2. Command Line Sample Application

2.4.1. EAL Initialization and cmdline Start

The first task is the initialization of the Environment Abstraction Layer (EAL). This is achieved as follows:

int main(int argc, char **argv)
{
    ret = rte_eal_init(argc, argv);
    if (ret < 0)
        rte_panic("Cannot init EAL\n");

Then, a new command line object is created and started to interact with the user through the console:

cl = cmdline_stdin_new(main_ctx, "example> ");
cmdline_interact(cl);
cmdline_stdin_exit(cl);

The cmd line_interact() function returns when the user types Ctrl-d and in this case, the application exits.

2.4.2. Defining a cmdline Context

A cmdline context is a list of commands that are listed in a NULL-terminated table, for example:

cmdline_parse_ctx_t main_ctx[] = {
    (cmdline_parse_inst_t *) &cmd_obj_del_show,
    (cmdline_parse_inst_t *) &cmd_obj_add,
    (cmdline_parse_inst_t *) &cmd_help,
     NULL,
};

Each command (of type cmdline_parse_inst_t) is defined statically. It contains a pointer to a callback function that is executed when the command is parsed, an opaque pointer, a help string and a list of tokens in a NULL-terminated table.

The rte_cmdline application provides a list of pre-defined token types:

• String Token: Match a static string, a list of static strings or any string.
• Number Token: Match a number that can be signed or unsigned, from 8-bit to 32-bit.
• IP Address Token: Match an IPv4 or IPv6 address or network.
• Ethernet* Address Token: Match a MAC address.

In this example, a new token type obj_list is defined and implemented in the parse_obj_list.c and parse_obj_list.h files.

For example, the cmd_obj_del_show command is defined as shown below:

struct cmd_obj_add_result {
    cmdline_fixed_string_t action;
    cmdline_fixed_string_t name;
    struct object *obj;
};

static void cmd_obj_del_show_parsed(void *parsed_result, struct cmdline *cl, attribute ((unused)) void *data)
{
   /* ... */
}

cmdline_parse_token_string_t cmd_obj_action = TOKEN_STRING_INITIALIZER(struct cmd_obj_del_show_result, action, "show#del");

parse_token_obj_list_t cmd_obj_obj = TOKEN_OBJ_LIST_INITIALIZER(struct cmd_obj_del_show_result, obj, &global_obj_list);

cmdline_parse_inst_t cmd_obj_del_show = {
    .f = cmd_obj_del_show_parsed, /* function to call */
    .data = NULL,  /* 2nd arg of func */
    .help_str = "Show/del an object",
    .tokens = { /* token list, NULL terminated */
        (void *)&cmd_obj_action,
        (void *)&cmd_obj_obj,
         NULL,
    },
};

This command is composed of two tokens:

• The first token is a string token that can be show or del.
• The second token is an object that was previously added using the add command in the global_obj_list variable.

Once the command is parsed, the rte_cmdline application fills a cmd_obj_del_show_result structure. A pointer to this structure is given as an argument to the callback function and can be used in the body of this function.