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Add support for external control via a Unix domain socket.

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This feature allows an external program to inject output into and
listen to input from a serial port via a Unix domain socket (path
specified via the -S/--socket command line flag, or the socket
config file option) while tio is running. This is useful for ad-hoc
scripting of serial port interactions while still permitting manual
control. Since many serial devices (at least on Linux) get confused
when opened by multiple processes, and most commands do not know
how to correctly open a serial device, this allows a more convenient
usage model than directly writing to the device node from an external
program.

Any input from clients connected to the socket is sent on the serial
port as if entered at the terminal where tio is running (except that
ctrl-t sequences are not recognized), and any input from the serial
port is multiplexed to the terminal and all connected clients.

Sockets remain open while the serial port is disconnected, and writes
will block.

Example usage 1 (issue a command):

  echo command | nc -UN /path/to/socket > /dev/null

Example usage 2 (use the expect command to script an interaction):

  #!/usr/bin/expect -f

  set timeout -1
  log_user 0

  spawn nc -UN /path/to/socket
  set uart $spawn_id

  send -i $uart "command1\n"
  expect -i $uart "prompt> "
  send -i $uart "command2\n"
  expect -i $uart "prompt> "
This commit is contained in:
Peter Collingbourne 2022-04-15 18:17:10 -07:00
parent 03e41b61a3
commit fb453160ef
11 changed files with 335 additions and 57 deletions
Download patch file Download diff file Expand all files Collapse all files

125
src/tty.c
View file

@ -31,6 +31,8 @@
#include <sys/param.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <fcntl.h>
#include <termios.h>
#include <stdbool.h>
@ -45,6 +47,7 @@
#include "misc.h"
#include "log.h"
#include "error.h"
#include "socket.h"
#ifdef HAVE_TERMIOS2
extern int setspeed2(int fd, int baudrate);
@ -494,6 +497,7 @@ void tty_wait_for_device(void)
{
fd_set rdfs;
int status;
int maxfd;
struct timeval tv;
static char input_char, previous_char = 0;
static bool first = true;
@ -517,26 +521,30 @@ void tty_wait_for_device(void)
FD_ZERO(&rdfs);
FD_SET(STDIN_FILENO, &rdfs);
maxfd = MAX(STDIN_FILENO, socket_add_fds(&rdfs, false));
/* Block until input becomes available or timeout */
status = select(STDIN_FILENO + 1, &rdfs, NULL, NULL, &tv);
status = select(maxfd + 1, &rdfs, NULL, NULL, &tv);
if (status > 0)
{
/* Input from stdin ready */
/* Read one character */
status = read(STDIN_FILENO, &input_char, 1);
if (status <= 0)
if (FD_ISSET(STDIN_FILENO, &rdfs))
{
error_printf("Could not read from stdin");
exit(EXIT_FAILURE);
/* Input from stdin ready */
/* Read one character */
status = read(STDIN_FILENO, &input_char, 1);
if (status <= 0)
{
error_printf("Could not read from stdin");
exit(EXIT_FAILURE);
}
/* Handle commands */
handle_command_sequence(input_char, previous_char, NULL, NULL);
previous_char = input_char;
}
/* Handle commands */
handle_command_sequence(input_char, previous_char, NULL, NULL);
previous_char = input_char;
socket_handle_input(&rdfs, NULL);
} else if (status == -1)
{
error_printf("select() failed (%s)", strerror(errno));
@ -686,19 +694,20 @@ int tty_connect(void)
}
#endif
maxfd = MAX(fd, STDIN_FILENO) + 1; /* Maximum bit entry (fd) to test */
/* Input loop */
while (true)
{
FD_ZERO(&rdfs);
FD_SET(fd, &rdfs);
FD_SET(STDIN_FILENO, &rdfs);
maxfd = MAX(fd, STDIN_FILENO);
maxfd = MAX(maxfd, socket_add_fds(&rdfs, true));
/* Block until input becomes available */
status = select(maxfd, &rdfs, NULL, NULL, NULL);
status = select(maxfd + 1, &rdfs, NULL, NULL, NULL);
if (status > 0)
{
bool forward = false;
if (FD_ISSET(fd, &rdfs))
{
/* Input from tty device ready */
@ -747,6 +756,8 @@ int tty_connect(void)
if (option.log)
log_write(input_char);
socket_write(input_char);
print_tainted = true;
if (input_char == '\n' && option.timestamp)
@ -760,7 +771,7 @@ int tty_connect(void)
}
if (FD_ISSET(STDIN_FILENO, &rdfs))
{
bool forward = true;
forward = true;
/* Input from stdin ready */
status = read(STDIN_FILENO, &input_char, 1);
@ -778,47 +789,51 @@ int tty_connect(void)
/* Handle commands */
handle_command_sequence(input_char, previous_char, &output_char, &forward);
if (forward)
{
/* Map output character */
if ((output_char == 127) && (map_o_del_bs))
output_char = '\b';
if ((output_char == '\r') && (map_o_cr_nl))
output_char = '\n';
/* Map newline character */
if ((output_char == '\n' || output_char == '\r') && (map_o_nl_crnl)) {
const char *crlf = "\r\n";
optional_local_echo(crlf[0]);
optional_local_echo(crlf[1]);
status = write(fd, crlf, 2);
if (status < 0)
warning_printf("Could not write to tty device");
tx_total += 2;
delay(option.output_delay);
} else
{
/* Send output to tty device */
optional_local_echo(output_char);
status = write(fd, &output_char, 1);
if (status < 0)
warning_printf("Could not write to tty device");
fsync(fd);
/* Update transmit statistics */
tx_total++;
/* Insert output delay */
delay(option.output_delay);
}
}
/* Save previous key */
previous_char = input_char;
}
else
{
forward = socket_handle_input(&rdfs, &output_char);
}
if (forward)
{
/* Map output character */
if ((output_char == 127) && (map_o_del_bs))
output_char = '\b';
if ((output_char == '\r') && (map_o_cr_nl))
output_char = '\n';
/* Map newline character */
if ((output_char == '\n' || output_char == '\r') && (map_o_nl_crnl)) {
const char *crlf = "\r\n";
optional_local_echo(crlf[0]);
optional_local_echo(crlf[1]);
status = write(fd, crlf, 2);
if (status < 0)
warning_printf("Could not write to tty device");
tx_total += 2;
delay(option.output_delay);
} else
{
/* Send output to tty device */
optional_local_echo(output_char);
status = write(fd, &output_char, 1);
if (status < 0)
warning_printf("Could not write to tty device");
fsync(fd);
/* Update transmit statistics */
tx_total++;
/* Insert output delay */
delay(option.output_delay);
}
}
} else if (status == -1)
{
error_printf("Error: select() failed (%s)", strerror(errno));