From e5bb08cc185a28d3e96bfddc7e9a0d837f89b2b8 Mon Sep 17 00:00:00 2001
From: Drew DeVault <sir@cmpwn.com>
Date: Thu, 28 Jan 2016 07:56:46 -0500
Subject: [PATCH] Print /proc/<pid>/maps on segfault

---
 common/log.c       | 20 ++++++++++++++++++++
 common/readline.c  | 27 ++++++++++++++++++++++++++-
 include/readline.h |  1 +
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/common/log.c b/common/log.c
index f9242bf4d..0c0ecf892 100644
--- a/common/log.c
+++ b/common/log.c
@@ -1,5 +1,6 @@
 #include "log.h"
 #include "sway.h"
+#include "readline.h"
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -142,6 +143,9 @@ void error_handler(int sig) {
 	void *array[max_lines];
 	char **bt;
 	size_t bt_len;
+	char maps_file[256];
+	char maps_buffer[1024];
+	FILE *maps;
 
 	sway_log(L_ERROR, "Error: Signal %d. Printing backtrace", sig);
 	bt_len = backtrace(array, max_lines);
@@ -155,6 +159,22 @@ void error_handler(int sig) {
 	for (i = 0; (size_t)i < bt_len; i++) {
 		sway_log(L_ERROR, "Backtrace: %s", bt[i]);
 	}
+
+	sway_log(L_ERROR, "Maps:");
+	pid_t pid = getpid();
+	if (snprintf(maps_file, 255, "/proc/%zd/maps", (size_t)pid) < 255) {
+		maps = fopen(maps_file, "r");
+		while (!feof(maps)) {
+			char *m = read_line_buffer(maps, maps_buffer, 1024);
+			if (!m) {
+				fclose(maps);
+				sway_log(L_ERROR, "Unable to allocate memory to show maps");
+				break;
+			}
+			sway_log(L_ERROR, m);
+		}
+		fclose(maps);
+	}
 #else
 	sway_log(L_ERROR, "Error: Signal %d.", sig);
 #endif
diff --git a/common/readline.c b/common/readline.c
index e75b183fe..76ed69268 100644
--- a/common/readline.c
+++ b/common/readline.c
@@ -3,7 +3,7 @@
 #include <stdio.h>
 
 char *read_line(FILE *file) {
-	int length = 0, size = 128;
+	size_t length = 0, size = 128;
 	char *string = malloc(size);
 	if (!string) {
 		return NULL;
@@ -37,3 +37,28 @@ char *read_line(FILE *file) {
 	string[length] = '\0';
 	return string;
 }
+
+char *read_line_buffer(FILE *file, char *string, size_t string_len) {
+	size_t length = 0;
+	if (!string) {
+		return NULL;
+	}
+	while (1) {
+		int c = getc(file);
+		if (c == EOF || c == '\n' || c == '\0') {
+			break;
+		}
+		if (c == '\r') {
+			continue;
+		}
+		string[length++] = c;
+		if (string_len <= length) {
+			return NULL;
+		}
+	}
+	if (length + 1 == string_len) {
+		return NULL;
+	}
+	string[length] = '\0';
+	return string;
+}
diff --git a/include/readline.h b/include/readline.h
index dbe937c15..b3e06d4b8 100644
--- a/include/readline.h
+++ b/include/readline.h
@@ -4,5 +4,6 @@
 #include <stdio.h>
 
 char *read_line(FILE *file);
+char *read_line_buffer(FILE *file, char *string, size_t string_len);
 
 #endif