Reading from logd in WRAP mode is expected to take a long time,

don't abort it after 30s.

Adds a new CTS test to verify the behaviour.

Bug: 64143705
Test: New and existing CTS tests pass. Manual testing with logcat.

(cherry picked from commit 64acdf77d6f89a72be9192b35e0fc34242c23e34)

Change-Id: Ic2ec131a3aee293ee865c46e62566ddd82ec2507

3 files changed, 135 insertions, 3 deletions

diff --git a/liblog/logd_reader.c b/liblog/logd_reader.c
index 600f4bb0b..603ba2469 100644
--- a/liblog/logd_reader.c
+++ b/liblog/logd_reader.c
@@ -590,20 +590,30 @@ static int logdRead(struct android_log_logger_list* logger_list,
 
   memset(log_msg, 0, sizeof(*log_msg));
 
+  unsigned int new_alarm = 0;
   if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
+    if ((logger_list->mode & ANDROID_LOG_WRAP) &&
+        (logger_list->start.tv_sec || logger_list->start.tv_nsec)) {
+      /* b/64143705 */
+      new_alarm = (ANDROID_LOG_WRAP_DEFAULT_TIMEOUT * 11) / 10 + 10;
+      logger_list->mode &= ~ANDROID_LOG_WRAP;
+    } else {
+      new_alarm = 30;
+    }
+
     memset(&ignore, 0, sizeof(ignore));
     ignore.sa_handler = caught_signal;
     sigemptyset(&ignore.sa_mask);
     /* particularily useful if tombstone is reporting for logd */
     sigaction(SIGALRM, &ignore, &old_sigaction);
-    old_alarm = alarm(30);
+    old_alarm = alarm(new_alarm);
   }
 
   /* NOTE: SOCK_SEQPACKET guarantees we read exactly one full entry */
   ret = recv(ret, log_msg, LOGGER_ENTRY_MAX_LEN, 0);
   e = errno;
 
-  if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
+  if (new_alarm) {
     if ((ret == 0) || (e == EINTR)) {
       e = EAGAIN;
       ret = -1;
diff --git a/liblog/tests/Android.mk b/liblog/tests/Android.mk
index 91044ab75..5571ce955 100644
--- a/liblog/tests/Android.mk
+++ b/liblog/tests/Android.mk
@@ -64,7 +64,8 @@ test_src_files := \
     log_radio_test.cpp \
     log_read_test.cpp \
     log_system_test.cpp \
-    log_time_test.cpp
+    log_time_test.cpp \
+    log_wrap_test.cpp
 
 # Build tests for the device (with .so). Run with:
 #   adb shell /data/nativetest/liblog-unit-tests/liblog-unit-tests
diff --git a/liblog/tests/log_wrap_test.cpp b/liblog/tests/log_wrap_test.cpp
new file mode 100644
index 000000000..ebf0b1505
--- /dev/null
+++ b/liblog/tests/log_wrap_test.cpp
@@ -0,0 +1,121 @@
+/*
+ * Copyright (C) 2013-2017 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 <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <android-base/chrono_utils.h>
+#include <android-base/stringprintf.h>
+#include <android/log.h>  // minimal logging API
+#include <gtest/gtest.h>
+#include <log/log_properties.h>
+#include <log/log_read.h>
+#include <log/log_time.h>
+#include <log/log_transport.h>
+
+#ifdef __ANDROID__
+static void read_with_wrap() {
+  android_set_log_transport(LOGGER_LOGD);
+
+  // Read the last line in the log to get a starting timestamp. We're assuming
+  // the log is not empty.
+  const int mode = ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK;
+  struct logger_list* logger_list =
+      android_logger_list_open(LOG_ID_MAIN, mode, 1000, 0);
+
+  ASSERT_NE(logger_list, nullptr);
+
+  log_msg log_msg;
+  int ret = android_logger_list_read(logger_list, &log_msg);
+  android_logger_list_close(logger_list);
+  ASSERT_GT(ret, 0);
+
+  log_time start(log_msg.entry.sec, log_msg.entry.nsec);
+  ASSERT_NE(start, log_time());
+
+  logger_list =
+      android_logger_list_alloc_time(mode | ANDROID_LOG_WRAP, start, 0);
+  ASSERT_NE(logger_list, nullptr);
+
+  struct logger* logger = android_logger_open(logger_list, LOG_ID_MAIN);
+  EXPECT_NE(logger, nullptr);
+  if (logger) {
+    android_logger_list_read(logger_list, &log_msg);
+  }
+
+  android_logger_list_close(logger_list);
+}
+
+static void caught_signal(int /* signum */) {
+}
+#endif
+
+// b/64143705 confirm fixed
+TEST(liblog, wrap_mode_blocks) {
+#ifdef __ANDROID__
+
+  android::base::Timer timer;
+
+  // The read call is expected to take up to 2 hours in the happy case.
+  // We only want to make sure it waits for longer than 30s, but we can't
+  // use an alarm as the implementation uses it. So we run the test in
+  // a separate process.
+  pid_t pid = fork();
+
+  if (pid == 0) {
+    // child
+    read_with_wrap();
+    _exit(0);
+  }
+
+  struct sigaction ignore, old_sigaction;
+  memset(&ignore, 0, sizeof(ignore));
+  ignore.sa_handler = caught_signal;
+  sigemptyset(&ignore.sa_mask);
+  sigaction(SIGALRM, &ignore, &old_sigaction);
+  alarm(45);
+
+  bool killed = false;
+  for (;;) {
+    siginfo_t info = {};
+    // This wait will succeed if the child exits, or fail with EINTR if the
+    // alarm goes off first - a loose approximation to a timed wait.
+    int ret = waitid(P_PID, pid, &info, WEXITED);
+    if (ret >= 0 || errno != EINTR) {
+      EXPECT_EQ(ret, 0);
+      if (!killed) {
+        EXPECT_EQ(info.si_status, 0);
+      }
+      break;
+    }
+    unsigned int alarm_left = alarm(0);
+    if (alarm_left > 0) {
+      alarm(alarm_left);
+    } else {
+      kill(pid, SIGTERM);
+      killed = true;
+    }
+  }
+
+  alarm(0);
+  EXPECT_GT(timer.duration(), std::chrono::seconds(40));
+#else
+  GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif
+}