spike_main/xspike.cc

   1 // See LICENSE for license details.
   2
   3 // xspike forks an xterm for spike's target machine console,
   4 // preserving the current terminal for debugging.
   5
   6 #include <unistd.h>
   7 #include <fcntl.h>
   8 #include <signal.h>
   9 #include <sys/wait.h>
  10 #include <cstdio>
  11 #include <climits>
  12 #include <cstring>
  13 #include <stdexcept>
  14
  15 static pid_t fork_spike(int tty_fd, int argc, char** argv);
  16 static pid_t fork_xterm(int* tty_fd);
  17
  18 int main(int argc, char** argv)
  19 {
  20   int tty_fd, wait_status, ret = -1;
  21   pid_t xterm, spike;
  22
  23   static bool signal_exit = false;
  24   auto handle_signal = [](int) { signal_exit = true; };
  25
  26   if ((xterm = fork_xterm(&tty_fd)) < 0)
  27   {
  28     fprintf(stderr, "could not open xterm\n");
  29     goto out;
  30   }
  31
  32   signal(SIGINT, handle_signal);
  33
  34   if ((spike = fork_spike(tty_fd, argc, argv)) < 0)
  35   {
  36     fprintf(stderr, "could not open spike\n");
  37     goto close_xterm;
  38   }
  39
  40   while ((ret = waitpid(spike, &wait_status, 0)) < 0)
  41     if (signal_exit)
  42       break;
  43
  44   if (ret < 0) // signal_exit
  45     kill(spike, SIGTERM);
  46   else
  47     ret = WIFEXITED(wait_status) ? WEXITSTATUS(wait_status) : -1;
  48
  49 close_xterm:
  50   kill(-xterm, SIGTERM);
  51 out:
  52   return ret;
  53 }
  54
  55 static pid_t fork_spike(int tty_fd, int argc, char** argv)
  56 {
  57   pid_t pid = fork();
  58   if (pid < 0)
  59     return -1;
  60
  61   if (pid == 0)
  62   {
  63     if (dup2(tty_fd, STDIN_FILENO) < 0 || dup2(tty_fd, STDOUT_FILENO) < 0)
  64       return -1;
  65     execvp("spike", argv);
  66     return -1;
  67   }
  68
  69   return pid;
  70 }
  71
  72 static pid_t fork_xterm(int* tty_fd)
  73 {
  74   static const char cmd[] = "3>&1 xterm -title xspike -e sh -c 'tty 1>&3; termios-xspike'";
  75
  76   int fds[2];
  77   if (pipe(fds) < 0)
  78     return -1;
  79
  80   pid_t pid = fork();
  81   if (pid < 0)
  82     return -1;
  83
  84   if (pid == 0)
  85   {
  86     setpgid(0, 0);
  87     if (dup2(fds[1], STDOUT_FILENO) < 0)
  88       return -1;
  89     execl("/bin/sh", "sh", "-c", cmd, NULL);
  90     return -1;
  91   }
  92
  93   char tty[PATH_MAX];
  94   ssize_t ttylen = read(fds[0], tty, sizeof(tty));
  95   if (ttylen <= 1 || tty[ttylen-1] != '\n')
  96     return -1;
  97   tty[ttylen-1] = '\0';
  98   if ((*tty_fd = open(tty, O_RDWR)) < 0)
  99     return -1;
 100
 101   return pid;
 102 }