Add google3 style logging to libbase.

ART already had a flavor of this, but it was specialized for their use
case a bit.

Note that the logging.* tests are currently disabled for the device
because there is no good way to capture the output of liblog. We can
make something that will execute logcat and then then scan the output,
but that's messy. Since we know it at least works on the host, we can
add better device tests later.

Change-Id: I47acd87a3312c0a5285b03f9c8dadef0c669f06a

9 files changed, 864 insertions, 24 deletions

diff --git a/base/Android.mk b/base/Android.mk
index 17d6ece..162c6cb 100644
--- a/base/Android.mk
+++ b/base/Android.mk
@@ -18,13 +18,17 @@ LOCAL_PATH := $(call my-dir)
 
 libbase_src_files := \
     file.cpp \
+    logging.cpp \
     stringprintf.cpp \
     strings.cpp \
 
 libbase_test_src_files := \
     file_test.cpp \
+    logging_test.cpp \
     stringprintf_test.cpp \
     strings_test.cpp \
+    test_main.cpp \
+    test_utils.cpp \
 
 libbase_cppflags := \
     -Wall \
@@ -77,6 +81,7 @@ include $(CLEAR_VARS)
 LOCAL_MODULE := libbase_test
 LOCAL_CLANG := true
 LOCAL_SRC_FILES := $(libbase_test_src_files)
+LOCAL_C_INCLUDES := $(LOCAL_PATH)
 LOCAL_CPPFLAGS := $(libbase_cppflags)
 LOCAL_SHARED_LIBRARIES := libbase
 LOCAL_MULTILIB := both
@@ -87,6 +92,7 @@ include $(BUILD_NATIVE_TEST)
 include $(CLEAR_VARS)
 LOCAL_MODULE := libbase_test
 LOCAL_SRC_FILES := $(libbase_test_src_files)
+LOCAL_C_INCLUDES := $(LOCAL_PATH)
 LOCAL_CPPFLAGS := $(libbase_cppflags)
 LOCAL_SHARED_LIBRARIES := libbase
 LOCAL_MULTILIB := both
diff --git a/base/CPPLINT.cfg b/base/CPPLINT.cfg
index 5ee068e..a61c08d 100644
--- a/base/CPPLINT.cfg
+++ b/base/CPPLINT.cfg
@@ -1,2 +1,2 @@
 set noparent
-filter=-build/header_guard
+filter=-build/header_guard,-build/include,-build/c++11
diff --git a/base/file_test.cpp b/base/file_test.cpp
index 34b8755..fc48b32 100644
--- a/base/file_test.cpp
+++ b/base/file_test.cpp
@@ -24,29 +24,7 @@
 
 #include <string>
 
-class TemporaryFile {
- public:
-  TemporaryFile() {
-    init("/data/local/tmp");
-    if (fd == -1) {
-      init("/tmp");
-    }
-  }
-
-  ~TemporaryFile() {
-    close(fd);
-    unlink(filename);
-  }
-
-  int fd;
-  char filename[1024];
-
- private:
-  void init(const char* tmp_dir) {
-    snprintf(filename, sizeof(filename), "%s/TemporaryFile-XXXXXX", tmp_dir);
-    fd = mkstemp(filename);
-  }
-};
+#include "test_utils.h"
 
 TEST(file, ReadFileToString_ENOENT) {
   std::string s("hello");
diff --git a/base/include/base/logging.h b/base/include/base/logging.h
new file mode 100644
index 0000000..5e115fe
--- /dev/null
+++ b/base/include/base/logging.h
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2015 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 BASE_LOGGING_H
+#define BASE_LOGGING_H
+
+#include <memory>
+#include <ostream>
+
+#include "base/macros.h"
+
+namespace android {
+namespace base {
+
+enum LogSeverity {
+  VERBOSE,
+  DEBUG,
+  INFO,
+  WARNING,
+  ERROR,
+  FATAL,
+};
+
+// Configure logging based on ANDROID_LOG_TAGS environment variable.
+// We need to parse a string that looks like
+//
+//      *:v jdwp:d dalvikvm:d dalvikvm-gc:i dalvikvmi:i
+//
+// The tag (or '*' for the global level) comes first, followed by a colon and a
+// letter indicating the minimum priority level we're expected to log.  This can
+// be used to reveal or conceal logs with specific tags.
+extern void InitLogging(char* argv[]);
+
+// Returns the command line used to invoke the current tool or nullptr if
+// InitLogging hasn't been performed.
+extern const char* GetCmdLine();
+
+// The command used to start the program, such as "/system/bin/dalvikvm". If
+// InitLogging hasn't been performed then just returns "unknown"
+extern const char* ProgramInvocationName();
+
+// A short version of the command used to start the program, such as "dalvikvm".
+// If InitLogging hasn't been performed then just returns "unknown"
+extern const char* ProgramInvocationShortName();
+
+// Logs a message to logcat on Android otherwise to stderr. If the severity is
+// FATAL it also causes an abort. For example:
+//
+//     LOG(FATAL) << "We didn't expect to reach here";
+#define LOG(severity)                                                        \
+  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::severity, \
+                              -1).stream()
+
+// A variant of LOG that also logs the current errno value. To be used when
+// library calls fail.
+#define PLOG(severity)                                                       \
+  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::severity, \
+                              errno).stream()
+
+// Marker that code is yet to be implemented.
+#define UNIMPLEMENTED(level) \
+  LOG(level) << __PRETTY_FUNCTION__ << " unimplemented "
+
+// Check whether condition x holds and LOG(FATAL) if not. The value of the
+// expression x is only evaluated once. Extra logging can be appended using <<
+// after. For example:
+//
+//     CHECK(false == true) results in a log message of
+//       "Check failed: false == true".
+#define CHECK(x)                                                            \
+  if (UNLIKELY(!(x)))                                                       \
+    ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::FATAL, \
+                                -1).stream()                                \
+        << "Check failed: " #x << " "
+
+// Helper for CHECK_xx(x,y) macros.
+#define CHECK_OP(LHS, RHS, OP)                                                \
+  for (auto _values = ::android::base::MakeEagerEvaluator(LHS, RHS);          \
+       UNLIKELY(!(_values.lhs OP _values.rhs));                               \
+       /* empty */)                                                           \
+  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::FATAL, -1) \
+          .stream()                                                           \
+      << "Check failed: " << #LHS << " " << #OP << " " << #RHS                \
+      << " (" #LHS "=" << _values.lhs << ", " #RHS "=" << _values.rhs << ") "
+
+// Check whether a condition holds between x and y, LOG(FATAL) if not. The value
+// of the expressions x and y is evaluated once. Extra logging can be appended
+// using << after. For example:
+//
+//     CHECK_NE(0 == 1, false) results in
+//       "Check failed: false != false (0==1=false, false=false) ".
+#define CHECK_EQ(x, y) CHECK_OP(x, y, == )
+#define CHECK_NE(x, y) CHECK_OP(x, y, != )
+#define CHECK_LE(x, y) CHECK_OP(x, y, <= )
+#define CHECK_LT(x, y) CHECK_OP(x, y, < )
+#define CHECK_GE(x, y) CHECK_OP(x, y, >= )
+#define CHECK_GT(x, y) CHECK_OP(x, y, > )
+
+// Helper for CHECK_STRxx(s1,s2) macros.
+#define CHECK_STROP(s1, s2, sense)                                         \
+  if (UNLIKELY((strcmp(s1, s2) == 0) != sense))                            \
+    LOG(FATAL) << "Check failed: "                                         \
+               << "\"" << s1 << "\""                                       \
+               << (sense ? " == " : " != ") << "\"" << s2 << "\""
+
+// Check for string (const char*) equality between s1 and s2, LOG(FATAL) if not.
+#define CHECK_STREQ(s1, s2) CHECK_STROP(s1, s2, true)
+#define CHECK_STRNE(s1, s2) CHECK_STROP(s1, s2, false)
+
+// Perform the pthread function call(args), LOG(FATAL) on error.
+#define CHECK_PTHREAD_CALL(call, args, what)                           \
+  do {                                                                 \
+    int rc = call args;                                                \
+    if (rc != 0) {                                                     \
+      errno = rc;                                                      \
+      PLOG(FATAL) << #call << " failed for " << what; \
+    }                                                                  \
+  } while (false)
+
+// CHECK that can be used in a constexpr function. For example:
+//
+//    constexpr int half(int n) {
+//      return
+//          DCHECK_CONSTEXPR(n >= 0, , 0)
+//          CHECK_CONSTEXPR((n & 1) == 0),
+//              << "Extra debugging output: n = " << n, 0)
+//          n / 2;
+//    }
+#define CHECK_CONSTEXPR(x, out, dummy)                                     \
+  (UNLIKELY(!(x)))                                                         \
+      ? (LOG(FATAL) << "Check failed: " << #x out, dummy) \
+      :
+
+// DCHECKs are debug variants of CHECKs only enabled in debug builds. Generally
+// CHECK should be used unless profiling identifies a CHECK as being in
+// performance critical code.
+#if defined(NDEBUG)
+static constexpr bool kEnableDChecks = false;
+#else
+static constexpr bool kEnableDChecks = true;
+#endif
+
+#define DCHECK(x) \
+  if (::android::base::kEnableDChecks) CHECK(x)
+#define DCHECK_EQ(x, y) \
+  if (::android::base::kEnableDChecks) CHECK_EQ(x, y)
+#define DCHECK_NE(x, y) \
+  if (::android::base::kEnableDChecks) CHECK_NE(x, y)
+#define DCHECK_LE(x, y) \
+  if (::android::base::kEnableDChecks) CHECK_LE(x, y)
+#define DCHECK_LT(x, y) \
+  if (::android::base::kEnableDChecks) CHECK_LT(x, y)
+#define DCHECK_GE(x, y) \
+  if (::android::base::kEnableDChecks) CHECK_GE(x, y)
+#define DCHECK_GT(x, y) \
+  if (::android::base::kEnableDChecks) CHECK_GT(x, y)
+#define DCHECK_STREQ(s1, s2) \
+  if (::android::base::kEnableDChecks) CHECK_STREQ(s1, s2)
+#define DCHECK_STRNE(s1, s2) \
+  if (::android::base::kEnableDChecks) CHECK_STRNE(s1, s2)
+#if defined(NDEBUG)
+#define DCHECK_CONSTEXPR(x, out, dummy)
+#else
+#define DCHECK_CONSTEXPR(x, out, dummy) CHECK_CONSTEXPR(x, out, dummy)
+#endif
+
+// Temporary class created to evaluate the LHS and RHS, used with
+// MakeEagerEvaluator to infer the types of LHS and RHS.
+template <typename LHS, typename RHS>
+struct EagerEvaluator {
+  EagerEvaluator(LHS l, RHS r) : lhs(l), rhs(r) {
+  }
+  LHS lhs;
+  RHS rhs;
+};
+
+// Helper function for CHECK_xx.
+template <typename LHS, typename RHS>
+static inline EagerEvaluator<LHS, RHS> MakeEagerEvaluator(LHS lhs, RHS rhs) {
+  return EagerEvaluator<LHS, RHS>(lhs, rhs);
+}
+
+// Explicitly instantiate EagerEvalue for pointers so that char*s aren't treated
+// as strings. To compare strings use CHECK_STREQ and CHECK_STRNE. We rely on
+// signed/unsigned warnings to protect you against combinations not explicitly
+// listed below.
+#define EAGER_PTR_EVALUATOR(T1, T2)               \
+  template <>                                     \
+  struct EagerEvaluator<T1, T2> {                 \
+    EagerEvaluator(T1 l, T2 r)                    \
+        : lhs(reinterpret_cast<const void*>(l)),  \
+          rhs(reinterpret_cast<const void*>(r)) { \
+    }                                             \
+    const void* lhs;                              \
+    const void* rhs;                              \
+  }
+EAGER_PTR_EVALUATOR(const char*, const char*);
+EAGER_PTR_EVALUATOR(const char*, char*);
+EAGER_PTR_EVALUATOR(char*, const char*);
+EAGER_PTR_EVALUATOR(char*, char*);
+EAGER_PTR_EVALUATOR(const unsigned char*, const unsigned char*);
+EAGER_PTR_EVALUATOR(const unsigned char*, unsigned char*);
+EAGER_PTR_EVALUATOR(unsigned char*, const unsigned char*);
+EAGER_PTR_EVALUATOR(unsigned char*, unsigned char*);
+EAGER_PTR_EVALUATOR(const signed char*, const signed char*);
+EAGER_PTR_EVALUATOR(const signed char*, signed char*);
+EAGER_PTR_EVALUATOR(signed char*, const signed char*);
+EAGER_PTR_EVALUATOR(signed char*, signed char*);
+
+// Data for the log message, not stored in LogMessage to avoid increasing the
+// stack size.
+class LogMessageData;
+
+// A LogMessage is a temporarily scoped object used by LOG and the unlikely part
+// of a CHECK. The destructor will abort if the severity is FATAL.
+class LogMessage {
+ public:
+  LogMessage(const char* file, unsigned int line, LogSeverity severity,
+             int error);
+
+  ~LogMessage();
+
+  // Returns the stream associated with the message, the LogMessage performs
+  // output when it goes out of scope.
+  std::ostream& stream();
+
+  // The routine that performs the actual logging.
+  static void LogLine(const char* file, unsigned int line, LogSeverity severity,
+                      const char* msg);
+
+  // A variant of the above for use with little stack.
+  static void LogLineLowStack(const char* file, unsigned int line,
+                              LogSeverity severity, const char* msg);
+
+ private:
+  const std::unique_ptr<LogMessageData> data_;
+
+  DISALLOW_COPY_AND_ASSIGN(LogMessage);
+};
+
+// Allows to temporarily change the minimum severity level for logging.
+class ScopedLogSeverity {
+ public:
+  explicit ScopedLogSeverity(LogSeverity level);
+  ~ScopedLogSeverity();
+
+ private:
+  LogSeverity old_;
+};
+
+}  // namespace base
+}  // namespace android
+
+#endif  // BASE_LOGGING_H
diff --git a/base/logging.cpp b/base/logging.cpp
new file mode 100644
index 0000000..3d6c0c2
--- /dev/null
+++ b/base/logging.cpp
@@ -0,0 +1,323 @@
+/*
+ * Copyright (C) 2015 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 "base/logging.h"
+
+#include <iostream>
+#include <limits>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include "base/strings.h"
+
+// Headers for LogMessage::LogLine.
+#ifdef __ANDROID__
+#include <android/set_abort_message.h>
+#include "cutils/log.h"
+#else
+#include <sys/types.h>
+#include <unistd.h>
+#endif
+
+// For GetTid.
+#if defined(__APPLE__)
+#include "AvailabilityMacros.h"  // For MAC_OS_X_VERSION_MAX_ALLOWED
+#include <sys/syscall.h>
+#include <sys/time.h>
+#elif !defined(__BIONIC__)
+#include <syscall.h>
+#endif
+
+namespace android {
+namespace base {
+
+static std::mutex logging_lock;
+
+static LogSeverity gMinimumLogSeverity = INFO;
+static std::unique_ptr<std::string> gCmdLine;
+static std::unique_ptr<std::string> gProgramInvocationName;
+static std::unique_ptr<std::string> gProgramInvocationShortName;
+
+#ifndef __ANDROID__
+static pid_t GetTid() {
+#if defined(__APPLE__)
+  uint64_t owner;
+  // Requires Mac OS 10.6
+  CHECK_PTHREAD_CALL(pthread_threadid_np, (NULL, &owner), __FUNCTION__);
+  return owner;
+#else
+  return syscall(__NR_gettid);
+#endif
+}
+#endif  // __ANDROID__
+
+const char* GetCmdLine() {
+  return (gCmdLine.get() != nullptr) ? gCmdLine->c_str() : nullptr;
+}
+
+const char* ProgramInvocationName() {
+  return (gProgramInvocationName.get() != nullptr)
+             ? gProgramInvocationName->c_str()
+             : "unknown";
+}
+
+const char* ProgramInvocationShortName() {
+  return (gProgramInvocationShortName.get() != nullptr)
+             ? gProgramInvocationShortName->c_str()
+             : "unknown";
+}
+
+void InitLogging(char* argv[]) {
+  if (gCmdLine.get() != nullptr) {
+    return;
+  }
+
+  // Stash the command line for later use. We can use /proc/self/cmdline on
+  // Linux to recover this, but we don't have that luxury on the Mac, and there
+  // are a couple of argv[0] variants that are commonly used.
+  if (argv != nullptr) {
+    gCmdLine.reset(new std::string(argv[0]));
+    for (size_t i = 1; argv[i] != nullptr; ++i) {
+      gCmdLine->append(" ");
+      gCmdLine->append(argv[i]);
+    }
+    gProgramInvocationName.reset(new std::string(argv[0]));
+    const char* last_slash = strrchr(argv[0], '/');
+    gProgramInvocationShortName.reset(
+        new std::string((last_slash != nullptr) ? last_slash + 1 : argv[0]));
+  } else {
+    // TODO: fall back to /proc/self/cmdline when argv is NULL on Linux.
+    gCmdLine.reset(new std::string("<unset>"));
+  }
+  const char* tags = getenv("ANDROID_LOG_TAGS");
+  if (tags == nullptr) {
+    return;
+  }
+
+  std::vector<std::string> specs;
+  Split(tags, ' ', &specs);
+  for (size_t i = 0; i < specs.size(); ++i) {
+    // "tag-pattern:[vdiwefs]"
+    std::string spec(specs[i]);
+    if (spec.size() == 3 && StartsWith(spec, "*:")) {
+      switch (spec[2]) {
+        case 'v':
+          gMinimumLogSeverity = VERBOSE;
+          continue;
+        case 'd':
+          gMinimumLogSeverity = DEBUG;
+          continue;
+        case 'i':
+          gMinimumLogSeverity = INFO;
+          continue;
+        case 'w':
+          gMinimumLogSeverity = WARNING;
+          continue;
+        case 'e':
+          gMinimumLogSeverity = ERROR;
+          continue;
+        case 'f':
+          gMinimumLogSeverity = FATAL;
+          continue;
+        // liblog will even suppress FATAL if you say 's' for silent, but that's
+        // crazy!
+        case 's':
+          gMinimumLogSeverity = FATAL;
+          continue;
+      }
+    }
+    LOG(FATAL) << "unsupported '" << spec << "' in ANDROID_LOG_TAGS (" << tags
+               << ")";
+  }
+}
+
+// This indirection greatly reduces the stack impact of having lots of
+// checks/logging in a function.
+class LogMessageData {
+ public:
+  LogMessageData(const char* file, unsigned int line, LogSeverity severity,
+                 int error)
+      : file_(file), line_number_(line), severity_(severity), error_(error) {
+    const char* last_slash = strrchr(file, '/');
+    file = (last_slash == nullptr) ? file : last_slash + 1;
+  }
+
+  const char* GetFile() const {
+    return file_;
+  }
+
+  unsigned int GetLineNumber() const {
+    return line_number_;
+  }
+
+  LogSeverity GetSeverity() const {
+    return severity_;
+  }
+
+  int GetError() const {
+    return error_;
+  }
+
+  std::ostream& GetBuffer() {
+    return buffer_;
+  }
+
+  std::string ToString() const {
+    return buffer_.str();
+  }
+
+ private:
+  std::ostringstream buffer_;
+  const char* const file_;
+  const unsigned int line_number_;
+  const LogSeverity severity_;
+  const int error_;
+
+  DISALLOW_COPY_AND_ASSIGN(LogMessageData);
+};
+
+LogMessage::LogMessage(const char* file, unsigned int line,
+                       LogSeverity severity, int error)
+    : data_(new LogMessageData(file, line, severity, error)) {
+}
+
+LogMessage::~LogMessage() {
+  if (data_->GetSeverity() < gMinimumLogSeverity) {
+    return;  // No need to format something we're not going to output.
+  }
+
+  // Finish constructing the message.
+  if (data_->GetError() != -1) {
+    data_->GetBuffer() << ": " << strerror(data_->GetError());
+  }
+  std::string msg(data_->ToString());
+
+  // Do the actual logging with the lock held.
+  {
+    std::lock_guard<std::mutex> lock(logging_lock);
+    if (msg.find('\n') == std::string::npos) {
+      LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetSeverity(),
+              msg.c_str());
+    } else {
+      msg += '\n';
+      size_t i = 0;
+      while (i < msg.size()) {
+        size_t nl = msg.find('\n', i);
+        msg[nl] = '\0';
+        LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetSeverity(),
+                &msg[i]);
+        i = nl + 1;
+      }
+    }
+  }
+
+  // Abort if necessary.
+  if (data_->GetSeverity() == FATAL) {
+#ifdef __ANDROID__
+    android_set_abort_message(msg.c_str());
+#endif
+    abort();
+  }
+}
+
+std::ostream& LogMessage::stream() {
+  return data_->GetBuffer();
+}
+
+#ifdef __ANDROID__
+static const android_LogPriority kLogSeverityToAndroidLogPriority[] = {
+    ANDROID_LOG_VERBOSE, ANDROID_LOG_DEBUG, ANDROID_LOG_INFO,
+    ANDROID_LOG_WARN,    ANDROID_LOG_ERROR, ANDROID_LOG_FATAL};
+static_assert(arraysize(kLogSeverityToAndroidLogPriority) == FATAL + 1,
+              "Mismatch in size of kLogSeverityToAndroidLogPriority and values "
+              "in LogSeverity");
+#endif
+
+void LogMessage::LogLine(const char* file, unsigned int line,
+                         LogSeverity log_severity, const char* message) {
+#ifdef __ANDROID__
+  const char* tag = ProgramInvocationShortName();
+  int priority = kLogSeverityToAndroidLogPriority[log_severity];
+  if (priority == ANDROID_LOG_FATAL) {
+    LOG_PRI(priority, tag, "%s:%u] %s", file, line, message);
+  } else {
+    LOG_PRI(priority, tag, "%s", message);
+  }
+#else
+  static const char* log_characters = "VDIWEF";
+  CHECK_EQ(strlen(log_characters), FATAL + 1U);
+  char severity = log_characters[log_severity];
+  fprintf(stderr, "%s %c %5d %5d %s:%u] %s\n", ProgramInvocationShortName(),
+          severity, getpid(), GetTid(), file, line, message);
+#endif
+}
+
+void LogMessage::LogLineLowStack(const char* file, unsigned int line,
+                                 LogSeverity log_severity, const char* message) {
+#ifdef __ANDROID__
+  // Use android_writeLog() to avoid stack-based buffers used by
+  // android_printLog().
+  const char* tag = ProgramInvocationShortName();
+  int priority = kLogSeverityToAndroidLogPriority[log_severity];
+  char* buf = nullptr;
+  size_t buf_size = 0u;
+  if (priority == ANDROID_LOG_FATAL) {
+    // Allocate buffer for snprintf(buf, buf_size, "%s:%u] %s", file, line,
+    // message) below.  If allocation fails, fall back to printing only the
+    // message.
+    buf_size = strlen(file) + 1 /* ':' */ +
+               std::numeric_limits<typeof(line)>::max_digits10 + 2 /* "] " */ +
+               strlen(message) + 1 /* terminating 0 */;
+    buf = reinterpret_cast<char*>(malloc(buf_size));
+  }
+  if (buf != nullptr) {
+    snprintf(buf, buf_size, "%s:%u] %s", file, line, message);
+    android_writeLog(priority, tag, buf);
+    free(buf);
+  } else {
+    android_writeLog(priority, tag, message);
+  }
+#else
+  static const char* log_characters = "VDIWEF";
+  CHECK_EQ(strlen(log_characters), FATAL + 1U);
+
+  const char* program_name = ProgramInvocationShortName();
+  write(STDERR_FILENO, program_name, strlen(program_name));
+  write(STDERR_FILENO, " ", 1);
+  write(STDERR_FILENO, &log_characters[log_severity], 1);
+  write(STDERR_FILENO, " ", 1);
+  // TODO: pid and tid.
+  write(STDERR_FILENO, file, strlen(file));
+  // TODO: line.
+  UNUSED(line);
+  write(STDERR_FILENO, "] ", 2);
+  write(STDERR_FILENO, message, strlen(message));
+  write(STDERR_FILENO, "\n", 1);
+#endif
+}
+
+ScopedLogSeverity::ScopedLogSeverity(LogSeverity level) {
+  old_ = gMinimumLogSeverity;
+  gMinimumLogSeverity = level;
+}
+
+ScopedLogSeverity::~ScopedLogSeverity() {
+  gMinimumLogSeverity = old_;
+}
+
+}  // namespace base
+}  // namespace android
diff --git a/base/logging_test.cpp b/base/logging_test.cpp
new file mode 100644
index 0000000..0a03e38
--- /dev/null
+++ b/base/logging_test.cpp
@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2015 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 "base/logging.h"
+
+#include <regex>
+#include <string>
+
+#include "base/file.h"
+#include "base/stringprintf.h"
+#include "test_utils.h"
+
+#include <gtest/gtest.h>
+
+#ifdef __ANDROID__
+#define HOST_TEST(suite, name) TEST(suite, DISABLED_ ## name)
+#else
+#define HOST_TEST(suite, name) TEST(suite, name)
+#endif
+
+class CapturedStderr {
+ public:
+  CapturedStderr() : old_stderr_(-1) {
+    init();
+  }
+
+  ~CapturedStderr() {
+    reset();
+  }
+
+  int fd() const {
+    return temp_file_.fd;
+  }
+
+ private:
+  void init() {
+    old_stderr_ = dup(STDERR_FILENO);
+    ASSERT_NE(-1, old_stderr_);
+    ASSERT_NE(-1, dup2(fd(), STDERR_FILENO));
+  }
+
+  void reset() {
+    ASSERT_NE(-1, dup2(old_stderr_, STDERR_FILENO));
+    ASSERT_EQ(0, close(old_stderr_));
+  }
+
+  TemporaryFile temp_file_;
+  int old_stderr_;
+};
+
+HOST_TEST(logging, CHECK) {
+  ASSERT_DEATH(CHECK(false), "Check failed: false ");
+  CHECK(true);
+
+  ASSERT_DEATH(CHECK_EQ(0, 1), "Check failed: 0 == 1 ");
+  CHECK_EQ(0, 0);
+
+  ASSERT_DEATH(CHECK_STREQ("foo", "bar"), R"(Check failed: "foo" == "bar")");
+  CHECK_STREQ("foo", "foo");
+}
+
+std::string make_log_pattern(android::base::LogSeverity severity,
+                             const char* message) {
+  static const char* log_characters = "VDIWEF";
+  char log_char = log_characters[severity];
+  return android::base::StringPrintf(
+      "%c[[:space:]]+[[:digit:]]+[[:space:]]+[[:digit:]]+ " __FILE__
+      ":[[:digit:]]+] %s",
+      log_char, message);
+}
+
+HOST_TEST(logging, LOG) {
+  ASSERT_DEATH(LOG(FATAL) << "foobar", "foobar");
+
+  {
+    CapturedStderr cap;
+    LOG(WARNING) << "foobar";
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+
+    std::regex message_regex(
+        make_log_pattern(android::base::WARNING, "foobar"));
+    ASSERT_TRUE(std::regex_search(output, message_regex));
+  }
+
+  {
+    CapturedStderr cap;
+    LOG(INFO) << "foobar";
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+
+    std::regex message_regex(
+        make_log_pattern(android::base::INFO, "foobar"));
+    ASSERT_TRUE(std::regex_search(output, message_regex));
+  }
+
+  {
+    CapturedStderr cap;
+    LOG(DEBUG) << "foobar";
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+    ASSERT_TRUE(output.empty());
+  }
+
+  {
+    android::base::ScopedLogSeverity severity(android::base::DEBUG);
+    CapturedStderr cap;
+    LOG(DEBUG) << "foobar";
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+
+    std::regex message_regex(
+        make_log_pattern(android::base::DEBUG, "foobar"));
+    ASSERT_TRUE(std::regex_search(output, message_regex));
+  }
+}
+
+HOST_TEST(logging, PLOG) {
+  {
+    CapturedStderr cap;
+    errno = ENOENT;
+    PLOG(INFO) << "foobar";
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+
+    std::regex message_regex(make_log_pattern(
+        android::base::INFO, "foobar: No such file or directory"));
+    ASSERT_TRUE(std::regex_search(output, message_regex));
+  }
+}
+
+HOST_TEST(logging, UNIMPLEMENTED) {
+  {
+    CapturedStderr cap;
+    errno = ENOENT;
+    UNIMPLEMENTED(ERROR);
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+
+    std::string expected_message =
+        android::base::StringPrintf("%s unimplemented ", __PRETTY_FUNCTION__);
+    std::regex message_regex(
+        make_log_pattern(android::base::ERROR, expected_message.c_str()));
+    ASSERT_TRUE(std::regex_search(output, message_regex));
+  }
+}
diff --git a/base/test_main.cpp b/base/test_main.cpp
new file mode 100644
index 0000000..c49ca4b
--- /dev/null
+++ b/base/test_main.cpp
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2015 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 <gtest/gtest.h>
+
+#include "base/logging.h"
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  android::base::InitLogging(argv);
+  return RUN_ALL_TESTS();
+}
diff --git a/base/test_utils.cpp b/base/test_utils.cpp
new file mode 100644
index 0000000..1f6d3cf
--- /dev/null
+++ b/base/test_utils.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2015 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 "test_utils.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+TemporaryFile::TemporaryFile() {
+  init("/data/local/tmp");
+  if (fd == -1) {
+    init("/tmp");
+  }
+}
+
+TemporaryFile::~TemporaryFile() {
+  close(fd);
+  unlink(filename);
+}
+
+void TemporaryFile::init(const char* tmp_dir) {
+  snprintf(filename, sizeof(filename), "%s/TemporaryFile-XXXXXX", tmp_dir);
+  fd = mkstemp(filename);
+}
diff --git a/base/test_utils.h b/base/test_utils.h
new file mode 100644
index 0000000..132d3a7
--- /dev/null
+++ b/base/test_utils.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2015 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 TEST_UTILS_H
+#define TEST_UTILS_H
+
+class TemporaryFile {
+ public:
+  TemporaryFile();
+  ~TemporaryFile();
+
+  int fd;
+  char filename[1024];
+
+ private:
+  void init(const char* tmp_dir);
+};
+
+#endif // TEST_UTILS_H