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Date: Thu, 23 Mar 2017 19:58:53 +0100
From: Roman Divacky <rdivacky@freebsd.org>
To: Warner Losh <imp@FreeBSD.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r315773 - head/sbin/devd
Message-ID: <20170323185853.GA87388@vlakno.cz>
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On Thu, Mar 23, 2017 at 02:36:51AM +0000, Warner Losh wrote:
> Author: imp
> Date: Thu Mar 23 02:36:51 2017
> New Revision: 315773
> URL: https://svnweb.freebsd.org/changeset/base/315773
> 
> Log:
>   Implement quote escaping. String values may now contain " if you
>   it is preceded by \.
>   
>   foo="I \"like\" C++"
>   
>   gives the value 'I "like" C++' to the variable 'foo'. If a character
>   other than " follows the \, both the \ and that character are passed
>   through.
>   
>   Differential Revision: https://reviews.freebsd.org/D6286
>   Sponsored by: Netflix
> 
> Modified:
>   head/sbin/devd/devd.cc
>   head/sbin/devd/devd.hh
> 
> Modified: head/sbin/devd/devd.cc
> ==============================================================================
> --- head/sbin/devd/devd.cc	Thu Mar 23 02:33:27 2017	(r315772)
> +++ head/sbin/devd/devd.cc	Thu Mar 23 02:36:51 2017	(r315773)
> @@ -411,6 +411,32 @@ var_list::is_set(const string &var) cons
>  	return (_vars.find(var) != _vars.end());
>  }
>  
> +/** fix_value
> + *
> + * Removes quoted characters that have made it this far. \" are
> + * converted to ". For all other characters, both \ and following
> + * character. So the string 'fre\:\"' is translated to 'fred\:"'.
> + */
> +const std::string &
> +var_list::fix_value(const std::string &val) const
> +{
> +	char *tmp, *dst;
> +	const char *src;
> +	std::string *rv;
> +
> +	dst = tmp = new char[val.length()];
> +	src = val.c_str();
> +	while (*src) {
> +		if (*src == '\\' && src[1] == '"')
> +			src++;
> +		else
> +			*dst++ = *src++;
> +	}
> +	rv = new string(tmp);
> +	delete tmp;
> +	return *rv;
> +}

Can the temporary char[] be stack allocated? Also, when returning a reference to
a heap allocated string who is responsible for freeing it? Perhaps you can just
return std::string and let the compiler optimize it?

Roman