[haiku-development] Re: How to Identify a file?

> Hi Fredrik,
>
>> > The mime type of a file should provide that information.
>> thanks..
>> this was the way I found it to work.. any suggestions on how to make it
>> smaller/ not that memory intense? I will move the code to it's own bool
>> VerifyFileType(entry_ref *ref, char *type) function. How do I make char
>> *type that can be more than 1 parameter? I want to send both "audio",
>> "video" and perhaps other super types? But this works nicely :)
>>
>> refsReceivedMessage are a BMessage and can have one file or allot of
>> files. Are hosted in src/apps/mediaplayer/playlist/Playlist.cpp around
>> line 278
>>
>> entry_ref ref;
>> BFile *file;
>> BNodeInfo *nodeinfo;
>> BMimeType* mimetype, temp;
>> char str[10];
>> for (int i = 0; refsReceivedMessage->FindRef("refs", i, &ref) == B_OK;
>> i++){
>>     file = new BFile(&ref, B_READ_ONLY);
>>     nodeinfo = new BNodeInfo(file);
>>     if(nodeinfo->GetType(str) == B_OK){
>>         mimetype = new BMimeType(str);
>>         if(mimetype->GetSupertype(&temp) == B_OK){
>>             if(temp == "audio" || temp == "video")
>>                 AppendToPlaylistRecursive(ref, playlist);
>>         }
>>     }
>> }
>
> I hope you don't mind if I point out some problems in this code. The
> biggest
np that's whay I wrote this mail :)

> problem is that you are leaking files, node infos and mime types, since
> you
> create them with "new" but never delete them. Much easier to create them
I know this are just to test what way to turn and what works where.

> on
> the stack. The string you provide to the GetType() function is too small,
> which will cause memory to be overwritten on the stack. Also, declaring
Noticed this the hard way :)

> all
> the variables in the beginning of a funcion is C style, but we are writing
> C++ and you should declare the variables where you need them. And it is
> better to chose names that reflect what the variables are for. Here is how
> I
> would adapt the code:
>
> entry_ref ref;
> for (int i = 0; refsReceivedMessage->FindRef("refs", i, &ref) == B_OK;
> i++) {
>       BFile file(&ref, B_READ_ONLY);
>       BNodeInfo nodeInfo(&file);
>       char mimeString[B_MIME_TYPE_LENGTH];
>       if (nodeInfo->GetType(mimeString) == B_OK) {
>               BMimeType fileType(mimeString);
>               BMimeType superType;
>               if (fileType->GetSupertype(&superType) == B_OK) {
>                       if (superType == "audio" || superType == "video")
>                               AppendToPlaylistRecursive(ref, playlist);
>               }
>       }
> }
>
> I am wondering where exactly you place this code, since you call
> AppendToPlaylistRecursive() in the end. Directly after receiving the refs
> message? It looks to me like recursive adding of folders wouldn't work
> anymore then. It could be better to have some kind of "filter" function,
> which is called directly before appending a file to the playlist. This
> function would just tell the appending function if a file should be
> appended
> or rejected. But it could work exactly like above, only in different
> context.
In the end this are my goal, i would have dune this in my other patch if I
have thought the same way I do when I'm programming C#, (you know your
function about tagging the menu items) but right now I'm learning how to
best solve this so your comments are needed :)

>
> Best regards,
> -Stephan
>
>
>
>


-- 
MVH
Fredrik Modéen


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