Add backtrace generation to MALLOC_DEBUG memory corruption reports

This patch allows astmm to access the backtrace generation code in Asterisk.
When memory is allocated, a backtrace is created and stored with the memory
region that tracks the allocation. If a memory corruption is detected, the
backtrace is printed to the astmm log. The backtrace will make use of the
BETTER_BACKTRACES build option if available.

As a result, this patch moves the backtrace generation code into its own file
and uses the non-wrapped versions of the C library memory allocation routines.
This allows the memory allocation code to safely use the backtrace generation
routines without infinitely recursing.

Review: https://reviewboard.asterisk.org/r/2567


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@391012 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/backtrace.h

@@ -0,0 +1,97 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 1999 - 2013, Digium, Inc.
+ *
+ * Matt Jordan <mjordan@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ * \brief Asterisk backtrace generation
+ *
+ * This file provides backtrace generation utilities
+ */
+
+
+#ifndef BACKTRACE_H_
+#define BACKTRACE_H_
+
+#define AST_MAX_BT_FRAMES 32
+
+#ifdef HAVE_BKTR
+#define ast_bt_get_addresses(bt) __ast_bt_get_addresses((bt))
+#define ast_bt_create() __ast_bt_create()
+#define ast_bt_destroy(bt) __ast_bt_destroy((bt))
+#define ast_bt_get_symbols(addresses, num_frames) __ast_bt_get_symbols((addresses), (num_frames))
+#else
+#define ast_bt_get_addresses(bt) 0
+#define ast_bt_create() NULL
+#define ast_bt_destroy(bt) NULL
+#define ast_bt_get_symbols(addresses, num_frames) NULL
+#endif
+
+/* \brief
+ *
+ * A structure to hold backtrace information. This structure provides an easy means to
+ * store backtrace information or pass backtraces to other functions.
+ */
+struct ast_bt {
+	/*! The addresses of the stack frames. This is filled in by calling the glibc backtrace() function */
+	void *addresses[AST_MAX_BT_FRAMES];
+	/*! The number of stack frames in the backtrace */
+	int num_frames;
+	/*! Tells if the ast_bt structure was dynamically allocated */
+	unsigned int alloced:1;
+};
+
+#ifdef HAVE_BKTR
+
+/* \brief
+ * Allocates memory for an ast_bt and stores addresses and symbols.
+ *
+ * \return Returns NULL on failure, or the allocated ast_bt on success
+ * \since 1.6.1
+ */
+struct ast_bt *__ast_bt_create(void);
+
+/* \brief
+ * Fill an allocated ast_bt with addresses
+ *
+ * \retval 0 Success
+ * \retval -1 Failure
+ * \since 1.6.1
+ */
+int __ast_bt_get_addresses(struct ast_bt *bt);
+
+/* \brief
+ *
+ * Free dynamically allocated portions of an ast_bt
+ *
+ * \retval NULL.
+ * \since 1.6.1
+ */
+void *__ast_bt_destroy(struct ast_bt *bt);
+
+/* \brief Retrieve symbols for a set of backtrace addresses
+ *
+ * \param addresses A list of addresses, such as the ->addresses structure element of struct ast_bt.
+ * \param num_frames Number of addresses in the addresses list
+ * \retval NULL Unable to allocate memory
+ * \return List of strings. This should be freed with a single call to free.
+ * \since 1.6.2.16
+ */
+char **__ast_bt_get_symbols(void **addresses, size_t num_frames);
+
+#endif /* HAVE_BKTR */
+
+#endif /* BACKTRACE_H_ */