fdtrack: add a test.

Test: logcat -c; fdtrack_test; logcat -d | grep fdtrack
Change-Id: Ie1101c9cf968299ec1f03f20097a2ed27f6e15bd

4 files changed, 180 insertions, 19 deletions

diff --git a/libfdtrack/Android.bp b/libfdtrack/Android.bp
index fd1351263..a907d9ae0 100644
--- a/libfdtrack/Android.bp
+++ b/libfdtrack/Android.bp
@@ -16,3 +16,11 @@ cc_library_shared {
     allow_undefined_symbols: true,
     recovery_available: true,
 }
+
+cc_test {
+    name: "fdtrack_test",
+    srcs: ["fdtrack_test.cpp"],
+    whole_static_libs: ["libBionicCtsGtestMain"],
+    static_libs: ["liblog"],
+    test_suites: ["device-tests"],
+}
diff --git a/libfdtrack/fdtrack.cpp b/libfdtrack/fdtrack.cpp
index 831a50d1b..b20e65ea1 100644
--- a/libfdtrack/fdtrack.cpp
+++ b/libfdtrack/fdtrack.cpp
@@ -27,6 +27,7 @@
  */
 
 #include <inttypes.h>
+#include <stdint.h>
 
 #include <array>
 #include <mutex>
@@ -47,6 +48,11 @@ struct FdEntry {
 };
 
 extern "C" void fdtrack_dump();
+
+using fdtrack_callback_t = bool (*)(int fd, const char* const* function_names,
+                                    const uint64_t* function_offsets, size_t count, void* arg);
+extern "C" void fdtrack_iterate(fdtrack_callback_t callback, void* arg);
+
 static void fd_hook(android_fdtrack_event* event);
 
 // Backtraces for the first 4k file descriptors ought to be enough to diagnose an fd leak.
@@ -61,6 +67,10 @@ static unwindstack::LocalUnwinder& Unwinder() {
 }
 
 __attribute__((constructor)) static void ctor() {
+  for (auto& entry : stack_traces) {
+    entry.backtrace.reserve(kStackDepth);
+  }
+
   signal(BIONIC_SIGNAL_FDTRACK, [](int) { fdtrack_dump(); });
   if (Unwinder().Init()) {
     android_fdtrack_hook_t expected = nullptr;
@@ -97,15 +107,12 @@ static void fd_hook(android_fdtrack_event* event) {
   }
 }
 
-void fdtrack_dump() {
-  if (!installed) {
-    async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack not installed");
-  } else {
-    async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack dumping...");
-  }
-
+void fdtrack_iterate(fdtrack_callback_t callback, void* arg) {
   bool prev = android_fdtrack_set_enabled(false);
+
   for (int fd = 0; fd < static_cast<int>(stack_traces.size()); ++fd) {
+    const char* function_names[kStackDepth];
+    uint64_t function_offsets[kStackDepth];
     FdEntry* entry = GetFdEntry(fd);
     if (!entry) {
       continue;
@@ -117,26 +124,60 @@ void fdtrack_dump() {
     }
 
     if (entry->backtrace.empty()) {
+      entry->mutex.unlock();
       continue;
-    }
-
-    uint64_t fdsan_owner = android_fdsan_get_owner_tag(fd);
+    } else if (entry->backtrace.size() < 2) {
+      async_safe_format_log(ANDROID_LOG_WARN, "fdtrack", "fd %d missing frames: size = %zu", fd,
+                            entry->backtrace.size());
 
-    if (fdsan_owner != 0) {
-      async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fd %d: (owner = %#" PRIx64 ")", fd,
-                            fdsan_owner);
-    } else {
-      async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fd %d: (unowned)", fd);
+      entry->mutex.unlock();
+      continue;
     }
 
-    const size_t frame_skip = 2;
+    constexpr size_t frame_skip = 2;
     for (size_t i = frame_skip; i < entry->backtrace.size(); ++i) {
-      auto& frame = entry->backtrace[i];
-      async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "  %zu: %s+%" PRIu64, i - frame_skip,
-                            frame.function_name.c_str(), frame.function_offset);
+      size_t j = i - frame_skip;
+      function_names[j] = entry->backtrace[i].function_name.c_str();
+      function_offsets[j] = entry->backtrace[i].function_offset;
     }
 
+    bool should_continue =
+        callback(fd, function_names, function_offsets, entry->backtrace.size() - frame_skip, arg);
+
     entry->mutex.unlock();
+
+    if (!should_continue) {
+      break;
+    }
   }
+
   android_fdtrack_set_enabled(prev);
 }
+
+void fdtrack_dump() {
+  if (!installed) {
+    async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack not installed");
+  } else {
+    async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack dumping...");
+  }
+
+  fdtrack_iterate(
+      [](int fd, const char* const* function_names, const uint64_t* function_offsets, size_t count,
+         void*) {
+        uint64_t fdsan_owner = android_fdsan_get_owner_tag(fd);
+        if (fdsan_owner != 0) {
+          async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fd %d: (owner = %#" PRIx64 ")", fd,
+                                fdsan_owner);
+        } else {
+          async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fd %d: (unowned)", fd);
+        }
+
+        for (size_t i = 0; i < count; ++i) {
+          async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "  %zu: %s+%" PRIu64, i,
+                                function_names[i], function_offsets[i]);
+        }
+
+        return true;
+      },
+      nullptr);
+}
diff --git a/libfdtrack/fdtrack_test.cpp b/libfdtrack/fdtrack_test.cpp
new file mode 100644
index 000000000..0edf0b81e
--- /dev/null
+++ b/libfdtrack/fdtrack_test.cpp
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <dlfcn.h>
+#include <err.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <map>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+struct FdtrackFrame {
+  const char* function_name;
+  uint64_t function_offset;
+};
+
+std::map<int, std::vector<FdtrackFrame>> RunFdtrack(std::function<void()> f) {
+  void* libfdtrack = dlopen("libfdtrack.so", RTLD_NOW);
+  if (!libfdtrack) {
+    errx(1, "failed to dlopen libfdtrack.so: %s", dlerror());
+  }
+
+  using fdtrack_callback_t = bool (*)(int fd, const char* const* function_names,
+                                      const uint64_t* function_offsets, size_t count, void* arg);
+  auto fdtrack_iterate = reinterpret_cast<void (*)(fdtrack_callback_t, void* arg)>(
+      dlsym(libfdtrack, "fdtrack_iterate"));
+  if (!fdtrack_iterate) {
+    errx(1, "failed to dlsym fdtrack_iterate");
+  }
+
+  f();
+
+  std::map<int, std::vector<FdtrackFrame>> result;
+  fdtrack_iterate(
+      [](int fd, const char* const* function_names, const uint64_t* function_offsets, size_t count,
+         void* arg) {
+        auto& map = *static_cast<decltype(result)*>(arg);
+        for (size_t i = 0; i < count; ++i) {
+          map[fd].push_back(FdtrackFrame{
+              .function_name = function_names[i],
+              .function_offset = function_offsets[i],
+          });
+        }
+
+        return true;
+      },
+      &result);
+
+  return result;
+}
+
+TEST(fdtrack, open) {
+  static int fd = -1;
+  auto result = RunFdtrack([]() { fd = open("/dev/null", O_RDONLY | O_CLOEXEC); });
+
+  ASSERT_NE(-1, fd);
+  ASSERT_EQ(1, result.size());
+  ASSERT_EQ(fd, result.begin()->first);
+  ASSERT_NE(nullptr, strstr(result.begin()->second.at(0).function_name, "open"));
+}
+
+TEST(fdtrack, close) {
+  static int fd1 = -1;
+  static int fd2 = -1;
+  static int fd3 = -1;
+  auto result = RunFdtrack([]() {
+    fd1 = open("/dev/null", O_RDONLY | O_CLOEXEC);
+    fd2 = open("/dev/null", O_RDONLY | O_CLOEXEC);
+    fd3 = open("/dev/null", O_RDONLY | O_CLOEXEC);
+    close(fd2);
+  });
+
+  ASSERT_NE(-1, fd1);
+  ASSERT_NE(-1, fd2);
+  ASSERT_NE(-1, fd3);
+
+  ASSERT_EQ(2, result.size());
+  ASSERT_EQ(1, result.count(fd1));
+  ASSERT_EQ(1, result.count(fd3));
+
+  ASSERT_NE(nullptr, strstr(result[fd1].at(0).function_name, "open"));
+  ASSERT_NE(nullptr, strstr(result[fd3].at(0).function_name, "open"));
+}
diff --git a/libfdtrack/libfdtrack.map.txt b/libfdtrack/libfdtrack.map.txt
index 7a54c35b3..7a23954d8 100644
--- a/libfdtrack/libfdtrack.map.txt
+++ b/libfdtrack/libfdtrack.map.txt
@@ -1,6 +1,7 @@
 LIBFDTRACK {
   global:
     fdtrack_dump;
+    fdtrack_iterate;
   local:
     *;
 };