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CS3: implement locks as xattrs #129

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merged 2 commits into from
Oct 19, 2023
Merged

CS3: implement locks as xattrs #129

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afe1b68
cs3: implement locks as xattrs when locks are not available
glpatcern Sep 15, 2023
28045aa
Enabled lockasxattr in the demo CS3 config
glpatcern Oct 19, 2023
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1 change: 1 addition & 0 deletions docker/etc/wopiserver.cs3.conf
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Original file line number Diff line number Diff line change
Expand Up @@ -29,3 +29,4 @@ wopikey = your.key.pem
revagateway = your.revad.org:19000
authtokenvalidity = 3600
sslverify = True
lockasattr = True
78 changes: 75 additions & 3 deletions src/core/cs3iface.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,9 @@

import core.commoniface as common

# key used if the `lockasattr` option is true, in order to store the lock payload without ensuring any lock semantic
LOCK_ATTR_KEY = 'wopi.advlock'

# module-wide state
ctx = {} # "map" to store some module context: cf. init()
log = None
Expand All @@ -33,8 +36,9 @@ def init(inconfig, inlog):
log = inlog
ctx['chunksize'] = inconfig.getint('io', 'chunksize')
ctx['ssl_verify'] = inconfig.getboolean('cs3', 'sslverify', fallback=True)
ctx['authtokenvalidity'] = inconfig.getint('cs3', 'authtokenvalidity')
ctx['lockexpiration'] = inconfig.getint('general', 'wopilockexpiration')
ctx['lockasattr'] = inconfig.getboolean('cs3', 'lockasattr', fallback=False)
ctx['locknotimpl'] = False
ctx['revagateway'] = inconfig.get('cs3', 'revagateway')
ctx['xattrcache'] = {} # this is a map cs3ref -> arbitrary_metadata as returned by Stat()
# prepare the gRPC channel and validate that the revagateway gRPC server is ready
Expand Down Expand Up @@ -234,6 +238,18 @@ def rmxattr(endpoint, filepath, userid, key, lockmd):

def setlock(endpoint, filepath, userid, appname, value):
'''Set a lock to filepath with the given value metadata and appname as holder'''
if ctx['lockasattr'] and ctx['locknotimpl']:
log.debug(f'msg="Using xattrs to execute setlock" filepath="{filepath}" value="{value}"')
try:
currvalue = getxattr(endpoint, filepath, userid, LOCK_ATTR_KEY)
log.info('msg="Invoked setlock on an already locked entity" filepath="%s" appname="%s" previouslock="%s"' %
(filepath, appname, currvalue))
raise IOError(common.EXCL_ERROR)
except KeyError:
expiration = int(time.time() + ctx['lockexpiration'])
setxattr(endpoint, filepath, userid, LOCK_ATTR_KEY, f'{appname}!{value}!{expiration}', None)
return

reference = _getcs3reference(endpoint, filepath)
lock = cs3spr.Lock(type=cs3spr.LOCK_TYPE_WRITE, app_name=appname, lock_id=value,
expiration={'seconds': int(time.time() + ctx['lockexpiration'])})
Expand All @@ -243,6 +259,10 @@ def setlock(endpoint, filepath, userid, appname, value):
log.info('msg="Invoked setlock on an already locked entity" filepath="%s" appname="%s" trace="%s" reason="%s"' %
(filepath, appname, res.status.trace, res.status.message.replace('"', "'")))
raise IOError(common.EXCL_ERROR)
if res.status.code == cs3code.CODE_UNIMPLEMENTED and ctx['lockasattr']:
ctx['locknotimpl'] = True
setlock(endpoint, filepath, userid, appname, value)
return
if res.status.code != cs3code.CODE_OK:
log.error('msg="Failed to setlock" filepath="%s" appname="%s" value="%s" trace="%s" code="%s" reason="%s"' %
(filepath, appname, value, res.status.trace, res.status.code, res.status.message.replace('"', "'")))
Expand All @@ -252,12 +272,29 @@ def setlock(endpoint, filepath, userid, appname, value):

def getlock(endpoint, filepath, userid):
'''Get the lock metadata for the given filepath'''
if ctx['lockasattr'] and ctx['locknotimpl']:
log.debug(f'msg="Using xattrs to execute getlock" filepath="{filepath}"')
try:
currvalue = getxattr(endpoint, filepath, userid, LOCK_ATTR_KEY)
return {
'lock_id': currvalue.split('!')[1],
'type': 2, # LOCK_TYPE_WRITE, though this is advisory!
'app_name': currvalue.split('!')[0],
'user': {},
'expiration': int(currvalue.split('!')[2])
}
except KeyError:
return None

reference = _getcs3reference(endpoint, filepath)
req = cs3sp.GetLockRequest(ref=reference)
res = ctx['cs3gw'].GetLock(request=req, metadata=[('x-access-token', userid)])
if res.status.code == cs3code.CODE_NOT_FOUND:
log.debug(f'msg="Invoked getlock on unlocked or missing file" filepath="{filepath}"')
return None
if res.status.code == cs3code.CODE_UNIMPLEMENTED and ctx['lockasattr']:
ctx['locknotimpl'] = True
return getlock(endpoint, filepath, userid)
if res.status.code != cs3code.CODE_OK:
log.error('msg="Failed to getlock" filepath="%s" trace="%s" code="%s" reason="%s"' %
(filepath, res.status.trace, res.status.code, res.status.message.replace('"', "'")))
Expand All @@ -281,6 +318,20 @@ def getlock(endpoint, filepath, userid):

def refreshlock(endpoint, filepath, userid, appname, value, oldvalue=None):
'''Refresh the lock metadata for the given filepath'''
if ctx['lockasattr'] and ctx['locknotimpl']:
log.debug(f'msg="Using xattrs to execute setlock" filepath="{filepath}" value="{value}"')
try:
currvalue = getxattr(endpoint, filepath, userid, LOCK_ATTR_KEY)
if currvalue.split('!')[0] == appname and (not oldvalue or currvalue.split('!')[1] == oldvalue):
raise KeyError
log.info('msg="Failed precondition on refreshlock" filepath="%s" appname="%s" previouslock="%s"' %
(filepath, appname, currvalue))
raise IOError(common.EXCL_ERROR)
except KeyError:
expiration = int(time.time() + ctx['lockexpiration'])
setxattr(endpoint, filepath, userid, LOCK_ATTR_KEY, f'{appname}!{value}!{expiration}', None)
return

reference = _getcs3reference(endpoint, filepath)
lock = cs3spr.Lock(type=cs3spr.LOCK_TYPE_WRITE, app_name=appname, lock_id=value,
expiration={'seconds': int(time.time() + ctx['lockexpiration'])})
Expand All @@ -290,6 +341,10 @@ def refreshlock(endpoint, filepath, userid, appname, value, oldvalue=None):
log.info('msg="Failed precondition on refreshlock" filepath="%s" appname="%s" trace="%s" reason="%s"' %
(filepath, appname, res.status.trace, res.status.message.replace('"', "'")))
raise IOError(common.EXCL_ERROR)
if res.status.code == cs3code.CODE_UNIMPLEMENTED and ctx['lockasattr']:
ctx['locknotimpl'] = True
refreshlock(endpoint, filepath, userid, appname, value, oldvalue)
return
if res.status.code != cs3code.CODE_OK:
log.warning('msg="Failed to refreshlock" filepath="%s" appname="%s" value="%s" trace="%s" code="%s" reason="%s"' %
(filepath, appname, value, res.status.trace, res.status.code, res.status.message.replace('"', "'")))
Expand All @@ -299,6 +354,19 @@ def refreshlock(endpoint, filepath, userid, appname, value, oldvalue=None):

def unlock(endpoint, filepath, userid, appname, value):
'''Remove the lock for the given filepath'''
if ctx['lockasattr'] and ctx['locknotimpl']:
log.debug(f'msg="Using xattrs to execute unlock" filepath="{filepath}" value="{value}"')
try:
currvalue = getxattr(endpoint, filepath, userid, LOCK_ATTR_KEY)
if currvalue.split('!')[0] == appname and currvalue.split('!')[1] == value:
raise KeyError
log.info('msg="Failed precondition on unlock" filepath="%s" appname="%s" previouslock="%s"' %
(filepath, appname, currvalue))
raise IOError(common.EXCL_ERROR)
except KeyError:
rmxattr(endpoint, filepath, userid, LOCK_ATTR_KEY, None)
return

reference = _getcs3reference(endpoint, filepath)
lock = cs3spr.Lock(type=cs3spr.LOCK_TYPE_WRITE, app_name=appname, lock_id=value)
req = cs3sp.UnlockRequest(ref=reference, lock=lock)
Expand All @@ -307,6 +375,10 @@ def unlock(endpoint, filepath, userid, appname, value):
log.info('msg="Failed precondition on unlock" filepath="%s" appname="%s" trace="%s" reason="%s"' %
(filepath, appname, res.status.trace, res.status.message.replace('"', "'")))
raise IOError(common.EXCL_ERROR)
if res.status.code == cs3code.CODE_UNIMPLEMENTED and ctx['lockasattr']:
ctx['locknotimpl'] = True
unlock(endpoint, filepath, userid, appname, value)
return
if res.status.code != cs3code.CODE_OK:
log.error('msg="Failed to unlock" filepath="%s" trace="%s" code="%s" reason="%s"' %
(filepath, res.status.trace, res.status.code, res.status.message.replace('"', "'")))
Expand Down Expand Up @@ -340,7 +412,7 @@ def readfile(endpoint, filepath, userid, lockid):
'x-access-token': userid,
'x-reva-transfer': protocol.token # needed if the downloads pass through the data gateway in reva
}
fileget = requests.get(url=protocol.download_endpoint, headers=headers, verify=ctx['ssl_verify'])
fileget = requests.get(url=protocol.download_endpoint, headers=headers, verify=ctx['ssl_verify'], timeout=30)
except requests.exceptions.RequestException as e:
log.error(f'msg="Exception when downloading file from Reva" reason="{e}"')
yield IOError(e)
Expand Down Expand Up @@ -394,7 +466,7 @@ def writefile(endpoint, filepath, userid, content, lockmd, islock=False):
'Upload-Length': size,
'x-reva-transfer': protocol.token # needed if the uploads pass through the data gateway in reva
}
putres = requests.put(url=protocol.upload_endpoint, data=content, headers=headers, verify=ctx['ssl_verify'])
putres = requests.put(url=protocol.upload_endpoint, data=content, headers=headers, verify=ctx['ssl_verify'], timeout=30)
except requests.exceptions.RequestException as e:
log.error(f'msg="Exception when uploading file to Reva" reason="{e}"')
raise IOError(e)
Expand Down
18 changes: 10 additions & 8 deletions wopiserver.conf
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Expand Up @@ -207,12 +207,14 @@ chunksize = 4194304
# Host and port of the Reva(-like) CS3-compliant GRPC gateway endpoint
#revagateway = your-reva-gateway-server.org:port

# HTTP (WebDAV) endpoint for uploading files
#datagateway = http://your-reva-server.org:port/data

# Reva/gRPC authentication token expiration time [seconds]
# The default value matches Reva's default
authtokenvalidity = 3600

# SSL certificate check for Reva
# SSL certificate check for the gateway
#sslverify = True

# This option enables storing the lock payload as arbitrary metadata (extended
# attributes), without using the CS3 Lock API. This may be useful to enable
# the usage of apps when the storage does not implement the locking semantic.
# The flip side is that there's no guaranteed protection against external
# concurrent edits, so this option is to be used with care, and it is strongly
# recommended to keep detectexternalmodifications = True.
# By default, it is assumed the Lock API is available.
#lockasattr = False