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-rw-r--r--util-linux/microcom.c135
1 files changed, 135 insertions, 0 deletions
diff --git a/util-linux/microcom.c b/util-linux/microcom.c
new file mode 100644
index 000000000..f6f8e07f6
--- /dev/null
+++ b/util-linux/microcom.c
@@ -0,0 +1,135 @@
+/* microcom.c
+ *
+ * bare bones 'talk to modem' program - similar to 'cu -l $device'
+ * inspired by mgetty's microcom
+ *
+ */
+#include "busybox.h"
+
+int microcom_main(int argc, char **argv);
+int microcom_main(int argc, char **argv)
+{
+ struct pollfd pfd[2];
+#define sfd (pfd[1].fd)
+ char *device_lock_file = NULL;
+ const char *s;
+ const char *opt_s = "9600";
+ unsigned speed;
+ int len;
+ int exitcode = 1;
+ struct termios tio0, tiosfd, tio;
+
+ getopt32(argv, "s:", &opt_s);
+ argc -= optind;
+ argv += optind;
+ if (!argv[0])
+ bb_show_usage();
+ speed = xatou(opt_s);
+
+ // try to create lock file in /var/lock
+ s = bb_basename(argv[0]);
+ if (!s[0]) {
+ errno = ENODEV;
+ bb_perror_msg_and_die("can't lock device");
+ }
+ device_lock_file = xasprintf("/var/lock/LCK..%s", s);
+ sfd = open(device_lock_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
+ if (sfd < 0) {
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(device_lock_file);
+ device_lock_file = NULL;
+ if (errno == EEXIST)
+ bb_perror_msg_and_die("can't lock device");
+ // We don't abort on other errors: /var/lock can be
+ // non-writable or non-existent
+ } else {
+ // %4d to make mgetty happy. It treats 4-bytes lock files as binary,
+ // not text, PID. Making 5+ char file. Brrr...
+ s = xasprintf("%4d\n", getpid());
+ write(sfd, s, strlen(s));
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free((char*)s);
+ close(sfd);
+ }
+
+ // open device
+ sfd = open(argv[0], O_RDWR | O_NDELAY);
+ if (sfd < 0) {
+ bb_perror_msg("can't open device");
+ goto unlock_and_exit;
+ }
+ fcntl(sfd, F_SETFL, O_RDWR); // why?
+
+ // put stdin to "raw mode", handle one character at a time
+ tcgetattr(STDIN_FILENO, &tio0);
+ tio = tio0;
+ tio.c_lflag &= ~(ICANON|ECHO);
+ tio.c_iflag &= ~(IXON|ICRNL);
+ tio.c_oflag &= ~(ONLCR);
+ tio.c_cc[VMIN] = 1;
+ tio.c_cc[VTIME] = 0;
+ if (tcsetattr(STDIN_FILENO, TCSANOW, &tio)) {
+ bb_perror_msg("can't tcsetattr for %s", "stdin");
+ goto unlock_and_exit;
+ }
+
+ /* same thing for modem (plus: set baud rate) - TODO: make CLI option */
+ tcgetattr(sfd, &tiosfd);
+ tio = tiosfd;
+ tio.c_lflag &= ~(ICANON|ECHO);
+ tio.c_iflag &= ~(IXON|ICRNL);
+ tio.c_oflag &= ~(ONLCR);
+ tio.c_cc[VMIN] = 1;
+ tio.c_cc[VTIME] = 0;
+ cfsetispeed(&tio, tty_value_to_baud(speed));
+ cfsetospeed(&tio, tty_value_to_baud(speed));
+ if (tcsetattr(sfd, TCSANOW, &tio)) {
+ bb_perror_msg("can't tcsetattr for %s", "device");
+ goto unlock_and_exit;
+ }
+
+ // disable SIGINT
+ signal(SIGINT, SIG_IGN);
+
+ // drain stdin
+ tcflush(STDIN_FILENO, TCIFLUSH);
+ printf("connected to '%s' (%d bps), exit with ctrl-X...\r\n", argv[0], speed);
+
+ // main loop: check with poll(), then read/write bytes across
+ pfd[0].fd = STDIN_FILENO;
+ pfd[0].events = POLLIN;
+ /*pfd[1].fd = sfd;*/
+ pfd[1].events = POLLIN;
+ while (1) {
+ int i;
+ while (-1 == poll(pfd, 2, -1) && EINTR == errno)
+ continue;
+ for (i = 0; i < 2; ++i) {
+ if (pfd[i].revents & POLLIN) {
+ len = read(pfd[i].fd, bb_common_bufsiz1, COMMON_BUFSIZE);
+ if (len > 0) {
+ if (!i && 24 == bb_common_bufsiz1[0])
+ goto done; // ^X exits
+ write(pfd[1-i].fd, bb_common_bufsiz1, len);
+ }
+ }
+ }
+ }
+ done:
+ tcsetattr(sfd, TCSANOW, &tiosfd);
+ tcsetattr(STDIN_FILENO, TCSANOW, &tio0);
+ tcflush(STDIN_FILENO, TCIFLUSH);
+
+ if (ENABLE_FEATURE_CLEAN_UP)
+ close(sfd);
+ exitcode = 0;
+
+ unlock_and_exit:
+ // delete lock file
+ if (device_lock_file) {
+ unlink(device_lock_file);
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(device_lock_file);
+ }
+ return exitcode;
+}