13 our @ISA = qw(Exporter DynaLoader);
15 # Items to export into callers namespace by default. Note: do not export
16 # names by default without a very good reason. Use EXPORT_OK instead.
17 # Do not simply export all your public functions/methods/constants.
19 # This allows declaration use Fuse ':all';
20 # If you do not need this, moving things directly into @EXPORT or @EXPORT_OK
23 'all' => [ qw(XATTR_CREATE XATTR_REPLACE fuse_get_context fuse_version FUSE_IOCTL_COMPAT FUSE_IOCTL_UNRESTRICTED FUSE_IOCTL_RETRY FUSE_IOCTL_MAX_IOV notify_poll pollhandle_destroy) ],
24 'xattr' => [ qw(XATTR_CREATE XATTR_REPLACE) ],
25 'ioctl' => [ qw(FUSE_IOCTL_COMPAT FUSE_IOCTL_UNRESTRICTED FUSE_IOCTL_RETRY FUSE_IOCTL_MAX_IOV) ],
28 our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
31 our $VERSION = '0.14';
34 # This AUTOLOAD is used to 'autoload' constants from the constant()
35 # XS function. If a constant is not found then control is passed
36 # to the AUTOLOAD in AutoLoader.
40 ($constname = $AUTOLOAD) =~ s/.*:://;
41 croak "& not defined" if $constname eq 'constant';
42 my $val = constant($constname, @_ ? $_[0] : 0);
45 $AutoLoader::AUTOLOAD = $AUTOLOAD;
46 goto &AutoLoader::AUTOLOAD;
49 croak "Your vendor has not defined Fuse macro $constname";
54 # Fixed between 5.005_53 and 5.005_61
56 *$AUTOLOAD = sub () { $val };
59 *$AUTOLOAD = sub { $val };
65 bootstrap Fuse $VERSION;
67 use constant FUSE_IOCTL_COMPAT => (1 << 0);
68 use constant FUSE_IOCTL_UNRESTRICTED => (1 << 1);
69 use constant FUSE_IOCTL_RETRY => (1 << 2);
70 use constant FUSE_IOCTL_MAX_IOV => 256;
73 my @names = qw(getattr readlink getdir mknod mkdir unlink rmdir symlink
74 rename link chmod chown truncate utime open read write statfs
75 flush release fsync setxattr getxattr listxattr removexattr);
76 my $fuse_version = fuse_version();
77 if ($fuse_version >= 2.3) {
78 push(@names, qw/opendir readdir releasedir fsyncdir init destroy/);
80 if ($fuse_version >= 2.5) {
81 push(@names, qw/access create ftruncate fgetattr/);
83 if ($fuse_version >= 2.6) {
84 push(@names, qw/lock utimens bmap/);
86 if ($fuse_version >= 2.8) {
87 # junk doesn't contain a function pointer, and hopefully
88 # never will; it's a "dead" zone in the struct
89 # fuse_operations where a flag bit is declared. we don't
90 # need to concern ourselves with it, and it appears any
91 # arch with a 64 bit pointer will align everything to
92 # 8 bytes, making the question of pointer alignment for
93 # the last 2 wrapper functions no big thing.
94 push(@names, qw/junk ioctl poll/);
96 my @subs = map {undef} @names;
98 my %mapping = map { $_ => $tmp++ } @names;
99 my @otherargs = qw(debug threaded mountpoint mountopts nullpath_ok);
107 while(my $name = shift) {
108 my ($subref) = shift;
109 if(exists($otherargs{$name})) {
110 $otherargs{$name} = $subref;
112 croak "There is no function $name" unless exists($mapping{$name});
113 croak "Usage: Fuse::main(getattr => \"main::my_getattr\", ...)" unless $subref;
114 $subs[$mapping{$name}] = $subref;
117 if($otherargs{threaded}) {
118 # make sure threads are both available, and loaded.
119 if($Config{useithreads}) {
120 if(exists($threads::{VERSION})) {
121 if(exists($threads::shared::{VERSION})) {
124 carp("Thread support requires you to use threads::shared.\nThreads are disabled.\n");
125 $otherargs{threaded} = 0;
128 carp("Thread support requires you to use threads and threads::shared.\nThreads are disabled.\n");
129 $otherargs{threaded} = 0;
132 carp("Thread support was not compiled into this build of perl.\nThreads are disabled.\n");
133 $otherargs{threaded} = 0;
136 perl_fuse_main(@otherargs{@otherargs},@subs);
139 # Autoload methods go after =cut, and are processed by the autosplit program.
146 Fuse - write filesystems in Perl using FUSE
151 my ($mountpoint) = "";
152 $mountpoint = shift(@ARGV) if @ARGV;
153 Fuse::main(mountpoint=>$mountpoint, getattr=>"main::my_getattr", getdir=>"main::my_getdir", ...);
157 This lets you implement filesystems in perl, through the FUSE
158 (Filesystem in USErspace) kernel/lib interface.
160 FUSE expects you to implement callbacks for the various functions.
162 In the following definitions, "errno" can be 0 (for a success),
163 -EINVAL, -ENOENT, -EONFIRE, any integer less than 1 really.
165 You can import standard error constants by saying something like
166 "use POSIX qw(EDOTDOT ENOANO);".
168 Every constant you need (file types, open() flags, error values,
169 etc) can be imported either from POSIX or from Fcntl, often both.
170 See their respective documentations, for more information.
172 =head2 EXPORTED SYMBOLS
176 You can request all exportable symbols by using the tag ":all".
178 You can request the extended attribute symbols by using the tag ":xattr".
179 This will export XATTR_CREATE and XATTR_REPLACE.
185 Takes arguments in the form of hash key=>value pairs. There are
186 many valid keys. Most of them correspond with names of callback
187 functions, as described in section 'FUNCTIONS YOUR FILESYSTEM MAY IMPLEMENT'.
188 A few special keys also exist:
192 =item debug => boolean
194 This turns FUSE call tracing on and off. Default is 0 (which means off).
196 =item mountpoint => string
198 The point at which to mount this filesystem. There is no default, you must
199 specify this. An example would be '/mnt'.
201 =item mountopts => string
203 This is a comma separated list of mount options to pass to the FUSE kernel
206 At present, it allows the specification of the allow_other
207 argument when mounting the new FUSE filesystem. To use this, you will also
208 need 'user_allow_other' in /etc/fuse.conf as per the FUSE documention
210 mountopts => "allow_other" or
213 =item threaded => boolean
215 This turns FUSE multithreading on and off. The default is 0, meaning your FUSE
216 script will run in single-threaded mode. Note that single-threaded mode also
217 means that you will not have to worry about reentrancy, though you will have to
218 worry about recursive lookups. In single-threaded mode, FUSE holds a global
219 lock on your filesystem, and will wait for one callback to return before
220 calling another. This can lead to deadlocks, if your script makes any attempt
221 to access files or directories in the filesystem it is providing. (This
222 includes calling stat() on the mount-point, statfs() calls from the 'df'
223 command, and so on and so forth.) It is worth paying a little attention and
224 being careful about this.
226 Enabling multithreading will cause FUSE to make multiple simultaneous calls
227 into the various callback functions of your perl script. If you enable
228 threaded mode, you can enjoy all the parallel execution and interactive
229 response benefits of threads, and you get to enjoy all the benefits of race
230 conditions and locking bugs, too. Please also ensure any other perl modules
231 you're using are also thread-safe.
233 (If enabled, this option will cause a warning if your perl interpreter was not
234 built with USE_ITHREADS, or if you have failed to use threads or
237 =item nullpath_ok => boolean
239 This flag tells Fuse to not pass paths for functions that operate on file
240 or directory handles. This will yield empty path parameters for functions
241 including read, write, flush, release, fsync, readdir, releasedir,
242 fsyncdir, truncate, fgetattr and lock. If you use this, you must return
243 file/directory handles from open, opendir and create. Default is 0 (off).
244 Only effective on Fuse 2.8 and up; with earlier versions, this does nothing.
248 =head3 Fuse::fuse_get_context
250 use Fuse "fuse_get_context";
251 my $caller_uid = fuse_get_context()->{"uid"};
252 my $caller_gid = fuse_get_context()->{"gid"};
253 my $caller_pid = fuse_get_context()->{"pid"};
255 Access context information about the current Fuse operation.
257 =head3 Fuse::fuse_version
259 Indicates the Fuse version in use; more accurately, indicates the version
260 of the Fuse API in use at build time. Returned as a decimal value; i.e.,
261 for Fuse API v2.6, will return "2.6".
263 =head3 Fuse::notify_poll
265 Only available if the Fuse module is built against libfuse 2.8 or later.
266 Use fuse_version() to determine if this is the case. Calling this function
267 with a pollhandle argument (as provided to the C<poll> operation
268 implementation) will send a notification to the caller poll()ing for
269 I/O operation availability. If more than one pollhandle is provided for
270 the same filehandle, only use the latest; you *can* send notifications
271 to them all, but it is unnecessary and decreases performance.
273 ONLY supply poll handles fed to you through C<poll> to this function.
274 Due to thread safety requirements, we can't currently package the pointer
275 up in an object the way we'd like to to prevent this situation, but your
276 filesystem server program may segfault, or worse, if you feed things to
277 this function which it is not supposed to receive. If you do anyway, we
278 take no responsibility for whatever Bad Things(tm) may happen.
280 =head3 Fuse::pollhandle_destroy
282 Only available if the Fuse module is built against libfuse 2.8 or later.
283 Use fuse_version() to determine if this is the case. This function destroys
284 a poll handle (fed to your program through C<poll>). When you are done
285 with a poll handle, either because it has been replaced, or because a
286 notification has been sent to it, pass it to this function to dispose of
289 ONLY supply poll handles fed to you through C<poll> to this function.
290 Due to thread safety requirements, we can't currently package the pointer
291 up in an object the way we'd like to to prevent this situation, but your
292 filesystem server program may segfault, or worse, if you feed things to
293 this function which it is not supposed to receive. If you do anyway, we
294 take no responsibility for whatever Bad Things(tm) may happen.
296 =head2 FUNCTIONS YOUR FILESYSTEM MAY IMPLEMENT
302 Returns a list, very similar to the 'stat' function (see
303 perlfunc). On error, simply return a single numeric scalar
304 value (e.g. "return -ENOENT();").
306 FIXME: the "ino" field is currently ignored. I tried setting it to 0
307 in an example script, which consistently caused segfaults.
309 Fields (the following was stolen from perlfunc(1) with apologies):
311 ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
312 $atime,$mtime,$ctime,$blksize,$blocks)
313 = getattr($filename);
315 Here are the meaning of the fields:
317 0 dev device number of filesystem
319 2 mode file mode (type and permissions)
320 3 nlink number of (hard) links to the file
321 4 uid numeric user ID of file's owner
322 5 gid numeric group ID of file's owner
323 6 rdev the device identifier (special files only)
324 7 size total size of file, in bytes
325 8 atime last access time in seconds since the epoch
326 9 mtime last modify time in seconds since the epoch
327 10 ctime inode change time (NOT creation time!) in seconds
329 11 blksize preferred block size for file system I/O
330 12 blocks actual number of blocks allocated
332 (The epoch was at 00:00 January 1, 1970 GMT.)
334 If you wish to provide sub-second precision timestamps, they may be
335 passed either as the fractional part of a floating-point value, or as a
336 two-element array, passed as an array ref, with the first element
337 containing the number of seconds since the epoch, and the second
338 containing the number of nanoseconds. This provides complete time
339 precision, as a floating point number starts losing precision at about
340 a tenth of a microsecond. So if you really care about that sort of thing...
344 Arguments: link pathname.
346 Returns a scalar: either a numeric constant, or a text string.
348 This is called when dereferencing symbolic links, to learn the target.
350 example rv: return "/proc/self/fd/stdin";
354 Arguments: Containing directory name.
356 Returns a list: 0 or more text strings (the filenames), followed by a numeric errno (usually 0).
358 This is used to obtain directory listings. It's opendir(), readdir(), filldir() and closedir() all in one call.
360 example rv: return ('.', 'a', 'b', 0);
364 Arguments: Filename, numeric modes, numeric device
366 Returns an errno (0 upon success, as usual).
368 This function is called for all non-directory, non-symlink nodes,
373 Arguments: New directory pathname, numeric modes.
377 Called to create a directory.
385 Called to remove a file, device, or symlink.
393 Called to remove a directory.
397 Arguments: Existing filename, symlink name.
401 Called to create a symbolic link.
405 Arguments: old filename, new filename.
409 Called to rename a file, and/or move a file from one directory to another.
413 Arguments: Existing filename, hardlink name.
417 Called to create hard links.
421 Arguments: Pathname, numeric modes.
425 Called to change permissions on a file/directory/device/symlink.
429 Arguments: Pathname, numeric uid, numeric gid.
433 Called to change ownership of a file/directory/device/symlink.
437 Arguments: Pathname, numeric offset.
441 Called to truncate a file, at the given offset.
445 Arguments: Pathname, numeric actime, numeric modtime.
449 Called to change access/modification times for a file/directory/device/symlink.
453 Arguments: Pathname, numeric flags (which is an OR-ing of stuff like O_RDONLY
454 and O_SYNC, constants you can import from POSIX), fileinfo hash reference.
456 Returns an errno, a file handle (optional).
458 No creation, or truncation flags (O_CREAT, O_EXCL, O_TRUNC) will be passed to open().
459 The fileinfo hash reference contains flags from the Fuse open call which may be modified by the module. The only fields presently supported are:
460 direct_io (version 2.4 onwards)
461 keep_cache (version 2.4 onwards)
462 nonseekable (version 2.9 onwards)
463 Your open() method needs only check if the operation is permitted for the given flags, and return 0 for success.
464 Optionally a file handle may be returned, which will be passed to subsequent read, write, flush, fsync and release calls.
468 Arguments: Pathname, numeric requested size, numeric offset, file handle
470 Returns a numeric errno, or a string scalar with up to $requestedsize bytes of data.
472 Called in an attempt to fetch a portion of the file.
476 Arguments: Pathname, scalar buffer, numeric offset, file handle. You can use length($buffer) to
478 Returns length($buffer) if successful (number of bytes written).
480 Called in an attempt to write (or overwrite) a portion of the file. Be prepared because $buffer could contain random binary data with NULs and all sorts of other wonderful stuff.
486 Returns any of the following:
492 $namelen, $files, $files_free, $blocks, $blocks_avail, $blocksize
496 -ENOANO(), $namelen, $files, $files_free, $blocks, $blocks_avail, $blocksize
500 Arguments: Pathname, file handle
502 Returns an errno or 0 on success.
504 Called to synchronise any cached data. This is called before the file
505 is closed. It may be called multiple times before a file is closed.
509 Arguments: Pathname, numeric flags passed to open, file handle
510 Returns an errno or 0 on success.
512 Called to indicate that there are no more references to the file. Called once
513 for every file with the same pathname and flags as were passed to open.
517 Arguments: Pathname, numeric flags
519 Returns an errno or 0 on success.
521 Called to synchronise the file's contents. If flags is non-zero,
522 only synchronise the user data. Otherwise synchronise the user and meta data.
526 Arguments: Pathname, extended attribute's name, extended attribute's value, numeric flags (which is an OR-ing of XATTR_CREATE and XATTR_REPLACE
528 Returns an errno or 0 on success.
530 Called to set the value of the named extended attribute.
532 If you wish to reject setting of a particular form of extended attribute name
533 (e.g.: regexps matching user\..* or security\..*), then return - EOPNOTSUPP.
535 If flags is set to XATTR_CREATE and the extended attribute already exists,
536 this should fail with - EEXIST. If flags is set to XATTR_REPLACE
537 and the extended attribute doesn't exist, this should fail with - ENOATTR.
539 XATTR_CREATE and XATTR_REPLACE are provided by this module, but not exported
540 by default. To import them:
550 Arguments: Pathname, extended attribute's name
552 Returns an errno, 0 if there was no value, or the extended attribute's value.
554 Called to get the value of the named extended attribute.
560 Returns a list: 0 or more text strings (the extended attribute names), followed by a numeric errno (usually 0).
564 Arguments: Pathname, extended attribute's name
566 Returns an errno or 0 on success.
570 Arguments: Pathname of a directory
571 Returns an errno, and a directory handle (optional)
573 Called when opening a directory for reading. If special handling is
574 required to open a directory, this operation can be implemented to handle
579 Arguments: Pathname of a directory, numeric offset, (optional) directory handle
581 Returns a list of 0 or more entries, followed by a numeric errno (usually 0).
582 The entries can be simple strings (filenames), or arrays containing an
583 offset number, the filename, and optionally an array ref containing the
584 stat values (as would be returned from getattr()).
586 This is used to read entries from a directory. It can be used to return just
587 entry names like getdir(), or can get a segment of the available entries,
588 which requires using array refs and the 2- or 3-item form, with offset values
589 starting from 1. If you wish to return the parameters to fill each entry's
590 struct stat, but do not wish to do partial entry lists/entry counting, set
591 the first element of each array to 0 always.
593 Note that if this call is implemented, it overrides getdir() ALWAYS.
597 Arguments: Pathname of a directory, (optional) directory handle
599 Returns an errno or 0 on success
601 Called when there are no more references to an opened directory. Called once
602 for each pathname or handle passed to opendir(). Similar to release(), but
603 for directories. Accepts a return value, but like release(), the response
604 code will not propagate to any corresponding closedir() calls.
608 Arguments: Pathname of a directory, numeric flags, (optional) directory handle
610 Returns an errno or 0 on success.
612 Called to synchronize any changes to a directory's contents. If flag is
613 non-zero, only synchronize user data, otherwise synchronize user data and
620 Returns (optionally) an SV to be passed as private_data via fuse_get_context().
624 Arguments: (optional) private data SV returned from init(), if any.
630 Arguments: Pathname, access mode flags
632 Returns an errno or 0 on success.
634 Determine if the user attempting to access the indicated file has access to
635 perform the requested actions. The user ID can be determined by calling
636 fuse_get_context(). See access(2) for more information.
640 Arguments: Pathname, create mask, open mode flags
642 Returns errno or 0 on success, and (optional) file handle.
644 Create a file with the path indicated, then open a handle for reading and/or
645 writing with the supplied mode flags. Can also return a file handle like
646 open() as part of the call.
650 Arguments: Pathname, numeric offset, (optional) file handle
652 Returns errno or 0 on success
654 Like truncate(), but on an opened file.
658 Arguments: Pathname, (optional) file handle
660 Returns a list, very similar to the 'stat' function (see
661 perlfunc). On error, simply return a single numeric scalar
662 value (e.g. "return -ENOENT();").
664 Like getattr(), but on an opened file.
668 Arguments: Pathname, numeric command code, hashref containing lock parameters, (optional) file handle
670 Returns errno or 0 on success
672 Used to lock or unlock regions of a file. Locking is handled locally, but this
673 allows (especially for networked file systems) for protocol-level locking
674 semantics to also be employed, if any are available.
676 See the Fuse documentation for more explanation of lock(). The needed symbols
677 for the lock constants can be obtained by importing Fcntl.
681 Arguments: Pathname, last accessed time, last modified time
683 Returns errno or 0 on success
685 Like utime(), but allows time resolution down to the nanosecond. Currently
686 times are passed as "numeric" (internally I believe these are represented
687 typically as "long double"), so the sub-second portion is represented as
688 fractions of a second.
690 Note that if this call is implemented, it overrides utime() ALWAYS.
694 Arguments: Pathname, numeric blocksize, numeric block number
696 Returns errno or 0 on success, and physical block number if successful
698 Used to map a block number offset in a file to the physical block offset
699 on the block device backing the file system. This is intended for
700 filesystems that are stored on an actual block device, with the 'blkdev'
705 Arguments: Pathname, (signed) ioctl command code, flags, data if ioctl op is a write, (optional) file handle
707 Returns errno or 0 on success, and data if ioctl op is a read
709 Used to handle ioctl() operations on files. See ioctl(2) for more
710 information on the fine details of ioctl operation numbers. May need to
711 h2ph system headers to get the necessary macros; keep in mind the macros
712 are highly OS-dependent.
714 Keep in mind that read and write are from the client perspective, so
715 read from our end means data is going *out*, and write means data is
716 coming *in*. It can be slightly confusing.
720 Arguments: Pathname, poll handle ID (or undef if none), event mask, (optional) file handle
722 Returns errno or 0 on success, and updated event mask on success
724 Used to handle poll() operations on files. See poll(2) to learn more about
725 event polling. Use IO::Poll to get the POLLIN, POLLOUT, and other symbols
726 to describe the events which can happen on the filehandle. Save the poll
727 handle ID to be passed to C<notify_poll> and C<pollhandle_destroy>
728 functions, if it is not undef. Threading will likely be necessary for this
731 There is not an "out of band" data transfer channel provided as part of
732 FUSE, so POLLPRI/POLLRDBAND/POLLWRBAND won't work.
734 Poll handle is currently a read-only scalar; we are investigating a way
735 to make this an object instead.
739 Mark Glines, E<lt>mark@glines.orgE<gt>
743 L<perl>, the FUSE documentation.