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/*
* Copyright (C) 2005 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//
// FIFO I/O.
//
#ifndef _LIBS_UTILS_PIPE_H
#define _LIBS_UTILS_PIPE_H
#ifdef HAVE_ANDROID_OS
#error DO NOT USE THIS FILE IN THE DEVICE BUILD
#endif
namespace android {
/*
* Simple anonymous unidirectional pipe.
*
* The primary goal is to create an implementation with minimal overhead
* under Linux. Making Windows, Mac OS X, and Linux all work the same way
* is a secondary goal. Part of this goal is to have something that can
* be fed to a select() call, so that the application can sleep in the
* kernel until something interesting happens.
*/
class Pipe {
public:
Pipe(void);
virtual ~Pipe(void);
/* Create the pipe */
bool create(void);
/* Create a read-only pipe, using the supplied handle as read handle */
bool createReader(unsigned long handle);
/* Create a write-only pipe, using the supplied handle as write handle */
bool createWriter(unsigned long handle);
/* Is this object ready to go? */
bool isCreated(void);
/*
* Read "count" bytes from the pipe. Returns the amount of data read,
* or 0 if no data available and we're non-blocking.
* Returns -1 on error.
*/
int read(void* buf, int count);
/*
* Write "count" bytes into the pipe. Returns number of bytes written,
* or 0 if there's no room for more data and we're non-blocking.
* Returns -1 on error.
*/
int write(const void* buf, int count);
/* Returns "true" if data is available to read */
bool readReady(void);
/* Enable or disable non-blocking I/O for reads */
bool setReadNonBlocking(bool val);
/* Enable or disable non-blocking I/O for writes. Only works on Linux. */
bool setWriteNonBlocking(bool val);
/*
* Get the handle. Only useful in some platform-specific situations.
*/
unsigned long getReadHandle(void);
unsigned long getWriteHandle(void);
/*
* Modify inheritance, i.e. whether or not a child process will get
* copies of the descriptors. Systems with fork+exec allow us to close
* the descriptors before launching the child process, but Win32
* doesn't allow it.
*/
bool disallowReadInherit(void);
bool disallowWriteInherit(void);
/*
* Close one side or the other. Useful in the parent after launching
* a child process.
*/
bool closeRead(void);
bool closeWrite(void);
private:
bool mReadNonBlocking;
bool mWriteNonBlocking;
unsigned long mReadHandle;
unsigned long mWriteHandle;
};
}; // android
#endif // _LIBS_UTILS_PIPE_H
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