Re: [pygame] Segfault on loading font from StringIO

[Russell Jones <russell.jones@xxxxxxxxx>]

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> wrote:

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