The bus error is gone but I’m not really comfortable with the reason why I don’t have that error anymore. Let’s explain a bit:
mmap() is a 6 argument function, all of them required.
Thomas Heller discovered under FreeBSD 6.0 with ktrace that it’s called with 8 parameters, not 6. The two argument in addition are all 0 if called with the 6-arg mmap from plain C.
If you call mmap() from ctypes the 7th parameter is zeroed, the 8th is a random hexadecimal. So it doesn’t work, because C calls it with 0.
A FreeBSD committer friend of mine told me instead that the syscall under mmap() is a 7 argument function, not 8.
Thomas Heller tried with 8 parameters and it worked. I, accordingly to my friend, tried with 7 instead and it worked well anyway.
So the mistery is still here but the error is gone.
You can discover odd things also under Unix, not only under Win32 
Eventually, this is the correct code:
[code lang="python"] from ctypes import * import ctypes.util
_libc = cdll.LoadLibrary(ctypes.util.find_library("c"))
f = open("foo", "w+") f.write("foo\0") f.flush()
_libc.mmap.restype = c_void_p m = _libc.mmap(0, 4, 3, 1, f.fileno(), 0, 0) print m if m != c_void_p(-1).value: c = cast(m, POINTER(c_char)) print [c[i] for i in range(4)] f.close() [/code]
ps. the title is taken from a Busta Rhymes old song 
