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/*
* token.c -- tokenize strings, a la strtok(3)
*
* Copyright (C) 2007 Oracle. All rights reserved.
* Copyright (C) 2007 Chuck Lever <chuck.lever@oracle.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* 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 0211-1301 USA
*
*/
/*
* We've constructed a simple string tokenizer that is better than
* strtok(3) in several ways:
*
* 1. It doesn't interfere with ongoing tokenizations using strtok(3).
* 2. It's re-entrant so we can nest tokenizations, if needed.
* 3. It can handle double-quoted delimiters (needed for 'context="sd,fslj"').
* 4. It doesn't alter the string we're tokenizing, so it can work
* on write-protected strings as well as writable strings.
*/
#include <ctype.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include "token.h"
struct tokenizer_state {
char *pos;
char delimiter;
int error;
};
static void find_next_nondelimiter(struct tokenizer_state *tstate)
{
while (*tstate->pos != '\0' && *tstate->pos == tstate->delimiter)
tstate->pos++;
}
static size_t find_next_delimiter(struct tokenizer_state *tstate)
{
size_t len = 0;
int quote_seen = 0;
while (*tstate->pos != '\0') {
if (*tstate->pos == '"')
quote_seen ^= 1;
if (!quote_seen && *tstate->pos == tstate->delimiter)
break;
len++;
tstate->pos++;
}
/* did the string terminate before the close quote? */
if (quote_seen) {
tstate->error = EINVAL;
return 0;
}
return len;
}
/**
* next_token - find the next token in a string and return it
* @tstate: pointer to tokenizer context object
*
* Returns the next token found in the current string.
* Returns NULL if there are no more tokens in the string,
* or if an error occurs.
*
* Side effect: tstate is updated
*/
char *next_token(struct tokenizer_state *tstate)
{
char *token;
size_t len;
if (!tstate || !tstate->pos || tstate->error)
return NULL;
find_next_nondelimiter(tstate);
if (*tstate->pos == '\0')
goto fail;
token = tstate->pos;
len = find_next_delimiter(tstate);
if (len) {
token = strndup(token, len);
if (token)
return token;
tstate->error = ENOMEM;
}
fail:
tstate->pos = NULL;
return NULL; /* no tokens found in this string */
}
/**
* init_tokenizer - return an initialized tokenizer context object
* @string: pointer to C string
* @delimiter: single character that delimits tokens in @string
*
* Returns an initialized tokenizer context object
*/
struct tokenizer_state *init_tokenizer(char *string, char delimiter)
{
struct tokenizer_state *tstate;
tstate = malloc(sizeof(*tstate));
if (tstate) {
tstate->pos = string;
tstate->delimiter = delimiter;
tstate->error = 0;
}
return tstate;
}
/**
* tokenizer_error - digs error value out of tokenizer context
* @tstate: pointer to tokenizer context object
*
*/
int tokenizer_error(struct tokenizer_state *tstate)
{
return tstate ? tstate->error : 0;
}
/**
* end_tokenizer - free a tokenizer context object
* @tstate: pointer to tokenizer context object
*
*/
void end_tokenizer(struct tokenizer_state *tstate)
{
free(tstate);
}
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