Initial import

[samba] / source / lib / clobber.c

diff --git a/source/lib/clobber.c b/source/lib/clobber.c
new file mode 100644 (file)
index 0000000..fb3a0dc
--- /dev/null
+++ b/source/lib/clobber.c
@@ -0,0 +1,60 @@
+/* 
+   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 */
+}