Re: [libvirt] [patch 2/5] Instantiate comments in ip(6)tables rules
Eric Blake <eblake(a)redhat.com> wrote on 09/24/2010 04:01:55 PM:
libvir-list
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
Ok, I made this change.
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).
I just tried the TCK test without and with double-escaping in libvirtd
and double-escaping does seem to be necessary otherwise `ls` and $(ls)
do get executed and their results end up in the comment. The spaces
are preserved, though, so I can revert the change to IFS.
> +/* 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
Yes, that does the trick. Thanks.
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.
Stefan
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