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/*
mtr -- a network diagnostic tool
Copyright (C) 2016 Matt Kimball
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "cmdparse.h"
#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
/*
NUL terminate the whitespace separated tokens in the command string.
This modifies command_string in-place with NUL characters.
Fill the tokens array with pointers to the tokens, and return the
number of tokens found.
*/
static
int tokenize_command(
char **tokens,
int max_tokens,
char *command_string)
{
int token_count = 0;
int on_space = 1;
int i;
for (i = 0; command_string[i]; i++) {
if (on_space) {
if (!isspace((unsigned char) command_string[i])) {
/* Take care not to exceed the token array length */
if (token_count >= max_tokens) {
return -1;
}
tokens[token_count++] = &command_string[i];
on_space = 0;
}
} else {
if (isspace((unsigned char) command_string[i])) {
command_string[i] = 0;
on_space = 1;
}
}
}
return token_count;
}
/*
Parse a command string (or command reply string) into a command_t
structure for later semantic interpretation. Returns EINVAL if the
command string is unparseable or zero for success.
command_string will be modified in-place with NUL characters terminating
tokens, and the command_t will use pointers to the contents of
command_string without copying, so any interpretation of the
command_t structure requires that the command_string memory has not yet
been freed or otherwise reused.
*/
int parse_command(
struct command_t *command,
char *command_string)
{
char *tokens[MAX_COMMAND_TOKENS];
int token_count;
int i;
memset(command, 0, sizeof(struct command_t));
/* Tokenize the string using whitespace */
token_count =
tokenize_command(tokens, MAX_COMMAND_TOKENS, command_string);
if (token_count < 2) {
errno = EINVAL;
return -1;
}
/* Expect the command token to be a numerical value */
errno = 0;
command->token = strtol(tokens[0], NULL, 10);
if (errno) {
errno = EINVAL;
return -1;
}
command->command_name = tokens[1];
/*
The tokens beyond the command name are expected to be in
name, value pairs.
*/
i = 2;
command->argument_count = 0;
while (i < token_count) {
/* It's an error if we get a name without a key */
if (i + 1 >= token_count) {
errno = EINVAL;
return -1;
}
/* It's an error if we get more arguments than we have space for */
if (command->argument_count >= MAX_COMMAND_ARGUMENTS) {
errno = EINVAL;
return -1;
}
command->argument_name[command->argument_count] = tokens[i];
command->argument_value[command->argument_count] = tokens[i + 1];
command->argument_count++;
i += 2;
}
return 0;
}
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