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diff --git a/source3/lib/clobber.c b/source3/lib/clobber.c
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+/*
+ Unix SMB/CIFS implementation.
+ Samba utility functions
+ Copyright (C) Martin Pool 2003
+ Copyright (C) Andrew Bartlett 2003
+
+ 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 2 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, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+
+#ifdef DEVELOPER
+const char *global_clobber_region_function;
+unsigned int global_clobber_region_line;
+#endif
+
+/**
+ * In developer builds, clobber a region of memory.
+ *
+ * If we think a string buffer is longer than it really is, this ought
+ * to make the failure obvious, by segfaulting (if in the heap) or by
+ * killing the return address (on the stack), or by trapping under a
+ * memory debugger.
+ *
+ * This is meant to catch possible string overflows, even if the
+ * actual string copied is not big enough to cause an overflow.
+ *
+ * In addition, under Valgrind the buffer is marked as uninitialized.
+ **/
+void clobber_region(const char *fn, unsigned int line, char *dest, size_t len)
+{
+#ifdef DEVELOPER
+ global_clobber_region_function = fn;
+ global_clobber_region_line = line;
+
+ /* F1 is odd and 0xf1f1f1f1 shouldn't be a valid pointer */
+ memset(dest, 0xF1, len);
+#ifdef VALGRIND
+ /* Even though we just wrote to this, from the application's
+ * point of view it is not initialized.
+ *
+ * (This is not redundant with the clobbering above. The
+ * marking might not actually take effect if we're not running
+ * under valgrind.) */
+ VALGRIND_MAKE_WRITABLE(dest, len);
+#endif /* VALGRIND */
+#endif /* DEVELOPER */
+}