mcheck: introduce essentials of mcheck

The core part of mcheck, but without memalign.
memalign - to be added in ensuing commits.

Signed-off-by: Eugene Uriev <eugeneuriev@gmail.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/include/mcheck.h b/include/mcheck.h
new file mode 100644
index 0000000..a049745
--- /dev/null
+++ b/include/mcheck.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.1+ */
+/*
+ * Copyright (C) 1996-2024 Free Software Foundation, Inc.
+ * This file is part of the GNU C Library.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ * <https://www.gnu.org/licenses/>.
+ */
+#ifndef _MCHECK_H
+#define _MCHECK_H       1
+
+/*
+ * Return values for `mprobe': these are the kinds of inconsistencies that
+ * `mcheck' enables detection of.
+ */
+enum mcheck_status {
+	MCHECK_DISABLED = -1,         /* Consistency checking is not turned on.  */
+	MCHECK_OK,                    /* Block is fine.  */
+	MCHECK_FREE,                  /* Block freed twice.  */
+	MCHECK_HEAD,                  /* Memory before the block was clobbered.  */
+	MCHECK_TAIL                   /* Memory after the block was clobbered.  */
+};
+
+typedef void (*mcheck_abortfunc_t)(enum mcheck_status);
+
+int mcheck(mcheck_abortfunc_t func);
+
+/*
+ * Check for aberrations in a particular malloc'd block. These are the
+ * same checks that `mcheck' does, when you free or reallocate a block.
+ */
+enum mcheck_status mprobe(void *__ptr);
+
+#endif