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1 /*
2  * Copyright (C) 2009 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ANDROID_USB_API_ADB_WINUSB_IO_COMPLETION_H__
18 #define ANDROID_USB_API_ADB_WINUSB_IO_COMPLETION_H__
19 /** \file
20   This file consists of declaration of class AdbWinUsbIOCompletion that
21   encapsulates a wrapper around OVERLAPPED Win32 structure returned from
22   asynchronous I/O requests issued via WinUsb API.
23 */
24 
25 #include "..\api\adb_io_completion.h"
26 #include "adb_winusb_endpoint_object.h"
27 
28 /** \brief Encapsulates encapsulates a wrapper around OVERLAPPED Win32
29   structure returned from asynchronous I/O requests issued via WinUsb API.
30 
31   A handle to this object is returned to the caller of each successful
32   asynchronous I/O request. Just like all other handles this handle
33   must be closed after it's no longer needed.
34 */
35 class AdbWinUsbIOCompletion : public AdbIOCompletion {
36  public:
37   /** \brief Constructs the object
38 
39     @param[in] parent_io_obj Parent WinUsb I/O object that created this
40            instance.
41     @param[in] expected_trans_size Number of bytes expected to be transferred
42           with the I/O.
43     @param[in] event_hndl Event handle that should be signaled when I/O
44            completes. Can be NULL. If it's not NULL this handle will be
45            used to initialize OVERLAPPED structure for this object.
46   */
47   AdbWinUsbIOCompletion(AdbWinUsbEndpointObject* parent_io_obj,
48                         ULONG expected_trans_size,
49                         HANDLE event_hndl);
50 
51  protected:
52   /** \brief Destructs the object.
53 
54     We hide destructor in order to prevent ourseves from accidentaly allocating
55     instances on the stack. If such attemp occur, compiler will error.
56   */
57   virtual ~AdbWinUsbIOCompletion();
58 
59   //
60   // Virtual overrides
61   //
62 
63  public:
64   /** \brief Releases the object.
65 
66     If refcount drops to zero as the result of this release, the object is
67     destroyed in this method. As a general rule, objects must not be touched
68     after this method returns even if returned value is not zero. We override
69     this method in order to make sure that objects of this class are deleted
70     in contect of the DLL they were created in. The problem is that since
71     objects of this class were created in context of AdbWinUsbApi module, they
72     are allocated from the heap assigned to that module. Now, if these objects
73     are deleted outside of AdbWinUsbApi module, this will lead to the heap
74     corruption in the module that deleted these objects. Since all objects of
75     this class are deleted in the Release method only, by overriding it we make
76     sure that we free memory in the context of the module where it was
77     allocated.
78     @return Value of the reference counter after object is released in this
79             method.
80   */
81   virtual LONG Release();
82 
83   //
84   // Abstract overrides
85   //
86 
87  public:
88   /** \brief Gets overlapped I/O result
89 
90     This method uses WinUsb_GetOverlappedResult to get results of the
91     overlapped I/O operation.
92     @param[out] ovl_data Buffer for the copy of this object's OVERLAPPED
93            structure. Can be NULL.
94     @param[out] bytes_transferred Pointer to a variable that receives the
95            number of bytes that were actually transferred by a read or write
96            operation. See SDK doc on GetOvelappedResult for more information.
97            Unlike regular GetOvelappedResult call this parameter can be NULL.
98     @param[in] wait If this parameter is true, the method does not return
99            until the operation has been completed. If this parameter is false
100            and the operation is still pending, the method returns false and
101            the GetLastError function returns ERROR_IO_INCOMPLETE.
102     @return true if I/O has been completed or false on failure or if request
103            is not yet completed. If false is returned GetLastError() provides
104            extended error information. If GetLastError returns
105            ERROR_IO_INCOMPLETE it means that I/O is not yet completed.
106   */
107   virtual bool GetOvelappedIoResult(LPOVERLAPPED ovl_data,
108                                     ULONG* bytes_transferred,
109                                     bool wait);
110 
111  public:
112   /// Gets WinUsb parent object
parent_winusb_io_object()113   AdbWinUsbEndpointObject* parent_winusb_io_object() const {
114     return reinterpret_cast<AdbWinUsbEndpointObject*>(parent_io_object());
115   }
116 };
117 
118 #endif  // ANDROID_USB_API_ADB_WINUSB_IO_COMPLETION_H__
119