[PATCH v2 04/10] eal: fix plugin dir walk

[Marat Khalili]

Thank you for doing this.

> +static bool
> +ends_with(const char *str, size_t str_len, const char *tail)

I too think we should have a general ends_with, I for one had to code one just this week. However, I do not think it should support non-null-terminated strings.

> +{
> +	size_t tail_len = strlen(tail);
> +
> +	return str_len >= tail_len && strncmp(&str[str_len - tail_len], tail,
> tail_len) == 0;
> +}

Note that when str is not null-terminated and both str_len and tail_len are zeroes &str[str_len - tail_len] will dereference one character after the end before taking a reference to it again, which would be a UB. (Won't happen in your case of course since your tail is always non-empty, but may happen if this function is moved into a general-use library.)

> @@ -417,13 +425,12 @@ eal_plugindir_init(const char *path)
>  	}
> 
>  	while ((dent = readdir(d)) != NULL) {
> +		size_t nlen = strnlen(dent->d_name, sizeof(dent->d_name));
>  		struct stat sb;
> -		int nlen = strnlen(dent->d_name, sizeof(dent->d_name));
> 
>  		/* check if name ends in .so or .so.ABI_VERSION */
> -		if (strcmp(&dent->d_name[nlen - 3], ".so") != 0 &&
> -		    strcmp(&dent->d_name[nlen - 4 - strlen(ABI_VERSION)],
> -			   ".so."ABI_VERSION) != 0)
> +		if (!ends_with(dent->d_name, nlen, ".so") &&
> +				!ends_with(dent->d_name, nlen, ".so."ABI_VERSION))
>  			continue;

I do not think we should try to handle the non-null-terminated dent->d_name case here, I'd just delete nlen and everything related to it. To be super-defensive we could add a check that `memchr(dent->d_name, 0, sizeof(dent->d_name)) != NULL`, but I don't think it's needed.