Re: [Xen-devel] [PATCH 07 of 10] xl: Fix 'script' param parsing in network-attach

[Marek Marczykowski <marmarek@xxxxxxxxxxxx>]

On 03.06.2011 10:16, Ian Campbell wrote:
> On Thu, 2011-06-02 at 23:35 +0100, Marek Marczykowski wrote:
>> # HG changeset patch
>> # User Marek Marczykowski <marmarek@xxxxxxxxxxxx>
>> # Date 1306963105 -7200
>> # Node ID 6811aa543e69379557ff7391ea3db8a5e7f7dde0
>> # Parent  eb7216a75b7d7a5de93c717401b447545022b582
>> xl: Fix 'script' param parsing in network-attach
>>
>> Fix 'script=' string length
>>
>> Signed-off-by: Marek Marczykowski <marmarek@xxxxxxxxxxxx>
>>
>> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
>> --- a/tools/libxl/xl_cmdimpl.c
>> +++ b/tools/libxl/xl_cmdimpl.c
>> @@ -4285,9 +4285,9 @@
>>          } else if (!strncmp("ip=", *argv, 3)) {
>>              free(nic.ip);
>>              nic.ip = strdup((*argv) + 3);
>> -        } else if (!strncmp("script=", *argv, 6)) {
>> +        } else if (!strncmp("script=", *argv, 7)) {
>>              free(nic.script);
>> -            nic.script = strdup((*argv) + 6);
>> +            nic.script = strdup((*argv) + 7);
> 
> Good catch.
> 
> The pre-existing use of all those
>       strncmp(A, *argv, open-coded-sizeof(A))
> must be a source of many such errors. A helper function (or macro) is
> probably the way to go. Do you fancy coding that up?

And the same size must be used in strdup offset...
Maybe something like this (solving also problem in 06 patch):
-----------
#define COMPARE_AND_REPLACE(pattern, dest) \
    } else if (!strncmp(pattern, *argv, sizeof(pattern))) { \
        free(dest); \
        dest = strdup((*argv) + sizeof(pattern));

(...)
    COMPARE_AND_REPLACE("script=", nic.script)
    COMPARE_AND_REPLACE("ip=", nic.ip)
---------
Looks weird because of no semicolon at the end of lines, but should
works. Unfortunately cannot be used in all places (like one below)...
What do you think?

> 
> Ian.
> 
>>          } else if (!strncmp("backend=", *argv, 8)) {
>>              if(libxl_name_to_domid(&ctx, ((*argv) + 8), &val)) {
>>                  fprintf(stderr, "Specified backend domain does not exist, 
>> defaulting to Dom0\n");



-- 
Pozdrawiam / Best Regards,
Marek Marczykowski         | RLU #390519
marmarek at mimuw edu pl   | xmpp:marmarek at staszic waw pl

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