Implement a function to remove emergency handlers when a signal is raised.

Make PCAP handlers deregister from this list when they are destructed. This avoid the signal handler calling destructed objects under very rare circumstances.

lib/include/srsran/common/mac_pcap_base.h

@@ -103,7 +103,8 @@ protected:
   srslog::basic_logger&                   logger;
   std::atomic<bool>                       running = {false};
   static_blocking_queue<pcap_pdu_t, 1024> queue;
-  uint16_t                                ue_id = 0;
+  uint16_t                                ue_id                = 0;
+  int                                     emergency_handler_id = -1;
 
 private:
   void pack_and_queue(uint8_t* payload,

lib/include/srsran/common/nas_pcap.h

@@ -23,16 +23,18 @@ class nas_pcap
 {
 public:
   nas_pcap();
-  void enable();
+  ~nas_pcap();
+  void     enable();
   uint32_t open(std::string filename_, uint32_t ue_id = 0, srsran_rat_t rat_type = srsran_rat_t::lte);
-  void close();
-  void write_nas(uint8_t* pdu, uint32_t pdu_len_bytes);
+  void     close();
+  void     write_nas(uint8_t* pdu, uint32_t pdu_len_bytes);
 
 private:
   bool        enable_write = false;
   std::string filename;
-  FILE*       pcap_file = nullptr;
-  uint32_t    ue_id     = 0;
+  FILE*       pcap_file            = nullptr;
+  uint32_t    ue_id                = 0;
+  int         emergency_handler_id = -1;
   void        pack_and_write(uint8_t* pdu, uint32_t pdu_len_bytes);
 };
 

lib/include/srsran/common/ngap_pcap.h

@@ -22,7 +22,7 @@ class ngap_pcap
 {
 public:
   ngap_pcap();
-  ~ngap_pcap()                      = default;
+  ~ngap_pcap();
   ngap_pcap(const ngap_pcap& other) = delete;
   ngap_pcap& operator=(const ngap_pcap& other) = delete;
   ngap_pcap(ngap_pcap&& other)                 = delete;
@@ -36,7 +36,8 @@ public:
 private:
   bool        enable_write = false;
   std::string filename;
-  FILE*       pcap_file = nullptr;
+  FILE*       pcap_file            = nullptr;
+  int         emergency_handler_id = -1;
 };
 
 } // namespace srsran

lib/include/srsran/common/s1ap_pcap.h

@@ -22,6 +22,7 @@ class s1ap_pcap
 {
 public:
   s1ap_pcap();
+  ~s1ap_pcap();
   s1ap_pcap(const s1ap_pcap& other) = delete;
   s1ap_pcap& operator=(const s1ap_pcap& other) = delete;
   s1ap_pcap(s1ap_pcap&& other)                 = delete;
@@ -35,7 +36,8 @@ public:
 private:
   bool        enable_write = false;
   std::string filename;
-  FILE*       pcap_file = nullptr;
+  FILE*       pcap_file            = nullptr;
+  int         emergency_handler_id = -1;
 };
 
 } // namespace srsran

lib/include/srsran/support/emergency_handlers.h

@@ -17,7 +17,11 @@ using emergency_cleanup_callback = void (*)(void*);
 
 // Add a cleanup function to be called when a kill signal is about to be delivered to the process. The handler may
 // optionally pass a pointer to identify what instance of the handler is being called.
-void add_emergency_cleanup_handler(emergency_cleanup_callback callback, void* data);
+// Returns the id of the handler as a positive value, otherwise returns -1 on error.
+int add_emergency_cleanup_handler(emergency_cleanup_callback callback, void* data);
+
+// Removes the emergency handler with the specified id.
+void remove_emergency_cleanup_handler(int id);
 
 // Executes all registered emergency cleanup handlers.
 void execute_emergency_cleanup_handlers();

lib/src/common/mac_pcap_base.cc

@@ -26,10 +26,15 @@ static void emergency_cleanup_handler(void* data)
 
 mac_pcap_base::mac_pcap_base() : logger(srslog::fetch_basic_logger("MAC")), thread("PCAP_WRITER_MAC")
 {
-  add_emergency_cleanup_handler(emergency_cleanup_handler, this);
+  emergency_handler_id = add_emergency_cleanup_handler(emergency_cleanup_handler, this);
 }
 
-mac_pcap_base::~mac_pcap_base() {}
+mac_pcap_base::~mac_pcap_base()
+{
+  if (emergency_handler_id > 0) {
+    remove_emergency_cleanup_handler(emergency_handler_id);
+  }
+}
 
 void mac_pcap_base::enable(bool enable_)
 {

lib/src/common/nas_pcap.cc

@@ -26,7 +26,14 @@ static void emergency_cleanup_handler(void* data)
 
 nas_pcap::nas_pcap()
 {
-  add_emergency_cleanup_handler(emergency_cleanup_handler, this);
+  emergency_handler_id = add_emergency_cleanup_handler(emergency_cleanup_handler, this);
+}
+
+nas_pcap::~nas_pcap()
+{
+  if (emergency_handler_id > 0) {
+    remove_emergency_cleanup_handler(emergency_handler_id);
+  }
 }
 
 void nas_pcap::enable()

lib/src/common/ngap_pcap.cc

@@ -26,7 +26,14 @@ static void emergency_cleanup_handler(void* data)
 
 ngap_pcap::ngap_pcap()
 {
-  add_emergency_cleanup_handler(emergency_cleanup_handler, this);
+  emergency_handler_id = add_emergency_cleanup_handler(emergency_cleanup_handler, this);
+}
+
+ngap_pcap::~ngap_pcap()
+{
+  if (emergency_handler_id > 0) {
+    remove_emergency_cleanup_handler(emergency_handler_id);
+  }
 }
 
 void ngap_pcap::enable()

lib/src/common/s1ap_pcap.cc

@@ -26,7 +26,14 @@ static void emergency_cleanup_handler(void* data)
 
 s1ap_pcap::s1ap_pcap()
 {
-  add_emergency_cleanup_handler(emergency_cleanup_handler, this);
+  emergency_handler_id = add_emergency_cleanup_handler(emergency_cleanup_handler, this);
+}
+
+s1ap_pcap::~s1ap_pcap()
+{
+  if (emergency_handler_id > 0) {
+    remove_emergency_cleanup_handler(emergency_handler_id);
+  }
 }
 
 void s1ap_pcap::enable()

lib/src/support/emergency_handlers.cc

@@ -11,6 +11,7 @@
  */
 
 #include "srsran/support/emergency_handlers.h"
+#include "srsran/config.h"
 #include "srsran/support/srsran_assert.h"
 
 namespace {
@@ -29,7 +30,7 @@ static constexpr unsigned    max_handlers = 12;
 static handler_instance      registered_handlers[max_handlers];
 static std::atomic<unsigned> num_handlers;
 
-void add_emergency_cleanup_handler(emergency_cleanup_callback callback, void* data)
+int add_emergency_cleanup_handler(emergency_cleanup_callback callback, void* data)
 {
   // Reserve a slot in the array.
   auto pos = num_handlers.fetch_add(1);
@@ -37,13 +38,25 @@ void add_emergency_cleanup_handler(emergency_cleanup_callback callback, void* da
   // Check if we have space in the array.
   if (pos >= max_handlers) {
     srsran_assert(0, "Exceeded the emergency cleanup handler registered limit");
-    return;
+    return SRSRAN_ERROR;
   }
 
   // Order is important here: write last the callback member as it is used to signal that the handler is valid when
   // reading the array.
   registered_handlers[pos].data.store(data);
   registered_handlers[pos].callback.store(callback);
+
+  return pos;
+}
+
+void remove_emergency_cleanup_handler(int id)
+{
+  if (id < 0 || static_cast<unsigned>(id) >= num_handlers) {
+    srsran_assert(0, "Invalid emergency handler id");
+    return;
+  }
+
+  registered_handlers[id].callback.store(nullptr);
 }
 
 void execute_emergency_cleanup_handlers()