librclone: add basic Python bindings with tests #4891

librclone/python/rclone.py

@@ -0,0 +1,94 @@
+"""
+Python interface to librclone.so using ctypes
+
+Create an rclone object
+
+    rclone = Rclone(shared_object="/path/to/librclone.so")
+
+Then call rpc calls on it
+
+    rclone.rpc("rc/noop", a=42, b="string", c=[1234])
+
+When finished, close it
+
+    rclone.close()
+"""
+
+__all__ = ('Rclone', 'RcloneException')
+
+import os
+import json
+import subprocess
+from ctypes import *
+
+class RcloneRPCResult(Structure):
+    """
+    This is returned from the C API when calling RcloneRPC
+    """
+    _fields_ = [("Output", c_char_p),
+                ("Status", c_int)]
+
+class RcloneException(Exception):
+    """
+    Exception raised from rclone
+
+    This will have the attributes:
+
+    output - a dictionary from the call
+    status - a status number
+    """
+    def __init__(self, output, status):
+        self.output = output
+        self.status = status
+        message = self.output.get('error', 'Unknown rclone error')
+        super().__init__(message)
+
+class Rclone():
+    """
+    Interface to Rclone via librclone.so
+
+    Initialise with shared_object as the file path of librclone.so
+    """
+    def __init__(self, shared_object="./librclone.so"):
+        self.rclone = CDLL(shared_object)
+        self.rclone.RcloneRPC.restype = RcloneRPCResult
+        self.rclone.RcloneRPC.argtypes = (c_char_p, c_char_p)
+        self.rclone.RcloneInitialize.restype = None
+        self.rclone.RcloneInitialize.argtypes = ()
+        self.rclone.RcloneFinalize.restype = None
+        self.rclone.RcloneFinalize.argtypes = ()
+        self.rclone.RcloneInitialize()
+    def rpc(self, method, **kwargs):
+        """
+        Call an rclone RC API call with the kwargs given.
+
+        The result will be a dictionary.
+
+        If an exception is raised from rclone it will of type
+        RcloneException.
+        """
+        method = method.encode("utf-8")
+        parameters = json.dumps(kwargs).encode("utf-8")
+        resp = self.rclone.RcloneRPC(method, parameters)
+        output = json.loads(resp.Output.decode("utf-8"))
+        status = resp.Status
+        if status != 200:
+            raise RcloneException(output, status)
+        return output
+    def close(self):
+        """
+        Call to finish with the rclone connection
+        """
+        self.rclone.RcloneFinalize()
+        self.rclone = None
+    @classmethod
+    def build(cls, shared_object):
+        """
+        Builds rclone to shared_object if it doesn't already exist
+
+        Requires go to be installed
+        """
+        if os.path.exists(shared_object):
+            return
+        print("Building "+shared_object)
+        subprocess.check_call(["go", "build", "--buildmode=c-shared", "-o", shared_object, "github.com/rclone/rclone/librclone"])