 working in codepage 852 on my disk. |
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Once I booted English OS/2 working in cp 850 and I created a file on my 852 |
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partition. It marked file name codepage as 850 - good. But when I again booted |
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Czech OS/2, the file was completely inaccessible under any name. It seems that |
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OS/2 uppercases the search pattern with its system code page (852) and file |
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name it's comparing to with its code page (850). These could never match. Is it |
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really what IBM developers wanted? But problems continued. When I created in |
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Czech OS/2 another file in that directory, that file was inaccessible too. OS/2 |
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probably uses different uppercasing method when searching where to place a file |
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(note, that files in HPFS directory must be sorted) and when searching for |
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a file. Finally when I opened this directory in PmShell, PmShell crashed (the |
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funny thing was that, when rebooted, PmShell tried to reopen this directory |
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again :-). chkdsk happily ignores these errors and only low-level disk |
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modification saved me. Never mix different language versions of OS/2 on one |
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system although HPFS was designed to allow that. |
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OK, I could implement complex codepage support to this driver but I think it |
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would cause more problems than benefit with such buggy implementation in OS/2. |
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So this driver simply uses first codepage it finds for uppercasing and |
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lowercasing no matter what's file codepage index. Usually all file names are in |
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this codepage - if you don't try to do what I described above :-) |
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Known bugs |
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========== |
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HPFS386 on OS/2 server is not supported. HPFS386 installed on normal OS/2 client |
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should work. If you have OS/2 server, use only read-only mode. I don't know how |
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to handle some HPFS386 structures like access control list or extended perm |
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list, I don't know how to delete them when file is deleted and how to not |
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overwrite them with extended attributes. Send me some info on these structures |
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and I'll make it. However, this driver should detect presence of HPFS386 |
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structures, remount read-only and not destroy them (I hope). |
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When there's not enough space for extended attributes, they will be truncated |
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and no error is returned. |
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OS/2 can't access files if the path is longer than about 256 chars but this |
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driver allows you to do it. chkdsk ignores such errors. |
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Sometimes you won't be able to delete some files on a very full filesystem |
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(returning error ENOSPC). That's because file in non-leaf node in directory tree |
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(one directory, if it's large, has dirents in tree on HPFS) must be replaced |
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with another node when deleted. And that new file might have larger name than |
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the old one so the new name doesn't fit in directory node (dnode). And that |
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would result in directory tree splitting, that takes disk space. Workaround is |
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to delete other files that are leaf (probability that the file is non-leaf is |
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about 1/50) or to truncate file first to make some space. |
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You encounter this problem only if you have many directories so that |
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preallocated directory band is full i.e.:: |
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number_of_directories / size_of_filesystem_in_mb > 4. |
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You can't delete open directories. |
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You can't rename over directories (what is it good for?). |
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Renaming files so that only case changes doesn't work. This driver supports it |
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but vfs doesn't. Something like 'mv file FILE' won't work. |
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All atimes and directory mtimes are not updated. That's because of performance |
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reasons. If you extremely wish to update them, let me know, I'll write it (but |
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it will be slow). |
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When the system is out of memory and swap, it may slightly corrupt filesystem |
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(lost files, unbalanced directories). (I guess all filesystem may do it). |
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When compiled, you get warning: function declaration isn't a prototype. Does |
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anybody know what does it mean? |
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What does "unbalanced tree" message mean? |
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========================================= |
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Old versions of this driver created sometimes unbalanced dnode trees. OS/2 |
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chkdsk doesn't scream if the tree is unbalanced (and sometimes creates |
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unbalanced trees too :-) but both HPFS and HPFS386 contain bug that it rarely |
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crashes when the tree is not balanced. This driver handles unbalanced trees |
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correctly and writes warning if it finds them. If you see this message, this is |
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probably because of directories created with old version of this driver. |
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Workaround is to move all files from that directory to another and then back |
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again. Do it in Linux, not OS/2! If you see this message in directory that is |
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whole created by this driver, it is BUG - let me know about it. |
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Bugs in OS/2 |
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============ |
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When you have two (or more) lost directories pointing each to other, chkdsk |
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locks up when repairing filesystem. |
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Sometimes (I think it's random) when you create a file with one-char name under |
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OS/2, OS/2 marks it as 'long'. chkdsk then removes this flag saying "Minor fs |
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error corrected". |
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File names like "a .b" are marked as 'long' by OS/2 but chkdsk "corrects" it and |
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marks them as short (and writes "minor fs error corrected"). This bug is not in |
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HPFS386. |
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Codepage bugs described above |
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============================= |
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If you don't install fixpacks, there are many, many more... |
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History |
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======= |
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====== ========================================================================= |
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0.90 First public release |
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0.91 Fixed bug that caused shooting to memory when write_inode was called on |
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open inode (rarely happened) |
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0.92 Fixed a little memory leak in freeing directory inodes |
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0.93 Fixed bug that locked up the machine when there were too many filenames |
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with first 15 characters same |
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Fixed write_file to zero file when writing behind file end |
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0.94 Fixed a little memory leak when trying to delete busy file or directory |
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0.95 Fixed a bug that i_hpfs_parent_dir was not updated when moving files |
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1.90 First version for 2.1.1xx kernels |
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1.91 Fixed a bug that chk_sectors failed when sectors were at the end of disk |
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Fixed a race-condition when write_inode is called while deleting file |
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Fixed a bug that could possibly happen (with very low probability) when |
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using 0xff in filenames. |
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Rewritten locking to avoid race-conditions |
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Mount option 'eas' now works |
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Fsync no longer returns error |
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Files beginning with '.' are marked hidden |
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Remount support added |
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Alloc is not so slow when filesystem becomes full |
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Atimes are no more updated because it slows down operation |
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Code cleanup (removed all commented debug prints) |
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1.92 Corrected a bug when sync was called just before closing file |
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1.93 Modified, so that it works with kernels >= 2.1.131, I don't know if it |
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works with previous versions |
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Fixed a possible problem with disks > 64G (but I don't have one, so I can't |
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test it) |
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Fixed a file overflow at 2G |
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Added new option 'timeshift' |
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Changed behaviour on HPFS386: It is now possible to operate on HPFS386 in |
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read-only mode |
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Fixed a bug that slowed down alloc and prevented allocating 100% space |
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(this bug was not destructive) |
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1.94 Added workaround for one bug in Linux |
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Fixed one buffer leak |
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Fixed some incompatibilities with large extended attributes (but it's still |
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not 100% ok, I have no info on it and OS/2 doesn't want to create them) |
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Rewritten allocation |
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Fixed a bug with i_blocks (du sometimes didn't display correct values) |
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Directories have no longer archive attribute set (some programs don't like |
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it) |
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Fixed a bug that it set badly one flag in large anode tree (it was not |
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destructive) |
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1.95 Fixed one buffer leak, that could happen on corrupted filesystem |
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Fixed one bug in allocation in 1.94 |
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1.96 Added workaround for one bug in OS/2 (HPFS locked up, HPFS386 reported |
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error sometimes when opening directories in PMSHELL) |
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Fixed a possible bitmap race |
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Fixed possible problem on large disks |
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You can now delete open files |
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Fixed a nondestructive race in rename |
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1.97 Support for HPFS v3 (on large partitions) |
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ZFixed a bug that it didn't allow creation of files > 128M |
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(it should be 2G) |
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1.97.1 Changed names of global symbols |
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Fixed a bug when chmoding or chowning root directory |
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1.98 Fixed a deadlock when using old_readdir |
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Better directory handling; workaround for "unbalanced tree" bug in OS/2 |
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1.99 Corrected a possible problem when there's not enough space while deleting |
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file |
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Now it tries to truncate the file if there's not enough space when |
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deleting |
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Removed a lot of redundant code |
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2.00 Fixed a bug in rename (it was there since 1.96) |
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Better anti-fragmentation strategy |
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2.01 Fixed problem with directory listing over NFS |
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Directory lseek now checks for proper parameters |
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Fixed race-condition in buffer code - it is in all filesystems in Linux; |
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when reading device (cat /dev/hda) while creating files on it, files |
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could be damaged |
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2.02 Workaround for bug in breada in Linux. breada could cause accesses beyond |
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end of partition |
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2.03 Char, block devices and pipes are correctly created |
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Fixed non-crashing race in unlink (Alexander Viro) |
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Now it works with Japanese version of OS/2 |
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2.04 Fixed error when ftruncate used to extend file |
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2.05 Fixed crash when got mount parameters without = |
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Fixed crash when allocation of anode failed due to full disk |
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Fixed some crashes when block io or inode allocation failed |
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2.06 Fixed some crash on corrupted disk structures |
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Better allocation strategy |
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Reschedule points added so that it doesn't lock CPU long time |
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It should work in read-only mode on Warp Server |
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2.07 More fixes for Warp Server. Now it really works |
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2.08 Creating new files is not so slow on large disks |
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An attempt to sync deleted file does not generate filesystem error |
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2.09 Fixed error on extremely fragmented files |
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====== =========================================================================
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