[Libguestfs] [PATCH] Fix lossy conversion of Content-Length

[Adrian Ambrożewicz]

W dniu 1/9/2020 o 14:07, Richard W.M. Jones pisze:
> On Wed, Jan 08, 2020 at 07:19:56AM -0600, Eric Blake wrote:
>> On 1/7/20 4:13 AM, Adrian Ambrożewicz wrote:
>>> Actual variable holding content length is int64_t, but it was assigned
>>> by explicit cast to size_t. On 32-bit systems it's a lossy conversion,
>>> so it was replaced by casting to int64_t instead.
>>>
>>> Signed-off-by: Adrian Ambrożewicz <adrian.ambrozewicz at linux.intel.com>
>>> ---
>>>   plugins/curl/curl.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/plugins/curl/curl.c b/plugins/curl/curl.c
>>> index 031bd32..fe1330e 100644
>>> --- a/plugins/curl/curl.c
>>> +++ b/plugins/curl/curl.c
>>> @@ -389,7 +389,7 @@ curl_open (int readonly)
>>>       goto err;
>>>     }
>>>
>>> -  h->exportsize = (size_t) d;
>>> +  h->exportsize = (int64_t) d;
>>
>> Why is a cast needed at all?
>> This is C, an implicit conversion
>> works just as well.
> 
> Present since the initial commit, but not present in the qemu
> block/curl.c driver which is where most of this code was derived from,
> so I suspect I simply added it "because reasons".
> 
> But even more to the point, why on earth does the
> CURLINFO_CONTENT_LENGTH_DOWNLOAD API return a double!  Well it seems
> as if they replaced that API with:
> 
> https://curl.haxx.se/libcurl/c/CURLINFO_CONTENT_LENGTH_DOWNLOAD_T.html
> 
> which is what we really ought to use instead.  This was added in Curl
> 7.55.0, released 2 and a half years ago, so I think we ought to use
> that instead.  Adrian could you write a patch to change over to that
> API?
> 
> Rich.
I see that you've already ACK-ed such change by Pino so I assume my 
patch is OK? Or should I remove casting altogether?
> 
>>>     nbdkit_debug ("content length: %" PRIi64, h->exportsize);
>>>
>>>     if (strncasecmp (url, "http://", strlen ("http://")) == 0 ||
>>
>> -- 
>> Eric Blake, Principal Software Engineer
>> Red Hat, Inc.           +1-919-301-3226
>> Virtualization:  qemu.org | libvirt.org
>>
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>