package Fuse; use 5.006; use strict; use warnings; use Errno; use Carp; require Exporter; require DynaLoader; use AutoLoader; use Data::Dumper; our @ISA = qw(Exporter DynaLoader); # Items to export into callers namespace by default. Note: do not export # names by default without a very good reason. Use EXPORT_OK instead. # Do not simply export all your public functions/methods/constants. # This allows declaration use Fuse ':all'; # If you do not need this, moving things directly into @EXPORT or @EXPORT_OK # will save memory. our %EXPORT_TAGS = ( 'all' => [ qw(FUSE_DEBUG XATTR_CREATE XATTR_REPLACE) ], 'debug' => [ qw(FUSE_DEBUG) ], 'xattr' => [ qw(XATTR_CREATE XATTR_REPLACE) ] ); our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } ); our @EXPORT = qw( FUSE_DEBUG ); our $VERSION = '0.06'; sub AUTOLOAD { # This AUTOLOAD is used to 'autoload' constants from the constant() # XS function. If a constant is not found then control is passed # to the AUTOLOAD in AutoLoader. my $constname; our $AUTOLOAD; ($constname = $AUTOLOAD) =~ s/.*:://; croak "& not defined" if $constname eq 'constant'; my $val = constant($constname, @_ ? $_[0] : 0); if ($! != 0) { if ($!{EINVAL}) { $AutoLoader::AUTOLOAD = $AUTOLOAD; goto &AutoLoader::AUTOLOAD; } else { croak "Your vendor has not defined Fuse macro $constname"; } } { no strict 'refs'; # Fixed between 5.005_53 and 5.005_61 if ($] >= 5.00561) { *$AUTOLOAD = sub () { $val }; } else { *$AUTOLOAD = sub { $val }; } } goto &$AUTOLOAD; } sub XATTR_CREATE { # See . return 1; } sub XATTR_REPLACE { # See . return 2; } bootstrap Fuse $VERSION; sub main { my (@subs) = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0); my (@names) = qw(getattr readlink getdir mknod mkdir unlink rmdir symlink rename link chmod chown truncate utime open read write statfs flush release fsync setxattr getxattr listxattr removexattr); my (@validOpts) = qw(allow_other); my ($tmp) = 0; my (%mapping) = map { $_ => $tmp++ } (@names); my (%optmap) = map { $_ => 1 } (@validOpts); my (%otherargs) = (debug=>0, mountpoint=>"", mountopts=>""); while(my $name = shift) { my ($subref) = shift; if(exists($otherargs{$name})) { $otherargs{$name} = $subref; } else { croak "There is no function $name" unless exists($mapping{$name}); croak "Usage: Fuse::main(getattr => &my_getattr, ...)" unless $subref; croak "Usage: Fuse::main(getattr => &my_getattr, ...)" unless ref($subref); croak "Usage: Fuse::main(getattr => &my_getattr, ...)" unless ref($subref) eq "CODE"; $subs[$mapping{$name}] = $subref; } } foreach my $opt ( split(/,/,$otherargs{mountopts}) ) { if ( ! exists($optmap{$opt}) ) { croak "Use of an invalid mountopt argument"; } } perl_fuse_main($otherargs{debug},$otherargs{mountpoint},$otherargs{mountopts},@subs); } # Autoload methods go after =cut, and are processed by the autosplit program. 1; __END__ =head1 NAME Fuse - write filesystems in Perl using FUSE =head1 SYNOPSIS use Fuse; my ($mountpoint) = ""; $mountpoint = shift(@ARGV) if @ARGV; Fuse::main(mountpoint=>$mountpoint, getattr=>\&my_getattr, getdir=>\&my_getdir, ...); =head1 DESCRIPTION This lets you implement filesystems in perl, through the FUSE (Filesystem in USErspace) kernel/lib interface. FUSE expects you to implement callbacks for the various functions. NOTE: I have only tested the things implemented in example.pl! It should work, but some things may not. In the following definitions, "errno" can be 0 (for a success), -EINVAL, -ENOENT, -EONFIRE, any integer less than 1 really. You can import standard error constants by saying something like "use POSIX qw(EDOTDOT ENOANO);". Every constant you need (file types, open() flags, error values, etc) can be imported either from POSIX or from Fcntl, often both. See their respective documentations, for more information. =head2 EXPORTED SYMBOLS FUSE_DEBUG by default. You can request all exportable symbols by using the tag ":all". You can request all debug symbols by using the tag ":debug". This will export FUSE_DEBUG. You can request the extended attribute symbols by using the tag ":xattr". This will export XATTR_CREATE and XATTR_REPLACE. =head2 FUNCTIONS =head3 Fuse::main Takes arguments in the form of hash key=>value pairs. There are many valid keys. Most of them correspond with names of callback functions, as described in section 'FUNCTIONS YOUR FILESYSTEM MAY IMPLEMENT'. A few special keys also exist: debug => boolean =over 1 This turns FUSE call tracing on and off. Default is 0 (which means off). =back mountpoint => string =over 1 The point at which to mount this filesystem. There is no default, you must specify this. An example would be '/mnt'. =back mountopts => string =over 1 This is a comma seperated list of mount options to pass to the FUSE kernel module. At present, it allows the specification of the allow_other argument when mounting the new FUSE filesystem. To use this, you will also need 'user_allow_other' in /etc/fuse.conf as per the FUSE documention mountopts => "allow_other" or mountopts => "" =back unthreaded => boolean =over 1 This turns FUSE multithreading off and on. NOTE: This perlmodule does not currently work properly in multithreaded mode! The author is unfortunately not familiar enough with perl-threads internals, and according to the documentation available at time of writing (2002-03-08), those internals are subject to changing anyway. Note that singlethreaded mode also means that you will not have to worry about reentrancy, though you will have to worry about recursive lookups (since the kernel holds a global lock on your filesystem and blocks waiting for one callback to complete before calling another). I hope to add full multithreading functionality later, but for now, I recommend you leave this option at the default, 1 (which means unthreaded, no threads will be used and no reentrancy is needed). =back =head2 FUNCTIONS YOUR FILESYSTEM MAY IMPLEMENT =head3 getattr Arguments: filename. Returns a list, very similar to the 'stat' function (see perlfunc). On error, simply return a single numeric scalar value (e.g. "return -ENOENT();"). FIXME: the "ino" field is currently ignored. I tried setting it to 0 in an example script, which consistently caused segfaults. Fields (the following was stolen from perlfunc(1) with apologies): ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size, $atime,$mtime,$ctime,$blksize,$blocks) = getattr($filename); Here are the meaning of the fields: 0 dev device number of filesystem 1 ino inode number 2 mode file mode (type and permissions) 3 nlink number of (hard) links to the file 4 uid numeric user ID of file's owner 5 gid numeric group ID of file's owner 6 rdev the device identifier (special files only) 7 size total size of file, in bytes 8 atime last access time in seconds since the epoch 9 mtime last modify time in seconds since the epoch 10 ctime inode change time (NOT creation time!) in seconds since the epoch 11 blksize preferred block size for file system I/O 12 blocks actual number of blocks allocated (The epoch was at 00:00 January 1, 1970 GMT.) =head3 readlink Arguments: link pathname. Returns a scalar: either a numeric constant, or a text string. This is called when dereferencing symbolic links, to learn the target. example rv: return "/proc/self/fd/stdin"; =head3 getdir Arguments: Containing directory name. Returns a list: 0 or more text strings (the filenames), followed by a numeric errno (usually 0). This is used to obtain directory listings. Its opendir(), readdir(), filldir() and closedir() all in one call. example rv: return ('.', 'a', 'b', 0); =head3 mknod Arguments: Filename, numeric modes, numeric device Returns an errno (0 upon success, as usual). This function is called for all non-directory, non-symlink nodes, not just devices. =head3 mkdir Arguments: New directory pathname, numeric modes. Returns an errno. Called to create a directory. =head3 unlink Arguments: Filename. Returns an errno. Called to remove a file, device, or symlink. =head3 rmdir Arguments: Pathname. Returns an errno. Called to remove a directory. =head3 symlink Arguments: Existing filename, symlink name. Returns an errno. Called to create a symbolic link. =head3 rename Arguments: old filename, new filename. Returns an errno. Called to rename a file, and/or move a file from one directory to another. =head3 link Arguments: Existing filename, hardlink name. Returns an errno. Called to create hard links. =head3 chmod Arguments: Pathname, numeric modes. Returns an errno. Called to change permissions on a file/directory/device/symlink. =head3 chown Arguments: Pathname, numeric uid, numeric gid. Returns an errno. Called to change ownership of a file/directory/device/symlink. =head3 truncate Arguments: Pathname, numeric offset. Returns an errno. Called to truncate a file, at the given offset. =head3 utime Arguments: Pathname, numeric actime, numeric modtime. Returns an errno. Called to change access/modification times for a file/directory/device/symlink. =head3 open Arguments: Pathname, numeric flags (which is an OR-ing of stuff like O_RDONLY and O_SYNC, constants you can import from POSIX). Returns an errno. No creation, or trunctation flags (O_CREAT, O_EXCL, O_TRUNC) will be passed to open(). Your open() method needs only check if the operation is permitted for the given flags, and return 0 for success. =head3 read Arguments: Pathname, numeric requestedsize, numeric offset. Returns a numeric errno, or a string scalar with up to $requestedsize bytes of data. Called in an attempt to fetch a portion of the file. =head3 write Arguments: Pathname, scalar buffer, numeric offset. You can use length($buffer) to find the buffersize. Returns an errno. Called in an attempt to write (or overwrite) a portion of the file. Be prepared because $buffer could contain random binary data with NULLs and all sorts of other wonderful stuff. =head3 statfs Arguments: none Returns any of the following: -ENOANO() or $namelen, $files, $files_free, $blocks, $blocks_avail, $blocksize or -ENOANO(), $namelen, $files, $files_free, $blocks, $blocks_avail, $blocksize =head3 flush Arguments: Pathname Returns an errno or 0 on success. Called to synchronise any cached data. This is called before the file is closed. It may be called multiple times before a file is closed. =head3 release Arguments: Pathname, numeric flags passed to open Returns an errno or 0 on success. Called to indicate that there are no more references to the file. Called once for every file with the same pathname and flags as were passed to open. =head3 fsync Arguments: Pathname, numeric flags Returns an errno or 0 on success. Called to synchronise the file's contents. If flags is non-zero, only synchronise the user data. Otherwise synchronise the user and meta data. =head3 setxattr Arguments: Pathname, extended attribute's name, extended attribute's value, numeric flags (which is an OR-ing of XATTR_CREATE and XATTR_REPLACE Returns an errno or 0 on success. Called to set the value of the named extended attribute. If you wish to reject setting of a particular form of extended attribute name (e.g.: regexps matching user\..* or security\..*), then return - EOPNOTSUPP. If flags is set to XATTR_CREATE and the extended attribute already exists, this should fail with - EEXIST. If flags is set to XATTR_REPLACE and the extended attribute doesn't exist, this should fail with - ENOATTR. XATTR_CREATE and XATTR_REPLACE are provided by this module, but not exported by default. To import them: use Fuse ':xattr'; or: use Fuse ':all'; =head3 getxattr Arguments: Pathname, extended attribute's name Returns an errno, 0 if there was no value, or the extended attribute's value. Called to get the value of the named extended attribute. =head3 listxattr Arguments: Pathname Returns a list: 0 or more text strings (the extended attribute names), followed by a numeric errno (usually 0). =head3 removexattr Arguments: Pathname, extended attribute's name Returns an errno or 0 on success. =head1 AUTHOR Mark Glines, Emark@glines.orgE =head1 SEE ALSO L, the FUSE documentation. =cut