| msg65933 - (view) |
Author: (ndbecker) |
Date: 2008-04-28 21:01 |
| IIUC, current ioctl is not capable of handling arbitrary argument types. This code will allow any arg type (such as structures with pointers to embedded structures). The code for _IOC is taken from linux and might not be portable.import ----- from ctypes import * libc = CDLL ('/lib/libc.so.6') #print libc.ioctl def set_ioctl_argtype (arg_type): libc.ioctl.argtypes = (c_int, c_int, arg_type) IOC_WRITE = 0x1 _IOC_NRBITS= 8 _IOC_TYPEBITS= 8 _IOC_SIZEBITS= 14 _IOC_DIRBITS= 2 _IOC_NRSHIFT= 0 _IOC_TYPESHIFT= (_IOC_NRSHIFT+_IOC_NRBITS) _IOC_SIZESHIFT= (_IOC_TYPESHIFT+_IOC_TYPEBITS) _IOC_DIRSHIFT= (_IOC_SIZESHIFT+_IOC_SIZEBITS) def IOC (dir, type, nr, size): return (((dir) << _IOC_DIRSHIFT) | \ ((type) << _IOC_TYPESHIFT) |
\ ((nr) << _IOC_NRSHIFT) |
\ ((size) << _IOC_SIZESHIFT)) def ioctl (fd, request, args): return libc.ioctl (fd, request, args) ---- Example (not complete): class eos_dl_args_t (Structure): _fields_ = [("length", c_ulong), ("data", c_void_p)] args = eos_dl_args_t() args.length = len (c) args.data = cast (pointer (c), c_void_p) from eioctl import * set_ioctl_argtype (POINTER (eos_dl_args_t)) EOS_IOC_MAGIC = 0xF4 request = IOC(IOC_WRITE, EOS_IOC_MAGIC, 0x00, 0) # ignore size err = ioctl (fd, request, args) |
| msg65938 - (view) |
Author: Martin v. Löwis (loewis) *  |
Date: 2008-04-28 22:11 |
| > IIUC, current ioctl is not capable of handling arbitrary argument > types. Can you please be a bit more explicit? What limitation do you see in fcntl.ioctl, and how does this fragment overcome the limitation? AFAICT, they do exactly the same thing. |
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| msg65940 - (view) |
Author: (ndbecker) |
Date: 2008-04-28 22:35 |
| On Monday 28 April 2008, Martin v. Löwis wrote: > Martin v. Löwis <martin@v.loewis.de> added the comment: > > IIUC, current ioctl is not capable of handling arbitrary argument > > types. > > Can you please be a bit more explicit? What limitation do you see in > fcntl.ioctl, and how does this fragment overcome the limitation? > AFAICT, they do exactly the same thing. > In the example I gave, the ioctl passes a structure: class eos_dl_args_t (Structure): _fields_ = [("length", c_ulong), ("data", c_void_p)] AFAIK, there is no way to do that with fcntl.ioctl, is there? |
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| msg65941 - (view) |
Author: Martin v. Löwis (loewis) * |
Date: 2008-04-28 22:55 |
| Passing structures is certainly possible. I'd try args = struct.pack("iP", len(c), cast (pointer (c), c_void_p).value) fcntl.ioctl(fd, request, args) Alternatively, args = eos_dl_args_t() ... args_p = cast(pointer(args), c_void_ptr).value fcntl.ioctl(fd, request, args_p) should also work, IIUC. |
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| msg65949 - (view) |
Author: (ndbecker) |
Date: 2008-04-29 01:23 |
| On Monday 28 April 2008, Martin v. Löwis wrote: > Martin v. Löwis <martin@v.loewis.de> added the comment: > > Passing structures is certainly possible. I'd try > > args = struct.pack("iP", len(c), cast (pointer (c), c_void_p).value) > fcntl.ioctl(fd, request, args) > > Alternatively, > > args = eos_dl_args_t() > ... > args_p = cast(pointer(args), c_void_ptr).value > fcntl.ioctl(fd, request, args_p) > > should also work, IIUC. > You are correct, both of the above work (at least on x86) |
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| msg65950 - (view) |
Author: Benjamin Peterson (benjamin.peterson) * |
Date: 2008-04-29 02:11 |
| So, should we close this? |
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| msg65957 - (view) |
Author: Martin v. Löwis (loewis) * |
Date: 2008-04-29 05:48 |
| I think we should close it. |
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| msg65959 - (view) |
Author: (ndbecker) |
Date: 2008-04-29 10:27 |
| OK. |
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