Open System Services Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

OSS Library Calls (t - v) tcdrain(3)
NAME
tcdrain - Waits for output to finish
LIBRARY
G-series native OSS processes: system library
H-series and J-series OSS processes: implicit libraries
SYNOPSIS
#include <termios.h>
int tcdrain(
int filedes);
PARAMETERS
filedes Specifies an open file descriptor.
DESCRIPTION
The tcdrain( ) function waits until all output written to the object referred to by the filedes
parameter has been transmitted.
The tcdrain( ) function, which suspends the calling process until the request is completed, is
redefined so that only the calling thread is suspended.
Attempts to use the tcdrain( ) function from a process that is a member of a background process
group on a filedes associated with its controlling terminal causes the process group to be sent a
SIGTTOU signal. If the calling process is blocking or ignoring the SIGTTOU signal, the pro-
cess is allowed to perform the operation and no signal is sent.
EXAMPLES
To wait until all output has been transmitted, enter:
rc = tcdrain(stdout);
RETURN VALUES
Upon successful completion, the value 0 (zero) is returned. Otherwise, the value -1 is returned
and errno is set to indicate the error.
ERRORS
If any of the following conditions occurs, the tcdrain( ) function sets errno to the corresponding
value:
[EBADF] The filedes parameter does not specify a valid file descriptor.
[EINTR] A signal interrupted the tcdrain( ) function.
[EIO] One of the following conditions exists:
• The process group of the caller is orphaned and the caller is not ignoring
or blocking the SIGTTOU signal.
• An input or output error occurred. The device holding the terminal file
might be in the down state, or both processors that provide access to the
device might have failed.
[EISGUARDIAN]
The value used for the filedes parameter is appropriate only in the Guardian
environment.
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