1 files changed, 106 insertions, 0 deletions
diff --git a/toys/net/microcom.c b/toys/net/microcom.c
new file mode 100644
index 00000000..d34e1fee
--- /dev/null
+++ b/toys/net/microcom.c
@@ -0,0 +1,106 @@
+/* microcom.c - Simple serial console.
+ *
+ * Copyright 2017 The Android Open Source Project.
+
+USE_MICROCOM(NEWTOY(microcom, "<1>1s:X", TOYFLAG_BIN))
+
+config MICROCOM
+  bool "microcom"
+  default y
+  help
+    usage: microcom [-s SPEED] [-X] DEVICE
+
+    Simple serial console.
+
+    -s  Set baud rate to SPEED
+    -X  Ignore ^@ (send break) and ^] (exit).
+*/
+
+#define FOR_microcom
+#include "toys.h"
+
+GLOBALS(
+  char *s;
+
+  int fd;
+  struct termios original_stdin_state, original_fd_state;
+)
+
+// Puts `fd` into raw mode, setting the baud rate if `speed` != 0,
+// and saving the original terminal state.
+static void xraw(int fd, const char *name, speed_t speed,
+                 struct termios *original)
+{
+  struct termios t;
+
+  if (tcgetattr(fd, &t)) perror_exit("tcgetattr %s", name);
+  *original = t;
+
+  cfmakeraw(&t);
+  if (speed) cfsetspeed(&t, speed);
+
+  if (tcsetattr(fd, TCSAFLUSH, &t)) perror_exit("tcsetattr %s", name);
+}
+
+static void restore_states(int i)
+{
+  tcsetattr(0, TCSAFLUSH, &TT.original_stdin_state);
+  tcsetattr(TT.fd, TCSAFLUSH, &TT.original_fd_state);
+}
+
+void microcom_main(void)
+{
+  int speeds[] = {50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
+                  4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
+                  500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
+                  2500000, 3000000, 3500000, 4000000};
+  struct pollfd fds[2];
+  int i, speed;
+
+  if (!TT.s) speed = 115200;
+  else speed = atoi(TT.s);
+
+  // Find speed in table, adjust to constant
+  for (i = 0; i < ARRAY_LEN(speeds); i++) if (speeds[i] == speed) break;
+  if (i == ARRAY_LEN(speeds)) error_exit("unknown speed: %s", TT.s);
+  speed = i+1+4081*(i>15);
+
+  // Open with O_NDELAY, but switch back to blocking for reads.
+  TT.fd = xopen(*toys.optargs, O_RDWR | O_NOCTTY | O_NDELAY);
+  if (-1==(i = fcntl(TT.fd, F_GETFL, 0)) || fcntl(TT.fd, F_SETFL, i&~O_NDELAY))
+    perror_exit_raw(*toys.optargs);
+
+  // Set both input and output to raw mode.
+  xraw(TT.fd, "fd", speed, &TT.original_fd_state);
+  xraw(0, "stdin", 0, &TT.original_stdin_state);
+  // ...and arrange to restore things, however we may exit.
+  sigatexit(restore_states);
+
+  fds[0].fd = TT.fd;
+  fds[0].events = POLLIN;
+  fds[1].fd = 0;
+  fds[1].events = POLLIN;
+
+  while (poll(fds, 2, -1) > 0) {
+    char buf[BUFSIZ];
+
+    // Read from connection, write to stdout.
+    if (fds[0].revents) {
+      ssize_t n = read(TT.fd, buf, sizeof(buf));
+      if (n > 0) xwrite(0, buf, n);
+      else break;
+    }
+
+    // Read from stdin, write to connection.
+    if (fds[1].revents) {
+      if (read(0, buf, 1) != 1) break;
+      if (!(toys.optflags & FLAG_X)) {
+        if (!*buf) {
+          tcsendbreak(TT.fd, 0);
+          continue;
+        } else if (*buf == (']'-'@')) break;
+      }
+      xwrite(TT.fd, buf, 1);
+    }
+  }
+}