Override dlclose() to do nothing.

Provide a custom no-op implementation of dlclose(), in order to prevent shared
object data from disappearing from profiler view. The server makes queries for
program executable code, which has to be always available, otherwise wrong
data may be provided, or the program may crash, due to referencing no longer
mapped memory.

The dlclose() documentation states that the function internally decreases the
reference count, and only does unload the shared object when the count reaches
zero. There is no guarantee that the shared object data will be unloaded
immediately after any dlclose call originating from the program. This function
override exploits this fact.

2 files changed, 27 insertions, 0 deletions

diff --git a/public/TracyClient.cpp b/public/TracyClient.cpp
index 4aa4647a..77f81a4a 100644
--- a/public/TracyClient.cpp
+++ b/public/TracyClient.cpp
@@ -28,6 +28,7 @@
 #include "client/tracy_rpmalloc.cpp"
 #include "client/TracyDxt1.cpp"
 #include "client/TracyAlloc.cpp"
+#include "client/TracyOverride.cpp"
 
 #if TRACY_HAS_CALLSTACK == 2 || TRACY_HAS_CALLSTACK == 3 || TRACY_HAS_CALLSTACK == 4 || TRACY_HAS_CALLSTACK == 6
 #  include "libbacktrace/alloc.cpp"
diff --git a/public/client/TracyOverride.cpp b/public/client/TracyOverride.cpp
new file mode 100644
index 00000000..591508a7
--- /dev/null
+++ b/public/client/TracyOverride.cpp
@@ -0,0 +1,26 @@
+#ifdef TRACY_ENABLE
+#  ifdef __linux__
+#    include "TracyDebug.hpp"
+#    ifdef TRACY_VERBOSE
+#      include <dlfcn.h>
+#      include <link.h>
+#    endif
+
+extern "C" int dlclose( void* hnd )
+{
+#ifdef TRACY_VERBOSE
+    struct link_map* lm;
+    if( dlinfo( hnd, RTLD_DI_LINKMAP, &lm ) == 0 )
+    {
+        TracyDebug( "Overriding dlclose for %s\n", lm->l_name );
+    }
+    else
+    {
+        TracyDebug( "Overriding dlclose for unknown object (%s)\n", dlerror() );
+    }
+#endif
+    return 0;
+}
+
+#  endif
+#endif