all: fix various "-Wcast-align=strict" warnings

The warning "-Wcast-align=strict" seems useful and will be enabled
next. Fix places that currently cause the warning by using the
new macro NM_CAST_ALIGN(). This macro also nm_assert()s that the alignment
is correct.

16 files changed, 42 insertions, 27 deletions

diff --git a/src/core/devices/bluetooth/nm-bluez-manager.c b/src/core/devices/bluetooth/nm-bluez-manager.c
index 6bc00faf39..ac26ede8cd 100644
--- a/src/core/devices/bluetooth/nm-bluez-manager.c
+++ b/src/core/devices/bluetooth/nm-bluez-manager.c
@@ -1010,8 +1010,9 @@ _network_server_get_bluez_manager(const NMBtVTableNetworkServer *vtable_network_
 {
     NMBluezManager *self;
 
-    self = (NMBluezManager *) (((char *) vtable_network_server)
-                               - G_STRUCT_OFFSET(NMBluezManager, _priv.vtable_network_server));
+    self = NM_CAST_ALIGN(NMBluezManager,
+                         (((char *) vtable_network_server)
+                          - G_STRUCT_OFFSET(NMBluezManager, _priv.vtable_network_server)));
 
     g_return_val_if_fail(NM_IS_BLUEZ_MANAGER(self), NULL);
 
diff --git a/src/core/nm-dbus-manager.c b/src/core/nm-dbus-manager.c
index 7fcbf6cad8..af7de8c458 100644
--- a/src/core/nm-dbus-manager.c
+++ b/src/core/nm-dbus-manager.c
@@ -1077,7 +1077,7 @@ nm_dbus_manager_lookup_object(NMDBusManager *self, const char *path)
     if (!ptr)
         return NULL;
 
-    obj = (NMDBusObject *) (((char *) ptr) - G_STRUCT_OFFSET(NMDBusObject, internal));
+    obj = NM_CAST_ALIGN(NMDBusObject, (((char *) ptr) - G_STRUCT_OFFSET(NMDBusObject, internal)));
     nm_assert(NM_IS_DBUS_OBJECT(obj));
     return obj;
 }
diff --git a/src/core/nm-dbus-utils.c b/src/core/nm-dbus-utils.c
index 096b647b91..05eca84faa 100644
--- a/src/core/nm-dbus-utils.c
+++ b/src/core/nm-dbus-utils.c
@@ -166,7 +166,7 @@ nm_dbus_utils_get_paths_for_clist(const CList *lst_head,
     i    = 0;
     strv = g_new(const char *, n + 1);
     c_list_for_each (iter, lst_head) {
-        NMDBusObject *obj = (NMDBusObject *) (((const char *) iter) - member_offset);
+        NMDBusObject *obj = NM_CAST_ALIGN(NMDBusObject, (((char *) iter) - member_offset));
 
         path = nm_dbus_object_get_path(obj);
         if (!path) {
diff --git a/src/core/nm-l3-ipv4ll.h b/src/core/nm-l3-ipv4ll.h
index b39762a81e..af74ce08ac 100644
--- a/src/core/nm-l3-ipv4ll.h
+++ b/src/core/nm-l3-ipv4ll.h
@@ -45,7 +45,7 @@ NM_IS_L3_IPV4LL(const NML3IPv4LL *self)
 {
     nm_assert(!self
               || (NM_IS_L3CFG(*((NML3Cfg **) self))
-                  && (*((int *) (((char *) self) + sizeof(gpointer)))) > 0));
+                  && *(NM_CAST_ALIGN(int, (((char *) self) + sizeof(gpointer)))) > 0));
     return !!self;
 }
 
diff --git a/src/core/nm-policy.c b/src/core/nm-policy.c
index 3cd11ba810..09e1ee8a20 100644
--- a/src/core/nm-policy.c
+++ b/src/core/nm-policy.c
@@ -108,9 +108,10 @@ _PRIV_TO_SELF(NMPolicyPrivate *priv)
 
     nm_assert(priv);
 
-    self = (NMPolicy *) (((char *) priv) - G_STRUCT_OFFSET(NMPolicy, _priv));
+    self = NM_CAST_ALIGN(NMPolicy, (((char *) priv) - G_STRUCT_OFFSET(NMPolicy, _priv)));
 
     nm_assert(NM_IS_POLICY(self));
+
     return self;
 }
 
diff --git a/src/core/ppp/nm-ppp-mgr.c b/src/core/ppp/nm-ppp-mgr.c
index 31c173a353..bebffaf37c 100644
--- a/src/core/ppp/nm-ppp-mgr.c
+++ b/src/core/ppp/nm-ppp-mgr.c
@@ -68,7 +68,7 @@ NM_UTILS_LOOKUP_STR_DEFINE(nm_ppp_mgr_callback_type_to_string,
 #define SELF_TO_USERDATA(self) (&(self)->idle_start)
 
 #define SELF_FROM_USERDATA(user_data) \
-    ((NMPppMgr *) (((const char *) (user_data)) - G_STRUCT_OFFSET(NMPppMgr, idle_start)))
+    NM_CAST_ALIGN(NMPppMgr, (((char *) (user_data)) - G_STRUCT_OFFSET(NMPppMgr, idle_start)))
 
 /*****************************************************************************/
 
diff --git a/src/libnm-client-impl/nm-client.c b/src/libnm-client-impl/nm-client.c
index 57d3607cf5..6eb5bc48c6 100644
--- a/src/libnm-client-impl/nm-client.c
+++ b/src/libnm-client-impl/nm-client.c
@@ -1254,9 +1254,9 @@ nml_dbus_object_get_property_location(NMLDBusObject             *dbobj,
 {
     char *target_c;
 
-    target_c = (char *) dbobj->nmobj;
+    target_c = ((gpointer) dbobj->nmobj);
     if (meta_iface->base_struct_offset > 0)
-        target_c = *((gpointer *) (&target_c[meta_iface->base_struct_offset]));
+        target_c = *NM_CAST_ALIGN(gpointer, &target_c[meta_iface->base_struct_offset]);
     return &target_c[meta_property->prop_struct_offset];
 }
 
diff --git a/src/libnm-client-impl/nm-object.c b/src/libnm-client-impl/nm-object.c
index 60b01ca8e8..add498e12d 100644
--- a/src/libnm-client-impl/nm-object.c
+++ b/src/libnm-client-impl/nm-object.c
@@ -43,10 +43,10 @@ _nm_object_get_private(NMObjectClass *klass, NMObject *self, guint16 extra_offse
 
     nm_assert(klass->priv_ptr_offset > 0);
 
-    ptr = (char *) self;
+    ptr = ((gpointer) self);
     ptr += klass->priv_ptr_offset;
     if (klass->priv_ptr_indirect)
-        ptr = *((gpointer *) ptr);
+        ptr = *NM_CAST_ALIGN(gpointer, ptr);
     return ptr + extra_offset;
 }
 
diff --git a/src/libnm-core-impl/tests/test-general.c b/src/libnm-core-impl/tests/test-general.c
index f7602f5422..74e3430895 100644
--- a/src/libnm-core-impl/tests/test-general.c
+++ b/src/libnm-core-impl/tests/test-general.c
@@ -6959,7 +6959,7 @@ test_setting_ip6_gateway(void)
 
         gateway_bytes = g_variant_get_fixed_array(gateway_var, &length, 1);
         g_assert_cmpint(length, ==, 16);
-        nmtst_assert_ip6_address((struct in6_addr *) gateway_bytes, "abcd::1");
+        nmtst_assert_ip6_address(NM_CAST_ALIGN(struct in6_addr, gateway_bytes), "abcd::1");
         g_variant_unref(gateway_var);
     }
     g_variant_unref(value);
diff --git a/src/libnm-crypto/nm-crypto-nss.c b/src/libnm-crypto/nm-crypto-nss.c
index b31ca55ee0..6ac52b2c24 100644
--- a/src/libnm-crypto/nm-crypto-nss.c
+++ b/src/libnm-crypto/nm-crypto-nss.c
@@ -450,10 +450,17 @@ _nm_crypto_verify_pkcs12(const guint8 *data, gsize data_len, const char *passwor
 
 #if __BYTE_ORDER == __LITTLE_ENDIAN
         {
-            guint16 *p, *p_end;
+            const guint16 *p_end;
+            guint16       *p;
 
-            p_end = (guint16 *) &(((guint8 *) pw.data)[ucs2_password.len]);
-            for (p = (guint16 *) pw.data; p < p_end; p++)
+            /* we cast here to guint16 pointers (which would trigger a "-Wcast-align").
+             * But this is safe, because ucs2_password.len is a multiple of 2 and
+             * because pw.data was an allocated buffer (that is presumably aligned
+             * correctly). */
+            nm_assert(ucs2_password.len % 2 == 0);
+
+            p_end = NM_CAST_ALIGN(guint16, &(((guint8 *) pw.data)[ucs2_password.len]));
+            for (p = NM_CAST_ALIGN(guint16, pw.data); p < p_end; p++)
                 *p = GUINT16_SWAP_LE_BE(*p);
         }
 #endif
diff --git a/src/libnm-glib-aux/nm-hash-utils.c b/src/libnm-glib-aux/nm-hash-utils.c
index 941aba019a..973422a198 100644
--- a/src/libnm-glib-aux/nm-hash-utils.c
+++ b/src/libnm-glib-aux/nm-hash-utils.c
@@ -106,7 +106,7 @@ nm_hash_static(guint static_seed)
      *
      * Also, ensure that we don't return zero (like for nm_hash_complete()).
      */
-    return ((*((const guint *) _get_hash_key())) ^ static_seed) ?: 3679500967u;
+    return ((*NM_CAST_ALIGN(guint, _get_hash_key())) ^ static_seed) ?: 3679500967u;
 }
 
 void
diff --git a/src/libnm-platform/nm-linux-platform.c b/src/libnm-platform/nm-linux-platform.c
index 8734aa7fd2..9bdc62872d 100644
--- a/src/libnm-platform/nm-linux-platform.c
+++ b/src/libnm-platform/nm-linux-platform.c
@@ -1348,7 +1348,8 @@ typedef struct {
     };
 } ParseNlmsgIter;
 
-#define NLMSG_TAIL(nmsg) ((struct rtattr *) (((char *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
+#define NLMSG_TAIL(nmsg) \
+    NM_CAST_ALIGN(struct rtattr, ((char *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len))
 
 /* copied from iproute2's addattr_l(). */
 static gboolean
@@ -9927,7 +9928,7 @@ continue_reading:
         goto stop;
     }
 
-    hdr = (struct nlmsghdr *) priv->netlink_recv_buf.buf;
+    hdr = NM_CAST_ALIGN(struct nlmsghdr, priv->netlink_recv_buf.buf);
     while (nlmsg_ok(hdr, n)) {
         WaitForNlResponseResult  seq_result;
         gboolean                 process_valid_msg = FALSE;
diff --git a/src/libnm-platform/nm-netlink.c b/src/libnm-platform/nm-netlink.c
index e08eee5e0a..fc70422642 100644
--- a/src/libnm-platform/nm-netlink.c
+++ b/src/libnm-platform/nm-netlink.c
@@ -325,7 +325,8 @@ nlmsg_parse_error(const struct nlmsghdr *nlh, const char **out_extack_msg)
         struct nlattr *tb[G_N_ELEMENTS(policy)];
         struct nlattr *tlvs;
 
-        tlvs = (struct nlattr *) ((char *) e + sizeof(*e) + e->msg.nlmsg_len - NLMSG_HDRLEN);
+        tlvs = NM_CAST_ALIGN(struct nlattr,
+                             (((char *) e) + sizeof(*e) + e->msg.nlmsg_len - NLMSG_HDRLEN));
         if (nla_parse_arr(tb, tlvs, nlh->nlmsg_len - sizeof(*e) - e->msg.nlmsg_len, policy) >= 0) {
             if (tb[NLMSGERR_ATTR_MSG])
                 *out_extack_msg = nla_get_string(tb[NLMSGERR_ATTR_MSG]);
@@ -842,7 +843,7 @@ genlmsg_len(const struct genlmsghdr *gnlh)
 {
     const struct nlmsghdr *nlh;
 
-    nlh = (const struct nlmsghdr *) ((const unsigned char *) gnlh - NLMSG_HDRLEN);
+    nlh = NM_CAST_ALIGN(const struct nlmsghdr, (((char *) gnlh) - NLMSG_HDRLEN));
     return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 }
 
@@ -1253,7 +1254,7 @@ continue_reading:
     if (n <= 0)
         return n;
 
-    hdr = (struct nlmsghdr *) buf;
+    hdr = NM_CAST_ALIGN(struct nlmsghdr, buf);
     while (nlmsg_ok(hdr, n)) {
         nm_auto_nlmsg struct nl_msg *msg = NULL;
 
diff --git a/src/libnm-platform/nm-netlink.h b/src/libnm-platform/nm-netlink.h
index 634be2b4a6..cdb8a81c32 100644
--- a/src/libnm-platform/nm-netlink.h
+++ b/src/libnm-platform/nm-netlink.h
@@ -340,7 +340,7 @@ nla_next(const struct nlattr *nla, int *remaining)
     int totlen = NLA_ALIGN(nla->nla_len);
 
     *remaining -= totlen;
-    return (struct nlattr *) ((char *) nla + totlen);
+    return NM_CAST_ALIGN(struct nlattr, (((char *) nla) + totlen));
 }
 
 #define nla_for_each_attr(pos, head, len, rem) \
@@ -434,7 +434,7 @@ nlmsg_next(struct nlmsghdr *nlh, int *remaining)
 
     *remaining -= totlen;
 
-    return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
+    return NM_CAST_ALIGN(struct nlmsghdr, (((char *) nlh) + totlen));
 }
 
 int  nlmsg_get_proto(struct nl_msg *msg);
@@ -493,8 +493,9 @@ nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
 static inline struct nlattr *
 nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
 {
-    unsigned char *data = nlmsg_data(nlh);
-    return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
+    char *data = nlmsg_data(nlh);
+
+    return NM_CAST_ALIGN(struct nlattr, (data + NLMSG_ALIGN(hdrlen)));
 }
 
 static inline struct nlattr *
diff --git a/src/libnm-platform/nmp-object.h b/src/libnm-platform/nmp-object.h
index 9fa260b57f..5f98deeda4 100644
--- a/src/libnm-platform/nmp-object.h
+++ b/src/libnm-platform/nmp-object.h
@@ -454,9 +454,12 @@ NMP_OBJECT_UP_CAST(const NMPlatformObject *plobj)
 {
     NMPObject *obj;
 
-    obj = plobj ? (NMPObject *) (&(((char *) plobj)[-((int) G_STRUCT_OFFSET(NMPObject, object))]))
+    obj = plobj ? NM_CAST_ALIGN(NMPObject,
+                                &(((char *) plobj)[-((int) G_STRUCT_OFFSET(NMPObject, object))]))
                 : NULL;
+
     nm_assert(!obj || (obj->parent._ref_count > 0 && NMP_CLASS_IS_VALID(obj->_class)));
+
     return obj;
 }
 #define NMP_OBJECT_UP_CAST(plobj) (NMP_OBJECT_UP_CAST((const NMPlatformObject *) (plobj)))
diff --git a/src/nmcli/utils.c b/src/nmcli/utils.c
index 8bd8da5f9f..957c0efaff 100644
--- a/src/nmcli/utils.c
+++ b/src/nmcli/utils.c
@@ -1116,7 +1116,7 @@ _print_fill(const NmcConfig    *nmc_config,
                         cell->text_to_free = TRUE;
                     }
                     if (to_free)
-                        g_strfreev((char **) to_free);
+                        g_strfreev(NM_CAST_ALIGN(char *, to_free));
                 }
             } else {
                 cell->text.plain   = value;