ifish (ifi sh) is a VERY basic shell implementation. It is basically a repl with 512 bytes
of memory that forks (see the rather strange safefork.c) for system calls.
The structure is broken into three main 'modules'
repl_history
repl_parsing
repl
repl_history uses a couple of static structs to keep track of memory. It provides the following interface:
void history_init()
void history_insert(char*)
int history_get_item(int, char*)
int history_delete_last_n_items(int)
All other functions in repl_history are static.
repl_parsing handles both searching the users path and tokenizing lines. It provides the following interface:
struct tokenized* parsing_tokenize_line(char*)
void parsing_free(struct tokenized*)
When a line is passed to parsing_tokenize_line a struct of type struct tokenized* is created.
This has two fields char* params[21] and char special_call.
The linebuffer is read and copied into into an array of type char* params[21]
If the first symbol is h then the tokens are parsed to make sure that they are a valid history call.
If so, the token->special_call field is set to either BUILTIN_DELETE_HISTORY or BUILTIN_EXECUTE_HISTORY
and the token struct is returned.
If there are semantic errors then NULL is returned.
If the first token is "exit" or "quit" then the token->special_call
field is set to USER_EXIT and the struct returned.
If none of these cases were true, then the path to the first token is found and the first pointer in the list of tokens is replaced.
If the last token is the symbol & the token->special_call field is set to RUN_IN_BACKGROUND