//parses a stage, returning a command struct
//modifies global variable t
CMD *stage()
{
CMD *tmp;
CMD *cmd = 0;
if (!t)
return 0;
tmp = mallocCMD();
while (t && (ISREDOUT(t->type) || ISREDIN(t->type)))
tmp = redirect(tmp);
if (!tmp)
return 0;
else if (!t)
{
DIE("Parse: null command\n");
return 0;
}
else if (t->type == PAR_LEFT)
{
cmd = mallocCMD();
cmd->type = SUBCMD;
t = t->next;
cmd->left = command();
if (!cmd->left)
{
DIE("Parse: null command\n");
freeCMD(cmd);
return 0;
}
else if (!t || t->type != PAR_RIGHT)
{
DIE("Parse: unbalanced parens\n");
freeCMD(cmd);
return 0;
}
else
{
t = t->next;
while(t && cmd && (ISREDOUT(t->type)
|| ISREDIN(t->type)))
cmd = redirect(cmd);
}
}
else
cmd = simple();
cmd = merge(cmd, tmp);
freeCMD(tmp);
return cmd;
}
//parses a SIMPLE statement, returning command struct
//modifies global variable t
CMD *simple()
{
CMD *cmd;
cmd = mallocCMD();
cmd->type = SIMPLE;
while (t && cmd != NULL)
{
if (t->type == SIMPLE)
{
(cmd->argc)++;
cmd->argv = realloc(cmd->argv, sizeof(char*)
* (cmd->argc + 1));
cmd->argv[cmd->argc] = 0;
cmd->argv[cmd->argc - 1] = malloc(strlen(t->text) + 1);
strcpy(cmd->argv[cmd->argc - 1], t->text);
t = t->next;
}
else if (ISREDOUT(t->type) || ISREDIN(t->type))
cmd = redirect(cmd);
else
break;
}
if (!cmd || !cmd->argc)
return 0;
else
return cmd;
}
//handles redirect statements for stage and simple
//input is a command struct, output is same struct with changed i/o
CMD *redirect(CMD* cmd)
{
if (ISREDOUT(t->type))
{
if (cmd->toType != NONE)
{
DIE("Parse: two output redirects\n");
freeCMD(cmd);
return 0;
}
cmd->toType = t->type;
t = t->next;
if (!t || t->type != SIMPLE)
{
DIE("Parse: missing filename\n");
freeCMD(cmd);
return 0;
}
cmd->toFile = malloc(strlen(t->text) + 1);
strcpy(cmd->toFile, t->text);
t = t->next;
}
else if (t->type == RED_IN || t->type == RED_HERE)
{
if (cmd->fromType != NONE)
{
DIE("Parse: two input redirects\n");
freeCMD(cmd);
return 0;
}
cmd->fromType = t->type;
t = t->next;
if (!t || t->type != SIMPLE)
{
DIE("Parse: missing filename\n");
freeCMD(cmd);
return 0;
}
if (cmd->fromType == RED_IN)
{
cmd->fromFile = malloc(strlen(t->text) + 1);
strcpy(cmd->fromFile, t->text);
}
else
{
cmd->fromFile = hereDoc(t->text);
}
t = t->next;
}
return cmd;
}
CMD* make_stage(token_list** list_ref)
{
token_list* list = *list_ref;
if (!list) return make_error_cmd("could not form stage (no tokens)");
CMD* stage_tree = mallocCMD(); // Current type is NONE
int next_type = NONE; // Hold the type of the head token of list
bool redir_in = false; // Has there been a previous input redirection?
bool redir_out = false;
// Loop until hit a pipe or a separator; raise an error if multiple redirect
// or both a command and subcommand
while ((next_type = type(list)) != -1 &&
!ISSEP(next_type) && !ISPIPE(next_type) && next_type != PAR_RIGHT) {
bool error = false; // Signals whether the current action results in an
// error
if (next_type == SIMPLE && stage_tree->type != SUBCMD) {
int argc = stage_tree->argc + 1;
char** argv = stage_tree->argv;
argv = realloc(argv, (argc + 1) * sizeof(char*)); // +1 for trailing
// NULL required
// by freeCMD
argv[argc - 1] = strdup(text(list));
argv[argc] = NULL;
stage_tree->argc = argc;
stage_tree->argv = argv;
stage_tree->type = SIMPLE;
} else if ((next_type == RED_IN || next_type == RED_HERE)
&& !redir_in) {
error = make_redirect(stage_tree, &redir_in, next_type, &list);
} else if (ISREDOUT(next_type) && !redir_out) {
error = make_redirect(stage_tree, &redir_out, next_type, &list);
} else if (next_type == PAR_LEFT &&
stage_tree->type == NONE) { // Can't have two subcommands in a stage
advance(&list); // Advance past left parentheses
CMD* subcmd_tree = make_cmd(&list);
error = subcmd_tree->type == ERROR || type(list) != PAR_RIGHT;
stage_tree->type = SUBCMD;
stage_tree->left = subcmd_tree;
} else {
error = true;
}
if (error) {
freeCMD(stage_tree);
return make_error_cmd("Invalid stage");
}
advance(&list);
}
// Make sure we didn't double-redirect
if (ISPIPE(next_type) && redir_out) {
freeCMD(stage_tree);
return make_error_cmd("Double redirect - pipe and >");
}
// Make sure there was actually an argument
if (stage_tree->type == NONE) {
freeCMD(stage_tree);
return make_error_cmd("No arguments for simple command");
}
assert(stage_tree->type != NONE);
*list_ref = list;
return stage_tree;
}
