Add strack trace debug function

Makefile.am

@@ -177,6 +177,7 @@ dist_tmate_SOURCES = \
 	session.c \
 	signal.c \
 	status.c \
+	tmate-debug.c \
 	tmate-ssh-client.c \
 	tmate-encoder.c \
 	tmate-decoder.c \

tmate-debug.c

@@ -0,0 +1,75 @@
+#include <execinfo.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <regex.h>
+#include "tmate.h"
+
+#if DEBUG
+
+static int print_resolved_stack_frame(const char *frame)
+{
+	char file[100];
+	char cmd[200];
+	char output[300];
+	char address[20];
+	char *line;
+	FILE *ps;
+
+	static regex_t _regex;
+	static regex_t *regex;
+	regmatch_t matches[3];
+
+	if (!regex) {
+		if (regcomp(&_regex, "(.+)\\(\\) \\[([^]]+)\\]", REG_EXTENDED))
+			return -1;
+		regex = &_regex;
+	}
+
+	if (regexec(regex, frame, 3, matches, 0))
+		return -1;
+
+	memcpy(file, &frame[matches[1].rm_so], matches[1].rm_eo - matches[1].rm_so);
+	file[matches[1].rm_eo - matches[1].rm_so] = 0;
+
+	memcpy(address, &frame[matches[2].rm_so], matches[2].rm_eo - matches[2].rm_so);
+	address[matches[2].rm_eo - matches[2].rm_so] = 0;
+
+	sprintf(cmd, "addr2line -e %s %s -f -p -s", file, address);
+
+	ps = popen(cmd, "r");
+	if (!ps)
+		return -1;
+
+	line = fgets(output, sizeof(output), ps);
+	pclose(ps);
+
+	if (!line)
+		return -1;
+
+	line[strlen(line)-1] = 0; /* remove \n */
+	tmate_debug("%s(%s) [%s]", file, line, address);
+	return 0;
+}
+#endif
+
+void tmate_print_trace(void)
+{
+	void *array[20];
+	size_t size;
+	char **strings;
+	size_t i;
+
+	size = backtrace (array, 20);
+	strings = backtrace_symbols (array, size);
+
+	tmate_debug ("============ %zd stack frames ============", size);
+
+	for (i = 1; i < size; i++) {
+#if DEBUG
+		if (print_resolved_stack_frame(strings[i]) < 0)
+#endif
+			tmate_debug("%s", strings[i]);
+	}
+
+	free (strings);
+}

tmate.h

@@ -109,4 +109,7 @@ extern void tmate_ssh_client_init(struct tmate_ssh_client *client,
 extern struct tmate_encoder *tmate_encoder;
 extern void tmate_client_start(void);
 
+/* tmate-debug.c */
+extern void tmate_print_trace (void);
+
 #endif