fix(glob matching): Correctly match longer strings with '*' or '**' pattern

If string is longer than 16 chars we are using Reflex library for
matching. When used pattern is '*' or '**' we are going to strip both of
stars and have empty pattern. We should in this edge case inject
manually star pattern.

Fixes #4948

Signed-off-by: mkaruza <mario@dragonflydb.io>

Author: mkaruza

src/core/glob_matcher.cc

@@ -236,7 +236,12 @@ GlobMatcher::GlobMatcher(string_view pattern, bool case_sensitive)
     regex.push_back('i');
   }
   regex.push_back(')');
-  regex.append(Glob2Regex(pattern));
+  if (pattern.empty()) {
+    // Edge case, pattern is empty so it was '*' or '**'. Set regex manually.
+    regex.append(Glob2Regex("*"sv));
+  } else {
+    regex.append(Glob2Regex(pattern));
+  }
   matcher_.pattern(regex);
 #elif USE_PCRE2
   string regex("(?s");  // dotall mode

src/server/dragonfly_test.cc

@@ -548,6 +548,23 @@ TEST_F(DflyEngineTest, PSubscribe) {
   EXPECT_EQ("a*", msg.pattern);
 }
 
+TEST_F(DflyEngineTest, PSubscribeMatchOnlyStar) {
+  single_response_ = false;
+  auto resp = pp_->at(1)->Await([&] { return Run({"psubscribe", "*"}); });
+  EXPECT_THAT(resp, ArrLen(3));
+  resp = pp_->at(0)->Await([&] { return Run({"PUBLISH", "1234567890123456", "abc"}); });
+  EXPECT_THAT(resp, IntArg(1));
+
+  pp_->AwaitFiberOnAll([](ProactorBase* pb) {});
+
+  ASSERT_EQ(1, SubscriberMessagesLen("IO1"));
+
+  const auto& msg = GetPublishedMessage("IO1", 0);
+  EXPECT_EQ("abc", msg.message);
+  EXPECT_EQ("1234567890123456", msg.channel);
+  EXPECT_EQ("*", msg.pattern);
+}
+
 TEST_F(DflyEngineTest, Unsubscribe) {
   auto resp = Run({"unsubscribe", "a"});
   EXPECT_THAT(resp.GetVec(), ElementsAre("unsubscribe", "a", IntArg(0)));