/[fuse.before_github]/perl-llin/Fuse.pm
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Revision 91 - (show annotations)
Tue May 23 15:38:12 2006 UTC (17 years, 10 months ago) by dpavlin
File size: 13337 byte(s)
bump version
1 package Fuse;
2
3 use 5.006;
4 use strict;
5 use warnings;
6 use Errno;
7 use Carp;
8 use Config;
9
10 require Exporter;
11 require DynaLoader;
12 use AutoLoader;
13 use Data::Dumper;
14 our @ISA = qw(Exporter DynaLoader);
15
16 # Items to export into callers namespace by default. Note: do not export
17 # names by default without a very good reason. Use EXPORT_OK instead.
18 # Do not simply export all your public functions/methods/constants.
19
20 # This allows declaration use Fuse ':all';
21 # If you do not need this, moving things directly into @EXPORT or @EXPORT_OK
22 # will save memory.
23 our %EXPORT_TAGS = (
24 'all' => [ qw(XATTR_CREATE XATTR_REPLACE) ],
25 'xattr' => [ qw(XATTR_CREATE XATTR_REPLACE) ]
26 );
27
28 our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
29
30 our @EXPORT = ();
31 our $VERSION = '0.07_4';
32
33 sub AUTOLOAD {
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.
37
38 my $constname;
39 our $AUTOLOAD;
40 ($constname = $AUTOLOAD) =~ s/.*:://;
41 croak "& not defined" if $constname eq 'constant';
42 my $val = constant($constname, @_ ? $_[0] : 0);
43 if ($! != 0) {
44 if ($!{EINVAL}) {
45 $AutoLoader::AUTOLOAD = $AUTOLOAD;
46 goto &AutoLoader::AUTOLOAD;
47 }
48 else {
49 croak "Your vendor has not defined Fuse macro $constname";
50 }
51 }
52 {
53 no strict 'refs';
54 # Fixed between 5.005_53 and 5.005_61
55 if ($] >= 5.00561) {
56 *$AUTOLOAD = sub () { $val };
57 }
58 else {
59 *$AUTOLOAD = sub { $val };
60 }
61 }
62 goto &$AUTOLOAD;
63 }
64
65 sub XATTR_CREATE {
66 # See <sys/xattr.h>.
67 return 1;
68 }
69
70 sub XATTR_REPLACE {
71 # See <sys/xattr.h>.
72 return 2;
73 }
74
75 bootstrap Fuse $VERSION;
76
77 sub main {
78 my @names = qw(getattr readlink getdir mknod mkdir unlink rmdir symlink
79 rename link chmod chown truncate utime open read write statfs
80 flush release fsync setxattr getxattr listxattr removexattr);
81 my @subs = map {undef} @names;
82 my @validOpts = qw(ro allow_other default_permissions fsname use_ino nonempty);
83 my $tmp = 0;
84 my %mapping = map { $_ => $tmp++ } @names;
85 my %optmap = map { $_ => 1 } @validOpts;
86 my @otherargs = qw(debug threaded mountpoint mountopts);
87 my %otherargs = (debug=>0, threaded=>0, mountpoint=>"", mountopts=>"");
88 while(my $name = shift) {
89 my ($subref) = shift;
90 if(exists($otherargs{$name})) {
91 $otherargs{$name} = $subref;
92 } else {
93 croak "There is no function $name" unless exists($mapping{$name});
94 croak "Usage: Fuse::main(getattr => \"main::my_getattr\", ...)" unless $subref;
95 $subs[$mapping{$name}] = $subref;
96 }
97 }
98 foreach my $opt ( map {m/^([^=]*)/; $1} split(/,/,$otherargs{mountopts}) ) {
99 next if exists($optmap{$opt});
100 croak "Fuse::main: invalid '$opt' argument in mountopts";
101 }
102 if($otherargs{threaded}) {
103 # make sure threads are both available, and loaded.
104 if($Config{useithreads}) {
105 if(exists($threads::{VERSION})) {
106 if(exists($threads::shared::{VERSION})) {
107 # threads will work.
108 } else {
109 carp("Thread support requires you to use threads::shared.\nThreads are disabled.\n");
110 $otherargs{threaded} = 0;
111 }
112 } else {
113 carp("Thread support requires you to use threads and threads::shared.\nThreads are disabled.\n");
114 $otherargs{threaded} = 0;
115 }
116 } else {
117 carp("Thread support was not compiled into this build of perl.\nThreads are disabled.\n");
118 $otherargs{threaded} = 0;
119 }
120 }
121 perl_fuse_main(@otherargs{@otherargs},@subs);
122 }
123
124 # Autoload methods go after =cut, and are processed by the autosplit program.
125
126 1;
127 __END__
128
129 =head1 NAME
130
131 Fuse - write filesystems in Perl using FUSE
132
133 =head1 SYNOPSIS
134
135 use Fuse;
136 my ($mountpoint) = "";
137 $mountpoint = shift(@ARGV) if @ARGV;
138 Fuse::main(mountpoint=>$mountpoint, getattr=>"main::my_getattr", getdir=>"main::my_getdir", ...);
139
140 =head1 DESCRIPTION
141
142 This lets you implement filesystems in perl, through the FUSE
143 (Filesystem in USErspace) kernel/lib interface.
144
145 FUSE expects you to implement callbacks for the various functions.
146
147 In the following definitions, "errno" can be 0 (for a success),
148 -EINVAL, -ENOENT, -EONFIRE, any integer less than 1 really.
149
150 You can import standard error constants by saying something like
151 "use POSIX qw(EDOTDOT ENOANO);".
152
153 Every constant you need (file types, open() flags, error values,
154 etc) can be imported either from POSIX or from Fcntl, often both.
155 See their respective documentations, for more information.
156
157 =head2 EXPORTED SYMBOLS
158
159 None by default.
160
161 You can request all exportable symbols by using the tag ":all".
162
163 You can request the extended attribute symbols by using the tag ":xattr".
164 This will export XATTR_CREATE and XATTR_REPLACE.
165
166 =head2 FUNCTIONS
167
168 =head3 Fuse::main
169
170 Takes arguments in the form of hash key=>value pairs. There are
171 many valid keys. Most of them correspond with names of callback
172 functions, as described in section 'FUNCTIONS YOUR FILESYSTEM MAY IMPLEMENT'.
173 A few special keys also exist:
174
175
176 debug => boolean
177
178 =over 1
179
180 This turns FUSE call tracing on and off. Default is 0 (which means off).
181
182 =back
183
184 mountpoint => string
185
186 =over 1
187
188 The point at which to mount this filesystem. There is no default, you must
189 specify this. An example would be '/mnt'.
190
191 =back
192
193 mountopts => string
194
195 =over 1
196
197 This is a comma seperated list of mount options to pass to the FUSE kernel
198 module.
199
200 At present, it allows the specification of the allow_other
201 argument when mounting the new FUSE filesystem. To use this, you will also
202 need 'user_allow_other' in /etc/fuse.conf as per the FUSE documention
203
204 mountopts => "allow_other" or
205 mountopts => ""
206
207 =back
208
209 threaded => boolean
210
211 =over 1
212
213 This turns FUSE multithreading on and off. The default is 0, meaning your FUSE
214 script will run in single-threaded mode. Note that single-threaded mode also
215 means that you will not have to worry about reentrancy, though you will have to
216 worry about recursive lookups. In single-threaded mode, FUSE holds a global
217 lock on your filesystem, and will wait for one callback to return before
218 calling another. This can lead to deadlocks, if your script makes any attempt
219 to access files or directories in the filesystem it is providing. (This
220 includes calling stat() on the mount-point, statfs() calls from the 'df'
221 command, and so on and so forth.) It is worth paying a little attention and
222 being careful about this.
223
224 Enabling multithreading will cause FUSE to make multiple simultaneous calls
225 into the various callback functions of your perl script. If you enable
226 threaded mode, you can enjoy all the parallel execution and interactive
227 response benefits of threads, and you get to enjoy all the benefits of race
228 conditions and locking bugs, too. Please also ensure any other perl modules
229 you're using are also thread-safe.
230
231 (If enabled, this option will cause a warning if your perl interpreter was not
232 built with USE_ITHREADS, or if you have failed to use threads or
233 threads::shared.)
234
235 =back
236
237 =head2 FUNCTIONS YOUR FILESYSTEM MAY IMPLEMENT
238
239 =head3 getattr
240
241 Arguments: filename.
242 Returns a list, very similar to the 'stat' function (see
243 perlfunc). On error, simply return a single numeric scalar
244 value (e.g. "return -ENOENT();").
245
246 FIXME: the "ino" field is currently ignored. I tried setting it to 0
247 in an example script, which consistently caused segfaults.
248
249 Fields (the following was stolen from perlfunc(1) with apologies):
250
251 ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
252 $atime,$mtime,$ctime,$blksize,$blocks)
253 = getattr($filename);
254
255 Here are the meaning of the fields:
256
257 0 dev device number of filesystem
258 1 ino inode number
259 2 mode file mode (type and permissions)
260 3 nlink number of (hard) links to the file
261 4 uid numeric user ID of file's owner
262 5 gid numeric group ID of file's owner
263 6 rdev the device identifier (special files only)
264 7 size total size of file, in bytes
265 8 atime last access time in seconds since the epoch
266 9 mtime last modify time in seconds since the epoch
267 10 ctime inode change time (NOT creation time!) in seconds
268 since the epoch
269 11 blksize preferred block size for file system I/O
270 12 blocks actual number of blocks allocated
271
272 (The epoch was at 00:00 January 1, 1970 GMT.)
273
274 =head3 readlink
275
276 Arguments: link pathname.
277 Returns a scalar: either a numeric constant, or a text string.
278
279 This is called when dereferencing symbolic links, to learn the target.
280
281 example rv: return "/proc/self/fd/stdin";
282
283 =head3 getdir
284
285 Arguments: Containing directory name.
286 Returns a list: 0 or more text strings (the filenames), followed by a numeric errno (usually 0).
287
288 This is used to obtain directory listings. Its opendir(), readdir(), filldir() and closedir() all in one call.
289
290 example rv: return ('.', 'a', 'b', 0);
291
292 =head3 mknod
293
294 Arguments: Filename, numeric modes, numeric device
295 Returns an errno (0 upon success, as usual).
296
297 This function is called for all non-directory, non-symlink nodes,
298 not just devices.
299
300 =head3 mkdir
301
302 Arguments: New directory pathname, numeric modes.
303 Returns an errno.
304
305 Called to create a directory.
306
307 =head3 unlink
308
309 Arguments: Filename.
310 Returns an errno.
311
312 Called to remove a file, device, or symlink.
313
314 =head3 rmdir
315
316 Arguments: Pathname.
317 Returns an errno.
318
319 Called to remove a directory.
320
321 =head3 symlink
322
323 Arguments: Existing filename, symlink name.
324 Returns an errno.
325
326 Called to create a symbolic link.
327
328 =head3 rename
329
330 Arguments: old filename, new filename.
331 Returns an errno.
332
333 Called to rename a file, and/or move a file from one directory to another.
334
335 =head3 link
336
337 Arguments: Existing filename, hardlink name.
338 Returns an errno.
339
340 Called to create hard links.
341
342 =head3 chmod
343
344 Arguments: Pathname, numeric modes.
345 Returns an errno.
346
347 Called to change permissions on a file/directory/device/symlink.
348
349 =head3 chown
350
351 Arguments: Pathname, numeric uid, numeric gid.
352 Returns an errno.
353
354 Called to change ownership of a file/directory/device/symlink.
355
356 =head3 truncate
357
358 Arguments: Pathname, numeric offset.
359 Returns an errno.
360
361 Called to truncate a file, at the given offset.
362
363 =head3 utime
364
365 Arguments: Pathname, numeric actime, numeric modtime.
366 Returns an errno.
367
368 Called to change access/modification times for a file/directory/device/symlink.
369
370 =head3 open
371
372 Arguments: Pathname, numeric flags (which is an OR-ing of stuff like O_RDONLY
373 and O_SYNC, constants you can import from POSIX).
374 Returns an errno.
375
376 No creation, or trunctation flags (O_CREAT, O_EXCL, O_TRUNC) will be passed to open().
377 Your open() method needs only check if the operation is permitted for the given flags, and return 0 for success.
378
379 =head3 read
380
381 Arguments: Pathname, numeric requestedsize, numeric offset.
382 Returns a numeric errno, or a string scalar with up to $requestedsize bytes of data.
383
384 Called in an attempt to fetch a portion of the file.
385
386 =head3 write
387
388 Arguments: Pathname, scalar buffer, numeric offset. You can use length($buffer) to
389 find the buffersize.
390 Returns an errno.
391
392 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.
393
394 =head3 statfs
395
396 Arguments: none
397 Returns any of the following:
398
399 -ENOANO()
400
401 or
402
403 $namelen, $files, $files_free, $blocks, $blocks_avail, $blocksize
404
405 or
406
407 -ENOANO(), $namelen, $files, $files_free, $blocks, $blocks_avail, $blocksize
408
409 =head3 flush
410
411 Arguments: Pathname
412 Returns an errno or 0 on success.
413
414 Called to synchronise any cached data. This is called before the file
415 is closed. It may be called multiple times before a file is closed.
416
417 =head3 release
418
419 Arguments: Pathname, numeric flags passed to open
420 Returns an errno or 0 on success.
421
422 Called to indicate that there are no more references to the file. Called once
423 for every file with the same pathname and flags as were passed to open.
424
425 =head3 fsync
426
427 Arguments: Pathname, numeric flags
428 Returns an errno or 0 on success.
429
430 Called to synchronise the file's contents. If flags is non-zero,
431 only synchronise the user data. Otherwise synchronise the user and meta data.
432
433 =head3 setxattr
434
435 Arguments: Pathname, extended attribute's name, extended attribute's value, numeric flags (which is an OR-ing of XATTR_CREATE and XATTR_REPLACE
436 Returns an errno or 0 on success.
437
438 Called to set the value of the named extended attribute.
439
440 If you wish to reject setting of a particular form of extended attribute name
441 (e.g.: regexps matching user\..* or security\..*), then return - EOPNOTSUPP.
442
443 If flags is set to XATTR_CREATE and the extended attribute already exists,
444 this should fail with - EEXIST. If flags is set to XATTR_REPLACE
445 and the extended attribute doesn't exist, this should fail with - ENOATTR.
446
447 XATTR_CREATE and XATTR_REPLACE are provided by this module, but not exported
448 by default. To import them:
449
450 use Fuse ':xattr';
451
452 or:
453
454 use Fuse ':all';
455
456 =head3 getxattr
457
458 Arguments: Pathname, extended attribute's name
459 Returns an errno, 0 if there was no value, or the extended attribute's value.
460
461 Called to get the value of the named extended attribute.
462
463 =head3 listxattr
464
465 Arguments: Pathname
466 Returns a list: 0 or more text strings (the extended attribute names), followed by a numeric errno (usually 0).
467
468 =head3 removexattr
469
470 Arguments: Pathname, extended attribute's name
471 Returns an errno or 0 on success.
472
473 =head1 AUTHOR
474
475 Mark Glines, E<lt>mark@glines.orgE<gt>
476
477 =head1 SEE ALSO
478
479 L<perl>, the FUSE documentation.
480
481 =cut

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