FreeTDM: Move custom backtrace code into ftdm_backtrace_walk() and helper functions.

Portability fix for uClibc and other (linux) environments that lack execinfo.h.

ftdm_backtrace_walk() and related return FTDM_NOTIMPL and print a message
if backtraces are not available in the current environment.
Signed-off-by: Stefan Knoblich <stkn@openisdn.net>

libs/freetdm/Makefile.am

@@ -79,7 +79,8 @@ libfreetdm_la_SOURCES = \
 	$(SRC)/ftdm_buffer.c \
 	$(SRC)/ftdm_threadmutex.c \
 	$(SRC)/ftdm_dso.c \
-	$(SRC)/ftdm_cpu_monitor.c
+	$(SRC)/ftdm_cpu_monitor.c \
+	$(SRC)/ftdm_backtrace.c
 
 library_include_HEADERS = \
 	$(SRC)/include/freetdm.h \

libs/freetdm/configure.ac

@@ -136,7 +136,7 @@ AC_CHECK_LIB([dl], [dlopen])
 AC_CHECK_LIB([pthread], [pthread_create])
 AC_CHECK_LIB([m], [cos])
 
-AC_CHECK_HEADERS([netdb.h sys/select.h])
+AC_CHECK_HEADERS([netdb.h sys/select.h execinfo.h])
 
 AC_CHECK_FUNC([gethostbyname_r],
 	[], [AC_CHECK_LIB([nsl], [gethostbyname_r])]

libs/freetdm/mod_freetdm/mod_freetdm.c

@@ -35,13 +35,6 @@
 #include "freetdm.h"
 
 //#define CUDATEL_DEBUG
-#ifdef CUDATEL_DEBUG
-#ifndef _BSD_SOURCE
-#define _BSD_SOURCE
-#endif
-#include <execinfo.h>
-#include <syscall.h>
-#endif
 
 #ifndef __FUNCTION__
 #define __FUNCTION__ __SWITCH_FUNC__
@@ -499,6 +492,21 @@ static switch_status_t channel_on_destroy(switch_core_session_t *session)
 	return SWITCH_STATUS_SUCCESS;
 }
 
+#ifdef CUDATEL_DEBUG
+struct cudatel_trace_priv {
+	const char *name;
+	int span_id;
+	int chan_id;
+};
+
+static void cudatel_trace(const int tid, const void *addr, const char *symbol, void *priv)
+{
+	struct cudatel_trace_priv *data = priv;
+	switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG, "[%d:%d][tid:%d] %s -> %s\n",
+			data->span_id, data->chan_id, tid, data->name, symbol);
+}
+#endif
+
 static switch_status_t channel_on_hangup(switch_core_session_t *session)
 {
 	switch_channel_t *channel = NULL;
@@ -558,19 +566,11 @@ static switch_status_t channel_on_hangup(switch_core_session_t *session)
 
 #ifdef CUDATEL_DEBUG
 	{
-		pid_t tid = 0;
-		size_t size = 0;
-		char **symbols = NULL;
-		void *stacktrace[50];
-		int si = 0;
-		size = backtrace(stacktrace, ftdm_array_len(stacktrace));
-		symbols = backtrace_symbols(stacktrace, size);
-		tid = syscall(SYS_gettid);
-		for (si = 0; si < size; si++) {
-			switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG, "[%d:%d][tid:%d] %s -> %s\n",
-					span_id, chan_id, tid, name, symbols[si]);
-		}
-		free(symbols);
+		struct cudatel_trace_priv trace_data;
+		trace_data.name = name;
+		trace_data.span_id = span_id;
+		trace_data.chan_id = chan_id;
+		ftdm_backtrace_walk(&cudatel_trace, &trace_data);
 	}
 #endif
 

libs/freetdm/src/ftdm_backtrace.c

+/*
+ *
+ *
+ */
+#define _BSD_SOURCE
+#include "private/ftdm_core.h"
+
+#ifdef HAVE_EXECINFO_H
+#include <stdlib.h>
+#include <unistd.h>
+#include <execinfo.h>
+#include <syscall.h>
+
+#define FTDM_BACKTRACE_MAX	50
+
+FT_DECLARE(ftdm_status_t) ftdm_backtrace_walk(void (* callback)(const int tid, const void *addr, const char *symbol, void *priv), void *priv)
+{
+	void *stacktrace[FTDM_BACKTRACE_MAX];
+	char **symbols = NULL;
+	size_t size = 0;
+	pid_t tid = 0;
+	int si = 0;
+
+	if (!callback) {
+		return FTDM_EINVAL;
+	}
+
+	tid = syscall(SYS_gettid);
+
+	size = backtrace(stacktrace, ftdm_array_len(stacktrace));
+	symbols = backtrace_symbols(stacktrace, size);
+
+	for (si = 0; si < size; si++) {
+		callback(tid, stacktrace[si], symbols[si], priv);
+	}
+
+	free(symbols);
+	return FTDM_SUCCESS;
+}
+
+#else	/* !HAVE_EXECINFO_H */
+
+FT_DECLARE(ftdm_status_t) ftdm_backtrace_walk(void (* callback)(const int tid, const void *addr, const char *symbol, void *priv), void *priv)
+{
+	ftdm_log(FTDM_LOG_DEBUG, "Stack traces are not available on this platform!\n");
+	return FTDM_NOTIMPL;
+}
+
+#endif
+
+
+static void span_backtrace(const int tid, const void *addr, const char *symbol, void *priv)
+{
+	ftdm_span_t *span = priv;
+	ftdm_log(FTDM_LOG_DEBUG, "[%d][tid:%d] %p -> %s\n",
+		ftdm_span_get_id(span), tid, addr, symbol);
+}
+
+FT_DECLARE(ftdm_status_t) ftdm_backtrace_span(ftdm_span_t *span)
+{
+	return ftdm_backtrace_walk(&span_backtrace, span);
+}
+
+
+static void chan_backtrace(const int tid, const void *addr, const char *symbol, void *priv)
+{
+	ftdm_channel_t *chan = priv;
+	ftdm_log(FTDM_LOG_DEBUG, "[%d:%d][tid:%d] %p -> %s\n",
+		ftdm_channel_get_span_id(chan), ftdm_channel_get_id(chan), tid, addr, symbol);
+}
+
+FT_DECLARE(ftdm_status_t) ftdm_backtrace_chan(ftdm_channel_t *chan)
+{
+	return ftdm_backtrace_walk(&chan_backtrace, chan);
+}

libs/freetdm/src/include/freetdm.h

@@ -1814,6 +1814,40 @@ FT_DECLARE(void) ftdm_global_set_config_directory(const char *path);
 /*! \brief Check if the FTDM library is initialized and running */
 FT_DECLARE(ftdm_bool_t) ftdm_running(void);
 
+/**
+ * Generate a stack trace and invoke a callback function for each entry
+ * \param[in]	callback	Callback function, that is invoked for each stack symbol
+ * \param[in]	priv		(User-)Private data passed to the callback
+ * \retval
+ *	FTDM_SUCCESS	On success
+ *	FTDM_NOTIMPL	Backtraces are not available
+ *	FTDM_EINVAL	Invalid arguments (callback was NULL)
+ */
+FT_DECLARE(ftdm_status_t) ftdm_backtrace_walk(void (* callback)(const int tid, const void *addr, const char *symbol, void *priv), void *priv);
+
+/**
+ * Convenience function to print a backtrace for a span.
+ * \note	The backtrace is generated with FTDM_LOG_DEBUG log level.
+ * \param[in]	span	Span object
+ * \retval
+ *	FTDM_SUCCESS	On success
+ *	FTDM_NOTIMPL	Backtraces are not available
+ *	FTDM_EINVAL	Invalid arguments (e.g. span was NULL)
+ */
+FT_DECLARE(ftdm_status_t) ftdm_backtrace_span(ftdm_span_t *span);
+
+/**
+ * Convenience function to print a backtrace for a channel.
+ * \note	The backtrace is generated with FTDM_LOG_DEBUG log level.
+ * \param[in]	chan	Channel object
+ * \retval
+ *	FTDM_SUCCESS	On success
+ *	FTDM_NOTIMPL	Backtraces are not available
+ *	FTDM_EINVAL	Invalid arguments (e.g. chan was NULL)
+ */
+FT_DECLARE(ftdm_status_t) ftdm_backtrace_chan(ftdm_channel_t *chan);
+
+
 FT_DECLARE_DATA extern ftdm_logger_t ftdm_log;
 
 /*! \brief Basic transcoding function prototype */

libs/freetdm/src/include/private/ftdm_core.h

@@ -104,10 +104,6 @@
 #include <sys/time.h>
 #endif
 
-#ifdef __linux__
-#include <execinfo.h>
-#endif
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>