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