void doExec (char *p, int oargc, char **oargv, int first) {
char *argv[ARGVMAX];
int argc;
closeAllPipes();
parseArgs (p, &argc, argv);
if (first) {
appendArgs (argc, argv, oargc, oargv);
}
argc = 0;
if (execvp (argv[0], argv) < 0)
quit ("exec failed");
}
int main() {
//Set up to ignore SIGINT and SIGQUIT
struct sigaction newact, oldact;
newact.sa_handler = SIG_IGN;
sigaction(SIGINT, &newact, &oldact);
sigaction(SIGQUIT, &newact, &oldact);
while(1) {
char* prompt = setPromptString();
printf("%s", prompt);
char* input_string = getInputString();
//Initialize array to hold commands
size_t commands_alloc_size = COMMANDS_INITIAL_SIZE;
int num_commands = 0;
command* commands = malloc(sizeof(command) * commands_alloc_size);
fillCommandArray(input_string, &commands, &num_commands, &commands_alloc_size);
bool wasShellCommand = handleShellCommand(commands[0]);
if (wasShellCommand == false) {
int** fds = createPipes(num_commands);
for (int i = 0; i < num_commands; ++i) {
pid_t fork_pid = fork();
if (fork_pid == -1) {
perror("Fork failed");
exit(1);
}
//Child process
else if (fork_pid == 0) {
sigaction(SIGINT, &oldact, NULL);
sigaction(SIGQUIT, &oldact, NULL);
executeCommand(fds, num_commands, commands[i], i);
}
}
//Clean up the shell process
closeAllPipes(fds, num_commands);
waitForAllChildProcesses(num_commands);
freeCommandArray(commands, num_commands);
}
}
return 0;
}
/*
Execute command while taking pipes into account
Input:
fds: an array to 2-int array file descriptors
num_commands: the number of commands
index: the current index of the command in the pipe chain
*/
void executeCommand(int** fds, int num_commands, command cmd, int index) {
//close stdin, duplicate previous command's pipe input to stdin
//except when this is first command
if (index != 0) {
int prev_cmd_index = index - 1;
if (dup2(fds[prev_cmd_index][0], 0) == -1) {
perror("dup2(fds[prev_cmd_index][0], 0) failed");
exit(1);
}
}
//Handle input redirection
else if (index == 0 && cmd.input_redirect_filename != NULL) {
int input_fd = open(cmd.input_redirect_filename, O_RDONLY);
if (input_fd == -1) {
perror("open input file failed");
exit(1);
}
if (dup2(input_fd, 0) == -1) {
perror("dup2(input_fd, 0) failed");
exit(1);
}
}
//close stdout, duplicate current pipe output to stdout
//except when this is the last command
if (index != (num_commands - 1)) {
if (dup2(fds[index][1], 1) == -1) {
perror("dup2(fds[index][1], 1) failed");
exit(1);
}
}
//Handle output redirection
else if (index == (num_commands - 1) && cmd.output_redirect_filename != NULL) {
int output_fd;
//Open file if it already exists
if (fileExists(cmd.output_redirect_filename) == true) {
if (cmd.output_append_flag == true) {
output_fd = open(cmd.output_redirect_filename, O_WRONLY | O_APPEND);
}
else {
output_fd = open(cmd.output_redirect_filename, O_WRONLY | O_TRUNC);
}
}
//Create file if it doesn't exist
else {
output_fd = open(cmd.output_redirect_filename, O_WRONLY | O_CREAT, 0777);
}
if (output_fd == -1) {
perror("open output file failed");
exit(1);
}
if (dup2(output_fd, 1) == -1) {
perror("dup2(output_fd, 1) failed");
exit(1);
}
}
closeAllPipes(fds, num_commands);
execvp(cmd.argv[0], cmd.argv);
perror("Command execution failed");
exit(1);
}