CreatePipe info  Overview  Group

The CreatePipe function creates an anonymous pipe, and returns handles to the read and write ends of the pipe.

BOOL CreatePipe(

PHANDLE hReadPipe,	// address of variable for read handle
PHANDLE hWritePipe,	// address of variable for write handle
LPSECURITY_ATTRIBUTES lpPipeAttributes,	// pointer to security attributes
DWORD nSize	// number of bytes reserved for pipe
);

Parameters

hReadPipe

Points to the variable that receives the read handle for the pipe.

hWritePipe

Points to the variable that receives the write handle for the pipe.

lpPipeAttributes

Pointer to a SECURITY_ATTRIBUTES structure that determines whether the returned handle can be inherited by child processes. If lpPipeAttributes is NULL, the handle cannot be inherited.

Windows NT: The lpSecurityDescriptor member of the structure specifies a security descriptor for the new pipe. If lpPipeAttributes is NULL, the pipe gets a default security descriptor.

Windows 95: The lpSecurityDescriptor member of the structure is ignored.

nSize

Specifies the buffer size for the pipe. The size is only a suggestion; the system uses the value to calculate an appropriate buffering mechanism. If this parameter is zero, the system uses the default buffer size.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

CreatePipe creates the pipe, assigning the specified pipe size to the storage buffer. CreatePipe also creates handles that the process uses to read from and write to the buffer in subsequent calls to the ReadFile and WriteFile functions.

To read from the pipe, a process uses the read handle in a call to the ReadFile function. ReadFile returns when one of the following is true: a write operation completes on the write end of the pipe, the number of bytes requested has been read, or an error occurs.

When a process uses WriteFile to write to an anonymous pipe, the write operation is not completed until all bytes are written. If the pipe buffer is full before all bytes are written, WriteFile does not return until another process or thread uses ReadFile to make more buffer space available.

See Also

ReadFile, SECURITY_ATTRIBUTES, WriteFile