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1 /* microcom.c - Simple serial console.
2  *
3  * Copyright 2017 The Android Open Source Project.
4 
5 USE_MICROCOM(NEWTOY(microcom, "<1>1s:X", TOYFLAG_USR|TOYFLAG_BIN))
6 
7 config MICROCOM
8   bool "microcom"
9   default y
10   help
11     usage: microcom [-s SPEED] [-X] DEVICE
12 
13     Simple serial console.
14 
15     -s	Set baud rate to SPEED
16     -X	Ignore ^@ (send break) and ^] (exit)
17 */
18 
19 #define FOR_microcom
20 #include "toys.h"
21 
GLOBALS(char * s;int fd;struct termios original_stdin_state,original_fd_state;)22 GLOBALS(
23   char *s;
24 
25   int fd;
26   struct termios original_stdin_state, original_fd_state;
27 )
28 
29 // TODO: tty_sigreset outputs ansi escape sequences, how to disable?
30 static void restore_states(int i)
31 {
32   tcsetattr(0, TCSAFLUSH, &TT.original_stdin_state);
33   tcsetattr(TT.fd, TCSAFLUSH, &TT.original_fd_state);
34 }
35 
microcom_main(void)36 void microcom_main(void)
37 {
38   struct pollfd fds[2];
39   int i, speed;
40 
41   if (!TT.s) speed = 115200;
42   else speed = atoi(TT.s);
43 
44   // Open with O_NDELAY, but switch back to blocking for reads.
45   TT.fd = xopen(*toys.optargs, O_RDWR | O_NOCTTY | O_NDELAY);
46   if (-1==(i = fcntl(TT.fd, F_GETFL, 0)) || fcntl(TT.fd, F_SETFL, i&~O_NDELAY))
47     perror_exit_raw(*toys.optargs);
48 
49   // Set both input and output to raw mode.
50   xset_terminal(TT.fd, 1, speed, &TT.original_fd_state);
51   set_terminal(0, 1, 0, &TT.original_stdin_state);
52   // ...and arrange to restore things, however we may exit.
53   sigatexit(restore_states);
54 
55   fds[0].fd = TT.fd;
56   fds[0].events = POLLIN;
57   fds[1].fd = 0;
58   fds[1].events = POLLIN;
59 
60   while (poll(fds, 2, -1) > 0) {
61     char buf[BUFSIZ];
62 
63     // Read from connection, write to stdout.
64     if (fds[0].revents) {
65       ssize_t n = read(TT.fd, buf, sizeof(buf));
66       if (n > 0) xwrite(0, buf, n);
67       else break;
68     }
69 
70     // Read from stdin, write to connection.
71     if (fds[1].revents) {
72       if (read(0, buf, 1) != 1) break;
73       if (!(toys.optflags & FLAG_X)) {
74         if (!*buf) {
75           tcsendbreak(TT.fd, 0);
76           continue;
77         } else if (*buf == (']'-'@')) break;
78       }
79       xwrite(TT.fd, buf, 1);
80     }
81   }
82 }
83