void resulthandler<T>::operator=(std::string text)
{
set_exitstatus(text);
}
////
// main
//
// The main function to the shell program.
//
int main (int argc, char **argv) {
(void) argc;
// variables
set_execname (argv[0]);
// loop until user exits
while (TRUE) { // repeat until user exits the shell
char cmdline[1025]; // will only accept 1024
bzero (cmdline, 1025);
char parsebuffer[2024];
bzero (parsebuffer, 2024);
char *tokens[512];
int toknum = 0;
// bool pipein = FALSE;
// bool pipeout = FALSE;
print_prompt(); // print the prompt
// get up to 1024 chars from the user
if (get_cmdline (cmdline) == FALSE) continue;
// break the line into tokens
if (parseline (cmdline, parsebuffer, tokens, &toknum)) {
// parseline returned an error
eprintf ("%s: %s\n", "Error",
"parsing error caused by incorrect usage");
continue;
}
// Check if the user wishes to exit the shell
if (check_exit (tokens, toknum)) exit (get_exitstatus());
// set the number of commands to be executed
int numcmds = set_numofcmds (tokens, toknum);
// the number of commands should not exceed 20
if (numcmds > 20) {
eprintf ("%s: %s\n", "ERROR", "cannot handle more than 20 commands");
continue;
}
// initialize the current start index of the tokens
int curstart;
int nextstart = 0;
int fd[2];
// int fdin[2];
// int fdout[2];
// loop fork-exec for each command
int i;
for (i = 0; i < numcmds && nextstart < toknum; ++i) {
// setup current command, update current start, and determine pipe
curstart = nextstart;
char *command = set_command (tokens, toknum, &nextstart);
// a null command will cause an error
if (command == NULL || command[0] == '\0') {
eprintf ("%s: %s\n", "FATAL ERROR", "encountered a null command");
break;
}
// make a new argv
int newargc = get_newargc (tokens, curstart, nextstart);
char *newargv[newargc + 1];
newargv[0] = command;
newargv[newargc] = NULL;
int j = 1;
int k;
for (k = curstart; k < nextstart && j < newargc; ++k) {
if (tokens[k][0] == '1') {
newargv[j] = &tokens[k][1];
++j;
}
}
/* // set pipe
pipeout = checktopipe (tokens, curstart, nextstart);
if (pipein) {
fdin[0] = fdout[0];
fdin[1] = fdout[1];
}
if (pipeout) {
pipe (fdout);
}
*/
// set redirection
char *input_redirect = get_redirectarg (tokens, curstart, nextstart, '<');
char *output_redirect = get_redirectarg (tokens, curstart, nextstart, '>');
if (input_redirect != NULL) {
// open file and set file descriptor
fd[0] = open (input_redirect, O_RDONLY, 0755);
}
if (output_redirect != NULL) {
// open file and set file descriptor
fd[1] = open (output_redirect, O_CREAT | O_WRONLY | O_TRUNC, 0644);
}
// fork child process
int status = 0;
int pid = fork();
if (pid != 0) {
/* this is the PARENT PROCESS */
/* // write to pipe from parent to child
if (pipein) {
close (fdin[0]);
if (dup2 (fdin[1], STDOUT_FILENO) == -1)
eprintf ("%s: %s\n", "ERROR",
"could not open and write to pipe from parent to child");
close (fdin[1]);
pipein = FALSE;
}
*/
// wait for any child process to finish
int waitstatus = waitpid (-1, &status, 0);
/* // read pipe from child to parent
if (pipeout) {
close (fdout[1]);
if (dup2 (fdout[0], STDIN_FILENO) == -1)
eprintf ("%s: %s\n", "ERROR",
"could not open and read pipe from child to parent");
pipein = TRUE;
}
*/ // close the file descriptors caused by redirection
// close stdin
if (input_redirect != NULL) close (fd[0]);
// close stdout
if (output_redirect != NULL) close (fd[1]);
// determine errors
if (waitstatus == 0) {
eprintf ("%s: %s\n", "ERROR", "error waiting on child process");
break;
}else if (waitstatus == -1) {
eprintf ("%s: %s\n", "ERROR", "error executing child process");
break;
}
if (status != 0) {
eprintf ("%s: %s: %s %d\n", "ERROR", command, "exit status of", status);
break;
}
}else {
/* this is the CHILD PROCESS */
// set up pipe in from a previous command
/* if (pipein) {
close (fdin[1]);
if (dup2 (fdin[0], STDIN_FILENO) == -1)
eprintf ("%s: %s\n", "ERROR",
"could not open and write to pipe from child to parent");
close (fdin[0]);
}
// set up pipe out to the next command
if (pipeout) {
close (fdout[0]);
if (dup2 (fdout[1], STDOUT_FILENO) == -1)
eprintf ("%s: %s\n", "ERROR",
"could not open and write to pipe from child to parent");
}
*/
// set up redirection
if (input_redirect != NULL) {
// open file and set file descriptor
// set file to stdin
if (dup2 (fd[0], STDIN_FILENO) == -1)
eprintf ("%s: %s \"%s\" %s\n", "ERROR", "could not open",
input_redirect, "for input redirection");
}
if (output_redirect != NULL) {
// open file and set file descriptor
// set stdout to file
if (dup2 (fd[1], STDOUT_FILENO) == -1)
eprintf ("%s: %s \"%s\" %s\n", "ERROR", "could not open",
output_redirect, "for output redirection");
}
// execute the command
set_exitstatus (execvp (command, newargv));
// if there was an error executing the command
eprintf ("%s: %s: %s\n", "ERROR", command, "could not execute");
return (get_exitstatus());
}
}
}
return get_exitstatus();
}
void resulthandler<T>::operator=(const int id)
{
set_exitstatus(id);
}
