8863b1212a
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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200507185529.GA14639@embeddedor
78 lines
1.8 KiB
C
78 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/******************************************************************************
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*
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* Copyright(c) 2003 - 2011 Intel Corporation. All rights reserved.
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*
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* Portions of this file are derived from the ieee80211 subsystem header files.
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*
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* Contact Information:
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* Intel Linux Wireless <ilw@linux.intel.com>
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* Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
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*
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*****************************************************************************/
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#ifndef __il_spectrum_h__
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#define __il_spectrum_h__
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enum { /* ieee80211_basic_report.map */
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IEEE80211_BASIC_MAP_BSS = (1 << 0),
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IEEE80211_BASIC_MAP_OFDM = (1 << 1),
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IEEE80211_BASIC_MAP_UNIDENTIFIED = (1 << 2),
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IEEE80211_BASIC_MAP_RADAR = (1 << 3),
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IEEE80211_BASIC_MAP_UNMEASURED = (1 << 4),
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/* Bits 5-7 are reserved */
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};
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struct ieee80211_basic_report {
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u8 channel;
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__le64 start_time;
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__le16 duration;
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u8 map;
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} __packed;
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enum { /* ieee80211_measurement_request.mode */
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/* Bit 0 is reserved */
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IEEE80211_MEASUREMENT_ENABLE = (1 << 1),
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IEEE80211_MEASUREMENT_REQUEST = (1 << 2),
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IEEE80211_MEASUREMENT_REPORT = (1 << 3),
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/* Bits 4-7 are reserved */
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};
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enum {
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IEEE80211_REPORT_BASIC = 0, /* required */
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IEEE80211_REPORT_CCA = 1, /* optional */
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IEEE80211_REPORT_RPI = 2, /* optional */
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/* 3-255 reserved */
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};
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struct ieee80211_measurement_params {
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u8 channel;
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__le64 start_time;
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__le16 duration;
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} __packed;
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struct ieee80211_info_element {
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u8 id;
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u8 len;
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u8 data[];
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} __packed;
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struct ieee80211_measurement_request {
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struct ieee80211_info_element ie;
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u8 token;
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u8 mode;
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u8 type;
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struct ieee80211_measurement_params params[];
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} __packed;
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struct ieee80211_measurement_report {
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struct ieee80211_info_element ie;
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u8 token;
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u8 mode;
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u8 type;
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union {
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struct ieee80211_basic_report basic[0];
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} u;
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} __packed;
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#endif
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