[FFmpeg-devel] url_exists function in avio.c opens instead of checking existence

Stefano Sabatini stefano.sabatini-lala
Tue Sep 14 15:07:09 CEST 2010

On date Thursday 2010-01-21 12:29:36 +0100, Stefano Sabatini encoded:
> On date Wednesday 2010-01-20 21:24:46 +0100, Maker aka Michele encoded:
> > > if ((ret = url_check(file, w) != AVERROR(ENOENT))  // the file exists
> > >    ask_for_overwrite_confirmation();
> > >
> > > uhm, yeah, may a function like "url_check" isn't really like url_exists,
> > but should be more useful.
> > But my opinion is that a file shouldn't be opened if we just want to know if
> > it is writable/readable. So, what about extending URLProtocol with a pointer
> > to function,  which checks if the url can be opened in a certain mode
> > (specific for each protocol)?
> (Quick reply as I'm pretty busy now)
> Options:
> 1) implement url_check()
> 2) extend url_exist() with a simple if (url == "file") then stat(...);,
> not elegant but it should work.
> 3) extend URLProtocol and make it implement an url_exist method() for
> each protocol, this looks a little overkill to me.
> I have no strong preference on these, so I'll let the decision to the
> maintainers, in the meaningwhile you may provide a patch implementing
> your favourite approach.

Ping. Another solution would be implementing a per protocol
url_check() function, which checks if a "protocol stream" can be
opened with a certain mode, and can be used for the testing if a file

In the case of the "file" protocol it would use stat(), and should
possibly fix the problem at hand.

FFmpeg = Furious & Fast Multimedia Philosophical Evil Gadget

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