support stack unwind on Android

.github/workflows/android-builds.yml

@@ -0,0 +1,40 @@
+name: Android
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: NDK-C++${{matrix.std}}-${{matrix.abi}}-${{matrix.build_type}}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+          std: [98, 11, 14, 17, 20]
+          abi: [arm64-v8a, armeabi-v7a, x86_64, x86]
+          build_type: [Debug]
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Setup Ninja
+      uses: ashutoshvarma/setup-ninja@master
+      with:
+        version: 1.10.0
+
+    - name: Configure
+      shell: bash
+      run: |
+        cmake -S . -B ${{runner.workspace}}/build_CXX${{matrix.std}}-${{matrix.abi}} \
+              -G "Ninja Multi-Config" \
+              -DCMAKE_CXX_EXTENSIONS=OFF \
+              -DCMAKE_CXX_STANDARD=${{matrix.std}} \
+              -DCMAKE_CXX_STANDARD_REQUIRED=ON \
+              -DCMAKE_TOOLCHAIN_FILE=${ANDROID_NDK_HOME}/build/cmake/android.toolchain.cmake \
+              -DANDROID_STL=c++_shared \
+              -DANDROID_NATIVE_API_LEVEL=28 \
+              -DANDROID_ABI=${{matrix.abi}} \
+    - name: Build
+      run: |
+        cmake --build ${{runner.workspace}}/build_CXX${{matrix.std}}-${{matrix.abi}} \
+              --config ${{matrix.build_type}}
+

CMakeLists.txt

@@ -96,7 +96,8 @@ find_package (Unwind)
 
 if (Unwind_FOUND)
   set (HAVE_LIB_UNWIND 1)
-  set (HAVE_UNWIND_H 1)
+else (Unwind_FOUND)
+  check_include_file_cxx (unwind.h HAVE_UNWIND_H)
 endif (Unwind_FOUND)
 
 check_include_file_cxx (dlfcn.h HAVE_DLFCN_H)

bazel/glog.bzl

@@ -53,7 +53,6 @@ def glog_library(namespace = "google", with_gflags = 1, **kwargs):
         "-DHAVE_CXX11_NULLPTR_T",
         "-DHAVE_STDINT_H",
         "-DHAVE_STRING_H",
-        "-DHAVE_UNWIND_H",
         "-DGLOG_CUSTOM_PREFIX_SUPPORT",
         "-I%s/glog_internal" % gendir,
     ] + (["-DHAVE_LIB_GFLAGS"] if with_gflags else [])
@@ -70,6 +69,7 @@ def glog_library(namespace = "google", with_gflags = 1, **kwargs):
         "-DHAVE_SYS_UTSNAME_H",
         # For src/utilities.cc.
         "-DHAVE_SYS_TIME_H",
+        "-DHAVE_UNWIND_H",
         # Enable dumping stacktrace upon sigaction.
         "-DHAVE_SIGACTION",
         # For logging.cc.

src/config.h.cmake.in

@@ -31,9 +31,6 @@
 /* Define to 1 if you have the `pthread' library (-lpthread). */
 #cmakedefine HAVE_LIBPTHREAD
 
-/* Define to 1 if you have the <libunwind.h> header file. */
-#cmakedefine HAVE_LIBUNWIND_H
-
 /* define if you have google gflags library */
 #cmakedefine HAVE_LIB_GFLAGS
 
@@ -115,8 +112,8 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #cmakedefine HAVE_UNISTD_H ${HAVE_UNISTD_H}
 
-/* Define to 1 if you have the <unwind.h> header file. */
-#cmakedefine HAVE_UNWIND_H ${HAVE_UNWIND_H}
+/* Define if you have the <unwind.h> header file. */
+#cmakedefine HAVE_UNWIND_H
 
 /* define if the compiler supports using expression for operator */
 #cmakedefine HAVE_USING_OPERATOR

src/logging.cc

@@ -770,10 +770,11 @@ static void WriteToStderr(const char* message, size_t len) {
 }
 
 inline void LogDestination::MaybeLogToStderr(LogSeverity severity,
-					     const char* message, size_t message_len, size_t /*prefix_len*/) {
+					     const char* message, size_t message_len, size_t prefix_len) {
   if ((severity >= FLAGS_stderrthreshold) || FLAGS_alsologtostderr) {
     ColoredWriteToStderr(severity, message, message_len);
 #ifdef GLOG_OS_WINDOWS
+    (void) prefix_len;
     // On Windows, also output to the debugger
     ::OutputDebugStringA(message);
 #elif defined(__ANDROID__)
@@ -787,6 +788,8 @@ inline void LogDestination::MaybeLogToStderr(LogSeverity severity,
     __android_log_write(android_log_levels[severity],
                         glog_internal_namespace_::ProgramInvocationShortName(),
                         message + prefix_len);
+#else
+    (void) prefix_len;
 #endif
   }
 }
@@ -1672,23 +1675,6 @@ ostream& LogMessage::stream() {
   return data_->stream_;
 }
 
-namespace {
-#if defined(__ANDROID__)
-int AndroidLogLevel(const int severity) {
-  switch (severity) {
-    case 3:
-      return ANDROID_LOG_FATAL;
-    case 2:
-      return ANDROID_LOG_ERROR;
-    case 1:
-      return ANDROID_LOG_WARN;
-    default:
-      return ANDROID_LOG_INFO;
-  }
-}
-#endif  // defined(__ANDROID__)
-}  // namespace
-
 // Flush buffered message, called by the destructor, or any other function
 // that needs to synchronize the log.
 void LogMessage::Flush() {
@@ -1724,12 +1710,6 @@ void LogMessage::Flush() {
   }
   LogDestination::WaitForSinks(data_);
 
-#if defined(__ANDROID__)
-  const int level = AndroidLogLevel((int)data_->severity_);
-  const std::string text = std::string(data_->message_text_);
-  __android_log_write(level, "native", text.substr(0,data_->num_chars_to_log_).c_str());
-#endif  // defined(__ANDROID__)
-
   if (append_newline) {
     // Fix the ostrstream back how it was before we screwed with it.
     // It's 99.44% certain that we don't need to worry about doing this.
@@ -1859,6 +1839,12 @@ void LogMessage::SendToLog() EXCLUSIVE_LOCKS_REQUIRED(log_mutex) {
     if (write(STDERR_FILENO, message, strlen(message)) < 0) {
       // Ignore errors.
     }
+#if defined(__ANDROID__)
+    // ANDROID_LOG_FATAL as this message is of FATAL severity.
+    __android_log_write(ANDROID_LOG_FATAL,
+                        glog_internal_namespace_::ProgramInvocationShortName(),
+                        message);
+#endif
     Fail();
   }
 }

src/stacktrace_x86_64-inl.h

@@ -47,7 +47,7 @@ typedef struct {
 
 
 // Workaround for the malloc() in _Unwind_Backtrace() issue.
-static _Unwind_Reason_Code nop_backtrace(struct _Unwind_Context *uc, void *opq) {
+static _Unwind_Reason_Code nop_backtrace(struct _Unwind_Context */*uc*/, void */*opq*/) {
   return _URC_NO_REASON;
 }
 

src/utilities.cc

@@ -54,6 +54,9 @@
 #ifdef HAVE_PWD_H
 # include <pwd.h>
 #endif
+#ifdef __ANDROID__
+#include <android/log.h>
+#endif
 
 #include "base/googleinit.h"
 
@@ -92,6 +95,12 @@ static void DebugWriteToStderr(const char* data, void *) {
   if (write(STDERR_FILENO, data, strlen(data)) < 0) {
     // Ignore errors.
   }
+#if defined(__ANDROID__)
+  // ANDROID_LOG_FATAL as fatal error occurred and now is dumping call stack.
+  __android_log_write(ANDROID_LOG_FATAL,
+                      glog_internal_namespace_::ProgramInvocationShortName(),
+                      data);
+#endif
 }
 
 static void DebugWriteToString(const char* data, void *arg) {

src/utilities.h

@@ -88,11 +88,11 @@
 
 #if defined(HAVE_LIB_UNWIND)
 # define STACKTRACE_H "stacktrace_libunwind-inl.h"
+#elif defined(HAVE_UNWIND_H)
+# define STACKTRACE_H "stacktrace_x86_64-inl.h"
 #elif !defined(NO_FRAME_POINTER)
 # if defined(__i386__) && __GNUC__ >= 2
 #  define STACKTRACE_H "stacktrace_x86-inl.h"
-# elif defined(__x86_64__) && __GNUC__ >= 2 && HAVE_UNWIND_H
-#  define STACKTRACE_H "stacktrace_x86_64-inl.h"
 # elif (defined(__ppc__) || defined(__PPC__)) && __GNUC__ >= 2
 #  define STACKTRACE_H "stacktrace_powerpc-inl.h"
 # elif defined(GLOG_OS_WINDOWS)