treewide: Make a bunch of pointer variables pointers to const

Sufficiently recent cppcheck (I'm using 2.13.0) seems to have added another
warning for pointer variables which could be pointer to const but aren't.
Use this to make a bunch of variables const pointers where they previously
weren't for no particular reason.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

arch.c

@@ -25,7 +25,8 @@
 #ifdef __x86_64__
 void arch_avx2_exec(char **argv)
 {
-	char exe[PATH_MAX] = { 0 }, *p;
+	char exe[PATH_MAX] = { 0 };
+	const char *p;
 
 	if (readlink("/proc/self/exe", exe, PATH_MAX - 1) < 0) {
 		perror("readlink /proc/self/exe");

conf.c

@@ -412,8 +412,9 @@ static void get_dns(struct ctx *c)
 	int dns4_set, dns6_set, dnss_set, dns_set, fd;
 	struct fqdn *s = c->dns_search;
 	struct lineread resolvconf;
+	char *line, *end;
+	const char *p;
 	int line_len;
-	char *line, *p, *end;
 
 	dns4_set = !c->ifi4 || !IN4_IS_ADDR_UNSPECIFIED(dns4);
 	dns6_set = !c->ifi6 || !IN6_IS_ADDR_UNSPECIFIED(dns6);
@@ -1025,7 +1026,7 @@ static int conf_runas(char *opt, unsigned int *uid, unsigned int *gid)
 	if (*endptr) {
 #ifndef GLIBC_NO_STATIC_NSS
 		/* Not numeric, look up as a username */
-		struct passwd *pw;
+		const struct passwd *pw;
 		/* cppcheck-suppress getpwnamCalled */
 		if (!(pw = getpwnam(uopt)) || !(*uid = pw->pw_uid))
 			return -ENOENT;
@@ -1042,7 +1043,7 @@ static int conf_runas(char *opt, unsigned int *uid, unsigned int *gid)
 	if (*endptr) {
 #ifndef GLIBC_NO_STATIC_NSS
 		/* Not numeric, look up as a group name */
-		struct group *gr;
+		const struct group *gr;
 		/* cppcheck-suppress getgrnamCalled */
 		if (!(gr = getgrnam(gopt)))
 			return -ENOENT;
@@ -1086,7 +1087,7 @@ static void conf_ugid(char *runas, uid_t *uid, gid_t *gid)
 	warn("Don't run as root. Changing to nobody...");
 	{
 #ifndef GLIBC_NO_STATIC_NSS
-		struct passwd *pw;
+		const struct passwd *pw;
 		/* cppcheck-suppress getpwnamCalled */
 		pw = getpwnam("nobody");
 		if (!pw) {
@@ -1173,14 +1174,15 @@ void conf(struct ctx *c, int argc, char **argv)
 	bool copy_addrs_opt = false, copy_routes_opt = false;
 	enum port_fwd_mode fwd_default = FWD_NONE;
 	bool v4_only = false, v6_only = false;
-	char *runas = NULL, *logfile = NULL;
 	struct in6_addr *dns6 = c->ip6.dns;
 	struct fqdn *dnss = c->dns_search;
 	struct in_addr *dns4 = c->ip4.dns;
 	unsigned int ifi4 = 0, ifi6 = 0;
+	const char *logfile = NULL;
 	const char *optstring;
 	int name, ret, b, i;
 	size_t logsize = 0;
+	char *runas = NULL;
 	uid_t uid;
 	gid_t gid;
 

dhcp.c

@@ -275,10 +275,10 @@ static void opt_set_dns_search(const struct ctx *c, size_t max_len)
 int dhcp(const struct ctx *c, const struct pool *p)
 {
 	size_t mlen, len, offset = 0, opt_len, opt_off = 0;
+	const struct ethhdr *eh;
+	const struct iphdr *iph;
+	const struct udphdr *uh;
 	struct in_addr mask;
-	struct ethhdr *eh;
-	struct iphdr *iph;
-	struct udphdr *uh;
 	unsigned int i;
 	struct msg *m;
 
@@ -312,7 +312,8 @@ int dhcp(const struct ctx *c, const struct pool *p)
 	offset += offsetof(struct msg, o);
 
 	while (opt_off + 2 < opt_len) {
-		uint8_t *olen, *type, *val;
+		const uint8_t *olen, *val;
+		uint8_t *type;
 
 		type = packet_get(p, 0, offset + opt_off,	1,	NULL);
 		olen = packet_get(p, 0, offset + opt_off + 1,	1,	NULL);

dhcpv6.c

@@ -426,10 +426,11 @@ search:
 int dhcpv6(struct ctx *c, const struct pool *p,
 	   const struct in6_addr *saddr, const struct in6_addr *daddr)
 {
-	struct opt_hdr *ia, *bad_ia, *client_id, *server_id;
-	struct in6_addr *src;
-	struct msg_hdr *mh;
-	struct udphdr *uh;
+	struct opt_hdr *ia, *bad_ia, *client_id;
+	const struct opt_hdr *server_id;
+	const struct in6_addr *src;
+	const struct msg_hdr *mh;
+	const struct udphdr *uh;
 	size_t mlen, n;
 
 	uh = packet_get(p, 0, 0, sizeof(*uh), &mlen);

log.c

@@ -222,7 +222,8 @@ void logfile_init(const char *name, const char *path, size_t size)
  */
 static void logfile_rotate_fallocate(int fd, const struct timespec *ts)
 {
-	char buf[BUFSIZ], *nl;
+	char buf[BUFSIZ];
+	const char *nl;
 	int n;
 
 	if (lseek(fd, 0, SEEK_SET) == -1)
@@ -260,7 +261,8 @@ static void logfile_rotate_fallocate(int fd, const struct timespec *ts)
 static void logfile_rotate_move(int fd, const struct timespec *ts)
 {
 	int header_len, write_offset, end, discard, n;
-	char buf[BUFSIZ], *nl;
+	char buf[BUFSIZ];
+	const char *nl;
 
 	header_len = snprintf(buf, BUFSIZ,
 			      "%s - log truncated at %lli.%04lli\n", log_header,

qrap.c

@@ -251,8 +251,8 @@ int main(int argc, char **argv)
 		}
 
 		if (!strcmp(argv[i], "-device") && i + 1 < argc) {
-			char *template = NULL;
-			char *p;
+			const char *template = NULL;
+			const char *p;
 
 			has_dev = 1;
 

tap.c

@@ -600,10 +600,10 @@ static int tap4_handler(struct ctx *c, const struct pool *in,
 resume:
 	for (seq_count = 0, seq = NULL; i < in->count; i++) {
 		size_t l2_len, l3_len, hlen, l4_len;
-		struct ethhdr *eh;
+		const struct ethhdr *eh;
+		const struct udphdr *uh;
 		struct iphdr *iph;
-		struct udphdr *uh;
-		char *l4h;
+		const char *l4h;
 
 		packet_get(in, i, 0, 0, &l2_len);
 
@@ -765,9 +765,9 @@ resume:
 	for (seq_count = 0, seq = NULL; i < in->count; i++) {
 		size_t l4_len, plen, check;
 		struct in6_addr *saddr, *daddr;
+		const struct ethhdr *eh;
+		const struct udphdr *uh;
 		struct ipv6hdr *ip6h;
-		struct ethhdr *eh;
-		struct udphdr *uh;
 		uint8_t proto;
 		char *l4h;
 
@@ -936,7 +936,7 @@ static void tap_sock_reset(struct ctx *c)
 void tap_handler_passt(struct ctx *c, uint32_t events,
 		       const struct timespec *now)
 {
-	struct ethhdr *eh;
+	const struct ethhdr *eh;
 	ssize_t n, rem;
 	char *p;
 

tcp.c

@@ -2296,7 +2296,7 @@ static int tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn,
 
 	for (i = idx, iov_i = 0; i < (int)p->count; i++) {
 		uint32_t seq, seq_offset, ack_seq;
-		struct tcphdr *th;
+		const struct tcphdr *th;
 		char *data;
 		size_t off;
 
@@ -2517,10 +2517,10 @@ int tcp_tap_handler(struct ctx *c, uint8_t pif, int af,
 		    const struct pool *p, int idx, const struct timespec *now)
 {
 	struct tcp_tap_conn *conn;
+	const struct tcphdr *th;
 	size_t optlen, len;
-	struct tcphdr *th;
+	const char *opts;
 	int ack_due = 0;
-	char *opts;
 	int count;
 
 	(void)pif;
@@ -3038,7 +3038,7 @@ void tcp_ns_sock_init(const struct ctx *c, in_port_t port)
  */
 static int tcp_ns_socks_init(void *arg)
 {
-	struct ctx *c = (struct ctx *)arg;
+	const struct ctx *c = (const struct ctx *)arg;
 	unsigned port;
 
 	ns_enter(c);

tcp_splice.c

@@ -127,7 +127,7 @@ static int tcp_splice_epoll_ctl(const struct ctx *c,
 				struct tcp_splice_conn *conn)
 {
 	int m = conn->in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
-	union epoll_ref ref[SIDES] = {
+	const union epoll_ref ref[SIDES] = {
 		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[0],
 		  .flowside = FLOW_SIDX(conn, 0) },
 		{ .type = EPOLL_TYPE_TCP, .fd = conn->s[1],

udp.c

@@ -821,10 +821,10 @@ int udp_tap_handler(struct ctx *c, uint8_t pif,
 	struct iovec m[UIO_MAXIOV];
 	struct sockaddr_in6 s_in6;
 	struct sockaddr_in s_in;
+	const struct udphdr *uh;
 	struct sockaddr *sa;
 	int i, s, count = 0;
 	in_port_t src, dst;
-	struct udphdr *uh;
 	socklen_t sl;
 
 	(void)c;
@@ -1045,7 +1045,7 @@ int udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
  * udp_sock_init_init() - Bind sockets in init namespace for inbound connections
  * @c:		Execution context
  */
-static void udp_sock_init_init(struct ctx *c)
+static void udp_sock_init_init(const struct ctx *c)
 {
 	unsigned dst;
 
@@ -1065,7 +1065,7 @@ static void udp_sock_init_init(struct ctx *c)
  */
 int udp_sock_init_ns(void *arg)
 {
-	struct ctx *c = (struct ctx *)arg;
+	const struct ctx *c = (const struct ctx *)arg;
 	unsigned dst;
 
 	ns_enter(c);

util.c

@@ -48,8 +48,8 @@
 char *ipv6_l4hdr(const struct pool *p, int idx, size_t offset, uint8_t *proto,
 		 size_t *dlen)
 {
-	struct ipv6_opt_hdr *o;
-	struct ipv6hdr *ip6h;
+	const struct ipv6_opt_hdr *o;
+	const struct ipv6hdr *ip6h;
 	char *base;
 	int hdrlen;
 	uint8_t nh;