On Mon 2020-11-30 14:57:58, Richard Fitzgerald wrote:
> Adds test_sscanf to test various number conversion cases, as
> number conversion was previously broken.
>
> This also tests the simple_strtoxxx() functions exported from
> vsprintf.c.
It is impressive.
Honestly, I do not feel to be expert on testing and mathematics.
I am not sure how comprehensive the test is. Also I am not
sure what experts would say about the tricks with random
numbers.
Anyway, this is much more than what I have expected. And it checks
great number of variants and corner cases.
I suggest only one small change, see below.
> --- /dev/null
> +++ b/lib/test_scanf.c
> @@ -0,0 +1,747 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Test cases for sscanf facility.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/bitops.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/overflow.h>
> +#include <linux/printk.h>
> +#include <linux/random.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +
> +#include "../tools/testing/selftests/kselftest_module.h"
> +
> +#define BUF_SIZE 1024
> +
> +static unsigned total_tests __initdata;
> +static unsigned failed_tests __initdata;
> +static char *test_buffer __initdata;
> +static char *fmt_buffer __initdata;
> +static struct rnd_state rnd_state __initdata;
> +
> +typedef int (*check_fn)(const void *check_data, const char *string,
> + const char *fmt, int n_args, va_list ap);
> +
> +static void __scanf(4, 6) __init
> +_test(check_fn fn, const void *check_data, const char *string, const char *fmt,
> + int n_args, ...)
> +{
> + va_list ap, ap_copy;
> + int ret;
> +
> + total_tests++;
> +
> + va_start(ap, n_args);
> + va_copy(ap_copy, ap);
> + ret = vsscanf(string, fmt, ap_copy);
> + va_end(ap_copy);
> +
> + if (ret != n_args) {
> + pr_warn("vsscanf(\"%s\", \"%s\", ...) returned %d expected %d\n",
> + string, fmt, ret, n_args);
> + goto fail;
> + }
> +
> + ret = (*fn)(check_data, string, fmt, n_args, ap);
> + if (ret)
> + goto fail;
> +
> + va_end(ap);
> +
> + return;
> +
> +fail:
> + failed_tests++;
> + va_end(ap);
> +}
> +
> +#define test_one_number(T, gen_fmt, scan_fmt, val, fn) \
> +do { \
> + const T expect_val = (T)(val); \
> + T result = ~expect_val; /* should be overwritten */ \
If I get it correctly, this is supposed to initialize the temporary
variable with a value that is different from the expected value.
It will cause test failure when it is not updated by vsscanf().
It does not work for zero value. A better solution might be to add
a constant, for example:
T result = expect_val + 3; /* do not match when not overwritten */ \
I did not use "+ 1" intentionally because it might hide some overflow
issues.
> + \
> + snprintf(test_buffer, BUF_SIZE, gen_fmt, expect_val); \
> + _test(fn, &expect_val, test_buffer, "%" scan_fmt, 1, &result); \
> +} while (0)
Otherwise, it looks good to me.
Best Regards,
Petr
