added RPCFS, which exposes a filesystem using XML-RPC

git-svn-id: http://pyfilesystem.googlecode.com/svn/trunk@110 67cdc799-7952-0410-af00-57a81ceafa0f

2 files changed, 363 insertions, 1 deletions

diff --git a/fs/rpcfs.py b/fs/rpcfs.py
new file mode 100644
index 0000000..4d2a676
--- /dev/null
+++ b/fs/rpcfs.py
@@ -0,0 +1,306 @@
+"""
+
+  fs.rpcfs:  Client and Server to expose an FS via XML-RPC
+
+This module provides the following pair of classes that can be used to expose
+a remote filesystem using XML-RPC:
+
+   RPCFSServer:   a subclass of SimpleXMLRPCServer that exposes the methods
+                  of an FS instance via XML-RPC
+
+   RPCFS:   a subclass of FS that delegates all filesystem operations to
+            a remote server using XML-RPC.
+
+If you need to use a more powerful server than SimpleXMLRPCServer, you can
+use the RPCFSInterface class to provide an XML-RPC-compatible wrapper around
+an FS object, which can then be exposed using whatever server you choose
+(e.g. Twisted's XML-RPC server).
+
+"""
+
+import xmlrpclib
+from SimpleXMLRPCServer import SimpleXMLRPCServer
+
+from fs.base import *
+
+from StringIO import StringIO
+
+
+class ObjProxy:
+    """Simple object proxy allowing us to replace read-only attributes.
+
+    This is used to put a modified 'close' method on files returned by
+    open(), such that they will be uploaded to the server when closed.
+    """
+
+    def __init__(self,obj):
+        self._obj = obj
+
+    def __getattr__(self,attr):
+        return getattr(self._obj,attr)
+
+class ReRaiseErrors:
+    """XML-RPC proxy wrapper that tries to re-raise Faults as actual errors."""
+    def __init__(self,proxy):
+        self._proxy = proxy
+    def __getattr__(self,attr):
+        val = getattr(self._proxy,attr)
+        if not callable(val):
+            return val
+        def func(*args,**kwds):
+            try:
+                val(*args,**kwds)
+            except xmlrpclib.Fault, e:
+                print "ERROR", e, e.faultCode, e.faultString
+
+def re_raise_faults(func):
+    """Decorator to re-raise XML-RPC faults as proper exceptions."""
+    def wrapper(*args,**kwds):
+        try:
+            return func(*args,**kwds)
+        except xmlrpclib.Fault, f:
+            # Make sure it's in a form we can handle
+            bits = f.faultString.split(" ")
+            if bits[0] not in ["<type","<class"]:
+                raise f
+            # Find the class/type object
+            bits = " ".join(bits[1:]).split(">:")
+            cls = bits[0]
+            msg = ">:".join(bits[1:])
+            while cls[0] in ["'",'"']:
+                cls = cls[1:]
+            while cls[-1] in ["'",'"']:
+                cls = cls[:-1]
+            cls = _object_by_name(cls)
+            # Re-raise using the remainder of the fault code as message
+            if cls:
+                raise cls(msg)
+            raise f
+    return wrapper
+
+
+def _object_by_name(name,root=None):
+    """Look up an object by dotted-name notation."""
+    bits = name.split(".")
+    if root is None:
+        try:
+            obj = globals()[bits[0]]
+        except KeyError:
+            try:
+                obj = __builtins__[bits[0]]
+            except KeyError:
+                obj = __import__(bits[0],globals())
+    else:
+        obj = getattr(root,bits[0])
+    if len(bits) > 1:
+        return _object_by_name(".".join(bits[1:]),obj)
+    else:
+        return obj
+    
+
+class ReRaiseFaults:
+    """XML-RPC proxy wrapper that re-raises Faults as proper Exceptions."""
+
+    def __init__(self,obj):
+        self._obj = obj
+
+    def __getattr__(self,attr):
+        val = getattr(self._obj,attr)
+        if callable(val):
+            val = re_raise_faults(val)
+        return val
+
+
+class RPCFS(FS):
+    """Access a filesystem exposed via XML-RPC.
+
+    This class provides the client-side logic for accessing a remote FS
+    object, and is dual to the RPCFSServer class also defined in this module.
+
+    Example:
+
+        fs = RPCFS("http://my.server.com/filesystem/location/")
+
+    """
+
+    def __init__(self, uri, transport=None):
+        """Constructor for RPCFS objects.
+
+        The only required argument is the uri of the server to connect
+        to.  This will be passed to the underlying XML-RPC server proxy
+        object along with any other arguments if they are provided.
+        """
+        self.uri = uri
+        if transport is not None:
+            proxy = xmlrpclib.ServerProxy(uri,transport,allow_none=True)
+        else:
+            proxy = xmlrpclib.ServerProxy(uri,allow_none=True)
+        self.proxy = ReRaiseFaults(proxy)
+
+    def __str__(self):
+        return '<RPCFS: %s>' % (self.uri,)
+
+    __repr__ = __str__
+
+    def open(self,path,mode):
+        # TODO: chunked transport of large files
+        if "r" in mode or "a" in mode:
+            try:
+                data = self.proxy.get_contents(path).data
+            except IOError:
+                if "w" not in mode and "a" not in mode:
+                    raise ResourceNotFoundError("NO_FILE",path)
+                if not self.isdir(dirname(path)):
+                    raise OperationFailedError("OPEN_FAILED", path,msg="Parent directory does not exist")
+        else:
+            data = ""
+        f = ObjProxy(StringIO(data))
+        if "a" not in mode:
+            f.seek(0,0)
+        else:
+            f.seek(0,2)
+        oldclose = f.close
+        def newclose():
+            f.flush()
+            self.proxy.set_contents(path,xmlrpclib.Binary(f.getvalue()))
+            oldclose()
+        f.close = newclose
+        return f
+
+    def exists(self,path):
+        return self.proxy.exists(path)
+
+    def isdir(self,path):
+        return self.proxy.isdir(path)
+
+    def isfile(self,path):
+        return self.proxy.isfile(path)
+
+    def listdir(self,path="./",wildcard=None,full=False,absolute=False,hidden=True,dirs_only=False,files_only=False):
+        return self.proxy.listdir(path,wildcard,full,absolute,hidden,dirs_only,files_only)
+
+    def makedir(self,path,mode=0777,recursive=False,allow_recreate=False):
+        return self.proxy.makedir(path,mode,recursive,allow_recreate)
+
+    def remove(self,path):
+        return self.proxy.remove(path)
+
+    def removedir(self,path,recursive=False):
+        return self.proxy.removedir(path,recursive)
+        
+    def rename(self,src,dst):
+        return self.proxy.rename(src,dst)
+
+    def getinfo(self,path):
+        return self.proxy.getinfo(path)
+
+    def desc(self,path):
+        return self.proxy.desc(path)
+
+    def getattr(self,path,attr):
+        return self.proxy.getattr(path,attr)
+
+    def setattr(self,path,attr,value):
+        return self.proxy.setattr(path,attr,value)
+
+    def copy(self,src,dst,overwrite=False,chunk_size=16384):
+        return self.proxy.copy(src,dst,overwrite,chunk_size)
+
+    def move(self,src,dst,chunk_size=16384):
+        return self.proxy.move(src,dst,chunk_size)
+
+    def movedir(self,src,dst,ignore_errors=False,chunk_size=16384):
+        return self.proxy.movedir(src,dst,ignore_errors,chunk_size)
+
+    def copydir(self,src,dst,ignore_errors=False,chunk_size=16384):
+        return self.proxy.copydir(src,dst,ignore_errors,chunk_size)
+
+
+class RPCFSInterface(object):
+    """Wrapper to expose an FS via a XML-RPC compatible interface."""
+
+    def __init__(self,fs):
+        self.fs = fs
+
+    def get_contents(self,path):
+        data = self.fs.getcontents(path)
+        return xmlrpclib.Binary(data)
+
+    def set_contents(self,path,data):
+        self.fs.createfile(path,data.data)
+
+    def exists(self,path):
+        return self.fs.exists(path)
+
+    def isdir(self,path):
+        return self.fs.isdir(path)
+
+    def isfile(self,path):
+        return self.fs.isfile(path)
+
+    def listdir(self,path="./",wildcard=None,full=False,absolute=False,hidden=True,dirs_only=False,files_only=False):
+        return list(self.fs.listdir(path,wildcard,full,absolute,hidden,dirs_only,files_only))
+
+    def makedir(self,path,mode=0777,recursive=False,allow_recreate=False):
+        return self.fs.makedir(path,mode,recursive,allow_recreate)
+
+    def remove(self,path):
+        return self.fs.remove(path)
+
+    def removedir(self,path,recursive=False):
+        return self.fs.removedir(path,recursive)
+        
+    def rename(self,src,dst):
+        return self.fs.rename(src,dst)
+
+    def getinfo(self,path):
+        return self.fs.getinfo(path)
+
+    def desc(self,path):
+        return self.fs.desc(path)
+
+    def getattr(self,path,attr):
+        return self.fs.getattr(path,attr)
+
+    def setattr(self,path,attr,value):
+        return self.fs.setattr(path,attr,value)
+
+    def copy(self,src,dst,overwrite=False,chunk_size=16384):
+        return self.fs.copy(src,dst,overwrite,chunk_size)
+
+    def move(self,src,dst,chunk_size=16384):
+        return self.fs.move(src,dst,chunk_size)
+
+    def movedir(self,src,dst,ignore_errors=False,chunk_size=16384):
+        return self.fs.movedir(src,dst,ignore_errors,chunk_size)
+
+    def copydir(self,src,dst,ignore_errors=False,chunk_size=16384):
+        return self.fs.copydir(src,dst,ignore_errors,chunk_size)
+
+
+class RPCFSServer(SimpleXMLRPCServer):
+    """Server to expose an FS object via XML-RPC.
+
+    Example:
+
+        fs = OSFS('/var/srv/myfiles')
+        s = RPCFSServer(fs,("",8080))
+        s.serve_forever()
+
+    """
+
+    def __init__(self,fs,addr,requestHandler=None,logRequests=None):
+        kwds = dict(allow_none=True)
+        if requestHandler is not None:
+            kwds['requestHandler'] = requestHandler
+        if logRequests is not None:
+            kwds['logRequests'] = logRequests
+        self.serve_more_requests = True
+        SimpleXMLRPCServer.__init__(self,addr,**kwds)
+        self.register_instance(RPCFSInterface(fs))
+
+    def serve_forever(self):
+        """Override serve_forever to allow graceful shutdown."""
+        while self.serve_more_requests:
+            self.handle_request()
+
diff --git a/fs/tests.py b/fs/tests.py
index 0552229..aed5f3e 100644
--- a/fs/tests.py
+++ b/fs/tests.py
@@ -617,10 +617,66 @@ class TestAppendZipFS(TestWriteZipFS):
         zip_fs.close()
 
 
+import s3fs
+class TestS3FS(TestOSFS):
+
+    bucket = "test-s3fs.rfk.id.au"
+
+    def setUp(self):
+        self.fs = s3fs.S3FS(self.bucket,"/unittest/files")
+        self._clear()
+
+    def _clear(self):
+        for (path,files) in self.fs.walk(search="depth"):
+            for fn in files:
+                self.fs.remove(pathjoin(path,fn))
+            if path and path != "/":
+                self.fs.removedir(path)
+    def tearDown(self):
+        self._clear()
+        for k in self.fs._s3bukt.list():
+            self.fs._s3bukt.delete_key(k)
+        self.fs._s3conn.delete_bucket(self.bucket)
+
+    def check(self, p):
+        return self.fs.exists(p)
+
+
+import rpcfs
+import threading
+import time
+class TestRPCFS(TestOSFS):
+
+    def setUp(self):
+        self.server = rpcfs.RPCFSServer(tempfs.TempFS(),("localhost",8000),logRequests=False)
+        self.server_thread = threading.Thread(target=self._run_server)
+        self.server_thread.start()
+        self.fs = rpcfs.RPCFS("http://localhost:8000")
+
+    def _run_server(self):
+        """Run the server, swallowing shutdown-related execptions."""
+        try:
+            self.server.serve_forever()
+        except:
+            pass
+
+    def tearDown(self):
+        try:
+          # Shut the server down.  We send one final request to
+          # bump the socket and make it recognise the shutdown.
+          self.server.serve_more_requests = False
+          self.server.server_close()
+          self.fs.exists("/")
+        except Exception:
+          pass
+
+    def check(self, p):
+        return self.fs.exists(p)
+
 
 if __name__ == "__main__":
     #t = TestFS()
     #t.setUp()
     #t.tearDown()
     import nose
-    nose.main()
\ No newline at end of file
+    nose.main()