Initial commit.

src/ldpreload.h

@@ -0,0 +1,49 @@
+/*
+ * Helper header for LD_PRELOAD related headers macros. Must be loaded _first_
+ * (for RTLD_NEXT)!
+ *
+ * Copyright (C) 2012-2013  Simon Ruderich
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LDPRELOAD_H
+#define LDPRELOAD_H 1
+
+/* Necessary for RTLD_NEXT. */
+#define _GNU_SOURCE
+
+/* abort() */
+#include <stdlib.h>
+/* dlsym() */
+#include <dlfcn.h>
+
+
+/* Load the function name using dlsym() if necessary and store it in pointer.
+ * Terminate program on failure. */
+#define DLSYM_FUNCTION(pointer, name) \
+    if (NULL == (pointer)) { \
+        char *error; \
+        dlerror(); /* Clear possibly existing error. */ \
+        \
+        *(void **) (&(pointer)) = dlsym(RTLD_NEXT, (name)); \
+        \
+        if (NULL != (error = dlerror())) { \
+            /* Not much we can do. Most likely the other output functions \
+             * failed to load too. */ \
+            abort(); \
+        } \
+    }
+
+#endif