1 files changed, 38 insertions, 9 deletions

diff --git a/src/modules.cpp b/src/modules.cpp
index 7a82028..a671d82 100644
--- a/src/modules.cpp
+++ b/src/modules.cpp
@@ -1,10 +1,27 @@
 // modules.cpp — /proc/self/maps parsing and module discovery
 #include "hl2h.h"
+#include <atomic>
 #include <elf.h>
-#include <mutex>
 #include <vector>
 
-static std::mutex g_modules_mutex;
+// Immutable snapshots. Readers load a pointer with acquire semantics and get a
+// module that never changes underneath them. find_modules() publishes a fresh
+// copy instead of mutating the current one; retired snapshots are deliberately
+// leaked so a reference already handed to another thread stays valid.
+static const Module g_no_module;
+static std::atomic<const Module *> g_client_snap{&g_no_module};
+static std::atomic<const Module *> g_engine_snap{&g_no_module};
+static std::atomic<const Module *> g_server_snap{&g_no_module};
+
+const Module &mod_client() {
+  return *g_client_snap.load(std::memory_order_acquire);
+}
+const Module &mod_engine() {
+  return *g_engine_snap.load(std::memory_order_acquire);
+}
+const Module &mod_server() {
+  return *g_server_snap.load(std::memory_order_acquire);
+}
 
 static bool basename_is(const char *path, const char *base) {
   size_t pl = strlen(path), bl = strlen(base);
@@ -55,6 +72,9 @@ void find_modules() {
       else if (engine.valid() && engine.ranges.back().file &&
                lo == engine.ranges.back().hi && hi - lo <= 0x1000000)
         m = &engine;
+      else if (server.valid() && server.ranges.back().file &&
+               lo == server.ranges.back().hi && hi - lo <= 0x1000000)
+        m = &server;
     }
     if (!m)
       continue;
@@ -72,16 +92,25 @@ void find_modules() {
     }
   }
   fclose(f);
-  // setup_thread and resolve_server_netvars can both call this; the old code
-  // reset the shared Module globals and reallocated their vectors live, which
-  // crashed under the startup thread. Publish complete snapshots instead.
-  std::lock_guard<std::mutex> lock(g_modules_mutex);
+  // setup_thread and resolve_server_netvars can both call this. Publish whole
+  // snapshots atomically so a reader never iterates a vector being reallocated.
   if (client.valid())
-    g_client = std::move(client);
+    g_client_snap.store(new Module(std::move(client)), std::memory_order_release);
   if (engine.valid())
-    g_engine = std::move(engine);
+    g_engine_snap.store(new Module(std::move(engine)), std::memory_order_release);
   if (server.valid())
-    g_server = std::move(server);
+    g_server_snap.store(new Module(std::move(server)), std::memory_order_release);
+}
+
+bool module_range(uintptr_t p, size_t n) {
+  if (n == 0)
+    return true;
+  uintptr_t last = p + (n - 1);
+  if (last < p)
+    return false; // address-space wrap
+  return (mod_client().contains(p) && mod_client().contains(last)) ||
+         (mod_engine().contains(p) && mod_engine().contains(last)) ||
+         (mod_server().contains(p) && mod_server().contains(last));
 }
 
 // ---------------------------------------------------------------------------