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Revision 3dbae15538972c9e1578cb216964c2840361a538 authored by Gustavo A. R. Silva on 15 February 2020, 01:03:12 UTC, committed by Dmitry Torokhov on 15 February 2020, 01:19:22 UTC 
Input: cyapa - 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200214172132.GA28389@embeddedor
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
1 parent 94bef5d
Raw File
makelst 
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
# A script to dump mixed source code & assembly
# with correct relocations from System.map
# Requires the following lines in makefile:
#%.lst: %.c
#	$(CC) $(c_flags) -g -c -o $*.o $< &&
#	$(srctree)/scripts/makelst $*.o System.map $(OBJDUMP) > $@
#
# Copyright (C) 2000 IBM Corporation
# Author(s): DJ Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
#            William Stearns <wstearns@pobox.com>
#

# awk style field access
field() {
  shift $1 ; echo $1
}

t1=`$3 --syms $1 | grep .text | grep -m1 " F "`
if [ -n "$t1" ]; then
  t2=`field 6 $t1`
  if [ ! -r $2 ]; then
    echo "No System.map" >&2
  else
    t3=`grep $t2 $2`
    t4=`field 1 $t3`
    t5=`field 1 $t1`
    t6=`printf "%lu" $((0x$t4 - 0x$t5))`
  fi
fi
$3 -r --source --adjust-vma=${t6:-0} $1
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