fix: coverity warnings (#2186)

* fix: silence check_return warning

Xref: https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924665\&defectInstanceId\=52245209\&mergedDefectId\=1494152

* fix: silence check_return warning

Xref: https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924692\&defectInstanceId\=52245241\&mergedDefectId\=1493826

* fix: silence check_return warning

Xref: https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924667\&defectInstanceId\=52245260\&mergedDefectId\=1493825

* fix: silence nullptr dereference warning

Xref: https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924667\&defectInstanceId\=52245260\&mergedDefectId\=1493825

* fix: uninitialized variable in rpc-server z_stream

Xref: https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924665\&defectInstanceId\=52245249\&mergedDefectId\=1494151

* fix: silence check_return warning

Xref: https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924665\&defectInstanceId\=52245261\&mergedDefectId\=1492904

* fix: silence nullptr dereference warning

https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924689\&defectInstanceId\=52245236\&mergedDefectId\=1492890

* fix: silence unchecked return value warning

Xref: https://scan5.coverity.com/reports.htm\#v48014/p10174/fileInstanceId\=203924666\&defectInstanceId\=52245259\&mergedDefectId\=1491888

gtk/Prefs.cc

@@ -220,7 +220,7 @@ std::vector<std::string> gtr_pref_strv_get(tr_quark const key)
 std::string gtr_pref_string_get(tr_quark const key)
 {
     auto sv = std::string_view{};
-    tr_variantDictFindStrView(getPrefs(), key, &sv);
+    (void)tr_variantDictFindStrView(getPrefs(), key, &sv);
     return std::string{ sv };
 }
 

libtransmission/rpc-server.cc

@@ -287,7 +287,13 @@ static void add_response(struct evhttp_request* req, tr_rpc_server* server, stru
 #else
             int const compressionLevel = Z_BEST_COMPRESSION;
 #endif
-            deflateInit2(&server->stream, compressionLevel, Z_DEFLATED, 15 + 16, 8, Z_DEFAULT_STRATEGY);
+            // "windowBits can also be greater than 15 for optional gzip encoding.
+            // Add 16 to windowBits to write a simple gzip header and trailer
+            // around the compressed data instead of a zlib wrapper."
+            if (Z_OK != deflateInit2(&server->stream, compressionLevel, Z_DEFLATED, 15 + 16, 8, Z_DEFAULT_STRATEGY))
+            {
+                tr_logAddNamedDbg(MY_NAME, "deflateInit2 failed: %s", server->stream.msg);
+            }
         }
 
         server->stream.next_in = static_cast<Bytef*>(content_ptr);

libtransmission/rpcimpl.cc

@@ -317,7 +317,7 @@ static char const* torrentRemove(
     tr_rpc_idle_data* /*idle_data*/)
 {
     auto delete_flag = bool{ false };
-    tr_variantDictFindBool(args_in, TR_KEY_delete_local_data, &delete_flag);
+    (void)tr_variantDictFindBool(args_in, TR_KEY_delete_local_data, &delete_flag);
 
     tr_rpc_callback_type type = delete_flag ? TR_RPC_TORRENT_TRASHING : TR_RPC_TORRENT_REMOVING;
 
@@ -1386,7 +1386,7 @@ static char const* torrentSetLocation(
     }
 
     auto move = bool{};
-    tr_variantDictFindBool(args_in, TR_KEY_move, &move);
+    (void)tr_variantDictFindBool(args_in, TR_KEY_move, &move);
 
     for (auto* tor : getTorrents(session, args_in))
     {
@@ -1515,7 +1515,7 @@ static void gotNewBlocklist(
     }
     else /* successfully fetched the blocklist... */
     {
-        z_stream stream;
+        auto stream = z_stream{};
         char const* configDir = tr_sessionGetConfigDir(session);
         size_t const buflen = 1024 * 128; /* 128 KiB buffer */
         auto* const buf = static_cast<uint8_t*>(tr_malloc(buflen));

libtransmission/session.cc

@@ -843,7 +843,7 @@ static void sessionSetImpl(void* vdata)
     }
 
     sv = ""sv;
-    tr_variantDictFindStrView(settings, TR_KEY_peer_congestion_algorithm, &sv);
+    (void)tr_variantDictFindStrView(settings, TR_KEY_peer_congestion_algorithm, &sv);
     session->setPeerCongestionAlgorithm(sv);
 
     if (tr_variantDictFindBool(settings, TR_KEY_blocklist_enabled, &boolVal))

tests/libtransmission/metainfo-test.cc

@@ -37,11 +37,20 @@ TEST(Metainfo, magnetLink)
     auto const parse_result = tr_torrentParse(ctor, &inf);
     EXPECT_EQ(TR_PARSE_OK, parse_result);
     EXPECT_EQ(0, inf.fileCount); // because it's a magnet link
-    EXPECT_EQ(2, inf.trackerCount);
-    EXPECT_STREQ("http://tracker.publicbt.com/announce", inf.trackers[0].announce);
-    EXPECT_STREQ("udp://tracker.publicbt.com:80", inf.trackers[1].announce);
+    ASSERT_EQ(2, inf.trackerCount);
+    if (inf.trackerCount >= 1)
+    {
+        EXPECT_STREQ("http://tracker.publicbt.com/announce", inf.trackers[0].announce);
+    }
+    if (inf.trackerCount >= 2)
+    {
+        EXPECT_STREQ("udp://tracker.publicbt.com:80", inf.trackers[1].announce);
+    }
     EXPECT_EQ(1, inf.webseedCount);
-    EXPECT_STREQ("http://transmissionbt.com", inf.webseeds[0]);
+    if (inf.webseedCount >= 1)
+    {
+        EXPECT_STREQ("http://transmissionbt.com", inf.webseeds[0]);
+    }
 
     auto* const link = tr_torrentInfoGetMagnetLink(&inf);
     EXPECT_STREQ(MagnetLink, link);

tests/libtransmission/subprocess-test.cc

@@ -139,24 +139,29 @@ TEST_P(SubprocessTest, SpawnAsyncArgs)
 
     buffer[0] = '\0';
     EXPECT_TRUE(tr_sys_file_read_line(fd, buffer.data(), buffer.size(), nullptr));
+    buffer.back() = '\0';
     EXPECT_EQ(test_arg1, buffer.data());
 
     buffer[0] = '\0';
     EXPECT_TRUE(tr_sys_file_read_line(fd, buffer.data(), buffer.size(), nullptr));
+    buffer.back() = '\0';
     EXPECT_EQ(test_arg2, buffer.data());
 
     buffer[0] = '\0';
     EXPECT_TRUE(tr_sys_file_read_line(fd, buffer.data(), buffer.size(), nullptr));
+    buffer.back() = '\0';
     EXPECT_EQ(test_arg3, buffer.data());
 
     if (allow_batch_metachars)
     {
         buffer[0] = '\0';
         EXPECT_TRUE(tr_sys_file_read_line(fd, buffer.data(), buffer.size(), nullptr));
+        buffer.back() = '\0';
         EXPECT_EQ(test_arg4, buffer.data());
     }
 
     EXPECT_FALSE(tr_sys_file_read_line(fd, buffer.data(), buffer.size(), nullptr));
+    buffer.back() = '\0';
 
     tr_sys_file_close(fd, nullptr);
 }