[libvirt] [PATCH] Allocate buffer to hold xend response

[Jim Fehlig]

Jim Meyering wrote:
>> -        if (VIR_ALLOC_N(*content, content_length) < 0 ) {
>> +        if (content_length > XEND_RCV_BUF_MAX_LEN) {
>> +            virXendError(VIR_ERR_INTERNAL_ERROR,
>> +                         _("Xend returned HTTP Content-Length of %d, "
>> +                           "which exceeds maximum of %d"),
>> +                         content_length,
>> +                         XEND_RCV_BUF_MAX_LEN);
>> +            return -1;
>> +        }
>> +
>>     
>
> This is subtle enough that a comment might avoid trouble later.
>
> /* Allocate one byte beyond the end of the largest buffer we will read.
>    Combined with the fact that VIR_ALLOC_N zeros the returned buffer,
>    this guarantees that "content" will always be NUL-terminated.  */
>   

Good idea.  I've added your wording verbatim.

>   
>> +        if (VIR_ALLOC_N(*content, content_length + 1) < 0 ) {
>>              virReportOOMError();
>>              return -1;
>>          }
>> @@ -380,7 +390,7 @@ xend_get(virConnectPtr xend, const char *path,
>>          virXendError(VIR_ERR_GET_FAILED,
>>                       _("%d status from xen daemon: %s:%s"),
>>                       ret, path,
>> -                     content ? *content: "NULL");
>> +                     content ? *content : "NULL");
>>     
>
> Oh!  I've just noticed that testing "content" is wrong,
> since it will always be non-NULL.  BTW, the parameter should
> be marked as such via "ATTRIBUTE_NONNULL (3)".
>   

I added ATTRIBUTE_NONNULL to xend_req() as well.

> The test should examine "*content", i.e.,
>
>                         *content ? *content : "NULL");
>
> Then I remembered the NULLSTR macro.
> You can replace the above with this:
>
>                         NULLSTR(*content));
>
>
> FYI, here's its definition:
>
>     $ git grep -A2 ine.NULLSTR
>     src/internal.h:# define NULLSTR(s) \
>     src/internal.h-    ((void)verify_true(sizeof *(s) == sizeof (char)), \
>     src/internal.h-     (s) ? (s) : "(null)")
>   

Cool, that's handy.  Updated patch attached.

Regards,
Jim
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