Initial commit

Nothing has actually been tested yet.

src/dlhook.h

@@ -0,0 +1,18 @@
+#ifndef NMI_DLHOOK_H
+#define NMI_DLHOOK_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// nmi_dlhook takes a lib handle from dlopen and redirects the specified symbol
+// to another, returning a pointer to the original one. Only calls from within
+// that library itself are affected (because it replaces that library's GOT). If
+// an error occurs, NULL is returned and if err is a valid pointer, it is set to
+// a malloc'd string describing it. This function requires glibc and Linux. It
+// should work on any architecture, and it should be resilient to most errors.
+void *nmi_dlhook(void *handle, const char *symname, void *target, char **err_out);
+
+#ifdef __cplusplus
+}
+#endif
+#endif