Convert instances of tor_snprintf+strdup into tor_asprintf

These were found by looking for tor_snprintf() instances that were
followed closely by tor_strdup(), though I probably converted some
other snprintfs as well.

10 files changed, 43 insertions, 111 deletions

diff --git a/changes/clean_asprintf b/changes/clean_asprintf
index fc1613f8d0..61382010e6 100644
--- a/changes/clean_asprintf
+++ b/changes/clean_asprintf
@@ -1,3 +1,5 @@
   o Code simplifications and refactoring
     - Use the smartlist_add_asprintf alias more consistently
       throughout the codebase.
+    - Convert more instances of tor_snprintf+tor_strdup into
+      tor_asprintf.
\ No newline at end of file
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c
index 216c926585..88916d6596 100644
--- a/src/or/circuitbuild.c
+++ b/src/or/circuitbuild.c
@@ -4441,10 +4441,8 @@ entry_guards_update_state(or_state_t *state)
         continue; /* don't write this one to disk */
       *next = line = tor_malloc_zero(sizeof(config_line_t));
       line->key = tor_strdup("EntryGuard");
-      line->value = tor_malloc(HEX_DIGEST_LEN+MAX_NICKNAME_LEN+2);
       base16_encode(dbuf, sizeof(dbuf), e->identity, DIGEST_LEN);
-      tor_snprintf(line->value,HEX_DIGEST_LEN+MAX_NICKNAME_LEN+2,
-                   "%s %s", e->nickname, dbuf);
+      tor_asprintf(&line->value, "%s %s", e->nickname, dbuf);
       next = &(line->next);
       if (e->unreachable_since) {
         *next = line = tor_malloc_zero(sizeof(config_line_t));
diff --git a/src/or/config.c b/src/or/config.c
index d4a4e0349a..a477a096ba 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -781,22 +781,20 @@ set_options(or_options_t *new_val, char **msg)
 extern const char tor_git_revision[]; /* from tor_main.c */
 
 /** The version of this Tor process, as parsed. */
-static char *_version = NULL;
+static char *the_tor_version = NULL;
 
 /** Return the current Tor version. */
 const char *
 get_version(void)
 {
-  if (_version == NULL) {
+  if (the_tor_version == NULL) {
     if (strlen(tor_git_revision)) {
-      size_t len = strlen(VERSION)+strlen(tor_git_revision)+16;
-      _version = tor_malloc(len);
-      tor_snprintf(_version, len, "%s (git-%s)", VERSION, tor_git_revision);
+      tor_asprintf(&the_tor_version, "%s (git-%s)", VERSION, tor_git_revision);
     } else {
-      _version = tor_strdup(VERSION);
+      the_tor_version = tor_strdup(VERSION);
     }
   }
-  return _version;
+  return the_tor_version;
 }
 
 /** Release additional memory allocated in options
@@ -841,7 +839,7 @@ config_free_all(void)
 
   tor_free(torrc_fname);
   tor_free(torrc_defaults_fname);
-  tor_free(_version);
+  tor_free(the_tor_version);
   tor_free(global_dirfrontpagecontents);
 }
 
@@ -1174,9 +1172,8 @@ options_act_reversible(const or_options_t *old_options, char **msg)
   control_ports_write_to_file();
 
   if (directory_caches_v2_dir_info(options)) {
-    size_t len = strlen(options->DataDirectory)+32;
-    char *fn = tor_malloc(len);
-    tor_snprintf(fn, len, "%s"PATH_SEPARATOR"cached-status",
+    char *fn = NULL;
+    tor_asprintf(&fn, "%s"PATH_SEPARATOR"cached-status",
                  options->DataDirectory);
     if (check_private_dir(fn, running_tor ? CPD_CREATE : CPD_CHECK,
                           options->User) < 0) {
@@ -3506,11 +3503,8 @@ options_validate(or_options_t *old_options, or_options_t *options,
       SMARTLIST_FOREACH(options->FirewallPorts, const char *, portno,
       {
         int p = atoi(portno);
-        char *s;
         if (p<0) continue;
-        s = tor_malloc(16);
-        tor_snprintf(s, 16, "*:%d", p);
-        smartlist_add(instead, s);
+        smartlist_add_asprintf(instead, "*:%d", p);
       });
       new_line->value = smartlist_join_strings(instead,",",0,NULL);
       /* These have been deprecated since 0.1.1.5-alpha-cvs */
diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c
index aba9ba2727..7de627d729 100644
--- a/src/or/connection_edge.c
+++ b/src/or/connection_edge.c
@@ -1165,11 +1165,10 @@ addressmap_rewrite(char *address, size_t maxlen, time_t *expires_out)
 static int
 addressmap_rewrite_reverse(char *address, size_t maxlen, time_t *expires_out)
 {
-  size_t len = maxlen + 16;
-  char *s = tor_malloc(len), *cp;
+  char *s, *cp;
   addressmap_entry_t *ent;
   int r = 0;
-  tor_snprintf(s, len, "REVERSE[%s]", address);
+  tor_asprintf(&s, "REVERSE[%s]", address);
   ent = strmap_get(addressmap, s);
   if (ent) {
     cp = tor_strdup(escaped_safe_str_client(ent->new_address));
diff --git a/src/or/control.c b/src/or/control.c
index 7bb11cd8c9..70bdadbb31 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -697,7 +697,6 @@ control_setconf_helper(control_connection_t *conn, uint32_t len, char *body,
     if (*eq == '=') {
       char *val=NULL;
       size_t val_len=0;
-      size_t ent_len;
       if (*body != '\"') {
         char *val_start = body;
         while (!TOR_ISSPACE(*body))
@@ -715,9 +714,7 @@ control_setconf_helper(control_connection_t *conn, uint32_t len, char *body,
           return 0;
         }
       }
-      ent_len = strlen(key)+val_len+3;
-      entry = tor_malloc(ent_len+1);
-      tor_snprintf(entry, ent_len, "%s %s", key, val);
+      tor_asprintf(&entry, "%s %s", key, val);
       tor_free(key);
       tor_free(val);
     } else {
@@ -1304,12 +1301,9 @@ handle_control_mapaddress(control_connection_t *conn, uint32_t len,
     if (smartlist_len(elts) == 2) {
       const char *from = smartlist_get(elts,0);
       const char *to = smartlist_get(elts,1);
-      size_t anslen = strlen(line)+512;
-      char *ans = tor_malloc(anslen);
       if (address_is_invalid_destination(to, 1)) {
-        tor_snprintf(ans, anslen,
+        smartlist_add_asprintf(reply,
                      "512-syntax error: invalid address '%s'", to);
-        smartlist_add(reply, ans);
         log_warn(LD_CONTROL,
                  "Skipping invalid argument '%s' in MapAddress msg", to);
       } else if (!strcmp(from, ".") || !strcmp(from, "0.0.0.0")) {
@@ -1317,28 +1311,22 @@ handle_control_mapaddress(control_connection_t *conn, uint32_t len,
               !strcmp(from,".") ? RESOLVED_TYPE_HOSTNAME : RESOLVED_TYPE_IPV4,
                tor_strdup(to));
         if (!address) {
-          tor_snprintf(ans, anslen,
+          smartlist_add_asprintf(reply,
                        "451-resource exhausted: skipping '%s'", line);
-          smartlist_add(reply, ans);
           log_warn(LD_CONTROL,
                    "Unable to allocate address for '%s' in MapAddress msg",
                    safe_str_client(line));
         } else {
-          tor_snprintf(ans, anslen, "250-%s=%s", address, to);
-          smartlist_add(reply, ans);
+          smartlist_add_asprintf(reply, "250-%s=%s", address, to);
         }
       } else {
         addressmap_register(from, tor_strdup(to), 1,
                             ADDRMAPSRC_CONTROLLER, 0, 0);
-        tor_snprintf(ans, anslen, "250-%s", line);
-        smartlist_add(reply, ans);
+        smartlist_add_asprintf(reply, "250-%s", line);
       }
     } else {
-      size_t anslen = strlen(line)+256;
-      char *ans = tor_malloc(anslen);
-      tor_snprintf(ans, anslen, "512-syntax error: mapping '%s' is "
+      smartlist_add_asprintf(reply, "512-syntax error: mapping '%s' is "
                    "not of expected form 'foo=bar'.", line);
-      smartlist_add(reply, ans);
       log_info(LD_CONTROL, "Skipping MapAddress '%s': wrong "
                            "number of items.",
                            safe_str_client(line));
@@ -2012,8 +2000,7 @@ getinfo_helper_events(control_connection_t *control_conn,
     } else if (!strcmp(question, "status/reachability-succeeded/dir")) {
       *answer = tor_strdup(check_whether_dirport_reachable() ? "1" : "0");
     } else if (!strcmp(question, "status/reachability-succeeded")) {
-      *answer = tor_malloc(16);
-      tor_snprintf(*answer, 16, "OR=%d DIR=%d",
+      tor_asprintf(answer, "OR=%d DIR=%d",
                    check_whether_orport_reachable() ? 1 : 0,
                    check_whether_dirport_reachable() ? 1 : 0);
     } else if (!strcmp(question, "status/bootstrap-phase")) {
@@ -2049,9 +2036,7 @@ getinfo_helper_events(control_connection_t *control_conn,
           }
       } else if (!strcmp(question, "status/version/num-versioning") ||
                  !strcmp(question, "status/version/num-concurring")) {
-        char s[33];
-        tor_snprintf(s, sizeof(s), "%d", get_n_authorities(V3_DIRINFO));
-        *answer = tor_strdup(s);
+        tor_asprintf(answer, "%d", get_n_authorities(V3_DIRINFO));
         log_warn(LD_GENERAL, "%s is deprecated; it no longer gives useful "
                  "information", question);
       }
diff --git a/src/or/directory.c b/src/or/directory.c
index 8087d7603d..572091a16a 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -1125,7 +1125,6 @@ directory_send_command(dir_connection_t *conn,
   char *url;
   char request[8192];
   const char *httpcommand = NULL;
-  size_t len;
 
   tor_assert(conn);
   tor_assert(conn->_base.type == CONN_TYPE_DIR);
@@ -1174,9 +1173,7 @@ directory_send_command(dir_connection_t *conn,
     case DIR_PURPOSE_FETCH_V2_NETWORKSTATUS:
       tor_assert(resource);
       httpcommand = "GET";
-      len = strlen(resource)+32;
-      url = tor_malloc(len);
-      tor_snprintf(url, len, "/tor/status/%s", resource);
+      tor_asprintf(&url, "/tor/status/%s", resource);
       break;
     case DIR_PURPOSE_FETCH_CONSENSUS:
       /* resource is optional.  If present, it's a flavor name */
@@ -1191,17 +1188,13 @@ directory_send_command(dir_connection_t *conn,
       tor_assert(resource);
       tor_assert(!payload);
       httpcommand = "GET";
-      len = strlen(resource)+32;
-      url = tor_malloc(len);
-      tor_snprintf(url, len, "/tor/keys/%s", resource);
+      tor_asprintf(&url, "/tor/keys/%s", resource);
       break;
     case DIR_PURPOSE_FETCH_STATUS_VOTE:
       tor_assert(resource);
       tor_assert(!payload);
       httpcommand = "GET";
-      len = strlen(resource)+32;
-      url = tor_malloc(len);
-      tor_snprintf(url, len, "/tor/status-vote/next/%s.z", resource);
+      tor_asprintf(&url, "/tor/status-vote/next/%s.z", resource);
       break;
     case DIR_PURPOSE_FETCH_DETACHED_SIGNATURES:
       tor_assert(!resource);
@@ -1212,16 +1205,12 @@ directory_send_command(dir_connection_t *conn,
     case DIR_PURPOSE_FETCH_SERVERDESC:
       tor_assert(resource);
       httpcommand = "GET";
-      len = strlen(resource)+32;
-      url = tor_malloc(len);
-      tor_snprintf(url, len, "/tor/server/%s", resource);
+      tor_asprintf(&url, "/tor/server/%s", resource);
       break;
     case DIR_PURPOSE_FETCH_EXTRAINFO:
       tor_assert(resource);
       httpcommand = "GET";
-      len = strlen(resource)+32;
-      url = tor_malloc(len);
-      tor_snprintf(url, len, "/tor/extra/%s", resource);
+      tor_asprintf(&url, "/tor/extra/%s", resource);
       break;
     case DIR_PURPOSE_FETCH_MICRODESC:
       tor_assert(resource);
@@ -1256,9 +1245,7 @@ directory_send_command(dir_connection_t *conn,
       tor_assert(strlen(resource) <= REND_DESC_ID_V2_LEN_BASE32);
       tor_assert(!payload);
       httpcommand = "GET";
-      len = strlen(resource) + 32;
-      url = tor_malloc(len);
-      tor_snprintf(url, len, "/tor/rendezvous2/%s", resource);
+      tor_asprintf(&url, "/tor/rendezvous2/%s", resource);
       break;
     case DIR_PURPOSE_UPLOAD_RENDDESC:
       tor_assert(!resource);
@@ -2519,7 +2506,6 @@ char *
 directory_dump_request_log(void)
 {
   smartlist_t *lines;
-  char tmp[256];
   char *result;
   strmap_iter_t *iter;
 
@@ -2535,9 +2521,8 @@ directory_dump_request_log(void)
     request_t *r;
     strmap_iter_get(iter, &key, &val);
     r = val;
-    tor_snprintf(tmp, sizeof(tmp), "%s  "U64_FORMAT"  "U64_FORMAT"\n",
+    smartlist_add_asprintf(lines, "%s  "U64_FORMAT"  "U64_FORMAT"\n",
                  key, U64_PRINTF_ARG(r->bytes), U64_PRINTF_ARG(r->count));
-    smartlist_add(lines, tor_strdup(tmp));
   }
   smartlist_sort_strings(lines);
   result = smartlist_join_strings(lines, "", 0, NULL);
@@ -3291,8 +3276,7 @@ directory_handle_command_get(dir_connection_t *conn, const char *headers,
 
 #if defined(EXPORTMALLINFO) && defined(HAVE_MALLOC_H) && defined(HAVE_MALLINFO)
 #define ADD_MALLINFO_LINE(x) do {                               \
-    tor_snprintf(tmp, sizeof(tmp), "%s %d\n", #x, mi.x);        \
-    smartlist_add(lines, tor_strdup(tmp));                      \
+    smartlist_add_asprintf(lines, "%s %d\n", #x, mi.x);        \
   }while(0);
 
   if (!strcmp(url,"/tor/mallinfo.txt") &&
@@ -3301,7 +3285,6 @@ directory_handle_command_get(dir_connection_t *conn, const char *headers,
     size_t len;
     struct mallinfo mi;
     smartlist_t *lines;
-    char tmp[256];
 
     memset(&mi, 0, sizeof(mi));
     mi = mallinfo();
diff --git a/src/or/dirserv.c b/src/or/dirserv.c
index e5995697dd..cc8dffb7ff 100644
--- a/src/or/dirserv.c
+++ b/src/or/dirserv.c
@@ -2906,9 +2906,7 @@ generate_v2_networkstatus_opinion(void)
     contact = "(none)";
 
   if (versioning) {
-    size_t v_len = 64+strlen(client_versions)+strlen(server_versions);
-    version_lines = tor_malloc(v_len);
-    tor_snprintf(version_lines, v_len,
+    tor_asprintf(&version_lines,
                  "client-versions %s\nserver-versions %s\n",
                  client_versions, server_versions);
   } else {
diff --git a/src/or/dirvote.c b/src/or/dirvote.c
index 72f49c7f47..f81ffa00be 100644
--- a/src/or/dirvote.c
+++ b/src/or/dirvote.c
@@ -581,15 +581,13 @@ make_consensus_method_list(int low, int high, const char *separator)
 {
   char *list;
 
-  char b[32];
   int i;
   smartlist_t *lst;
   lst = smartlist_create();
   for (i = low; i <= high; ++i) {
     if (!consensus_method_is_supported(i))
       continue;
-    tor_snprintf(b, sizeof(b), "%d", i);
-    smartlist_add(lst, tor_strdup(b));
+    smartlist_add_asprintf(lst, "%d", i);
   }
   list = smartlist_join_strings(lst, separator, 0, NULL);
   tor_assert(list);
@@ -810,8 +808,6 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G,
   int64_t Wmg = -1, Wme = -1, Wmd = -1;
   int64_t Wed = -1, Wee = -1;
   const char *casename;
-  char buf[512];
-  int r;
 
   if (G <= 0 || M <= 0 || E <= 0 || D <= 0) {
     log_warn(LD_DIR, "Consensus with empty bandwidth: "
@@ -1019,7 +1015,7 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G,
    *
    * NOTE: This list is sorted.
    */
-  r = tor_snprintf(buf, sizeof(buf),
+  smartlist_add_asprintf(chunks,
      "bandwidth-weights Wbd=%d Wbe=%d Wbg=%d Wbm=%d "
      "Wdb=%d "
      "Web=%d Wed=%d Wee=%d Weg=%d Wem=%d "
@@ -1030,13 +1026,6 @@ networkstatus_compute_bw_weights_v10(smartlist_t *chunks, int64_t G,
      (int)weight_scale, (int)Wed, (int)Wee, (int)Wed, (int)Wee,
      (int)weight_scale, (int)Wgd, (int)Wgg, (int)Wgg,
      (int)weight_scale, (int)Wmd, (int)Wme, (int)Wmg, (int)weight_scale);
-  if (r<0) {
-    log_warn(LD_BUG,
-             "Not enough space in buffer for bandwidth-weights line.");
-    *buf = '\0';
-    return 0;
-  }
-  smartlist_add(chunks, tor_strdup(buf));
 
   log_notice(LD_CIRC, "Computed bandwidth weights for %s with v10: "
              "G="I64_FORMAT" M="I64_FORMAT" E="I64_FORMAT" D="I64_FORMAT
@@ -1060,8 +1049,6 @@ networkstatus_compute_bw_weights_v9(smartlist_t *chunks, int64_t G, int64_t M,
   int64_t Wmg = -1, Wme = -1, Wmd = -1;
   int64_t Wed = -1, Wee = -1;
   const char *casename;
-  char buf[512];
-  int r;
 
   if (G <= 0 || M <= 0 || E <= 0 || D <= 0) {
     log_warn(LD_DIR, "Consensus with empty bandwidth: "
@@ -1323,7 +1310,7 @@ networkstatus_compute_bw_weights_v9(smartlist_t *chunks, int64_t G, int64_t M,
    *
    * NOTE: This list is sorted.
    */
-  r = tor_snprintf(buf, sizeof(buf),
+  smartlist_add_asprintf(chunks,
      "Wbd=%d Wbe=%d Wbg=%d Wbm=%d "
      "Wdb=%d "
      "Web=%d Wed=%d Wee=%d Weg=%d Wem=%d "
@@ -1334,12 +1321,7 @@ networkstatus_compute_bw_weights_v9(smartlist_t *chunks, int64_t G, int64_t M,
      (int)weight_scale, (int)Wed, (int)Wee, (int)Wed, (int)Wee,
      (int)weight_scale, (int)Wgd, (int)Wgg, (int)Wgg,
      (int)weight_scale, (int)Wmd, (int)Wme, (int)Wmg, (int)weight_scale);
-  if (r<0) {
-    log_warn(LD_BUG,
-             "Not enough space in buffer for bandwidth-weights line.");
-    *buf = '\0';
-  }
-  smartlist_add(chunks, tor_strdup(buf));
+
   log_notice(LD_CIRC, "Computed bandwidth weights for %s with v9: "
              "G="I64_FORMAT" M="I64_FORMAT" E="I64_FORMAT" D="I64_FORMAT
              " T="I64_FORMAT,
@@ -2318,20 +2300,19 @@ networkstatus_format_signatures(networkstatus_t *consensus,
       base16_encode(sk, sizeof(sk), sig->signing_key_digest, DIGEST_LEN);
       base16_encode(id, sizeof(id), sig->identity_digest, DIGEST_LEN);
       if (flavor == FLAV_NS) {
-        tor_snprintf(buf, sizeof(buf),
+        smartlist_add_asprintf(elements,
                      "%s %s %s\n-----BEGIN SIGNATURE-----\n",
                      keyword, id, sk);
       } else {
         const char *digest_name =
           crypto_digest_algorithm_get_name(sig->alg);
-        tor_snprintf(buf, sizeof(buf),
+        smartlist_add_asprintf(elements,
                      "%s%s%s %s %s %s\n-----BEGIN SIGNATURE-----\n",
                      keyword,
                      for_detached_signatures ? " " : "",
                      for_detached_signatures ? flavor_name : "",
                      digest_name, id, sk);
       }
-      smartlist_add(elements, tor_strdup(buf));
       base64_encode(buf, sizeof(buf), sig->signature, sig->signature_len);
       strlcat(buf, "-----END SIGNATURE-----\n", sizeof(buf));
       smartlist_add(elements, tor_strdup(buf));
@@ -2354,7 +2335,6 @@ char *
 networkstatus_get_detached_signatures(smartlist_t *consensuses)
 {
   smartlist_t *elements;
-  char buf[4096];
   char *result = NULL, *sigs = NULL;
   networkstatus_t *consensus_ns = NULL;
   tor_assert(consensuses);
@@ -2383,12 +2363,11 @@ networkstatus_get_detached_signatures(smartlist_t *consensuses)
     format_iso_time(fu_buf, consensus_ns->fresh_until);
     format_iso_time(vu_buf, consensus_ns->valid_until);
 
-    tor_snprintf(buf, sizeof(buf),
+    smartlist_add_asprintf(elements,
                  "consensus-digest %s\n"
                  "valid-after %s\n"
                  "fresh-until %s\n"
                  "valid-until %s\n", d, va_buf, fu_buf, vu_buf);
-    smartlist_add(elements, tor_strdup(buf));
   }
 
   /* Get all the digests for the non-FLAV_NS consensuses */
@@ -2407,9 +2386,8 @@ networkstatus_get_detached_signatures(smartlist_t *consensuses)
       if (tor_mem_is_zero(ns->digests.d[alg], DIGEST256_LEN))
         continue;
       base16_encode(d, sizeof(d), ns->digests.d[alg], DIGEST256_LEN);
-      tor_snprintf(buf, sizeof(buf), "additional-digest %s %s %s\n",
+      smartlist_add_asprintf(elements, "additional-digest %s %s %s\n",
                    flavor_name, alg_name, d);
-      smartlist_add(elements, tor_strdup(buf));
     }
   } SMARTLIST_FOREACH_END(ns);
 
diff --git a/src/or/rephist.c b/src/or/rephist.c
index b7bd2387fe..4129fe2bbd 100644
--- a/src/or/rephist.c
+++ b/src/or/rephist.c
@@ -941,7 +941,6 @@ rep_hist_get_router_stability_doc(time_t now)
   DIGESTMAP_FOREACH(history_map, id, or_history_t *, hist) {
     const node_t *node;
     char dbuf[BASE64_DIGEST_LEN+1];
-    char header_buf[512];
     char *info;
     digest_to_base64(dbuf, id);
     node = node_get_by_id(id);
@@ -954,7 +953,7 @@ rep_hist_get_router_stability_doc(time_t now)
         format_iso_time(tbuf, published);
       else
         strlcpy(tbuf, "???", sizeof(tbuf));
-      tor_snprintf(header_buf, sizeof(header_buf),
+      smartlist_add_asprintf(chunks,
                    "router %s %s %s\n"
                    "published %s\n"
                    "relevant-flags %s%s%s\n"
@@ -966,10 +965,9 @@ rep_hist_get_router_stability_doc(time_t now)
                    node->ri && node->ri->is_hibernating ? "Hibernating " : "",
                    node_get_declared_uptime(node));
     } else {
-      tor_snprintf(header_buf, sizeof(header_buf),
+      smartlist_add_asprintf(chunks,
                    "router %s {no descriptor}\n", dbuf);
     }
-    smartlist_add(chunks, tor_strdup(header_buf));
     info = rep_hist_format_router_status(hist, now);
     if (info)
       smartlist_add(chunks, info);
diff --git a/src/or/router.c b/src/or/router.c
index 7d9d2724f7..f8aa1e3b05 100644
--- a/src/or/router.c
+++ b/src/or/router.c
@@ -1973,11 +1973,8 @@ router_dump_router_to_string(char *s, size_t maxlen, routerinfo_t *router,
   format_iso_time(published, router->cache_info.published_on);
 
   if (router->declared_family && smartlist_len(router->declared_family)) {
-    size_t n;
-    char *family = smartlist_join_strings(router->declared_family, " ", 0, &n);
-    n += strlen("family ") + 2; /* 1 for \n, 1 for \0. */
-    family_line = tor_malloc(n);
-    tor_snprintf(family_line, n, "family %s\n", family);
+    char *family = smartlist_join_strings(router->declared_family, " ", 0, NULL);
+    tor_asprintf(&family_line, "family %s\n", family);
     tor_free(family);
   } else {
     family_line = tor_strdup("");