Subject: Re: [PATCH 1/6] lib/cmdline.c: Add backslash support to kernel commandline parsing.

From: Al Viro <[email-masked]>
Date: Fri, 15 Sep 2017 18:14:09 +0100

On Fri, Sep 15, 2017 at 07:02:46PM +0200, Michal Suchanek wrote:

>  	for (i = 0; args[i]; i++) {
> -		if (isspace(args[i]) && !in_quote)
> +		if (isspace(args[i]) && !in_quote && !backslash)
>  			break;
> -		if (equals == 0) {
> -			if (args[i] == '=')
> -				equals = i;
> +
> +		if ((equals == 0) && (args[i] == '='))
> +			equals = i;
> +
> +		if (!backslash) {
> +			if ((args[i] == '"') || (args[i] == '\\')) {
> +				if (args[i] == '"')
> +					in_quote = !in_quote;
> +				if (args[i] == '\\')
> +					backslash = 1;
> +
> +				memmove(args + 1, args, i);
> +				args++;
> +				i--;
> +			}
> +		} else {
> +			backslash = 0;
>  		}
> -		if (args[i] == '"')
> -			in_quote = !in_quote;
>  	}

... and that makes for Unidiomatic Work With Strings Award for this September.
Using memmove() for string rewrite is almost always bad taste; in this case
it's also (as usual) broken.