From 4c8fb05cb4d6ddcd67299008db54af423f86fd05 Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: Sat, 1 Jul 2017 19:01:01 +0200
Subject: [PATCH] can-utils: remove strict-aliasing compiler warning

GitHub user 'crossband' raised an issue regarding the strict-aliasing compiler
warning in his specific setup: https://github.com/linux-can/can-utils/issues/42

In fact memcpy() and memset() are a better solution than the former pointer
magics, so remove the issues and the compiler warning flag too.

Reported-by: crossband (https://github.com/crossband)
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 Makefile     |  3 +--
 candump.c    |  4 ++--
 cangen.c     |  8 +++++---
 cansniffer.c | 28 +++++++++++++++-------------
 slcanpty.c   |  2 +-
 5 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/Makefile b/Makefile
index ee94340..67ddf8c 100644
--- a/Makefile
+++ b/Makefile
@@ -43,8 +43,7 @@ PREFIX ?= /usr/local
 
 MAKEFLAGS = -k
 
-CFLAGS    = -O2 -Wall -Wno-parentheses \
-	    -fno-strict-aliasing
+CFLAGS    = -O2 -Wall -Wno-parentheses
 
 CPPFLAGS += -Iinclude \
 	    -D_FILE_OFFSET_BITS=64 \
diff --git a/candump.c b/candump.c
index f328c66..d707bd9 100644
--- a/candump.c
+++ b/candump.c
@@ -689,9 +689,9 @@ int main(int argc, char **argv)
 				     cmsg && (cmsg->cmsg_level == SOL_SOCKET);
 				     cmsg = CMSG_NXTHDR(&msg,cmsg)) {
 					if (cmsg->cmsg_type == SO_TIMESTAMP)
-						tv = *(struct timeval *)CMSG_DATA(cmsg);
+						memcpy(&tv, CMSG_DATA(cmsg), sizeof(tv));
 					else if (cmsg->cmsg_type == SO_RXQ_OVFL)
-						dropcnt[i] = *(__u32 *)CMSG_DATA(cmsg);
+						memcpy(&dropcnt[i], CMSG_DATA(cmsg), sizeof(__u32));
 				}
 
 				/* check for (unlikely) dropped frames on this specific socket */
diff --git a/cangen.c b/cangen.c
index bd22b7d..769fac2 100644
--- a/cangen.c
+++ b/cangen.c
@@ -150,6 +150,7 @@ int main(int argc, char **argv)
 	int mtu, maxdlen;
 	uint64_t incdata = 0;
 	int incdlc = 0;
+	unsigned long rnd;
 	unsigned char fixdata[CANFD_MAX_DLEN];
 
 	int opt;
@@ -400,9 +401,10 @@ int main(int argc, char **argv)
 
 		if (data_mode == MODE_RANDOM) {
 
-			/* that's what the 64 bit alignment of data[] is for ... :) */
-			*(unsigned long*)(&frame.data[0]) = random();
-			*(unsigned long*)(&frame.data[4]) = random();
+			rnd = random();
+			memcpy(&frame.data[0], &rnd, 4);
+			rnd = random();
+			memcpy(&frame.data[4], &rnd, 4);
 
 			/* omit extra random number generation for CAN FD */
 			if (canfd && frame.len > 8) {
diff --git a/cansniffer.c b/cansniffer.c
index 39b3e2b..7b0a3fa 100644
--- a/cansniffer.c
+++ b/cansniffer.c
@@ -64,8 +64,6 @@
 
 #include "terminal.h"
 
-#define U64_DATA(p) (*(unsigned long long*)(p)->data)
-
 #define SETFNAME "sniffset."
 #define ANYDEV   "any"
 
@@ -370,7 +368,9 @@ void rx_setup (int fd, int id){
 	txmsg.msg_head.ival2.tv_sec  = 0;
 	txmsg.msg_head.ival2.tv_usec = 0;
 	txmsg.msg_head.nframes = 1;
-	U64_DATA(&txmsg.frame) = (__u64) 0xFFFFFFFFFFFFFFFFULL;
+
+	/* set all bits to be relevant */
+	memset(&txmsg.frame.data, 0xFF, 8);
 
 	if (filter_id_only)
 		txmsg.msg_head.flags |= RX_FILTER_ID;
@@ -478,7 +478,7 @@ int handle_keyb(int fd){
 
 	case '*' :
 		for (i=0; i < 2048; i++)
-			U64_DATA(&sniftab[i].notch) = (__u64) 0;
+			memset(&sniftab[i].notch.data, 0, 8);
 		break;
 
 	default:
@@ -492,7 +492,7 @@ int handle_keyb(int fd){
 
 int handle_bcm(int fd, long currcms){
 
-	int nbytes, id;
+	int nbytes, id, i;
 
 	struct {
 		struct bcm_msg_head msg_head;
@@ -518,8 +518,9 @@ int handle_bcm(int fd, long currcms){
 	}
 
 	sniftab[id].current = bmsg.frame;
-	U64_DATA(&sniftab[id].marker) |= 
-		U64_DATA(&sniftab[id].current) ^ U64_DATA(&sniftab[id].last);
+	for (i=0; i < 8; i++)
+		sniftab[id].marker.data[i] |= sniftab[id].current.data[i] ^ sniftab[id].last.data[i];
+
 	sniftab[id].timeout = (timeout)?(currcms + timeout):0;
 
 	if (is_clr(id, DISPLAY))
@@ -533,7 +534,7 @@ int handle_bcm(int fd, long currcms){
 
 int handle_timeo(int fd, long currcms){
 
-	int i;
+	int i, j;
 	int force_redraw = 0;
 	static unsigned int frame_count;
 
@@ -547,8 +548,10 @@ int handle_timeo(int fd, long currcms){
 	}
 
 	if (notch) {
-		for (i=0; i < 2048; i++)
-			U64_DATA(&sniftab[i].notch) |= U64_DATA(&sniftab[i].marker);
+		for (i=0; i < 2048; i++) {
+			for (j=0; j < 8; j++)
+				sniftab[i].notch.data[j] |= sniftab[i].marker.data[j];
+		}
 		notch = 0;
 	}
 
@@ -569,7 +572,7 @@ int handle_timeo(int fd, long currcms){
 						}
 						else
 							if ((sniftab[i].hold) && (sniftab[i].hold < currcms)) {
-								U64_DATA(&sniftab[i].marker) = (__u64) 0;
+								memset(&sniftab[i].marker.data, 0, 8);
 								print_snifline(i);
 								sniftab[i].hold = 0; /* disable update by hold */
 							}
@@ -670,8 +673,7 @@ void print_snifline(int id){
 
 	putchar('\n');
 
-	U64_DATA(&sniftab[id].marker) = (__u64) 0;
-
+	memset(&sniftab[id].marker.data, 0, 8);
 };
 
 
diff --git a/slcanpty.c b/slcanpty.c
index 5cf14ef..431ca68 100644
--- a/slcanpty.c
+++ b/slcanpty.c
@@ -246,7 +246,7 @@ rx_restart:
 	else
 		ptr = 9; /* dlc position Tiiiiiiiid */
 
-	*(unsigned long long *) (&frame.data) = 0ULL; /* clear data[] */
+	memset(&frame.data, 0, 8); /* clear data[] */
 
 	if ((cmd | 0x20) == 'r' && buf[ptr] != '0') {