New method for running AddressSanitizer

Old method broke after some CS2 update, because Valve started passing RTLD_DEEPBIND to dlopen themselves. So we have to override all dlopen calls to remove the flag.

Credit to Poggu for coming up with dlhook

configure.py

@@ -39,8 +39,9 @@
 parser.options.add_argument('--targets', type=str, dest='targets', default=None,
                             help="Override the target architecture (use commas to separate multiple targets).")
 # AddressSanitizer Instructions:
-# Recompile Metamod with RTLD_DEEPBIND removed (may break some std functionality)
-# Run server with LD_PRELOAD=/usr/lib/clang/11/lib/linux/libclang_rt.asan-x86_64.so (for SteamRT3)
+# Copy devtools/dlhook/libasan.so.dlhook.so to the server
+# Run server with LD_PRELOAD="/path/to/libasan.so.dlhook.so /usr/lib/clang/11/lib/linux/libclang_rt.asan-x86_64.so" (for SteamRT3)
+# Note this may break some std functionality
 parser.options.add_argument('--asan', action='store_const', const='1', dest='asan',
                        help='Build for AddressSanitizer')
 parser.Configure()

devtools/dlhook/src/compile.sh

@@ -0,0 +1 @@
+gcc -fPIC -rdynamic -shared dlhook.c -o libasan.so.dlhook.so

devtools/dlhook/src/dlhook.c

@@ -0,0 +1,15 @@
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <stdio.h>
+
+void *dlopen(const char *filename, int flags)
+{
+	printf("CALLED DLOPEN!!\n");
+	typedef void *(*dlopen_t)(const char *filename, int flags);
+	static dlopen_t func;
+
+	if(!func)
+			func = (dlopen_t)dlsym(RTLD_NEXT, "dlopen");
+
+	return(func(filename, flags & ~RTLD_DEEPBIND));
+}