/**
* Redirección de la E/S estándar.
* Esta función se llama por el BSP antes de llamar a main, y una vez que se
* han inicializado los dispositivos, para fijar la E/S estándar del sistema,
* que por defecto está asignada a /dev/null.
* @param stdin_dev Nombre del dispositivo que se usará para la entrada estándar
* @param stdout_dev Nombre del dispositivo que se usará para la salida estándar
* @param stderr_dev Nombre del dispositivo que se usará para el error estándar
*/
static void bsp_io_redirect(const char* stdin_dev, const char* stdout_dev, const char* stderr_dev)
{
/* Redireccionamos la E/S estándar */
redirect_fd (STDIN_FILENO, stdin_dev, O_RDONLY, 0777);
redirect_fd (STDOUT_FILENO, stdout_dev, O_WRONLY, 0777);
redirect_fd (STDERR_FILENO, stderr_dev, O_WRONLY, 0777);
}
int daemonize() {
pid_t pid;
/* Fork once to ensure we aren't the process group leader */
pid = fork();
if (pid < 0) {
guacd_log_error("Could not fork() parent: %s", strerror(errno));
return 1;
}
/* Exit if we are the parent */
if (pid > 0) {
guacd_log_info("Exiting and passing control to PID %i", pid);
_exit(0);
}
/* Start a new session (if not already group leader) */
setsid();
/* Fork again so the session group leader exits */
pid = fork();
if (pid < 0) {
guacd_log_error("Could not fork() group leader: %s", strerror(errno));
return 1;
}
/* Exit if we are the parent */
if (pid > 0) {
guacd_log_info("Exiting and passing control to PID %i", pid);
_exit(0);
}
/* Change to root directory */
if (chdir(GUACD_ROOT) < 0) {
guacd_log_error(
"Unable to change working directory to "
GUACD_ROOT);
return 1;
}
/* Reopen the 3 stdxxx to /dev/null */
if (redirect_fd(STDIN_FILENO, O_RDONLY)
|| redirect_fd(STDOUT_FILENO, O_WRONLY)
|| redirect_fd(STDERR_FILENO, O_WRONLY)) {
guacd_log_error(
"Unable to redirect standard file descriptors to "
GUACD_DEV_NULL);
return 1;
}
/* Success */
return 0;
}
// Execute cmd. Never returns.
void
runcmd(struct cmd *cmd)
{
int p[2], r, old_fd;
struct execcmd *ecmd;
struct pipecmd *pcmd;
struct redircmd *rcmd;
if(cmd == 0)
exit(0);
switch(cmd->type){
default:
fprintf(stderr, "unknown runcmd\n");
exit(-1);
case ' ':
ecmd = (struct execcmd*)cmd;
if(ecmd->argv[0] == 0)
exit(0);
// fprintf(stderr, "exec not implemented\n");
// Your code here ...
// yeli: print all arguments
#if 0
int idx = 0;
for (idx = 0; idx < MAXARGS; ++idx)
{
if (0 == ecmd->argv[idx])
break;
fprintf(stdout,"argv %d: %s\n", idx, ecmd->argv[idx]);
}
#endif
if (-1 == execvp(ecmd->argv[0], ecmd->argv))
fprintf(stderr, "failed to exec %s\n", ecmd->argv[0]);
break;
case '>':
case '<':
rcmd = (struct redircmd*)cmd;
// fprintf(stderr, "redir not implemented\n");
// Your code here ...
int file_fd = open(rcmd->file, rcmd->mode);//open file
if (-1 == file_fd)
{
fprintf(stderr, "fail to open file %s\n", rcmd->file);
break;
}
old_fd = redirect_fd(file_fd, rcmd->fd);//old_fd point to stdin file
if (-1 == old_fd)
{
fprintf(stderr, "fail to redirect %d to file %s\n", rcmd->fd, rcmd->file);
}
else
{
runcmd(rcmd->cmd);
file_fd = redirect_fd(old_fd, rcmd->fd);
}
close(file_fd);
break;
case '|':
pcmd = (struct pipecmd*)cmd;
// fprintf(stderr, "pipe not implemented\n");
// Your code here ...
int fds[2];
pipe(fds);
int pid = fork();
if (0 < pid)
{
//child, fds[0] for read, redirect it to stdin
close(fds[1]);
old_fd = redirect_fd(fds[0], STDIN_FILENO);
runcmd(pcmd->right);
fds[0] = redirect_fd(old_fd, STDIN_FILENO);
close(fds[0]);
}
else
{
//father, fds[1] for write, redirect it to stdout
close(fds[0]);
redirect_fd(fds[1], STDOUT_FILENO);
runcmd(pcmd->left);
fds[1] = redirect_fd(old_fd, STDOUT_FILENO);
close(fds[1]);
}
break;
}
exit(0);
}