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      1 /*
      2  * Copyright (C) 2010 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 NET_FD_H_included
     18 #define NET_FD_H_included
     19 
     20 /**
     21  * Wraps access to the int inside a java.io.FileDescriptor, taking care of throwing exceptions.
     22  */
     23 class NetFd {
     24 public:
     25     NetFd(JNIEnv* env, jobject fileDescriptor)
     26         : mEnv(env), mFileDescriptor(fileDescriptor), mFd(-1)
     27     {
     28     }
     29 
     30     bool isClosed() {
     31         mFd = jniGetFDFromFileDescriptor(mEnv, mFileDescriptor);
     32         bool closed = (mFd == -1);
     33         if (closed) {
     34             jniThrowException(mEnv, "java/net/SocketException", "Socket closed");
     35         }
     36         return closed;
     37     }
     38 
     39     int get() const {
     40         return mFd;
     41     }
     42 
     43 private:
     44     JNIEnv* mEnv;
     45     jobject mFileDescriptor;
     46     int mFd;
     47 
     48     // Disallow copy and assignment.
     49     NetFd(const NetFd&);
     50     void operator=(const NetFd&);
     51 };
     52 
     53 /**
     54  * Used to retry syscalls that can return EINTR. This differs from TEMP_FAILURE_RETRY in that
     55  * it also considers the case where the reason for failure is that another thread called
     56  * Socket.close.
     57  */
     58 #define NET_FAILURE_RETRY(fd, exp) ({               \
     59     typeof (exp) _rc;                               \
     60     do {                                            \
     61         _rc = (exp);                                \
     62         if (_rc == -1) {                            \
     63             if (fd.isClosed() || errno != EINTR) {  \
     64                 break;                              \
     65             }                                       \
     66         }                                           \
     67     } while (_rc == -1);                            \
     68     _rc; })
     69 
     70 #endif // NET_FD_H_included
     71