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1[[tags: egg]]
2
3== 9p
4
5[[toc:]]
6
7=== Description
8
9A pure Scheme implementation of the [[http://9p.cat-v.org|9p networked filesystem protocol]].
10
11=== Author
12
13[[Peter Bex]]
14
15=== Requirements
16
17Requires the [[iset]] egg.
18
19=== Download
20
21[[http://www.call-with-current-continuation.org/eggs/9p.egg|9p.egg]]
22
23=== Documentation
24
259p is an implementation of the networked file system protocol known as 9P, specifically version 9P2000 which is also known as "Styx".
26This protocol is used by the [[http://cm.bell-labs.com/plan9|Plan 9 operating system]] and the [[http://wmii.suckless.org|wmii window manager]], among others.
27
28This implementation includes a low-level implementation of the protocol that is suitable both for writing clients and servers and a high-level client implementation.  There currently are no concrete plans for a high-level server implementation, but contributions are of course very welcome :)
29
30The low-level implementation is documented below under [[#9p-lolevel|9p-lolevel]] and the high-level client implementation under [[#9p-client|9p-client]].  The high-level client is discussed first, because this is the one you will most likely need.
31
32=== 9p-client
33
34The basic library was modeled after Chicken's [[Unit posix]] and a few choice other procedures that interact with the filesystem.  Most procedures from Unit posix are available under the same name.  When you include the module together with posix, don't forget to prefix either these procedures or those of posix! Where possible, the procedure's signature has been unmodified, except for an additional leading argument that specifies the connection with the 9p server.
35
36==== Usage
37
38  (use 9p-client)
39  (use utf8)
40
41It is highly recommended you require utf8 in your applications, as 9p is a utf8-aware protocol.  It is not a dependency of this egg because in some situations you might decide it's safe to leave it out, for performance or memory footprint reasons.
42
43==== Connection management
44
45===== client-connect
46
47Before doing anything else, you must establish a connection with the server.  This is done with the {{client-connect}} procedure.
48
49<procedure>(client-connect inport outport [user] [mountpoint])</procedure>
50
51The {{inport}} and {{outport}} arguments are the ports you use to communicate to the server.  The {{user}} argument is the name of the user that creates the files.  It defaults to the empty string.  There is no support for authentication, so the user name is simply used for newly created files on servers that support usernames (wmii doesn't, for example).  The {{mountpoint}} also defaults to the empty string, which selects the "default mount point" on the server.  If the server has multiple mountpoints it exports, you can select with this argument.
52
53The procedure returns a connection object you must keep and use in all subsequent 9p procedure calls.
54
55You can use the following procedures to obtain some more information on the connection:
56
57<procedure>(connection-outport connection)</procedure>
58<procedure>(connection-inport connection)</procedure>
59
60Get back the underlying ports you passed to {{client-connect}}.
61
62<procedure>(connection-message-size connection)</procedure>
63
64The maximum size of a low-level message as negotiated in the connection handshake.  Not very useful unless you would like to write some custom messages.  This ''includes'' the size of the tag (2 bytes) and the message type (1 byte).
65
66
67===== client-disconnect
68
69<procedure>(client-disconnect connection)</procedure>
70
71Disconnect from the server described by {{connection}}.  This clunks any fids that are still open (in Unix terms: closes any open file descriptors).
72
73===== connection?
74
75<procedure>(connection? object)</procedure>
76
77You can verify an object is a connection to a 9p server with this predicate.
78
79==== Files as ports
80
81===== with-output-to-file
82
83<procedure>(with-output-to-file connection file thunk)</procedure>
84
85Open {{file}} on the 9p connection {{connection}} and call {{thunk}} with the {{current-output-port}} set to a port that writes to the file. When the thunk finishes, the port is closed.
86
87===== call-with-output-file
88
89<procedure>(call-with-output-file connection file procedure)</procedure>
90
91Open {{file}} on the 9p connection {{connection}} and call {{procedure}} with an output-port that corresponds to the file. When the procedure finishes, the port is closed.  Procedure should accept one argument, the output-port.
92
93===== open-output-file
94
95<procedure>(open-output-file connection file [mode])</procedure>
96
97Create an output port that will write to the given {{file}} on the 9p connection {{connection}}.  If the file exists, it is truncated.  If it does not exist yet it will be created.  If the optional {{mode}} is given, it determines with what permissions the file will be created, if it is a new file.  See [[#Permission bits|below]] for the list of file permissions.
98
99Don't forget to close the output port (with {{close-output-port}}) when you finish writing to it!
100
101===== with-input-from-file
102
103<procedure>(with-input-from-file connection file thunk)</procedure>
104
105Open {{file}} on the 9p connection {{connection}} and call {{thunk}} with the {{current-input-port}} set to a port that reads from the file. When the thunk finishes, the port is closed.
106
107===== call-with-input-file
108
109<procedure>(call-with-input-file connection file procedure)</procedure>
110
111Open {{file}} on the 9p connection {{connection}} and call {{procedure}} with an input-port that corresponds to the file. When the procedure finishes, the port is closed.  Procedure should accept one argument, the input-port.
112
113===== open-input-file
114
115<procedure>(open-input-file connection file)</procedure>
116
117Create an input port that will read from the given {{file}} on the 9p connection {{connection}}.
118
119Don't forget to close the input port (with {{close-input-port}} when you finish reading from it!
120
121==== Directories
122
123===== directory?
124
125<procedure>(directory? connection path)</procedure>
126
127Returns {{#t}} if the given {{path}} on the {{connection}} is a directory, {{#f}} if not.
128
129===== create-directory
130
131<procedure>(create-directory connection path permissions)</procedure>
132
133Create a directory on the {{connection}} with the given {{path}}.  It will have the specified {{permissions}}, see [[#Permission bits|below]] for the available permissions.
134
135===== directory
136
137<procedure>(directory connection directory [show-dotfiles?])</procedure>
138
139Returns a list with the contents of the {{directory}} on the {{connection}}. Files beginning with {{.}} are included only if {{show-dotfiles?}} is given and not #f.
140
141==== Files
142
143===== regular-file?
144
145<procedure>(regular-file? connection path)</procedure>
146
147Returns {{#t}} if the given {{path}} on the {{connection}} is a regular file, {{#f}} if not.  9p does not support symlinks or FIFOs, so this is the same as {{(not (directory? connection path))}}, even if the underlying FS is a Unix FS (the 9p egg currently does not (and probably will never) support [[http://v9fs.sourceforge.net/rfc/9p2000.u.html|9P2000.u]]).
148
149===== delete-file
150
151<procedure>(delete-file connection path)</procedure>
152
153Delete the file indicated by {{path}} on the {{connection}}. If the file does not exist or you do not have permission to delete it, an error is signaled.
154
155===== file-stat
156
157<procedure>(file-stat connection path)</procedure>
158
159Returns a 9-element vector which contains information about the file indicated by {{path}} on the {{connection}}.  It has the following contents:
160
161* The QID of the file (The qid can be queried with the [[#QIDs|QID procedures]] from 9p-lolevel.
162* The permission mode (See [[#Permission bits|the permission bits section]] for a description)
163* The access time of the file.  This is an integer which indicates the server-time when the file was last accessed.  There is no way to determine what the server's time is using the 9p protocol, so you can only use this for comparing timestamps of files on the same server unless you use an additional protocol to find out about the server's current time and zone.
164* The modification time of the file.  This is an integer which indicates the server-time when the file was last modified.
165* The file's size in bytes.
166* The filename of the file.
167* The user who owns the file (a string, not a uid, because Plan9 has only user and group names, not numerical ids).
168* The group who owns the file (a string)
169* The user who last modified the file (a string)
170
171===== file-permissions
172
173<procedure>(file-permissions connection path)</procedure>
174
175Returns the permissions of the file indicated by {{path}} on the {{connection}}. See [[#Permission bits|the permission bits section]] for a description of the possible bits.
176
177===== file-access-time
178
179<procedure>(file-access-time connection path)</procedure>
180
181Returns the access time of the file indicated by {{path}} on the {{connection}}.  See the notes under [[#file-stat]].
182
183
184===== file-modification-time
185
186<procedure>(file-modification-time connection path)</procedure>
187
188Returns the modification time of the file indicated by {{path}} on the {{connection}}.  See the notes under [[#file-stat]].
189
190===== file-size
191
192<procedure>(file-size connection path)</procedure>
193
194Returns the size, in bytes, of the file indicated by {{path}} on the {{connection}}.
195
196===== file-owner
197
198<procedure>(file-owner connection path)</procedure>
199
200Returns the name of the owner, as a string, of the file indicated by {{path}} on the {{connection}}.
201
202===== file-group
203
204<procedure>(file-group connection path)</procedure>
205
206Returns the name of the owning group, as a string, of the file indicated by {{path}} on the {{connection}}.
207
208===== file-last-modified-by
209
210<procedure>(file-last-modified-by connection path)</procedure>
211
212Returns the name of the user, as a string, who last changed the file indicated by {{path}} on the {{connection}}.
213
214==== File handles and low-level calls
215
216These calls are not on the protocol level, as the [[#9p-lolevel]] library procedures, but they are more low-level than the other procedures in the [[#9p-client]] library because they allow you to work on the file handle level.
217
218===== file-open
219
220<procedure>(file-open connection path mode)</procedure>
221
222Opens the file indicated by {{path}} on the {{connection}} with the given {{mode}} and returns an opaque handle object which you can use for the other procedures described in this section.  For bit flags that the {{mode}} can take, see [[#Open flags|the open flags section]].
223
224===== file-create
225
226<procedure>(file-create connection path permissions mode)</procedure>
227
228Creates and opens the file indicated by {{path}} on the {{connection}} with the given {{permission}} and {{mode}} and returns an opaque handle object which you can use for the other procedures described in this section.  For bit flags that the {{mode}} can take, see [[#Open flags|the open flags section]].  For bit flags that the {{permission}} can take, see [[#Permission bits|the permission bits section]].
229
230
231===== file-close
232
233<procedure>(file-close handle)</procedure>
234
235Close the file indicated by {{handle}}.  It is not an error to close a file more than once.
236
237===== file-read
238
239<procedure>(file-read handle size)</procedure>
240
241Read {{size}} bytes from the file with the given {{handle}}.  This procedure returns a list with two values: the buffer containing the data and the number of bytes read.
242
243===== file-write
244
245<procedure>(file-write handle buffer [size])</procedure>
246
247Writes the contents of the string or bytevector {{buffer}} into the file with the given {{handle}}. If the optional argument {{size}} is given, then only the specified number of bytes are written.
248
249===== set-file-position!
250
251<procedure>(set-file-position! handle position [whence])</procedure>
252
253Sets the current read/write position of {{handle}} to {{position}}, which should be an exact integer. {{whence}} specifies how the position is to interpreted and should be one of the values {{seek/set}}, {{seek/cur}} and {{seek/end}}. It defaults to {{seek/set}}.
254
255===== file-position
256
257<procedure>(file-position handle)</procedure>
258
259Returns the current read/write position of the {{handle}}.
260
261===== handle-stat
262
263<procedure>(handle-stat handle)</procedure>
264
265Just like [[#file-stat]], except it works on a handle instead of on a connection with a filename.
266
267===== Low-level handle access
268
269If you want to get really dirty and low-level you can modify file handles with the following procedures.  This is not recommended, but sometimes required if you want to do some custom things just above the protocol level and extend the client library instead of writing your own.
270
271====== path-walk
272
273<procedure>(path-walk connection path [starting-point])</procedure>
274
275Obtain a handle for the file identified by {{path}} on the {{connection}} ''without opening it''.  You must not forget to clunk the handle's FID (or just call {{file-close}} on the handle).  {{starting-point}} is an optional handle to a directory from which to start walking.  It defaults to the root directory (/).
276
277====== with-handle-to
278
279If all you need is a temporary handle/FID for a message to the server, you can use this utility procedure:
280
281<procedure>(with-handle-to connection path procedure)</procedure>
282
283This will call {{procedure}} with one argument: a temporary handle which represents the {{path}} on the {{connection}}.  After the procedure returns, the handle will be deallocated and the FID will no longer be valid.  This returns whatever {{procedure}} returned.  If a condition is signaled, the handle will be deallocated properly and the FID clunked.
284
285====== alloc-handle
286
287The 9p-client library keeps track of FIDs for you so you do not have to remember numbers.  If you wish to send low-level messages yourself you should allocate and release FIDs through the library so your FIDs can't clash with the FIDs the library uses:
288
289<procedure>(alloc-handle connection)</procedure>
290
291Allocate a handle on the connection.  This returns a handle object which you can query with the following procedures:
292
293<procedure>(handle-connection handle)</procedure>
294<procedure>(handle-fid handle)</procedure>
295<procedure>(handle-position handle)</procedure>
296<procedure>(handle-iounit handle)</procedure>
297
298The fid is allocated from an internal pool of free fids.  The position is initialized to 0, and used as an offset for read/write procedures (the server does not keep track of this for us in the 9p protocol).
299
300The iounit defaults to {{#f}} and you are expected to set it manually (normally, [[file-open]] and [[file-create]] do this for you). is returned as part of the Ropen and Rcreate replies and is the maximum size of a data transfer (either read or write).  If the server returns 0, the iounit should default to the size returned by {{connection-message-size}} minus 24.
301
302
303====== release-handle
304
305Once you are done with a handle, you must either pass the handle to [[file-close]] (or just disconnect with [[client-disconnect]]) or call {{release-handle}}:
306
307<procedure>(release-handle handle)</procedure>
308
309'''important''': be sure to clunk the handle's fid first.  {{release-handle}} does ''not'' clunk the fid.
310
311
312===== Sending messages
313
314A code using 9p-client normally never needs to send raw messages, but in case it does, there is one convenience procedure that does just a bit more than the raw [[#9p-lolevel]] procedures do:
315
316<procedure>(request connection type . args)</procedure>
317
318This creates a new {{message}} object (see below) with a tag and the given {{type}}.  {{args}} are the message-contents.  It then sends this request to the server and awaits a response.  The response should match the request (a {{Twhatever}} should result in a {{Rwhatever}} message), or a condition of type {{(exn 9p-response-error)}} is signaled.  If the server returns an error (via {{Rerror}}), a condition of type {{(exn 9p-server-error)}} is signaled.  The response object (a message object) is returned.
319
320=== 9p-lolevel
321
322This library allows you to build your own client or server abstraction library.  This documentation will not make a lot of sense if you haven't read the [[http://9p.cat-v.org/documentation|9p protocol documentation]].
323
324==== Usage
325
326  (use 9p-lolevel)
327  (use utf8)
328
329Again, utf8 is highly recommended but not strictly required.
330
331==== Messages
332
333Messages are main concept in the 9p protocol.  They can be created as follows:
334
335<procedure>(make-message type tag contents)</procedure>
336
337The type is a symbol, one of
338  Tversion Rversion
339  Tauth Rauth
340  Tattach Rattach
341  Rerror
342  Tflush Rflush
343  Twalk Rwalk
344  Topen Ropen
345  Tcreate Rcreate
346  Tread Rread
347  Twrite Rwrite
348  Tclunk Rclunk
349  Tremove Rremove
350  Tstat Rstat
351  Twstat Rwstat
352
353As you can see, all messages (except Rerror) come in pairs: there is a transmit message (that starts with a T) and a response message (that starts with an R).  The client sends transmit messages and the server sends response message in return.  It must either send the matching response message or Rerror.  It is not allowed to return a different message, nor is it allowed for the client to send a response message or the server to send a transmit message.
354
355The tag is a unique identifier that allows the client to keep track of what it sent and what responses belong to what transmissions.  The client sends a message with a given tag and the server will respond with the matching response message bearing the same tag.  This allows a client to send messages ''asynchronously'', as long as they all have a different tag.  Then the responses can come in any order and be handled at any time and still be understood if the client keeps a list of sent tags and what transmissions belonged to them.  The [[9p-client]] library always sends messages synchronously, waiting for replies before sending new transmissions.  This allows it to use a constant tag all the time.
356
357The contents are a list whose contents differ per message type.  For instance, a Tversion message's contents consist of an {{msize}} (a maximum message size) and a {{string}} which indicates the protocol version.  Currently the 9p-lolevel implicitly assumes the 9P2000 version of the protocol because of the way it is constructed.  If it turns out to be useful to support different versions, the egg's API will most likely change in order to allow for more flexibility.
358
359You can of course query and modify the message objects with the following procedures:
360<procedure>(message? object)</procedure>
361<procedure>(message-type message)</procedure>
362<procedure>(message-type-set! message new-type)</procedure>
363<procedure>(message-tag message)</procedure>
364<procedure>(message-tag-set! message new-tag)</procedure>
365<procedure>(message-contents message)</procedure>
366<procedure>(message-contents-set! message new-contents)</procedure>
367
368===== send-message
369
370<procedure>(send-message outport message)</procedure>
371
372Sends the {{message}} on the output-port {{outport}}.
373
374===== receive-message
375
376<procedure>(receive-message inport)</procedure>
377
378Waits for a message on input-port {{inport}} and returns a 9p message-object.
379 
380==== QIDs
381
382A QID is an unique identifier for a file on the server; two QIDs are the same iff they point to the same file.  A QID has three fields which can be queried with the following procedures:
383
384<procedure>(qid-type qid)</procedure>
385<procedure>(qid-version qid)</procedure>
386<procedure>(qid-path qid)</procedure>
387
388You can create a QID using the {{make-qid}} procedure:
389
390<procedure>(make-qid type version path)</procedure>
391
392Finally, you can check if an object is a QID object with the {{qid?}} predicate:
393
394<procedure>(qid? object)</procedure>
395
396The fields of the QID will be described next.
397
398First, the type of a QID is a bitwise field which consists of several of the following constants ORed together:
399
400<constant>qtfile</constant>
401 
402{{qtfile}} indicates that the file is, in fact, a file.  Because everything in Plan9 is a file, this is always true, even for directories.  It does ''not'' mean that the file is a regular file.
403 
404<constant>qtdir</constant>
405
406{{qtdir}} indicates that the file is a directory.
407
408<constant>qtappend</constant>
409
410{{qtappend}} indicates that the file is an append-only file.
411
412<constant>qtexcl</constant>
413
414{{qtexcl}} indicates that the file is marked for exclusive-use.  This means that only one client can have this file open at any time.
415
416<constant>qtauth</constant>
417
418{{qtauth}} indicates that the file is an authentication file established by AUTH messages.
419 
420<constant>qttmp</constant>
421
422{{qttmp}} indicates that the file is a "temporary file".  In practice this means that the file is not included in nightly backups.
423
424The version of a QID is a version number for the file which is incremented every time the file is modified.
425
426The path of a QID is an integer that is unique among all files in the file hierarchy (ie, this uniquely identifies the file in the FS).
427
428==== Permission bits
429
430The permissions below can be ORed together bitwise to produce the desired permission mode.  When creating new files, the execute bit is ignored by the server unless you're creating a directory, so it is safe to always include it.
431
432'''Note:''' The 9p protocol documentation is not very consistent in naming these.  Sometimes it refers to permissions as ''mode'', and sometimes as ''perm'' or ''permission''.  On other occasions, it refers to the [[#Open flags|open flags]] as ''mode''.  Read carefully and check the context!
433
434<constant>perm/irusr</constant>
435<constant>perm/iwusr</constant>
436<constant>perm/ixusr</constant>
437
438These constants determine the permissions for the user who owns the file: read, write and execute, respectively.
439
440<constant>perm/irgrp</constant>
441<constant>perm/iwgrp</constant>
442<constant>perm/ixgrp</constant>
443
444These constants determine the permissions for the group that owns the file: read, write and execute, respectively.
445
446<constant>perm/iroth</constant>
447<constant>perm/iwoth</constant>
448<constant>perm/ixoth</constant>
449
450These constants determine the permissions for others: read, write and execute, respectively.
451
452There are some additional "permissions" that can be used on {{Tcreate}} messages, which are not really permissions but rather modes that change the way the file behaves (hence the inconsistence of the docs).  These are like the 'special' bits in Unix like sticky/setuid etc.  These are the following:
453
454<constant>dmdir</constant>
455
456This is used to create directories instead of files with {{Tcreate}}.
457
458<constant>dmappend</constant>
459
460The file can only be appended to.
461
462<constant>dmexcl</constant>
463
464The file is 'exclusive', it can only be opened by one client at a time.
465
466<constant>dmauth</constant>
467
468The file is an authentication file, as established by AUTH messages.
469
470<constant>dmtmp</constant>
471
472The file is to be considered "temporary".  In practice this means that it is not included in nightly backups.
473
474==== Open flags
475
476These flags are useful when opening a new file (for use in the {{Topen}}/{{Tcreate}} messages).  These can be ORed together bitwise to produce the desired mode.
477
478<constant>open/rdonly</constant>
479
480The file is to be opened only for reading.
481
482<constant>open/wronly</constant>
483
484The file is to be opened only for writing.
485
486<constant>open/rdwr</constant>
487
488The file is to be opened both for reading and writing.
489
490<constant>open/trunc</constant>
491
492The file is to be truncated on opening.
493
494<constant>open/rclose</constant>
495
496The file is to be removed upon closing (ie, when the FID is clunked).
497
498==== Utility procedures
499
500===== data->directory-listing
501
502<procedure>(data->directory-listing data show-dotfiles?)</procedure>
503
504Because the 9p protocol requires you to use the {{Tread}}/{{Rread}} messages to read both from files and directories, the {{Rread}} response can be considered to be a polymorphic type.  In case of files, the data is simply a bytestream, but in case of directories, the data will be structured.  This means the data needs to be decoded.
505
506This procedures decodes the {{data}} obtained from the {{Rread}} message and returns a list of filenames which are the directory listing for the directory that was read.  If {{show-dotfiles?}} is {{#f}} files starting with a dot are excluded from the list.
507
508Note: The converse procedure, {{directory-listing->data}}, is currently not implemented.
509
510=== Example
511
512==== 9p-client
513
514Here's a simple example that talks to a wmii server.  Note that if
515you're really looking for a Scheme library to script your wmiirc
516files, you probably want the [[wmiirc]] egg instead of using the raw
5179p protocol directly.
518
519<examples><example>
520<init>
521(require-library 9p-client unix-sockets)
522
523(import (prefix 9p-client 9p:))
524</init>
525<expr>
526(receive (in out)
527    (unix-connect (sprintf "/tmp/ns.~A.:0/wmii" (getenv "USER")))
528  (let ((con (9p:client-connect in out)))
529    (printf "Current tabs on left bar: ~A\n" (9p:directory con "/lbar"))
530    (printf "Label on first tab on left bar: ~A\n"
531            (9p:with-input-from-file con `("lbar" ,(car (9p:directory con "/lbar"))) read-string ))
532    ;; Write something to the right bar
533    (9p:with-output-to-file con "/rbar/status" (lambda () (printf "Yo, what's up?")))
534    (9p:client-disconnect con)))
535</expr>
536</example></examples>
537
538This prints something like
539
540  Current tabs on left bar: (3 2 1)
541  Label on first tab on left bar: #888888 #222222 #333333 3
542
543And it shows the string "Yo, what's up?" on your status bar.
544
545=== Changelog
546
547* 0.7 Fix import handling for unit "files"
548* 0.6 Port to hygienic Chicken, fix handle auto-closing bug
549* 0.5 Add mutex handling to ensure thread-safety
550* 0.4 When reading files, EOF gets reported only when the file really is at an end (fixes reading from FIFO-like files)
551* 0.3 Don't allow output 9p ports to return values when all other values are (void), allow multiple return values in with-output/with-input thunks
552* 0.2 Fix 9p:open-output-file bug, make path-walk accept handles
553* 0.1 Initial release
554
555
556=== License
557
558  Copyright (c) 2008, Peter Bex
559  All rights reserved.
560 
561  Redistribution and use in source and binary forms, with or without
562  modification, are permitted provided that the following conditions are
563  met:
564 
565  Redistributions of source code must retain the above copyright
566  notice, this list of conditions and the following disclaimer.
567 
568  Redistributions in binary form must reproduce the above copyright
569  notice, this list of conditions and the following disclaimer in the
570  documentation and/or other materials provided with the distribution.
571 
572  Neither the name of the author nor the names of its contributors may
573  be used to endorse or promote products derived from this software
574  without specific prior written permission.
575 
576  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
577  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
578  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
579  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
580  COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
581  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
582  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
583  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
584  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
585  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
586  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
587  OF THE POSSIBILITY OF SUCH DAMAGE.
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