[ros-dev] Re: [ros-diffs] [weiden] 16553: handle memory allocation errors in GetEnvironmentVariable() and ensure the string is always null-terminated

[Joseph Galbraith]

> +	VarValue.MaximumLength = (nSize != 0 ? (nSize - 1) * sizeof(WCHAR) : 0);
> 
>  	VarValue.Buffer = lpBuffer;
>  
>  	Status = RtlQueryEnvironmentVariable_U (NULL,
> @@ -125,13 +150,17 @@
> 
>  		SetLastErrorByStatus (Status);
>  		if (Status == STATUS_BUFFER_TOO_SMALL)
>  		{
> 
> -			return (VarValue.Length / sizeof(WCHAR)) +  1;
> 
> +			return (VarValue.Length / sizeof(WCHAR)) + 1;
> 
>  		}
>  		else
>  		{
>  			return 0;
>  		}
>  	}
> 
> +	
> +	/* make sure the string is NULL-terminated! RtlQueryEnvironmentVariable_U
> +           only terminates it if MaximumLength < Length */
> +	VarValue.Buffer[VarValue.Length / sizeof(WCHAR)] = L'\0';


Is it possible for an environment variable's value to be empty?

If it is, RtlQueryEnvironmentVariable_U() could succeeded even
if a zero length buffer is passed in.  And then, would we crash
appending the NUL termination?

Since GetEnvironmentVariable has to have a buffer of at least
one character to succeed, maybe we should add such a guard to
the top of the function...

Thanks,

Joseph