From 0a12a96ceef2fc7459a729696fbc0ab716d2a68a Mon Sep 17 00:00:00 2001
From: huangqinjin <huangqinjin@gmail.com>
Date: Mon, 11 May 2020 23:11:52 +0800
Subject: [PATCH] Output to logcat on Android

---
 CMakeLists.txt |  4 ++++
 src/logging.cc | 26 +++++++++++++++++++++-----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c8773af14..4cc2e7189 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -570,6 +570,10 @@ if (gflags_FOUND)
   endif (NOT BUILD_SHARED_LIBS)
 endif (gflags_FOUND)
 
+if (ANDROID)
+  target_link_libraries (glog PUBLIC log)
+endif()
+
 set_target_properties (glog PROPERTIES VERSION ${PROJECT_VERSION})
 set_target_properties (glog PROPERTIES SOVERSION ${PROJECT_VERSION_MAJOR})
 
diff --git a/src/logging.cc b/src/logging.cc
index ddcf91007..e09115090 100644
--- a/src/logging.cc
+++ b/src/logging.cc
@@ -73,6 +73,10 @@
 # include "stacktrace.h"
 #endif
 
+#ifdef __ANDROID__
+#include <android/log.h>
+#endif
+
 using std::string;
 using std::vector;
 using std::setw;
@@ -500,7 +504,7 @@ class LogDestination {
   // Take a log message of a particular severity and log it to stderr
   // iff it's of a high enough severity to deserve it.
   static void MaybeLogToStderr(LogSeverity severity, const char* message,
-			       size_t len);
+			       size_t message_len, size_t prefix_len);
 
   // Take a log message of a particular severity and log it to email
   // iff it's of a high enough severity to deserve it.
@@ -735,12 +739,23 @@ static void WriteToStderr(const char* message, size_t len) {
 }
 
 inline void LogDestination::MaybeLogToStderr(LogSeverity severity,
-					     const char* message, size_t len) {
+					     const char* message, size_t message_len, size_t prefix_len) {
   if ((severity >= FLAGS_stderrthreshold) || FLAGS_alsologtostderr) {
-    ColoredWriteToStderr(severity, message, len);
+    ColoredWriteToStderr(severity, message, message_len);
 #ifdef OS_WINDOWS
     // On Windows, also output to the debugger
-    ::OutputDebugStringA(string(message,len).c_str());
+    ::OutputDebugStringA(message);
+#elif defined(__ANDROID__)
+    // On Android, also output to logcat
+    const int android_log_levels[NUM_SEVERITIES] = {
+      ANDROID_LOG_INFO,
+      ANDROID_LOG_WARN,
+      ANDROID_LOG_ERROR,
+      ANDROID_LOG_FATAL,
+    };
+    __android_log_write(android_log_levels[severity],
+                        glog_internal_namespace_::ProgramInvocationShortName(),
+                        message + prefix_len);
 #endif
   }
 }
@@ -1597,7 +1612,8 @@ void LogMessage::SendToLog() EXCLUSIVE_LOCKS_REQUIRED(log_mutex) {
                                      data_->num_chars_to_log_);
 
     LogDestination::MaybeLogToStderr(data_->severity_, data_->message_text_,
-                                     data_->num_chars_to_log_);
+                                     data_->num_chars_to_log_,
+                                     data_->num_prefix_chars_);
     LogDestination::MaybeLogToEmail(data_->severity_, data_->message_text_,
                                     data_->num_chars_to_log_);
     LogDestination::LogToSinks(data_->severity_,