debuggerd: Dump list of open files on process crash.

Test: Open a bunch of files, wait for the process to crash, verify dubuggerd
includes the list of open files the tombstone it generates.
Test: Added OpenFilesListTest to debuggerd_test.

Bug: 32013594

Change-Id: I6f939ae1d04dc58dc99abff0ed930da9e0ef0d1c

debuggerd/Android.mk

@@ -18,6 +18,7 @@ LOCAL_SRC_FILES:= \
     debuggerd.cpp \
     elf_utils.cpp \
     getevent.cpp \
+    open_files_list.cpp \
     signal_sender.cpp \
     tombstone.cpp \
     utility.cpp \
@@ -108,9 +109,11 @@ include $(BUILD_EXECUTABLE)
 
 debuggerd_test_src_files := \
     utility.cpp \
+    open_files_list.cpp \
     test/dump_memory_test.cpp \
     test/elf_fake.cpp \
     test/log_fake.cpp \
+    test/open_files_list_test.cpp \
     test/property_fake.cpp \
     test/ptrace_fake.cpp \
     test/tombstone_test.cpp \

debuggerd/debuggerd.cpp

@@ -55,6 +55,7 @@
 
 #include "backtrace.h"
 #include "getevent.h"
+#include "open_files_list.h"
 #include "signal_sender.h"
 #include "tombstone.h"
 #include "utility.h"
@@ -452,7 +453,8 @@ static void ptrace_siblings(pid_t pid, pid_t main_tid, pid_t ignore_tid, std::se
 }
 
 static bool perform_dump(const debugger_request_t& request, int fd, int tombstone_fd,
-                         BacktraceMap* backtrace_map, const std::set<pid_t>& siblings,
+                         BacktraceMap* backtrace_map, const OpenFilesList& open_files,
+                         const std::set<pid_t>& siblings,
                          int* crash_signal, std::string* amfd_data) {
   if (TEMP_FAILURE_RETRY(write(fd, "\0", 1)) != 1) {
     ALOGE("debuggerd: failed to respond to client: %s\n", strerror(errno));
@@ -471,7 +473,8 @@ static bool perform_dump(const debugger_request_t& request, int fd, int tombston
       case SIGSTOP:
         if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
           ALOGV("debuggerd: stopped -- dumping to tombstone");
-          engrave_tombstone(tombstone_fd, backtrace_map, request.pid, request.tid, siblings,
+          engrave_tombstone(tombstone_fd, backtrace_map, open_files,
+                            request.pid, request.tid, siblings,
                             request.abort_msg_address, amfd_data);
         } else if (request.action == DEBUGGER_ACTION_DUMP_BACKTRACE) {
           ALOGV("debuggerd: stopped -- dumping to fd");
@@ -498,7 +501,8 @@ static bool perform_dump(const debugger_request_t& request, int fd, int tombston
       case SIGTRAP:
         ALOGV("stopped -- fatal signal\n");
         *crash_signal = signal;
-        engrave_tombstone(tombstone_fd, backtrace_map, request.pid, request.tid, siblings,
+        engrave_tombstone(tombstone_fd, backtrace_map, open_files,
+                          request.pid, request.tid, siblings,
                           request.abort_msg_address, amfd_data);
         break;
 
@@ -593,6 +597,10 @@ static void worker_process(int fd, debugger_request_t& request) {
   // Generate the backtrace map before dropping privileges.
   std::unique_ptr<BacktraceMap> backtrace_map(BacktraceMap::Create(request.pid));
 
+  // Collect the list of open files before dropping privileges.
+  OpenFilesList open_files;
+  populate_open_files_list(request.pid, &open_files);
+
   int amfd = -1;
   std::unique_ptr<std::string> amfd_data;
   if (request.action == DEBUGGER_ACTION_CRASH) {
@@ -610,8 +618,8 @@ static void worker_process(int fd, debugger_request_t& request) {
   }
 
   int crash_signal = SIGKILL;
-  succeeded = perform_dump(request, fd, tombstone_fd, backtrace_map.get(), siblings,
-                           &crash_signal, amfd_data.get());
+  succeeded = perform_dump(request, fd, tombstone_fd, backtrace_map.get(), open_files,
+                           siblings, &crash_signal, amfd_data.get());
   if (succeeded) {
     if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
       if (!tombstone_path.empty()) {

debuggerd/open_files_list.cpp

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "DEBUG"
+
+#include <dirent.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android/log.h>
+
+#include "open_files_list.h"
+
+#include "utility.h"
+
+void populate_open_files_list(pid_t pid, OpenFilesList* list) {
+  std::string fd_dir_name = "/proc/" + std::to_string(pid) + "/fd";
+  std::unique_ptr<DIR, int (*)(DIR*)> dir(opendir(fd_dir_name.c_str()), closedir);
+  if (dir == nullptr) {
+    ALOGE("failed to open directory %s: %s", fd_dir_name.c_str(), strerror(errno));
+    return;
+  }
+
+  struct dirent* de;
+  while ((de = readdir(dir.get())) != nullptr) {
+    if (*de->d_name == '.') {
+      continue;
+    }
+
+    int fd = atoi(de->d_name);
+    std::string path = fd_dir_name + "/" + std::string(de->d_name);
+    std::string target;
+    if (android::base::Readlink(path, &target)) {
+      list->emplace_back(fd, target);
+    } else {
+      ALOGE("failed to readlink %s: %s", path.c_str(), strerror(errno));
+      list->emplace_back(fd, "???");
+    }
+  }
+}
+
+void dump_open_files_list_to_log(const OpenFilesList& files, log_t* log, const char* prefix) {
+  for (auto& file : files) {
+    _LOG(log, logtype::OPEN_FILES, "%sfd %i: %s\n", prefix, file.first, file.second.c_str());
+  }
+}
+

debuggerd/open_files_list.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _DEBUGGERD_OPEN_FILES_LIST_H
+#define _DEBUGGERD_OPEN_FILES_LIST_H
+
+#include <sys/types.h>
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "utility.h"
+
+typedef std::vector<std::pair<int, std::string>> OpenFilesList;
+
+/* Populates the given list with open files for the given process. */
+void populate_open_files_list(pid_t pid, OpenFilesList* list);
+
+/* Dumps the open files list to the log. */
+void dump_open_files_list_to_log(const OpenFilesList& files, log_t* log, const char* prefix);
+
+#endif // _DEBUGGERD_OPEN_FILES_LIST_H

debuggerd/test/open_files_list_test.cpp

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <gtest/gtest.h>
+
+#include "android-base/test_utils.h"
+
+#include "open_files_list.h"
+
+// Check that we can produce a list of open files for the current process, and
+// that it includes a known open file.
+TEST(OpenFilesListTest, BasicTest) {
+  // Open a temporary file that we can check for in the list of open files.
+  TemporaryFile tf;
+
+  // Get the list of open files for this process.
+  OpenFilesList list;
+  populate_open_files_list(getpid(), &list);
+
+  // Verify our open file is in the list.
+  bool found = false;
+  for (auto&  file : list) {
+    if (file.first == tf.fd) {
+      EXPECT_EQ(file.second, std::string(tf.path));
+      found = true;
+      break;
+    }
+  }
+  EXPECT_TRUE(found);
+}

debuggerd/tombstone.cpp

@@ -46,6 +46,7 @@
 #include "backtrace.h"
 #include "elf_utils.h"
 #include "machine.h"
+#include "open_files_list.h"
 #include "tombstone.h"
 
 #define STACK_WORDS 16
@@ -620,7 +621,8 @@ static void dump_logs(log_t* log, pid_t pid, unsigned int tail) {
 }
 
 // Dumps all information about the specified pid to the tombstone.
-static void dump_crash(log_t* log, BacktraceMap* map, pid_t pid, pid_t tid,
+static void dump_crash(log_t* log, BacktraceMap* map,
+                       const OpenFilesList& open_files, pid_t pid, pid_t tid,
                        const std::set<pid_t>& siblings, uintptr_t abort_msg_address) {
   // don't copy log messages to tombstone unless this is a dev device
   bool want_logs = __android_log_is_debuggable();
@@ -639,6 +641,9 @@ static void dump_crash(log_t* log, BacktraceMap* map, pid_t pid, pid_t tid,
     }
   }
 
+  _LOG(log, logtype::OPEN_FILES, "\nopen files:\n");
+  dump_open_files_list_to_log(open_files, log, "    ");
+
   if (want_logs) {
     dump_logs(log, pid, 0);
   }
@@ -697,7 +702,8 @@ int open_tombstone(std::string* out_path) {
   return fd;
 }
 
-void engrave_tombstone(int tombstone_fd, BacktraceMap* map, pid_t pid, pid_t tid,
+void engrave_tombstone(int tombstone_fd, BacktraceMap* map,
+                       const OpenFilesList& open_files, pid_t pid, pid_t tid,
                        const std::set<pid_t>& siblings, uintptr_t abort_msg_address,
                        std::string* amfd_data) {
   log_t log;
@@ -711,5 +717,5 @@ void engrave_tombstone(int tombstone_fd, BacktraceMap* map, pid_t pid, pid_t tid
 
   log.tfd = tombstone_fd;
   log.amfd_data = amfd_data;
-  dump_crash(&log, map, pid, tid, siblings, abort_msg_address);
+  dump_crash(&log, map, open_files, pid, tid, siblings, abort_msg_address);
 }

debuggerd/tombstone.h

@@ -32,7 +32,8 @@ class BacktraceMap;
 int open_tombstone(std::string* path);
 
 /* Creates a tombstone file and writes the crash dump to it. */
-void engrave_tombstone(int tombstone_fd, BacktraceMap* map, pid_t pid, pid_t tid,
+void engrave_tombstone(int tombstone_fd, BacktraceMap* map,
+                       const OpenFilesList& open_files, pid_t pid, pid_t tid,
                        const std::set<pid_t>& siblings, uintptr_t abort_msg_address,
                        std::string* amfd_data);
 

debuggerd/utility.h

@@ -70,7 +70,8 @@ enum logtype {
   MAPS,
   MEMORY,
   STACK,
-  LOGS
+  LOGS,
+  OPEN_FILES
 };
 
 // Log information onto the tombstone.