[FFmpeg-devel] [PATCH] Allow mpjpeg demuxer to process MIME parts which do not include Content-Length header.

Alexander Agranovsky alex at sighthound.com
Mon Nov 30 13:41:21 CET 2015

On 11/30/15 7:34 AM, wm4 wrote:
> On Mon, 30 Nov 2015 07:27:14 -0500
> Alexander Agranovsky <alex at sighthound.com> wrote:
>> On 11/30/15 2:41 AM, Nicolas George wrote:
>>> Le nonidi 9 frimaire, an CCXXIV, Alexander Agranovsky a écrit :
>>>> Please see the updated patches attached. The trimming loop that was subject
>>>> of the discussion had been rewritten to use indices rather than pointer
>>>> arithmetics.
>>> This kind of drastic change was not necessary, you can do the same with
>>> pointers. IMHO, the best way of dealing with that situation is this: when
>>> dealing with the end of the string, have the pointer point AFTER the end of
>>> the string, i.e.:
>>> 	char *p = string + strlen(string); // not -1
>>> 	if (p > string && av_isspace(p[-1]))
>>> 	    *(--p) = 0;
>> That works too.
>>>> +    char*       boundary;
>>> Here and in all new code, please use "char *var" instead of "char* var" for
>>> consistency. There is a good reason for that: "char* a, b" means that a is a
>>> pointer and b is not, grouping the pointer mark with the type is misleading.
>> Without getting into a religious debate, not my favorite part of the
>> style ;)
>> Will change the code to match the style of existing, though.
>>>> +                "Expected boundary '%s' not found, instead found a line of %lu bytes\n",
>>>> +                expected_boundary,
>>>> +                strlen(line));
>>> "%lu" is not correct for size_t. The correct type would be %zu, but it is
>>> possible that we have to use another construct to avoid bugs from microsoft
>>> libraries, see other instances in the code for examples.
>> As pointed later in the thread, lu is used elsewhere. And yes, MS makes
>> it interesting in this case.
> No, I meant %zu. lu really isn't safe. It will fail on 64 bit Windows,
> for one. (But what Nicolas meant was that %zu could fail on Windows
> because Windows is stuck in the past, but we work that around if
> necessary - I think.)
>>>> -            size = parse_content_length(value);
>>>> -            if (size < 0)
>>>> -                return size;
>>>> +            *size = parse_content_length(value);
>>> Did you remove the check on purpose?
>> Yes. Invalid Content-Length, just as no Content-Length at all, should
>> not prevent us from processing the part.
> Probably not a good idea to ignore when the server sends us definitely
> broken data. I'd prefer failure or at least an error message.
I'll add a warning, how about that?

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