refactor source tree organization, switch to meson

src/main-executable/r_debug.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+// for getting _r_debug out of the dynamic section
+// this is needed by the shim bionic linker to register stuff with gdb
+#include <elf.h>
+#include <link.h>
+
+// the dynamic section
+extern Elf64_Dyn _DYNAMIC[];
+
+extern struct r_debug *_r_debug_ptr;
+// this has to be called from the main executable, since that's the only one guaranteed to have the debug section filled in
+void init__r_debug() {
+#if defined(_r_debug)
+// _r_debug is defined by glibc and is declared as extern in link.h
+	_r_debug_ptr = &_r_debug;
+#else
+	int i = 0;
+	Elf64_Dyn current;
+
+	do {
+		current = _DYNAMIC[i];
+		if(current.d_tag == DT_DEBUG) {
+			_r_debug_ptr = (struct r_debug *)current.d_un.d_ptr;
+			break;
+		}
+		i++;
+	} while(current.d_tag != 0);
+
+	if(!_r_debug_ptr) {
+		fprintf(stderr, "error: no DEBUG tag in the dynamic section, treating this as fatal\n");
+		exit(1);
+	}
+#endif
+}