Re: [pygame] Segfault on loading font from StringIO

[Radomir Dopieralski <pygame@xxxxxxxxxxxx>]

On Wed, Jan 4, 2012 at 05:56, Lenard Lindstrom <len-l@xxxxxxxxx> wrote:
> Hi,
>
>
> On 02/01/12 05:45 AM, Radomir Dopieralski wrote:
>>
>> I think that this comment is related to this problem:
>> http://archives.seul.org/pygame/users/Jan-2004/msg00035.html
>
> No, this is a different problem. pygame.font.Font probably could not find
> the default font file and segfaulted rather than throw a nice Python
> exception. This may have been fixed. I can check.
>
>
>> On Mon, Jan 2, 2012 at 13:46, Russell Jones<russell.jones@xxxxxxxxx>
>> Âwrote:
>>>
>>> In summary, the font reading function in SDL relies on a filename, so as
>>> it
>>> stands, reading from a file-like object won't work. Covering the buffer
>>> to a
>>> string causes the data to be interpreted as a filename, which
>>> unsurprisingly
>>> gives an IOError saying the font filename can't be read (line 600 of
>>> font.c).
>>>
>>> I had a look on Debian testing in a VM, and it seems to be happening in
>>> SDL_RWFromFile, which is not in font.c, but is called by its functions. I
>>> couldn't see where the error was happening in font.c as there are no
>>> pygame
>>> debug symbols available. I'm guessing it's the line
>>> rw = RWopsFromPython (fileobj)
>>> (RWopsFromPython is from rwobject.c and calls get_standard_rwop, which
>>> calls
>>> either SDL_RWFromFile or SDL_RWFromFP if it can't extract a name from
>>> fileobj)
>>>
>>> It seems likely to be related to this comment in font_init() : /*check if
>>> it
>>> is a valid file, else SDL_ttf segfaults*/. I guess SDL_RWFromMem could be
>>> used with some kind of translation from the buffer, or SDL_RWFromFile
>>> could
>>> be altered to accept a file object. The SDL API spec for FromFile relies
>>> on
>>> a filename, however, and FromFile does the opening of the file itself
>>> using
>>> that.
>>>
>>> Russell
>>>
>>> On 1 January 2012 10:50, Radomir Dopieralski<pygame@xxxxxxxxxxxx> Âwrote:
>>>>
>>>> Hello everyone,
>>>>
>>>> I'm having a problem loading a font file from a python file-like
>>>> object. According to the documentation at
>>>> http://www.pygame.org/docs/ref/font.html#pygame.font.Font this should
>>>> be possible, however, I get a segmentation fault every time I pass a
>>>> file-like object that is not created by opening a real file. I want to
>>>> load all my assets from a zip archive, so it's not possible to have a
>>>> real file in the filesystem.
>>>>
>>>> A simple test case:
>>>>
>>>> import pygame
>>>> import StringIO
>>>>
>>>> pygame.font.init()
>>>>
>>>> f = open("somefont.ttf", "r")
>>>> font = pygame.font.Font(f, 8) # Works fine
>>>> f.close()
>>>>
>>>> f = open("somefont.ttf", "r")
>>>> buffer = StringIO.StringIO(f.read())
>>>> f.close()
>>>> font = pygame.font.Font(buffer, 8) # Segfault
>>>>
>>>> Is there any way to make it work as documented? If the documentation
>>>> is wrong, is there any way to create a pygame font object without
>>>> creating a real file in the filesystem?
>>>>
>>>> Thanks,
>>>> --
>>>> Radomir Dopieralski
>>>
>>>
> The Font type should accept any Python object with read(), seek() and
> close() methods. However, Pygame 1.9.1 and earlier have a Font bug involving
> file like objects that are not actual file objects. Basically, threading is
> improperly handled. It probably worked if early versions of the freetype
> library were single threaded. But freetype now appears to be multithreaded.
> Therefore the segfault. I fixed this for Pygame 1.9.2 (still in development)
> so I get no segfault; it works as advertised.

Thank you very much!
I'm sure that it will be released before I finish my project, so that
really helps a lot.

-- 
Radomir Dopieralski