Merge in own message queue module

1 files changed, 173 insertions, 0 deletions

diff --git a/portato/ipc.pyx b/portato/ipc.pyx
new file mode 100644
index 0000000..e9340cf
--- /dev/null
+++ b/portato/ipc.pyx
@@ -0,0 +1,173 @@
+# -*- coding: utf-8 -*-
+#
+# File: portato/ipc.pyx
+# This file is part of the Portato-Project, a graphical portage-frontend.
+#
+# Copyright (C) 2006-2009 René 'Necoro' Neumann
+# This is free software.  You may redistribute copies of it under the terms of
+# the GNU General Public License version 2.
+# There is NO WARRANTY, to the extent permitted by law.
+#
+# Written by René 'Necoro' Neumann <necoro@necoro.net>
+
+class MessageQueueError(Exception):
+    """
+    Base class for different queue errors.
+    """
+    pass
+
+class MessageQueueRemovedError (MessageQueueError):
+    """
+    This class is used iff the queue is already removed.
+    """
+    pass
+
+cdef class MessageQueue (object):
+    """
+    A simple interface to the SysV message queues.
+    """
+
+    CREAT = IPC_CREAT
+    EXCL = IPC_EXCL
+    
+    cdef int msgid
+    cdef readonly key_t key
+
+    def __init__ (self, key = None, int flags = 0):
+        """
+        Create a new MessageQueue instance. Depending on the passed in flags,
+        different behavior occurs. See man msgget for the details.
+
+        If key is None, a random key is created.
+        """
+
+        if (flags & IPC_EXCL) and not (flags & IPC_CREAT):
+            raise ValueError("EXCL must be combined with CREAT.")
+
+        if key is None and not (flags & IPC_EXCL):
+            raise ValueError("The key can only be None if EXCL is set.")
+
+        # make sure there is nothing ... obscure
+        flags &= (IPC_CREAT | IPC_EXCL)
+
+        flags |= 0600 # mode
+
+        if key is None:
+            check = True
+            while check:
+                self.key = self.random_key()
+                self.msgid = msgget(self.key, flags)
+                check = (self.msgid == -1 and errno == EEXIST)
+        else:
+            self.key = key
+            self.msgid = msgget(key, flags)
+
+        if self.msgid == -1:
+            if errno == EACCES:
+                raise MessageQueueError("Permission denied.")
+            elif errno == EEXIST:
+                raise MessageQueueError("Queue already exists.")
+            elif errno == ENOENT:
+                raise MessageQueueError("Queue does not exist and CREAT is not set.")
+            elif errno == ENOMEM or errno == ENOSPC:
+                raise MemoryError("Insufficient ressources.")
+            else:
+                raise OSError(errno, strerror(errno))
+
+    def remove (self):
+        """
+        Removes the message queue.
+        """
+        cdef msqid_ds info
+        cdef int ret
+
+        ret = msgctl(self.msgid, IPC_RMID, &info)
+
+        if ret == -1:
+            if errno == EIDRM or errno == EINVAL:
+                raise MessageQueueRemovedError("Queue already removed.")
+            elif errno == EPERM:
+                raise MessageQueueError("Permission denied.")
+            else:
+                raise OSError(errno, strerror(errno))
+
+    def send (self, message, int type = 1):
+        """
+        Sends a message with a specific type.
+
+        The type must be larger zero.
+        Also note, that this is always blocking.
+        """
+        cdef msg_data * msg
+        cdef int ret
+        cdef long size = len(message)
+
+        if type <= 0:
+            raise ValueError("type must be > 0")
+
+        if size >= MAX_MESSAGE_SIZE:
+            raise ValueError("Message must be smaller than %d", MAX_MESSAGE_SIZE)
+
+        msg = <msg_data*>PyMem_Malloc(sizeof(msg_data) + size)
+
+        if msg is NULL:
+            raise MemoryError("Out of memory")
+
+        memcpy(msg.mtext, <char*>message, size)
+        msg.mtype = type
+
+        with nogil:
+            ret = msgsnd(self.msgid, msg, size, 0)
+
+        try:
+            if ret == -1:
+                if errno == EIDRM or errno == EINVAL:
+                    raise MessageQueueRemovedError("Queue was removed.")
+                elif errno == EINTR:
+                    raise MessageQueueError("Signaled while waiting.")
+                elif errno == EACCES:
+                    raise MessageQueueError("Permission denied.")
+                else:
+                    raise OSError(errno, strerror(errno))
+        finally:
+            PyMem_Free(msg)
+
+    def receive (self):
+        """
+        Receives a message from the queue and returns the (msg, type) pair.
+
+        Note that this method is always blocking.
+        """
+        cdef msg_data * msg
+        cdef int ret
+        cdef object retTuple
+
+        msg = <msg_data*>PyMem_Malloc(sizeof(msg_data) + MAX_MESSAGE_SIZE)
+
+        if msg is NULL:
+            raise MemoryError("Out of memory")
+
+        msg.mtype = 0
+
+        with nogil:
+            ret = msgrcv(self.msgid, msg, <size_t>MAX_MESSAGE_SIZE, 0, 0)
+        
+        try:
+            if ret == -1:
+                if errno == EIDRM or errno == EINVAL:
+                    raise MessageQueueRemovedError("Queue was removed.")
+                elif errno == EINTR:
+                    raise MessageQueueError("Signaled while waiting.")
+                elif errno == EACCES:
+                    raise MessageQueueError("Permission denied.")
+                else:
+                    raise OSError(errno, strerror(errno))
+
+            retTuple = (PyString_FromStringAndSize(msg.mtext, ret), msg.mtype)
+        finally:
+            PyMem_Free(msg)
+
+        return retTuple
+
+    cdef key_t random_key (self):
+        return <int>(<double>rand() / (<double>RAND_MAX + 1) * INT_MAX)