>From 73c47a162ddc455f265d7eb29eaad5474f9a678e Mon Sep 17 00:00:00 2001
From: Brand Huntsman <address@hidden>
Date: Sun, 14 Jan 2018 23:19:37 -0700
Subject: [PATCH] restore terminal and print backtrace for segfaults and
 assertions

Signed-off-by: Brand Huntsman <address@hidden>
---
 src/Makefile.am |  3 +++
 src/nano.c      | 27 ++++++++++++++++++++++++---
 src/nano.h      |  9 ++++++++-
 src/proto.h     |  1 +
 4 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/src/Makefile.am b/src/Makefile.am
index 625434c2..f9422e47 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,6 +1,9 @@
 AM_CPPFLAGS = -DLOCALEDIR=\"$(localedir)\" -DSYSCONFDIR=\"$(sysconfdir)\" \
 	-I$(top_builddir)/lib -I$(top_srcdir)/lib
 
+# -rdynamic is needed by print_backtrace() to show function names
+LDFLAGS = -rdynamic
+
 CLEANFILES = revision.h
 
 if BUILDING_FROM_GIT
diff --git a/src/nano.c b/src/nano.c
index a21625cf..63abee1b 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -1890,8 +1890,32 @@ void do_output(char *output, size_t output_len, bool allow_cntrls)
 		update_line(openfile->current, openfile->current_x);
 }
 
+void print_backtrace(int skip_to)
+{
+	void *callstack[16];
+	int i, frames = backtrace(callstack, 16);
+	char **strings = backtrace_symbols(callstack, frames);
+	for(i = skip_to + 1; i < frames; i++) printf("|  %s\n", strings[i]);
+	free(strings);
+	exit(1);
+}
+
+void segfault_handler(int nothing)
+{
+	endwin();
+	tcsetattr(0, TCSANOW, &oldterm);
+	printf("Segmentation fault\n");
+	print_backtrace(1); /* hide segfault_handler() */
+}
+
 int main(int argc, char **argv)
 {
+	/* Initialize segfault handler. */
+	signal(SIGSEGV, segfault_handler);
+
+	/* Back up the terminal settings so that they can be restored. */
+	tcgetattr(0, &oldterm);
+
 	int stdin_flags, optchr;
 #if defined(ENABLED_WRAPORJUSTIFY) && defined(ENABLE_NANORC)
 	bool fill_used = FALSE;
@@ -1985,9 +2009,6 @@ int main(int argc, char **argv)
 	console = (getenv("DISPLAY") == NULL);
 #endif
 
-	/* Back up the terminal settings so that they can be restored. */
-	tcgetattr(0, &oldterm);
-
 	/* Get the state of standard input and ensure it uses blocking mode. */
 	stdin_flags = fcntl(0, F_GETFL, 0);
 	if (stdin_flags != -1)
diff --git a/src/nano.h b/src/nano.h
index 55abf1e8..f2239dfb 100644
--- a/src/nano.h
+++ b/src/nano.h
@@ -120,7 +120,14 @@
 #include <dirent.h>
 #include <regex.h>
 #include <signal.h>
-#include <assert.h>
+#include <execinfo.h>
+
+#define assert(expr) if(!(expr)){ \
+	endwin(); \
+	tcsetattr(0, TCSANOW, &oldterm); \
+	printf("Assertion (%s) failed: %s %s() %d\n", #expr, __FILE__, __func__, __LINE__); \
+	print_backtrace(0); \
+}
 
 /* If we aren't using an ncurses with mouse support, exclude any
  * mouse routines, as they are useless then. */
diff --git a/src/proto.h b/src/proto.h
index d82d0cbd..a52d4ab1 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -446,6 +446,7 @@ int do_input(bool allow_funcs);
 int do_mouse(void);
 #endif
 void do_output(char *output, size_t output_len, bool allow_cntrls);
+void print_backtrace(int skip_to);
 
 /* Most functions in prompt.c. */
 #ifdef ENABLE_MOUSE
-- 
2.13.6