Investigate and fix macOS CI test failure (#370)

Makefile.am

@@ -134,6 +134,7 @@ DIALECT_NEUTRAL_TESTS = tests/case-00-hello.bash \
 	tests/case-20-repeat-count.bash \
 	tests/case-21-exit-Q-status.bash \
 	tests/case-22-empty-process-name.bash \
+	tests/case-23-multi-address-hostname.bash \
 	tests/case-30-json-output.bash \
 	tests/case-31-jsonl-output.bash
 TESTS = $(DIALECT_NEUTRAL_TESTS)

src/arg.c

@@ -1604,6 +1604,8 @@ int enter_network_address(struct lsof_context *ctx, /* context */
     }
     if (sn)
         (void)free((FREE_P *)sn);
+    if (n.proto)
+        (void)free((FREE_P *)n.proto);
     if (hn)
         (void)free((FREE_P *)hn);
     return (0);
@@ -1627,18 +1629,6 @@ static int enter_nwad(struct lsof_context *ctx, /* context */
     static int na = 0;
     struct nwad nc;
     struct nwad *np;
-    /*
-     * Allocate space for the argument specification.
-     */
-    if (strlen(s)) {
-        if (!(n->arg = mkstrcpy(s, (MALLOC_S *)NULL))) {
-            (void)fprintf(stderr, "%s: no space for Internet argument: -i ",
-                          Pn);
-            safestrprt(s, stderr, 1);
-            Error(ctx);
-        }
-    } else
-        n->arg = (char *)NULL;
     /*
      * Loop through all hostent addresses.
      */
@@ -1687,8 +1677,35 @@ static int enter_nwad(struct lsof_context *ctx, /* context */
         }
         /*
          * Construct and link the address specification.
+         *
+         * Each nwad owns copies of its argument and protocol strings.  A
+         * hostent may contain several addresses, so sharing the strings
+         * between the resulting nwad entries would make lsof_destroy() free
+         * the same allocation more than once.
          */
         *np = nc;
+        np->arg = (char *)NULL;
+        if (strlen(s)) {
+            if (!(np->arg = mkstrcpy(s, (MALLOC_S *)NULL))) {
+                (void)fprintf(stderr,
+                              "%s: no space for Internet argument: -i ", Pn);
+                safestrprt(s, stderr, 1);
+                (void)free((FREE_P *)np);
+                Error(ctx);
+            }
+        }
+        if (n->proto) {
+            if (!(np->proto = mkstrcpy(n->proto, (MALLOC_S *)NULL))) {
+                (void)fprintf(stderr, "%s: no space for protocol name: -i ",
+                              Pn);
+                safestrprt(s, stderr, 1);
+                if (np->arg)
+                    (void)free((FREE_P *)np->arg);
+                (void)free((FREE_P *)np);
+                Error(ctx);
+            }
+        } else
+            np->proto = (char *)NULL;
         np->sport = sp;
         np->eport = ep;
         np->f = 0;

tests/case-23-multi-address-hostname.bash

@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+# Regression test for https://github.com/lsof-org/lsof/issues/370
+#
+# A host name can resolve to several addresses.  lsof creates one nwad entry
+# for each address, and lsof_destroy() frees the argument and protocol strings
+# of every entry.  If those strings are shared between entries, lsof frees the
+# same allocation more than once and aborts before it can flush its output.
+source tests/common.bash
+
+if ! command -v python3 >/dev/null 2>&1; then
+    echo "SKIP: python3 not available" >> "$report"
+    exit 77
+fi
+
+host=$(hostname)
+naddr=$(python3 - "$host" <<'PY'
+import socket
+import sys
+
+host = sys.argv[1]
+count = 0
+for family in (socket.AF_INET, socket.AF_INET6):
+    try:
+        infos = socket.getaddrinfo(host, None, family, socket.SOCK_STREAM)
+    except OSError:
+        continue
+    count = max(count, len({info[4][0] for info in infos}))
+print(count)
+PY
+)
+
+if [ "${naddr:-0}" -lt 2 ]; then
+    echo "SKIP: $host resolves to fewer than two addresses in one family" \
+        >> "$report"
+    exit 77
+fi
+
+{
+    echo "host name: $host ($naddr addresses in one address family)"
+    $lsof -a -i@"$host" -p $$ >/dev/null 2>&1
+    status=$?
+    case $status in
+    0|1)
+        echo "PASS: lsof -a -i@$host -p $$ exited with status $status"
+        ;;
+    *)
+        echo "FAIL: lsof -a -i@$host -p $$ exited with status $status"
+        exit 1
+        ;;
+    esac
+} >> "$report" 2>&1