[libvirt] [patch 2/5] Instantiate comments in ip(6)tables rules

[Eric Blake]

On 09/24/2010 01:38 PM, Stefan Berger wrote:

> To prevent consecutive spaces in comments from becoming a single space
> (by bash), the IFS variable is now set to an empty string. Also, commands
> are now executed using bash's 'eval' command.

-#define CMD_EXEC   "res=`${cmd}`" CMD_SEPARATOR
+#define CMD_EXEC   "res=`eval ${cmd}`" CMD_SEPARATOR

Underquoted.  To be robust, this needs to be:

"res=`eval \"$cmd\"" CMD_SEPARATOR

which will then avoid your need for the empty IFS hack and double 
escaping (you'll still need single escaping, but that's a bit more 
manageable).

> +/* avoiding a compiler warning trough own implementation */
> +static const char *
> +_strchr(const char *s, int c)
> +{
> +    while (*s && *s != (char)c)
> +        s++;
> +    if (*s)
> +        return s;
> +    return NULL;
> +}
>

Ouch.  That's probably 4x slower than the glibc version.  I'd much 
rather see:

#undef strchr

or

(strchr)(a, b)

which then guarantees that you get the function call, rather than the 
macro expansion; after all, the macro expansion just defers to the 
function call if both arguments are non-constants, not to mention the 
fact that the -Wlogical-op warning is only triggered by the macro and 
not by the function.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org