From f0911e20b10fe2bfc221dba824f60c185e49a13f Mon Sep 17 00:00:00 2001
From: Bernhard Tittelbach <xro@realraum.at>
Date: Wed, 3 Mar 2010 03:12:27 +0000
Subject: [PATCH] small serial console utility that can hopefully run on
 embedded systems

---
 serial_console/serial.c |  174 +++++++++++++++++++++++++++++++++++++++++++++++
 serial_console/serial.h |   12 ++++
 2 files changed, 186 insertions(+)
 create mode 100644 serial_console/serial.c
 create mode 100644 serial_console/serial.h

diff --git a/serial_console/serial.c b/serial_console/serial.c
new file mode 100644
index 0000000..47044f3
--- /dev/null
+++ b/serial_console/serial.c
@@ -0,0 +1,174 @@
+#include "serial.h"
+
+
+int setup_tty(int fd)
+{
+  struct termios tmio;
+  
+  int ret = tcgetattr(fd, &tmio);
+  if(ret) {
+    fprintf(stderr, "Error on tcgetattr(): %s", strerror(errno));
+    return ret;
+  }
+
+  ret = cfsetospeed(&tmio, B9600);
+  if(ret) {
+    fprintf(stderr, "Error on cfsetospeed(): %s", strerror(errno));
+    return ret;
+  }
+
+  ret = cfsetispeed(&tmio, B9600);
+  if(ret) {
+    fprintf(stderr, "Error on cfsetispeed(): %s", strerror(errno));
+    return ret;
+  }
+
+  tmio.c_lflag &= ~ECHO;
+
+  ret = tcsetattr(fd, TCSANOW, &tmio);
+  if(ret) {
+    fprintf(stderr, "Error on tcsetattr(): %s", strerror(errno));
+    return ret;
+  }
+  
+  ret = tcflush(fd, TCIFLUSH);
+  if(ret) {
+    fprintf(stderr, "Error on tcflush(): %s", strerror(errno));
+    return ret;
+  }
+
+  fd_set fds;
+  struct timeval tv;
+  FD_ZERO(&fds);
+  FD_SET(fd, &fds);
+  tv.tv_sec = 0;
+  tv.tv_usec = 50000;
+  for(;;) {
+    ret = select(fd+1, &fds, NULL, NULL, &tv);
+    if(ret > 0) {
+      char buffer[100];
+      ret = read(fd, buffer, sizeof(buffer));
+    }
+    else
+      break;
+  }
+
+  return 0;
+}
+
+
+int set_tty_raw(int fd, struct termios *termios_prev)
+{
+  struct termios tmio;
+  
+  int ret = tcgetattr(fd, &tmio);
+  if(ret) {
+    fprintf(stderr, "Error on tcgetattr(): %s", strerror(errno));
+    return ret;
+  }
+  
+  memcpy(termios_prev, &tmio,sizeof(struct termios));
+  
+  cfmakeraw(&tmio);
+  
+  ret = tcsetattr(fd, TCSANOW, &tmio);
+  if(ret) {
+    fprintf(stderr, "Error on tcsetattr(): %s", strerror(errno));
+    return ret;
+  }  
+  
+  fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK);
+  
+  return 0;
+}
+
+int restore_tty(int fd, struct termios  *termios_prev)
+{
+  int ret = tcsetattr(fd, TCSANOW, termios_prev);
+  if(ret) {
+    fprintf(stderr, "Error on tcsetattr(): %s", strerror(errno));
+    return ret;
+  }
+}
+
+void  connect_terminal(int door_fd)
+{
+  if (door_fd < 3)
+    return;
+  fd_set fds_r;
+  char buffer[256];
+  int num_byte=0;
+  FD_ZERO(&fds_r);
+
+  FD_SET(STDIN_FILENO,&fds_r);
+  FD_SET(door_fd,&fds_r);
+  while (select(door_fd+1,&fds_r,0,0,0) > 0)
+  {
+    if (FD_ISSET(door_fd,&fds_r))
+    {
+      if (num_byte = read(door_fd,buffer, 1) > 0)
+      {
+        write(STDOUT_FILENO,buffer,num_byte);
+      }
+      if (num_byte == 0 || (num_byte <0 && errno != EAGAIN))
+        return;
+    }    
+    if (FD_ISSET(STDIN_FILENO,&fds_r))
+    {
+      while(num_byte = read(STDIN_FILENO,buffer, 256) > 0)
+      {
+        write(door_fd,buffer,num_byte);
+      }
+      if (num_byte <0 && errno != EAGAIN)
+        return;
+    }
+    
+    FD_SET(STDIN_FILENO,&fds_r);
+    FD_SET(door_fd,&fds_r);
+  }
+}
+
+int main(int argc, char* argv[])
+{
+  int ret = 0;
+  int door_fd = 0;
+  struct termios tmio_prev;
+  
+  for(;;) 
+  {
+    door_fd = open(door_dev_, O_RDWR | O_NONBLOCK); // | O_NOCTTY
+    if(door_fd < 0)
+      ret = 2;
+    else {
+      ret = setup_tty(door_fd);
+      if(ret)
+        ret = 2;
+      else
+      {
+        ret = set_tty_raw(STDIN_FILENO,&tmio_prev);
+        if (ret)
+          break;
+        
+        connect_terminal(door_fd);
+        
+        ret = restore_tty(STDIN_FILENO,&tmio_prev);
+        if (ret)
+          break;        
+      }
+    }
+
+    if (ret == 2) {
+      fprintf(stderr, "%s error, trying to reopen in 5 seconds..", door_dev_);
+      if(door_fd > 0)
+        close(door_fd);
+      sleep(5);
+    }
+    else
+      break;
+  }
+
+  if(door_fd > 0)
+    close(door_fd);
+  return(ret);
+}
+
diff --git a/serial_console/serial.h b/serial_console/serial.h
new file mode 100644
index 0000000..8056131
--- /dev/null
+++ b/serial_console/serial.h
@@ -0,0 +1,12 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <termios.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/select.h>
+
+char const *door_dev_="/dev/ttyUSB0";
+
-- 
1.7.10.4