cppcheck: Make many pointers const

Newer versions of cppcheck (as of 2.12.0, at least) added a warning for
pointers which could be declared to point at const data, but aren't.
Based on that, make many pointers throughout the codebase const.

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

18 files changed, 50 insertions, 46 deletions

diff --git a/conf.c b/conf.c
index 0ad6e23..551a9da 100644
--- a/conf.c
+++ b/conf.c
@@ -419,7 +419,8 @@ bind_fail:
  * @addr:	Address found in /etc/resolv.conf
  * @conf:	Pointer to reference of current entry in array of IPv4 resolvers
  */
-static void add_dns4(struct ctx *c, struct in_addr *addr, struct in_addr **conf)
+static void add_dns4(struct ctx *c, const struct in_addr *addr,
+		     struct in_addr **conf)
 {
 	/* Guest or container can only access local addresses via redirect */
 	if (IN4_IS_ADDR_LOOPBACK(addr)) {
@@ -1177,7 +1178,7 @@ static void conf_ugid(char *runas, uid_t *uid, gid_t *gid)
 void conf(struct ctx *c, int argc, char **argv)
 {
 	int netns_only = 0;
-	struct option options[] = {
+	const struct option options[] = {
 		{"debug",	no_argument,		NULL,		'd' },
 		{"quiet",	no_argument,		NULL,		'q' },
 		{"foreground",	no_argument,		NULL,		'f' },
diff --git a/isolation.c b/isolation.c
index 1866724..f394e93 100644
--- a/isolation.c
+++ b/isolation.c
@@ -303,7 +303,7 @@ void isolate_user(uid_t uid, gid_t gid, bool use_userns, const char *userns,
  * Mustn't:
  *  - Remove syscalls we need to daemonise
  */
-int isolate_prefork(struct ctx *c)
+int isolate_prefork(const struct ctx *c)
 {
 	int flags = CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWUTS;
 	uint64_t ns_caps = 0;
diff --git a/isolation.h b/isolation.h
index 6ca00bf..846b2af 100644
--- a/isolation.h
+++ b/isolation.h
@@ -10,7 +10,7 @@
 void isolate_initial(void);
 void isolate_user(uid_t uid, gid_t gid, bool use_userns, const char *userns,
 		  enum passt_modes mode);
-int isolate_prefork(struct ctx *c);
+int isolate_prefork(const struct ctx *c);
 void isolate_postfork(const struct ctx *c);
 
 #endif /* ISOLATION_H */
diff --git a/log.c b/log.c
index 63d7801..c57bc8d 100644
--- a/log.c
+++ b/log.c
@@ -216,7 +216,7 @@ void logfile_init(const char *name, const char *path, size_t size)
  *
  * #syscalls lseek ppc64le:_llseek ppc64:_llseek armv6l:_llseek armv7l:_llseek
  */
-static void logfile_rotate_fallocate(int fd, struct timespec *ts)
+static void logfile_rotate_fallocate(int fd, const struct timespec *ts)
 {
 	char buf[BUFSIZ], *nl;
 	int n;
@@ -253,7 +253,7 @@ static void logfile_rotate_fallocate(int fd, struct timespec *ts)
  * #syscalls lseek ppc64le:_llseek ppc64:_llseek armv6l:_llseek armv7l:_llseek
  * #syscalls ftruncate
  */
-static void logfile_rotate_move(int fd, 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;
@@ -318,7 +318,7 @@ out:
  *
  * fallocate() passed as EXTRA_SYSCALL only if FALLOC_FL_COLLAPSE_RANGE is there
  */
-static int logfile_rotate(int fd, struct timespec *ts)
+static int logfile_rotate(int fd, const struct timespec *ts)
 {
 	if (fcntl(fd, F_SETFL, O_RDWR /* Drop O_APPEND: explicit lseek() */))
 		return -errno;
diff --git a/netlink.c b/netlink.c
index 6c57a68..768c6fd 100644
--- a/netlink.c
+++ b/netlink.c
@@ -345,7 +345,7 @@ int nl_route_get_def(int s, unsigned int ifi, sa_family_t af, void *gw)
  *
  * Return: 0 on success, negative error code on failure
  */
-int nl_route_set_def(int s, unsigned int ifi, sa_family_t af, void *gw)
+int nl_route_set_def(int s, unsigned int ifi, sa_family_t af, const void *gw)
 {
 	struct req_t {
 		struct nlmsghdr nlh;
@@ -593,7 +593,7 @@ int nl_addr_get(int s, unsigned int ifi, sa_family_t af,
  * Return: 0 on success, negative error code on failure
  */
 int nl_addr_set(int s, unsigned int ifi, sa_family_t af,
-		void *addr, int prefix_len)
+		const void *addr, int prefix_len)
 {
 	struct req_t {
 		struct nlmsghdr nlh;
@@ -758,7 +758,7 @@ int nl_link_get_mac(int s, unsigned int ifi, void *mac)
  *
  * Return: 0 on success, negative error code on failure
  */
-int nl_link_set_mac(int s, unsigned int ifi, void *mac)
+int nl_link_set_mac(int s, unsigned int ifi, const void *mac)
 {
 	struct req_t {
 		struct nlmsghdr nlh;
diff --git a/netlink.h b/netlink.h
index 9f4f8f4..3a1f0de 100644
--- a/netlink.h
+++ b/netlink.h
@@ -12,17 +12,17 @@ extern int nl_sock_ns;
 void nl_sock_init(const struct ctx *c, bool ns);
 unsigned int nl_get_ext_if(int s, sa_family_t af);
 int nl_route_get_def(int s, unsigned int ifi, sa_family_t af, void *gw);
-int nl_route_set_def(int s, unsigned int ifi, sa_family_t af, void *gw);
+int nl_route_set_def(int s, unsigned int ifi, sa_family_t af, const void *gw);
 int nl_route_dup(int s_src, unsigned int ifi_src,
 		 int s_dst, unsigned int ifi_dst, sa_family_t af);
 int nl_addr_get(int s, unsigned int ifi, sa_family_t af,
 		void *addr, int *prefix_len, void *addr_l);
 int nl_addr_set(int s, unsigned int ifi, sa_family_t af,
-		void *addr, int prefix_len);
+		const void *addr, int prefix_len);
 int nl_addr_dup(int s_src, unsigned int ifi_src,
 		int s_dst, unsigned int ifi_dst, sa_family_t af);
 int nl_link_get_mac(int s, unsigned int ifi, void *mac);
-int nl_link_set_mac(int s, unsigned int ifi, void *mac);
+int nl_link_set_mac(int s, unsigned int ifi, const void *mac);
 int nl_link_up(int s, unsigned int ifi, int mtu);
 
 #endif /* NETLINK_H */
diff --git a/pasta.c b/pasta.c
index 9bc26d5..5fd44fe 100644
--- a/pasta.c
+++ b/pasta.c
@@ -362,7 +362,7 @@ void pasta_ns_conf(struct ctx *c)
  *
  * Return: inotify file descriptor, -1 on failure or if not needed/applicable
  */
-int pasta_netns_quit_init(struct ctx *c)
+int pasta_netns_quit_init(const struct ctx *c)
 {
 	int flags = O_NONBLOCK | O_CLOEXEC;
 	union epoll_ref ref = { .type = EPOLL_TYPE_NSQUIT };
@@ -399,7 +399,7 @@ int pasta_netns_quit_init(struct ctx *c)
 void pasta_netns_quit_handler(struct ctx *c, int inotify_fd)
 {
 	char buf[sizeof(struct inotify_event) + NAME_MAX + 1];
-	struct inotify_event *in_ev = (struct inotify_event *)buf;
+	const struct inotify_event *in_ev = (struct inotify_event *)buf;
 
 	if (read(inotify_fd, buf, sizeof(buf)) < (ssize_t)sizeof(*in_ev))
 		return;
diff --git a/pasta.h b/pasta.h
index 8722ca1..5d20063 100644
--- a/pasta.h
+++ b/pasta.h
@@ -13,7 +13,7 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
 		    int argc, char *argv[]);
 void pasta_ns_conf(struct ctx *c);
 void pasta_child_handler(int signal);
-int pasta_netns_quit_init(struct ctx *c);
+int pasta_netns_quit_init(const struct ctx *c);
 void pasta_netns_quit_handler(struct ctx *c, int inotify_fd);
 
 #endif /* PASTA_H */
diff --git a/tap.c b/tap.c
index 93db989..93bb348 100644
--- a/tap.c
+++ b/tap.c
@@ -203,7 +203,7 @@ void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
  * @len:	ICMP packet length, including ICMP header
  */
 void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
-		    void *in, size_t len)
+		    const void *in, size_t len)
 {
 	char buf[USHRT_MAX];
 	void *ip4h = tap_push_l2h(c, buf, ETH_P_IP);
@@ -291,7 +291,7 @@ void tap_udp6_send(const struct ctx *c,
  */
 void tap_icmp6_send(const struct ctx *c,
 		    const struct in6_addr *src, const struct in6_addr *dst,
-		    void *in, size_t len)
+		    const void *in, size_t len)
 {
 	char buf[USHRT_MAX];
 	void *ip6h = tap_push_l2h(c, buf, ETH_P_IPV6);
@@ -315,7 +315,7 @@ void tap_icmp6_send(const struct ctx *c,
  *
  * #syscalls:pasta write
  */
-static size_t tap_send_frames_pasta(struct ctx *c,
+static size_t tap_send_frames_pasta(const struct ctx *c,
 				    const struct iovec *iov, size_t n)
 {
 	size_t i;
@@ -414,7 +414,7 @@ static size_t tap_send_frames_passt(const struct ctx *c,
  * @iov:	Array of buffers, each containing one frame (with L2 headers)
  * @n:		Number of buffers/frames in @iov
  */
-void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n)
+void tap_send_frames(const struct ctx *c, const struct iovec *iov, size_t n)
 {
 	size_t m;
 
@@ -706,7 +706,7 @@ append:
 	}
 
 	for (j = 0, seq = tap4_l4; j < seq_count; j++, seq++) {
-		struct pool *p = (struct pool *)&seq->p;
+		const struct pool *p = (const struct pool *)&seq->p;
 		size_t k;
 
 		tap_packet_debug(NULL, NULL, seq, 0, NULL, p->count);
@@ -869,7 +869,7 @@ append:
 	}
 
 	for (j = 0, seq = tap6_l4; j < seq_count; j++, seq++) {
-		struct pool *p = (struct pool *)&seq->p;
+		const struct pool *p = (const struct pool *)&seq->p;
 		size_t k;
 
 		tap_packet_debug(NULL, NULL, NULL, seq->protocol, seq,
@@ -1022,7 +1022,7 @@ redo:
 	pool_flush(pool_tap6);
 restart:
 	while ((len = read(c->fd_tap, pkt_buf + n, TAP_BUF_BYTES - n)) > 0) {
-		struct ethhdr *eh = (struct ethhdr *)(pkt_buf + n);
+		const struct ethhdr *eh = (struct ethhdr *)(pkt_buf + n);
 
 		if (len < (ssize_t)sizeof(*eh) || len > (ssize_t)ETH_MAX_MTU) {
 			n += len;
diff --git a/tap.h b/tap.h
index 021fb7c..68509d1 100644
--- a/tap.h
+++ b/tap.h
@@ -62,7 +62,7 @@ void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
 		   struct in_addr dst, in_port_t dport,
 		   const void *in, size_t len);
 void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
-		    void *in, size_t len);
+		    const void *in, size_t len);
 const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
 				     const struct in6_addr *src);
 void tap_udp6_send(const struct ctx *c,
@@ -71,9 +71,9 @@ void tap_udp6_send(const struct ctx *c,
 		   uint32_t flow, const void *in, size_t len);
 void tap_icmp6_send(const struct ctx *c,
 		    const struct in6_addr *src, const struct in6_addr *dst,
-		    void *in, size_t len);
+		    const void *in, size_t len);
 int tap_send(const struct ctx *c, const void *data, size_t len);
-void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n);
+void tap_send_frames(const struct ctx *c, const struct iovec *iov, size_t n);
 void tap_update_mac(struct tap_hdr *taph,
 		    const unsigned char *eth_d, const unsigned char *eth_s);
 void tap_listen_handler(struct ctx *c, uint32_t events);
diff --git a/tcp.c b/tcp.c
index 680874f..1204e7b 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1016,7 +1016,7 @@ void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
  * tcp_sock4_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets
  * @c:		Execution context
  */
-static void tcp_sock4_iov_init(struct ctx *c)
+static void tcp_sock4_iov_init(const struct ctx *c)
 {
 	struct iphdr iph = L2_BUF_IP4_INIT(IPPROTO_TCP);
 	struct iovec *iov;
@@ -1237,7 +1237,7 @@ static void tcp_hash_remove(const struct ctx *c,
  * @old:	Old location of tcp_tap_conn
  * @new:	New location of tcp_tap_conn
  */
-static void tcp_tap_conn_update(struct ctx *c, struct tcp_tap_conn *old,
+static void tcp_tap_conn_update(const struct ctx *c, struct tcp_tap_conn *old,
 				struct tcp_tap_conn *new)
 {
 	struct tcp_tap_conn *entry, *prev = NULL;
@@ -1327,7 +1327,7 @@ void tcp_table_compact(struct ctx *c, union tcp_conn *hole)
  */
 static void tcp_conn_destroy(struct ctx *c, union tcp_conn *conn_union)
 {
-	struct tcp_tap_conn *conn = &conn_union->tap;
+	const struct tcp_tap_conn *conn = &conn_union->tap;
 
 	close(conn->sock);
 	if (conn->timer != -1)
@@ -1349,7 +1349,7 @@ static void tcp_rst_do(struct ctx *c, struct tcp_tap_conn *conn);
  * tcp_l2_flags_buf_flush() - Send out buffers for segments with no data (flags)
  * @c:		Execution context
  */
-static void tcp_l2_flags_buf_flush(struct ctx *c)
+static void tcp_l2_flags_buf_flush(const struct ctx *c)
 {
 	tap_send_frames(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
 	tcp6_l2_flags_buf_used = 0;
@@ -1362,7 +1362,7 @@ static void tcp_l2_flags_buf_flush(struct ctx *c)
  * tcp_l2_data_buf_flush() - Send out buffers for segments with data
  * @c:		Execution context
  */
-static void tcp_l2_data_buf_flush(struct ctx *c)
+static void tcp_l2_data_buf_flush(const struct ctx *c)
 {
 	tap_send_frames(c, tcp6_l2_iov, tcp6_l2_buf_used);
 	tcp6_l2_buf_used = 0;
@@ -2098,7 +2098,7 @@ static void tcp_conn_from_tap(struct ctx *c,
  *
  * Return: 0 on success, negative error code from recv() on failure
  */
-static int tcp_sock_consume(struct tcp_tap_conn *conn, uint32_t ack_seq)
+static int tcp_sock_consume(const struct tcp_tap_conn *conn, uint32_t ack_seq)
 {
 	/* Simply ignore out-of-order ACKs: we already consumed the data we
 	 * needed from the buffer, and we won't rewind back to a lower ACK
@@ -2124,14 +2124,14 @@ static int tcp_sock_consume(struct tcp_tap_conn *conn, uint32_t ack_seq)
  * @seq:	Sequence number to be sent
  * @now:	Current timestamp
  */
-static void tcp_data_to_tap(struct ctx *c, struct tcp_tap_conn *conn,
+static void tcp_data_to_tap(const struct ctx *c, struct tcp_tap_conn *conn,
 			    ssize_t plen, int no_csum, uint32_t seq)
 {
 	struct iovec *iov;
 
 	if (CONN_V4(conn)) {
 		struct tcp4_l2_buf_t *b = &tcp4_l2_buf[tcp4_l2_buf_used];
-		uint16_t *check = no_csum ? &(b - 1)->iph.check : NULL;
+		const uint16_t *check = no_csum ? &(b - 1)->iph.check : NULL;
 
 		iov = tcp4_l2_iov + tcp4_l2_buf_used++;
 		iov->iov_len = tcp_l2_buf_fill_headers(c, conn, b, plen,
@@ -2704,7 +2704,7 @@ static void tcp_snat_inbound(const struct ctx *c, union inany_addr *addr)
 static void tcp_tap_conn_from_sock(struct ctx *c,
 				   union tcp_listen_epoll_ref ref,
 				   struct tcp_tap_conn *conn, int s,
-				   struct sockaddr *sa,
+				   const struct sockaddr *sa,
 				   const struct timespec *now)
 {
 	conn->c.spliced = false;
diff --git a/tcp_conn.h b/tcp_conn.h
index d67ea62..0751e00 100644
--- a/tcp_conn.h
+++ b/tcp_conn.h
@@ -190,7 +190,7 @@ extern union tcp_conn tc[];
 extern int init_sock_pool4	[TCP_SOCK_POOL_SIZE];
 extern int init_sock_pool6	[TCP_SOCK_POOL_SIZE];
 
-void tcp_splice_conn_update(struct ctx *c, struct tcp_splice_conn *new);
+void tcp_splice_conn_update(const struct ctx *c, struct tcp_splice_conn *new);
 void tcp_table_compact(struct ctx *c, union tcp_conn *hole);
 void tcp_splice_destroy(struct ctx *c, union tcp_conn *conn_union);
 void tcp_splice_timer(struct ctx *c, union tcp_conn *conn_union);
diff --git a/tcp_splice.c b/tcp_splice.c
index a572aca..54fc317 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -253,7 +253,7 @@ static void conn_event_do(const struct ctx *c, struct tcp_splice_conn *conn,
  * @c:		Execution context
  * @new:	New location of tcp_splice_conn
  */
-void tcp_splice_conn_update(struct ctx *c, struct tcp_splice_conn *new)
+void tcp_splice_conn_update(const struct ctx *c, struct tcp_splice_conn *new)
 {
 	tcp_splice_epoll_ctl(c, new);
 	if (tcp_splice_epoll_ctl(c, new))
@@ -486,7 +486,8 @@ static void tcp_splice_dir(struct tcp_splice_conn *conn, int ref_sock,
  * Return: true if able to create a spliced connection, false otherwise
  * #syscalls:pasta setsockopt
  */
-bool tcp_splice_conn_from_sock(struct ctx *c, union tcp_listen_epoll_ref ref,
+bool tcp_splice_conn_from_sock(const struct ctx *c,
+			       union tcp_listen_epoll_ref ref,
 			       struct tcp_splice_conn *conn, int s,
 			       const struct sockaddr *sa)
 {
diff --git a/tcp_splice.h b/tcp_splice.h
index e7a583a..dc486f1 100644
--- a/tcp_splice.h
+++ b/tcp_splice.h
@@ -10,7 +10,8 @@ struct tcp_splice_conn;
 
 void tcp_splice_sock_handler(struct ctx *c, struct tcp_splice_conn *conn,
 			     int s, uint32_t events);
-bool tcp_splice_conn_from_sock(struct ctx *c, union tcp_listen_epoll_ref ref,
+bool tcp_splice_conn_from_sock(const struct ctx *c,
+			       union tcp_listen_epoll_ref ref,
 			       struct tcp_splice_conn *conn, int s,
 			       const struct sockaddr *sa);
 void tcp_splice_init(struct ctx *c);
diff --git a/udp.c b/udp.c
index ed1b7a5..cadf393 100644
--- a/udp.c
+++ b/udp.c
@@ -691,7 +691,7 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
  *
  * Return: size of tap frame with headers
  */
-static void udp_tap_send(struct ctx *c,
+static void udp_tap_send(const struct ctx *c,
 			 unsigned int start, unsigned int n,
 			 in_port_t dstport, bool v6, const struct timespec *now)
 {
@@ -726,7 +726,7 @@ static void udp_tap_send(struct ctx *c,
  *
  * #syscalls recvmmsg
  */
-void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
+void udp_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events,
 		      const struct timespec *now)
 {
 	/* For not entirely clear reasons (data locality?) pasta gets
diff --git a/udp.h b/udp.h
index 0ee0695..7837134 100644
--- a/udp.h
+++ b/udp.h
@@ -8,7 +8,7 @@
 
 #define UDP_TIMER_INTERVAL		1000 /* ms */
 
-void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
+void udp_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events,
 		      const struct timespec *now);
 int udp_tap_handler(struct ctx *c, int af, const void *saddr, const void *daddr,
 		    const struct pool *p, int idx, const struct timespec *now);
diff --git a/util.c b/util.c
index 34c32b9..1f35382 100644
--- a/util.c
+++ b/util.c
@@ -320,7 +320,8 @@ void bitmap_clear(uint8_t *map, int bit)
  */
 int bitmap_isset(const uint8_t *map, int bit)
 {
-	unsigned long *word = (unsigned long *)map + BITMAP_WORD(bit);
+	const unsigned long *word
+		= (const unsigned long *)map + BITMAP_WORD(bit);
 
 	return !!(*word & BITMAP_BIT(bit));
 }
@@ -337,7 +338,7 @@ int bitmap_isset(const uint8_t *map, int bit)
  * #syscalls:pasta ppc64le:_llseek ppc64:_llseek armv6l:_llseek armv7l:_llseek
  */
 void procfs_scan_listen(struct ctx *c, uint8_t proto, int ip_version, int ns,
-			uint8_t *map, uint8_t *exclude)
+			uint8_t *map, const uint8_t *exclude)
 {
 	char *path, *line;
 	struct lineread lr;
diff --git a/util.h b/util.h
index 57a05fb..60d6872 100644
--- a/util.h
+++ b/util.h
@@ -218,7 +218,7 @@ void bitmap_clear(uint8_t *map, int bit);
 int bitmap_isset(const uint8_t *map, int bit);
 char *line_read(char *buf, size_t len, int fd);
 void procfs_scan_listen(struct ctx *c, uint8_t proto, int ip_version, int ns,
-			uint8_t *map, uint8_t *exclude);
+			uint8_t *map, const uint8_t *exclude);
 void ns_enter(const struct ctx *c);
 bool ns_is_init(void);
 void write_pidfile(int fd, pid_t pid);
@@ -235,7 +235,7 @@ int write_file(const char *path, const char *buf);
  * clang-tidy suppressions, because the warning doesn't show on the syscall
  * itself but later when we access the supposedly uninitialised field.
  */
-static inline void sa_init(struct sockaddr *sa, socklen_t *sl)
+static inline void sa_init(struct sockaddr *sa, const socklen_t *sl)
 {
 #ifdef CLANG_TIDY_58992
 	if (sa)