In my program, when I was trying to close the master file descriptor, suddenly my program got crashed and I haven't seen any cores. Could someone help me with this? I am providing the code that I have used. This is the code I copied from the internet(http://www.rkoucha.fr/tech_corner/pty_pdip.html), The only difference is that instead of fork I spawn a thread. I know some small info I miss. Could someone please shed the light?
Thanks in advance!!!
int ScalingCommandReceiver::execute_ptcoi_commands_sequence(const char * bc_name, std::vector<cmd_output_pair>& cmd_seq, std::string& output_str)
{
int fdm, fds;
int rc;
output_str.clear();
fdm = posix_openpt(O_RDWR);
if (fdm < 0)
{
output_str.append("Error on posix_openpt() \n");
return -1;
}
rc = grantpt(fdm);
if (rc != 0)
{
output_str.append("Error on grantpt() \n");
close(fdm);
return -1;
}
rc = unlockpt(fdm);
if (rc != 0)
{
output_str.append("Error on unlockpt() \n");
close(fdm);
return -1;
}
// Open the slave side ot the PTY
fds = open(ptsname(fdm), O_RDWR);
if (fds < 0)
{
output_str.append("Error on posix_openpt() \n");
close(fdm);
return -1;
}
std::string cp_name ("bc3");
pt_session_struct *file_refs = NULL;
file_refs = (pt_session_struct*) ::malloc(sizeof(pt_session_struct));
if (file_refs == NULL) {
output_str.append("ERROR: Failed to create the struct info for the thread! \n");
close(fdm);
close(fds);
return -1;
}
file_refs->fds = fds;
file_refs->cp_name = (char*)bc_name;
//Spawn a thread
if (ACE_Thread::spawn(ptcoi_command_thread, file_refs, THR_DETACHED) < 0) {
output_str.append("ERROR: Failed to start ptcoi_command_thread thread! \n");
close(fdm);
close(fds);
::free(file_refs);
return -1;
}
int i = 0;
while (i <= cmd_seq_dim)
{
char buffer[4096] = {'\0'};
ssize_t bytes_read = 0;
int read_res = 0;
do
{
// get the output in buffer
if((read_res = read(fdm, (buffer + bytes_read), sizeof(buffer))) > 0)
{
// The number of bytes read is returned and the file position is advanced by this number.
// Let's advance also buffer position.
bytes_read += read_res;
}
}
while((read_res > 0) && !strchr(buffer, cpt_prompt) && (std::string(buffer).find(ptcoi_warning) == std::string::npos));
if (bytes_read > 0) // No error
{
// Send data on standard output or wherever you want
//Do some operations here
}
else
{
output_str.append("\nFailed to read from master PTY \n");
}
if(i < cmd_seq_dim)
{
// Send data on the master side of PTY
write(fdm, cmd_seq[i].first.c_str(), cmd_seq[i].first.length());
}
++i;
} // End while
if(/*have some internal condition*/)
{
close(fdm); //Here I observe the crash :-(
return 0; // OK
}
else
{
output_str.append ("\nCPT printouts not expected.\n");
close(fdm);
return -1; // Failure
}
close(fdm);
return 0; // OK
}
ACE_THR_FUNC_RETURN ScalingCommandReceiver::ptcoi_command_thread(void* ptrParam)
{
pt_session_struct* fd_list = (pt_session_struct*) ptrParam;
struct termios slave_orig_term_settings; // Saved terminal settings
struct termios new_term_settings; // Current terminal settings
int fds = fd_list->fds;
char* cp_name = fd_list->cp_name;
::free (fd_list);
// Save the defaults parameters of the slave side of the PTY
tcgetattr(fds, &slave_orig_term_settings);
// Set RAW mode on slave side of PTY
new_term_settings = slave_orig_term_settings;
cfmakeraw (&new_term_settings);
tcsetattr (fds, TCSANOW, &new_term_settings);
int stdinCopy, stdoutCopy, stdErr;
stdinCopy = dup (0);
stdoutCopy = dup (1);
stdErr = dup (2);
// The slave side of the PTY becomes the standard input and outputs of the child process
close(0); // Close standard input (current terminal)
close(1); // Close standard output (current terminal)
close(2); // Close standard error (current terminal)
dup(fds); // PTY becomes standard output (0)
dup(fds); // PTY becomes standard output (1)
dup(fds); // PTY becomes standard error (2)
// Now the original file descriptor is useless
close(fds);
// Make the current process a new session leader
//setsid();
// As the child is a session leader, set the controlling terminal to be the slave side of the PTY
// (Mandatory for programs like the shell to make them manage correctly their outputs)
ioctl(0, TIOCSCTTY, 1);
// Execution of the program
char PTCOI [64] = {0};
snprintf(PTCOI, sizeof(PTCOI), "/opt/ap/mas/bin/mas_cptaspmml PTCOI -cp %s -echo 7", cp_name);
system(PTCOI); //my command
close(0); // Close standard input (current terminal)
close(1); // Close standard output (current terminal)
close(2); // Close standard error (current terminal)
dup2 (stdinCopy, 0);
dup2 (stdoutCopy, 1);
dup2 (stdErr, 2);
close (stdinCopy);
close (stdoutCopy);
close (stdErr);
return 0;
}
