From 3cb1b7fd2f4b3fd656758060582001f1e78c3e12 Mon Sep 17 00:00:00 2001
From: Milian Wolff <mail@milianw.de>
Date: Mon, 17 Apr 2017 21:14:15 +0200
Subject: [PATCH] Call libc and libstdc++ freeres functions in
 heaptrack_preload on exit

These functions are used by Valgrind already and can be used to force
a clean shutdown of libc and libstdc++. Both usually don't bother
freeing their global resources, which used to be reported as memory
leaks by heaptrack. By calling the freeres functions we now get a
clean shutdown of the libc_leaks.c example without any memory leaks
reported.

Thanks to Maxim Golov for pointing out this hidden functionality and
providing a test case.

BUG: 378765
---
 src/track/heaptrack_preload.cpp | 19 +++++++++++++++++++
 tests/manual/CMakeLists.txt     |  2 ++
 tests/manual/libc_leaks.c       | 30 ++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 tests/manual/libc_leaks.c

diff --git a/src/track/heaptrack_preload.cpp b/src/track/heaptrack_preload.cpp
index 149b194..ae18913 100644
--- a/src/track/heaptrack_preload.cpp
+++ b/src/track/heaptrack_preload.cpp
@@ -40,6 +40,13 @@ using namespace std;
 #  define HAVE_CFREE 0
 #endif
 
+extern "C" {
+__attribute__((weak)) void __libc_freeres();
+}
+namespace __gnu_cxx {
+__attribute__((weak)) extern void __freeres();
+}
+
 namespace {
 
 namespace hooks {
@@ -120,6 +127,18 @@ void* dummy_calloc(size_t num, size_t size) noexcept
 
 void init()
 {
+    atexit([]() {
+        // free internal libstdc++ resources
+        // see also Valgrind's `--run-cxx-freeres` option
+        if (&__gnu_cxx::__freeres) {
+            __gnu_cxx::__freeres();
+        }
+        // free internal libc resources, cf: https://bugs.kde.org/show_bug.cgi?id=378765
+        // see also Valgrind's `--run-libc-freeres` option
+        if (&__libc_freeres) {
+            __libc_freeres();
+        }
+    });
     heaptrack_init(getenv("DUMP_HEAPTRACK_OUTPUT"),
                    [] {
                        hooks::calloc.original = &dummy_calloc;
diff --git a/tests/manual/CMakeLists.txt b/tests/manual/CMakeLists.txt
index 62ebdd8..831c7e2 100644
--- a/tests/manual/CMakeLists.txt
+++ b/tests/manual/CMakeLists.txt
@@ -15,3 +15,5 @@ add_executable(test_aggregation test_aggregation.cpp)
 
 add_executable(signals signals.cpp)
 target_link_libraries(signals ${CMAKE_THREAD_LIBS_INIT})
+
+add_executable(libc_leaks libc_leaks.c)
diff --git a/tests/manual/libc_leaks.c b/tests/manual/libc_leaks.c
new file mode 100644
index 0000000..748187c
--- /dev/null
+++ b/tests/manual/libc_leaks.c
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2017 Maxim Golov <maxim.golov@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <time.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv)
+{
+    time_t t = time(0);
+    struct tm tmbuf;
+    gmtime_r(&t, &tmbuf);
+    char buf[16];
+    strftime(buf, sizeof(buf), "%d", &tmbuf);
+}
-- 
2.7.4