unblock SIGUSR1 only around accept()

DataDog · Sep 19, 2024 · d63c6b3 · d63c6b3
1 parent 6fea9c9
commit d63c6b3
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Showing 2 changed files with 26 additions and 16 deletions.
diff --git a/appsec/src/helper/network/acceptor.cpp b/appsec/src/helper/network/acceptor.cpp
@@ -84,7 +84,7 @@ socket::ptr acceptor::accept()
     int s = ::accept(sock_, reinterpret_cast<struct sockaddr *>(&addr), &len);
     if (s == -1) {
         if (errno == EINTR || errno == EAGAIN) {
-            throw dds::timeout_error();
+            return {};
         }
 
         throw std::system_error(errno, std::generic_category());

diff --git a/appsec/src/helper/runner.cpp b/appsec/src/helper/runner.cpp
@@ -34,16 +34,19 @@ network::base_acceptor::ptr acceptor_from_config(const config::config &cfg)
     return std::make_unique<network::local::acceptor>(sock_path);
 }
 
-void unblock_sigusr1()
+void block_sigusr1()
 {
-    // the signal handler need not do anything (just interrupt accept())
-    struct sigaction alarmer = {};
-    alarmer.sa_handler = [](int) {};
-    if (sigaction(SIGUSR1, &alarmer, nullptr) < 0) {
+    sigset_t mask;
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGUSR1);
+    if (pthread_sigmask(SIG_UNBLOCK, &mask, nullptr) != 0) {
         throw std::runtime_error{
-            "Failed to set SIGUSR1 handler: errno " + std::to_string(errno)};
+            "Failed to block SIGUSR1: errno " + std::to_string(errno)};
     }
+}
 
+void unblock_sigusr1()
+{
     sigset_t mask;
     sigemptyset(&mask);
     sigaddset(&mask, SIGUSR1);
@@ -53,6 +56,16 @@ void unblock_sigusr1()
     }
 }
 
+void handle_sigusr1()
+{
+    // the signal handler need not do anything (just interrupt accept())
+    struct sigaction alarmer = {};
+    alarmer.sa_handler = [](int) {};
+    if (sigaction(SIGUSR1, &alarmer, nullptr) < 0) {
+        throw std::runtime_error{
+            "Failed to set SIGUSR1 handler: errno " + std::to_string(errno)};
+    }
+}
 } // namespace
 
 runner::runner(const config::config &cfg, std::atomic<bool> &interrupted)
@@ -76,18 +89,15 @@ void runner::run()
 {
     try {
         SPDLOG_INFO("Runner running");
-        unblock_sigusr1();
+        handle_sigusr1();
+
         while (!interrupted()) {
-            network::base_socket::ptr socket;
-            try {
-                socket = acceptor_->accept();
-            } catch (const timeout_error &e) {
-                continue;
-            }
+            unblock_sigusr1();
+            network::base_socket::ptr socket = acceptor_->accept();
+            block_sigusr1();
 
             if (!socket) {
-                SPDLOG_CRITICAL("Acceptor returned invalid socket. Bug.");
-                break;
+                continue; // interrupted / timeout
             }
 
             if (interrupted()) {