From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cyril Hrubis <chrubis@suse.cz>
Date: Wed, 4 May 2016 15:34:53 +0200
Subject: [LTP] [PATCH V2 6/9] testcases/lib: Add tst_random decmical
 integer generator
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Hi!
>  include $(top_srcdir)/include/mk/generic_leaf_target.mk
> diff --git a/testcases/lib/tst_random.c b/testcases/lib/tst_random.c
> new file mode 100644
> index 0000000..91a5247
> --- /dev/null
> +++ b/testcases/lib/tst_random.c
> @@ -0,0 +1,104 @@
> +/*
> + * Copyright (c) 2016 Red Hat Inc.
> + *
> + * 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 would 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 the Free Software Foundation,
> + * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> + *
> + * Author: Chunyu Hu <chuhu@redhat.com>
> + *
> + */
> +
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/time.h>
> +
> +static void print_help(void)
> +{
> +	printf("Usage: tst_random <value1> [value2]\n");
> +	printf("       Generated random will be between value1 and value2.\n");
> +	printf("       If only value1 is specified, value2 will treated as 0.\n");
> +}
> +
> +static int get_seed(void)
> +{
> +	struct timeval tv;
> +	gettimeofday(&tv, NULL);
> +	return tv.tv_usec;
> +}
> +
> +static long rand_range(long min, long max)
> +{
> +	return rand() % (max - min + 1) + min;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	int opt;
> +	long min = 0, max = 0, tmp = 0;
> +	long rval = 0;
> +	char *end;
> +
> +	while ((opt = getopt(argc, argv, ":h")) != -1) {
> +		switch (opt) {
> +		case 'h':
> +			print_help();
> +			return 0;
> +		default:
> +			print_help();
> +			return 1;
> +		}
> +	}
> +
> +	if (argc < 2 || argc > 3) {
> +		print_help();
> +		return 1;
> +	}
> +
> +	if (optind >= argc) {
> +		fprintf(stderr, "ERROR: Expected one or two range_val arguments\n\n");
> +		print_help();
> +		return 1;
> +	}

We exit if getopt() finds any options in argv[] so optind == 1 here and
since we check for argc < 2 before this this if is never true.


> +	max = strtol(argv[optind], &end, 10);

Here as well optind == 1 by definition.

> +	if (argv[optind] == end) {
> +		fprintf(stderr, "ERROR: Invalid range value1 '%s'\n\n",
> +			argv[optind]);
> +		print_help();
> +		return 1;
> +	}

Well if we bother with strtol() we may check that argv[1] != '\0' and
end == '\0' which will ensure that whole parameter was a valid string.

> +	if (argc == 3) {
> +		min = strtol(argv[optind+1], &end, 10);

Here as well use just 2 instead of optind + 1.

> +		if (argv[optind+1] == end) {
> +			fprintf(stderr, "ERROR: Invalid range value2 '%s'\n\n",
> +				argv[optind+1]);
> +			print_help();
> +			return 1;
> +		}
> +		if (min > max) {
> +			tmp = min;
> +			min = max;
> +			max = tmp;
> +		}

Well we may also do:

	rval = (min > max) ? rand_range(max, min) : rand_range(min, max);

In the code below instead, but that is merely cosmetic.

> +	}
> +
> +	srand(get_seed());
> +	rval = rand_range(min, max);
> +	printf("%ld\n", rval);
> +
> +	return rval;

We should just return 0 here since the return value is limited to one
byte. Exporting interface that works only in certain cases is a recipe
for a disaster.

-- 
Cyril Hrubis
chrubis@suse.cz