Eliminate most shadowing for local variable names.

Shadowing is when a variable with a given name in an inner scope hides a
different variable with the same name in a surrounding scope.  This is
generally undesirable because it can confuse programmers.  This commit
eliminates most of it.

Found with -Wshadow=local in GCC 7.  The repo is not really ready to enable
this option by default because of a few cases that are harder to fix, and
harmless, such as nested use of CMAP_FOR_EACH.

Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Andy Zhou <azhou@ovn.org>

lib/classifier.c

@@ -793,8 +793,6 @@ classifier_remove(struct classifier *cls, const struct cls_rule *cls_rule)
             && --subtable->max_count == 0) {
             /* Find the new 'max_priority' and 'max_count'. */
             int max_priority = INT_MIN;
-            struct cls_match *head;
-
             CMAP_FOR_EACH (head, cmap_node, &subtable->rules) {
                 if (head->priority > max_priority) {
                     max_priority = head->priority;

lib/daemon-unix.c

@@ -1002,11 +1002,11 @@ daemon_set_new_user(const char *user_spec)
         grpstr += strspn(grpstr, " \t\r\n");
 
         if (*grpstr) {
-            struct group grp, *res;
+            struct group grp, *gres;
 
             bufsize = init_bufsize;
             buf = xmalloc(bufsize);
-            while ((e = getgrnam_r(grpstr, &grp, buf, bufsize, &res))
+            while ((e = getgrnam_r(grpstr, &grp, buf, bufsize, &gres))
                          == ERANGE) {
                 if (!enlarge_buffer(&buf, &bufsize)) {
                     break;
@@ -1018,7 +1018,7 @@ daemon_set_new_user(const char *user_spec)
                            "(%s), aborting.", pidfile, grpstr,
                            ovs_strerror(e));
             }
-            if (res == NULL) {
+            if (gres == NULL) {
                 VLOG_FATAL("%s: group %s not found, aborting.", pidfile,
                            grpstr);
             }

lib/db-ctl-base.c

@@ -313,9 +313,9 @@ get_row_by_id(struct ctl_context *ctx,
         if (!id->key) {
             name = datum->n == 1 ? &datum->keys[0] : NULL;
         } else {
-            const union ovsdb_atom key
+            const union ovsdb_atom key_atom
                 = { .string = CONST_CAST(char *, id->key) };
-            unsigned int i = ovsdb_datum_find_key(datum, &key,
+            unsigned int i = ovsdb_datum_find_key(datum, &key_atom,
                                                   OVSDB_TYPE_STRING);
             name = i == UINT_MAX ? NULL : &datum->values[i];
         }

lib/dpctl.c

@@ -336,7 +336,8 @@ dpctl_set_if(int argc, const char *argv[], struct dpctl_params *dpctl_p)
         struct smap args;
         odp_port_t port_no;
         char *option;
-        int error = 0;
+
+        error = 0;
 
         argcopy = xstrdup(argv[i]);
         name = strtok_r(argcopy, ",", &save_ptr);
@@ -1787,8 +1788,7 @@ dpctl_normalize_actions(int argc, const char *argv[],
     qsort(afs, n_afs, sizeof *afs, compare_actions_for_flow);
 
     for (i = 0; i < n_afs; i++) {
-        struct actions_for_flow *af = afs[i];
-
+        af = afs[i];
         sort_output_actions(af->actions.data, af->actions.size);
 
         for (encaps = 0; encaps < FLOW_MAX_VLAN_HEADERS; encaps ++) {

lib/dpif-netdev.c

@@ -1016,14 +1016,13 @@ dpif_netdev_pmd_info(struct unixctl_conn *conn, int argc, const char *argv[],
         } else {
             unsigned long long stats[DP_N_STATS];
             uint64_t cycles[PMD_N_CYCLES];
-            int i;
 
             /* Read current stats and cycle counters */
-            for (i = 0; i < ARRAY_SIZE(stats); i++) {
-                atomic_read_relaxed(&pmd->stats.n[i], &stats[i]);
+            for (size_t j = 0; j < ARRAY_SIZE(stats); j++) {
+                atomic_read_relaxed(&pmd->stats.n[j], &stats[j]);
             }
-            for (i = 0; i < ARRAY_SIZE(cycles); i++) {
-                atomic_read_relaxed(&pmd->cycles.n[i], &cycles[i]);
+            for (size_t j = 0; j < ARRAY_SIZE(cycles); j++) {
+                atomic_read_relaxed(&pmd->cycles.n[j], &cycles[j]);
             }
 
             if (type == PMD_INFO_CLEAR_STATS) {

lib/hash.c

@@ -87,7 +87,6 @@ hash_bytes128(const void *p_, size_t len, uint32_t basis, ovs_u128 *out)
     uint32_t h2 = basis;
     uint32_t h3 = basis;
     uint32_t h4 = basis;
-    uint32_t k1, k2, k3, k4;
 
     /* Body */
     for (int i = 0; i < nblocks; i++) {
@@ -134,6 +133,7 @@ hash_bytes128(const void *p_, size_t len, uint32_t basis, ovs_u128 *out)
     }
 
     /* Tail */
+    uint32_t k1, k2, k3, k4;
     k1 = k2 = k3 = k4 = 0;
     tail = data + nblocks * 16;
     switch (len & 15) {

lib/learn.c

@@ -342,14 +342,13 @@ learn_parse_spec(const char *orig, char *name, char *value,
                                  name, value);
             }
 
-            char *error = learn_parse_load_immediate(&imm, dst_value + 2, value, spec,
-                                                     ofpacts);
+            error = learn_parse_load_immediate(&imm, dst_value + 2, value, spec,
+                                               ofpacts);
             if (error) {
                 return error;
             }
         } else {
             struct ofpact_reg_move move;
-            char *error;
 
             error = nxm_parse_reg_move(&move, value);
             if (error) {
@@ -363,7 +362,7 @@ learn_parse_spec(const char *orig, char *name, char *value,
             spec->dst = move.dst;
         }
     } else if (!strcmp(name, "output")) {
-        char *error = mf_parse_subfield(&spec->src, value);
+        error = mf_parse_subfield(&spec->src, value);
         if (error) {
             return error;
         }

lib/lldp/lldpd.c

@@ -339,7 +339,7 @@ lldpd_decode(struct lldpd *cfg, char *frame, int s,
 
     /* No, but do we already know the system? */
     if (!oport) {
-        bool found = false;
+        found = false;
         VLOG_DBG("MSAP is unknown, search for the chassis");
 
         LIST_FOR_EACH (ochassis, list, &cfg->g_chassis) {

lib/netdev-dummy.c

@@ -1102,11 +1102,11 @@ netdev_dummy_send(struct netdev *netdev, int qid OVS_UNUSED,
 
         /* Reply to ARP requests for 'dev''s assigned IP address. */
         if (dev->address.s_addr) {
-            struct dp_packet packet;
+            struct dp_packet dp;
             struct flow flow;
 
-            dp_packet_use_const(&packet, buffer, size);
-            flow_extract(&packet, &flow);
+            dp_packet_use_const(&dp, buffer, size);
+            flow_extract(&dp, &flow);
             if (flow.dl_type == htons(ETH_TYPE_ARP)
                 && flow.nw_proto == ARP_OP_REQUEST
                 && flow.nw_dst == dev->address.s_addr) {
@@ -1118,10 +1118,10 @@ netdev_dummy_send(struct netdev *netdev, int qid OVS_UNUSED,
         }
 
         if (dev->tx_pcap) {
-            struct dp_packet packet;
+            struct dp_packet dp;
 
-            dp_packet_use_const(&packet, buffer, size);
-            ovs_pcap_write(dev->tx_pcap, &packet);
+            dp_packet_use_const(&dp, buffer, size);
+            ovs_pcap_write(dev->tx_pcap, &dp);
             fflush(dev->tx_pcap);
         }
 

lib/netdev-linux.c

@@ -5373,7 +5373,7 @@ get_stats_via_netlink(const struct netdev *netdev_, struct netdev_stats *stats)
             netdev_stats_from_rtnl_link_stats64(stats, nl_attr_get(a));
             error = 0;
         } else {
-            const struct nlattr *a = nl_attr_find(reply, 0, IFLA_STATS);
+            a = nl_attr_find(reply, 0, IFLA_STATS);
             if (a && nl_attr_get_size(a) >= sizeof(struct rtnl_link_stats)) {
                 netdev_stats_from_rtnl_link_stats(stats, nl_attr_get(a));
                 error = 0;

lib/odp-util.c

@@ -4264,13 +4264,11 @@ static int
 parse_odp_key_mask_attr(const char *s, const struct simap *port_names,
                         struct ofpbuf *key, struct ofpbuf *mask)
 {
-    ovs_u128 ufid;
-    int len;
-
     /* Skip UFID. */
-    len = odp_ufid_from_string(s, &ufid);
-    if (len) {
-        return len;
+    ovs_u128 ufid;
+    int ufid_len = odp_ufid_from_string(s, &ufid);
+    if (ufid_len) {
+        return ufid_len;
     }
 
     SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY);

lib/ofp-print.c

@@ -2344,12 +2344,12 @@ ofp_async_config_reason_to_string(uint32_t reason,
 #define OFP_ASYNC_CONFIG_REASON_BUFSIZE (INT_STRLEN(int) + 1)
 static void
 ofp_print_set_async_config(struct ds *string, const struct ofp_header *oh,
-                           enum ofptype type)
+                           enum ofptype ofptype)
 {
     struct ofputil_async_cfg basis = OFPUTIL_ASYNC_CFG_INIT;
     struct ofputil_async_cfg ac;
 
-    bool is_reply = type == OFPTYPE_GET_ASYNC_REPLY;
+    bool is_reply = ofptype == OFPTYPE_GET_ASYNC_REPLY;
     enum ofperr error = ofputil_decode_set_async_config(oh, is_reply,
                                                         &basis, &ac);
     if (error) {

lib/ofp-util.c

@@ -8314,7 +8314,6 @@ ofputil_pull_ofp14_port_stats(struct ofputil_port_stats *ops,
                                                         len);
     while (properties.size > 0) {
         struct ofpbuf payload;
-        enum ofperr error;
         uint64_t type = 0;
 
         error = ofpprop_pull(&properties, &payload, &type);

lib/ovsdb-idl.c

@@ -787,10 +787,10 @@ ovsdb_idl_check_consistency(const struct ovsdb_idl *idl)
                     ok = false;
                 }
             }
-            for (size_t i = 0; i < n_dsts; i++) {
+            for (size_t j = 0; j < n_dsts; j++) {
                 VLOG_ERR("%s row "UUID_FMT" missing arc to row "UUID_FMT,
                          table->class->name, UUID_ARGS(&row->uuid),
-                         UUID_ARGS(&dsts[i]));
+                         UUID_ARGS(&dsts[j]));
                 ok = false;
             }
         }

lib/table.c

@@ -490,7 +490,6 @@ table_print_json__(const struct table *table, const struct table_style *style)
 {
     struct json *json, *headings, *data;
     size_t x, y;
-    char *s;
 
     json = json_object_create();
     if (table->caption) {
@@ -526,7 +525,7 @@ table_print_json__(const struct table *table, const struct table_style *style)
     }
     json_object_put(json, "data", data);
 
-    s = json_to_string(json, style->json_flags);
+    char *s = json_to_string(json, style->json_flags);
     json_destroy(json);
     puts(s);
     free(s);

lib/unixctl.c

@@ -371,14 +371,11 @@ kill_connection(struct unixctl_conn *conn)
 void
 unixctl_server_run(struct unixctl_server *server)
 {
-    struct unixctl_conn *conn, *next;
-    int i;
-
     if (!server) {
         return;
     }
 
-    for (i = 0; i < 10; i++) {
+    for (int i = 0; i < 10; i++) {
         struct stream *stream;
         int error;
 
@@ -396,6 +393,7 @@ unixctl_server_run(struct unixctl_server *server)
         }
     }
 
+    struct unixctl_conn *conn, *next;
     LIST_FOR_EACH_SAFE (conn, next, node, &server->conns) {
         int error = run_connection(conn);
         if (error && error != EAGAIN) {

lib/vconn.c

@@ -877,7 +877,6 @@ vconn_transact_noreply(struct vconn *vconn, struct ofpbuf *request,
     for (;;) {
         struct ofpbuf *msg;
         ovs_be32 msg_xid;
-        int error;
 
         error = vconn_recv_block(vconn, &msg);
         if (error) {

lib/vlog.c

@@ -843,7 +843,6 @@ vlog_get_levels(void)
     struct ds s = DS_EMPTY_INITIALIZER;
     struct vlog_module *mp;
     struct svec lines = SVEC_EMPTY_INITIALIZER;
-    char *line;
     size_t i;
 
     ds_put_format(&s, "                 console    syslog    file\n");
@@ -869,6 +868,8 @@ vlog_get_levels(void)
     ovs_mutex_unlock(&log_file_mutex);
 
     svec_sort(&lines);
+
+    char *line;
     SVEC_FOR_EACH (i, line, &lines) {
         ds_put_cstr(&s, line);
     }

ofproto/ofproto-dpif-xlate.c

@@ -1901,14 +1901,14 @@ mirror_packet(struct xlate_ctx *ctx, struct xbundle *xbundle,
             }
         } else if (xvlan.v[0].vid != out_vlan
                    && !eth_addr_is_reserved(ctx->xin->flow.dl_dst)) {
-            struct xbundle *xbundle;
+            struct xbundle *xb;
             uint16_t old_vid = xvlan.v[0].vid;
 
             xvlan.v[0].vid = out_vlan;
-            LIST_FOR_EACH (xbundle, list_node, &xbridge->xbundles) {
-                if (xbundle_includes_vlan(xbundle, &xvlan)
-                    && !xbundle_mirror_out(xbridge, xbundle)) {
-                    output_normal(ctx, xbundle, &xvlan);
+            LIST_FOR_EACH (xb, list_node, &xbridge->xbundles) {
+                if (xbundle_includes_vlan(xb, &xvlan)
+                    && !xbundle_mirror_out(xbridge, xb)) {
+                    output_normal(ctx, xb, &xvlan);
                 }
             }
             xvlan.v[0].vid = old_vid;
@@ -7068,8 +7068,9 @@ xlate_send_packet(const struct ofport_dpif *ofport, bool oam,
     }
 
     if (oam) {
-        const ovs_be16 oam = htons(NX_TUN_FLAG_OAM);
-        ofpact_put_set_field(&ofpacts, mf_from_id(MFF_TUN_FLAGS), &oam, &oam);
+        const ovs_be16 flag = htons(NX_TUN_FLAG_OAM);
+        ofpact_put_set_field(&ofpacts, mf_from_id(MFF_TUN_FLAGS),
+                             &flag, &flag);
     }
 
     ofpact_put_OUTPUT(&ofpacts)->port = xport->ofp_port;

ofproto/ofproto-dpif.c

@@ -4722,7 +4722,6 @@ group_dpif_credit_stats(struct group_dpif *group,
         bucket->stats.packet_count += stats->n_packets;
         bucket->stats.byte_count += stats->n_bytes;
     } else { /* Credit to all buckets */
-        struct ofputil_bucket *bucket;
         LIST_FOR_EACH (bucket, list_node, &group->up.buckets) {
             bucket->stats.packet_count += stats->n_packets;
             bucket->stats.byte_count += stats->n_bytes;
@@ -5203,14 +5202,10 @@ dpif_show_backer(const struct dpif_backer *backer, struct ds *ds)
 
             smap_init(&config);
             if (!netdev_get_config(ofport->netdev, &config)) {
-                const struct smap_node **nodes;
-                size_t i;
-
-                nodes = smap_sort(&config);
-                for (i = 0; i < smap_count(&config); i++) {
-                    const struct smap_node *node = nodes[i];
-                    ds_put_format(ds, "%c %s=%s", i ? ',' : ':',
-                                  node->key, node->value);
+                const struct smap_node **nodes = smap_sort(&config);
+                for (size_t k = 0; k < smap_count(&config); k++) {
+                    ds_put_format(ds, "%c %s=%s", k ? ',' : ':',
+                                  nodes[k]->key, nodes[k]->value);
                 }
                 free(nodes);
             }

ovn/controller/ofctrl.c

@@ -1026,7 +1026,6 @@ ofctrl_put(struct hmap *flow_table, struct shash *pending_ct_zones,
         }
 
         /* Store the barrier's xid with any newly sent ct flushes. */
-        struct shash_node *iter;
         SHASH_FOR_EACH(iter, pending_ct_zones) {
             struct ct_zone_pending_entry *ctzpe = iter->data;
             if (ctzpe->state == CT_ZONE_OF_SENT && !ctzpe->of_xid) {

ovn/controller/patch.c

@@ -256,7 +256,7 @@ patch_run(struct controller_ctx *ctx, const struct ovsrec_bridge *br_int,
      * database but shouldn't.  Delete them from the database. */
     struct shash_node *port_node, *port_next_node;
     SHASH_FOR_EACH_SAFE (port_node, port_next_node, &existing_ports) {
-        struct ovsrec_port *port = port_node->data;
+        port = port_node->data;
         shash_delete(&existing_ports, port_node);
         remove_port(ctx, port);
     }

ovn/controller/physical.c

@@ -816,11 +816,11 @@ consider_mc_group(enum mf_field_id mff_ovn_geneve,
                      remote_ofpacts_p);
         }
 
-        const char *chassis;
+        const char *chassis_name;
         const struct chassis_tunnel *prev = NULL;
-        SSET_FOR_EACH (chassis, &remote_chassis) {
+        SSET_FOR_EACH (chassis_name, &remote_chassis) {
             const struct chassis_tunnel *tun
-                = chassis_tunnel_find(chassis);
+                = chassis_tunnel_find(chassis_name);
             if (!tun) {
                 continue;
             }