String tokenizer

split.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int is_sep(const char s, const char *separators)
{
    int i;

    for (i = 0; i < strlen(separators); i++) {
	if (s == separators[i]) {
	    return 1;
	}
    }

    return 0;
}

char **split(const char *input, const char *sep)
{
    int i = 0;
    int capacity = 1;
    int token_start_idx = -1;
    int token_count = 0;
    int token_length = 0;
    char **result = NULL;
    char **tmp = NULL;
    char *token = NULL;
    int input_length = strlen(input);
    
    result = calloc(sizeof(*result), capacity);
    for (; i < input_length + 1; i++) {
	if (i == input_length || is_sep(input[i], sep)) {
	    if (token_start_idx > -1) {
		/* we have seen some token, need begin/end info */
		token_length = i - token_start_idx;
		if (token_count >= capacity) {
		    capacity *= 2;

		    tmp = realloc(result, sizeof(*result) * capacity);
		    if (!tmp) {
			perror("realloc");
			goto err_out;
		    }

		    result = tmp;
		}

		/*
		 * hello_
		 * 012345 - 5 - 0 = 5; +1 for null character
		 */
		token = malloc(token_length + 1);
		if (!token) {
		    perror("malloc");
		    goto err_out;
		}

		memcpy(token, input + token_start_idx, token_length);
		token[token_length] = '\0';
		result[token_count] = token;

		token_start_idx = -1;
		token_count++;
	    }
	} else {
	    /* Current character is not a separator */
	    if (token_start_idx < 0) {
		token_start_idx = i;
	    }
	}
    }

    tmp = realloc(result, sizeof(*result) * (token_count + 1));
    if (! tmp) {
	perror("realloc");
	goto err_out;
    }

    result = tmp;
    result[token_count] = NULL;

    return result;
err_out:
    return NULL;
}

void free_r(void **ptr)
{
    int i = 0;
    for (; ptr[i] != NULL; i++) {
	free(ptr[i]);
    }

    free(ptr);
}

int main(int argc, char **argv)
{
    char **result = NULL;
    int i = 0;

    if (argc != 3) {
	fprintf(stderr, "Usage: %s string separator\n", argv[0]);
	return 1;
    }

    result = split(argv[1], argv[2]);
    if (!result) {
	printf("split() failed\n");
	return 1;
    }

    while (result[i] != NULL) {
	printf("%s\n", result[i]);
	i++;
    }

    free_r((void **)result);

    return 0;
}