linux-next/include/linux/usbdevice_fs.h
Gustavo A. R. Silva 6bc3f3979e USB: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200220132017.GA29262@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-23 19:24:51 +01:00

82 lines
2.2 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*****************************************************************************/
/*
* usbdevice_fs.h -- USB device file system.
*
* Copyright (C) 2000
* Thomas Sailer (sailer@ife.ee.ethz.ch)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* History:
* 0.1 04.01.2000 Created
*/
/*****************************************************************************/
#ifndef _LINUX_USBDEVICE_FS_H
#define _LINUX_USBDEVICE_FS_H
#include <uapi/linux/usbdevice_fs.h>
#ifdef CONFIG_COMPAT
#include <linux/compat.h>
struct usbdevfs_ctrltransfer32 {
u8 bRequestType;
u8 bRequest;
u16 wValue;
u16 wIndex;
u16 wLength;
u32 timeout; /* in milliseconds */
compat_caddr_t data;
};
struct usbdevfs_bulktransfer32 {
compat_uint_t ep;
compat_uint_t len;
compat_uint_t timeout; /* in milliseconds */
compat_caddr_t data;
};
struct usbdevfs_disconnectsignal32 {
compat_int_t signr;
compat_caddr_t context;
};
struct usbdevfs_urb32 {
unsigned char type;
unsigned char endpoint;
compat_int_t status;
compat_uint_t flags;
compat_caddr_t buffer;
compat_int_t buffer_length;
compat_int_t actual_length;
compat_int_t start_frame;
compat_int_t number_of_packets;
compat_int_t error_count;
compat_uint_t signr;
compat_caddr_t usercontext; /* unused */
struct usbdevfs_iso_packet_desc iso_frame_desc[];
};
struct usbdevfs_ioctl32 {
s32 ifno;
s32 ioctl_code;
compat_caddr_t data;
};
#endif
#endif /* _LINUX_USBDEVICE_FS_H */