Perform a flow-control operation on a data stream
Synopsis:
#include <termios.h>
int tcflow( int filedes,
int action );
Arguments:
- filedes
- A file descriptor that's associated with the data stream that you want to
perform the operation on.
- action
- The action you want to perform; see below.
Library:
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
Description:
The tcflow() function performs a flow-control operation
on the data stream associated with filedes, depending on the
values in action.
At least the following actions are defined in <termios.h>:
- TCOOFF
- Use software flow control to suspend output on the device
associated with filedes.
- TCOOFFHW
- Use hardware flow control to suspend output on the device
associated with filedes.
- TCOON
- Use software flow control to resume output on the device
associated with filedes.
- TCOONHW
- Use hardware flow control to resume output on the device
associated with filedes.
- TCIOFF
- Cause input to be flow-controlled by sending a
STOP character immediately across the communication line associated
with filedes, (that is, software flow control).
- TCIOFFHW
- Cause input to be flow-controlled by using hardware control.
- TCION
- Resume input by sending a START character immediately across
the communication line associated with
filedes (that is, software flow control).
- TCIONHW
- Cause input to be resumed by using hardware flow control.
Returns:
- 0
- Success.
- -1
- An error occurred
(errno is set).
Errors:
- EBADF
- Invalid filedes argument.
- EINVAL
- Invalid action argument.
- ENOSYS
- The resource manager associated with filedes doesn't support
this call.
- ENOTTY
- The argument filedes doesn't refer to a terminal device.
Examples:
#include <termios.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
int main( void )
{
int fd;
fd = open( "/dev/ser1", O_RDWR );
/* Resume output on flow-controlled device */
tcflow( fd, TCOON );
close( fd );
return EXIT_SUCCESS;
}
Classification:
POSIX 1003.1
| Safety: |
|
|---|
| Cancellation point |
No |
| Interrupt handler |
No |
| Signal handler |
Yes |
| Thread |
Yes |