An unnamed pipe permits two related processes to communicate: typically, a parent and its child. One process sends output to the write end of the pipe, whereas the other process receives input from the read end of the pipe. A pipe automatically buffers its input to a maximum of 4K (BSD), or 40K (System V).

An os_unnamed_pipe is often used in conjunction with the os_process constructors to fork a child process using pipes for communication.

Legal I/O control:	`O_NONBLOCK, O_CLOSE_ON_EXEC, O_ASYNC`
Default I/O control:	0 (blocking)

Interface

Constructor

os_unnamed_pipe( os_ioctl_t control )

Constructs an object to reference a new unnamed pipe with I/O control setting control (default 0, blocking).

Throws: os_unix_toolkit_error

Destructor

~os_unnamed_pipe()

Destroys the object, closing the object's descriptor if necessary.

bool operator<( const os_unnamed_pipe& pipe ) const

Returns true if the object is considered to be less than pipe .

bool operator==( const os_unnamed_pipe& pipe ) const

Returns true if the object's read and write ends are the same as pipe .

(os_adapter)

operator os_adapter() const

Returns an os_adapter to the object.

auto_close

bool auto_close() const

Returns true if the object's pipe ends are closed on destruction.

auto_close

void auto_close( bool flag )

If flag is true , closes the object's pipe ends on destruction.

buffer_limit

long buffer_limit() const

Returns the maximum number of bytes that may be atomically written to pipe. If both of ends are closed, return OS_UNDEFINED .

Throws: os_unix_toolkit_error

clear

void clear()

Sets the object's state to good.

close

void close()

Closes both of the object's ends.

Throws: os_unix_toolkit_error

eof

bool eof() const

Returns true if the unnamed pipe is at the end of the object's input.

event_on_eof

void event_on_eof( bool flag )

If flag is true , the object generates an event on EOF.

event_on_eof

bool event_on_eof() const

Returns true if the object generates an event on EOF.

good

bool good() const

Returns true if the object is in a good state and not at EOF.

is_open

bool is_open() const

Returns true if either of the object's ends is open.

bool ok() const

Returns true if the object has not failed.

print

void print( ostream& stream ) const

Prints pipe to stream .

read

ssize_t read( void* buffer , size_t bytes )

Reads up to the specified number of bytes of data into buffer from the pipe. Returns the number of bytes actually read, or returns -1 on error.

Throws: os_unix_toolkit_error

read_end

os_desc_t read_end()

Returns a reference to the object's read end.

write

ssize_t write( const void* buffer , size_t bytes )

Writes up to the specified number of bytes of data from buffer to the pipe. Returns the number of bytes actually written, or returns -1 on error.

Throws: os_unix_toolkit_error

write_end

os_desc_t write_end()

Returns a reference to the object's write end.

unnamed_pipe

Library

Declaration

Options

Interface

Non-Member Functions