void eval_line(const char* s) {
int type;
char* token;
// Your code here!
// build the command
command* c = command_alloc();
while ((s = parse_shell_token(s, &type, &token)) != NULL)
command_append_arg(c, token);
// execute it
if (c->argc)
run_list(c);
command_free(c);
}
void eval_command_line(const char* s, zombies* z) {
int type;
char* token;
// commandlist contains command groups separated by ';' or '&'
command** commandlist = (command**) malloc(sizeof(command*));
// keep track of how many command groups wehave
int listcontent = 1;
// Your code here!
// build the command
command* c = command_alloc();
// the first command group
commandlist[0] = c;
while ((s = parse_shell_token(s, &type, &token)) != NULL) {
if(type == TOKEN_CONTROL) {
// seeing a ';' means we have to make a new command group
if(token[0] == ';') {
c = command_alloc();
commandlist = (command**) realloc(commandlist, (listcontent + 1)*sizeof(command*));
commandlist[listcontent] = c;
++listcontent;
// seeing a '&' means we have to make a new command group
} else if(token[0] == '&' && !token[1]) {
c->background = 1;
c = command_alloc();
commandlist = (command**) realloc(commandlist, (listcontent + 1)*sizeof(command*));
commandlist[listcontent] = c;
++listcontent;
// putting into new command group so that we can conditionally evaluate it
} else if(token[0] == '&' && token[1] == '&') {
c = command_alloc();
c->needcondition = 0;
commandlist = (command**) realloc(commandlist, (listcontent + 1)*sizeof(command*));
commandlist[listcontent] = c;
++listcontent;
// within a command group, mark it as piping if seeing '|'
} else if(token[0] == '|' && !token[1]) {
c->piping = 1;
command_append_arg(c, type, token);
// putting into new command group so that we can conditionally evaluate it
} else if(token[0] == '|' && token[1] == '|') {
c = command_alloc();
c->needcondition = 1;
commandlist = (command**) realloc(commandlist, (listcontent + 1)*sizeof(command*));
commandlist[listcontent] = c;
++listcontent;
}
} else if(type == TOKEN_REDIRECTION) {
// redirecting standard input
if(token[0] == '<' || token[0] == '0') {
c->redirectstdin = 1;
// redirecting standard output
} else if(token[0] == '>' || token[0] == '1') {
c->redirectstdout = 1;
// redirecting standard error
} else if(token[0] == '2' && token[1] == '>') {
c->redirectstderr = 1;
}
} else {
// the token following a redirection token must be a file name that should be dup'ed
// then clears the flag
if(c->redirectstdin) {
c->stdinfilename = token;
c->redirectstdin = 0;
} else if(c->redirectstdout) {
c->stdoutfilename = token;
c->redirectstdout = 0;
} else if(c->redirectstderr) {
c->stderrfilename = token;
c->redirectstderr = 0;
// all other normal tokens
} else {
command_append_arg(c, type, token);
}
}
}
// execute the command
int condition = -1; // exit condition of previous command
for(int i = 0; i < listcontent; i++) {
if (commandlist[i]->argc)
// test if this command group should run
if (commandlist[i]->needcondition == -1 || (commandlist[i]->needcondition == 0 && condition == 0) || (commandlist[i]->needcondition == 1 && condition != 0))
eval_command(commandlist[i], &condition, z);
command_free(commandlist[i]);
}
free(commandlist);
}