Revert "Revert "Create libbase.""

This reverts commit a7870d88167f619e758b5bcd15b410d16da7c16b.
diff --git a/base/.clang-format b/base/.clang-format
new file mode 100644
index 0000000..2b83a1f
--- /dev/null
+++ b/base/.clang-format
@@ -0,0 +1,11 @@
+BasedOnStyle: Google
+AllowShortBlocksOnASingleLine: false
+AllowShortFunctionsOnASingleLine: false
+
+CommentPragmas: NOLINT:.*
+DerivePointerAlignment: false
+IndentWidth: 2
+PointerAlignment: Left
+TabWidth: 2
+UseTab: Never
+PenaltyExcessCharacter: 32
diff --git a/base/Android.mk b/base/Android.mk
new file mode 100644
index 0000000..3b64ab0
--- /dev/null
+++ b/base/Android.mk
@@ -0,0 +1,96 @@
+#
+# 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.
+#
+
+LOCAL_PATH := $(call my-dir)
+
+libbase_src_files := \
+    file.cpp \
+    stringprintf.cpp \
+
+libbase_test_src_files := \
+    file_test.cpp \
+    stringprintf_test.cpp \
+
+libbase_cppflags := \
+    -Wall \
+    -Wextra \
+    -Werror \
+
+# Device
+# ------------------------------------------------------------------------------
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbase
+LOCAL_CLANG := true
+LOCAL_SRC_FILES := $(libbase_src_files)
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
+LOCAL_CPPFLAGS := $(libbase_cppflags)
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_MULTILIB := both
+include $(BUILD_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbase
+LOCAL_CLANG := true
+LOCAL_WHOLE_STATIC_LIBRARIES := libbase
+LOCAL_SHARED_LIBRARIES := liblog
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_MULTILIB := both
+include $(BUILD_SHARED_LIBRARY)
+
+# Host
+# ------------------------------------------------------------------------------
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbase
+LOCAL_CLANG := true
+LOCAL_SRC_FILES := $(libbase_src_files)
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
+LOCAL_CPPFLAGS := $(libbase_cppflags)
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_MULTILIB := both
+include $(BUILD_HOST_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbase
+LOCAL_CLANG := true
+LOCAL_WHOLE_STATIC_LIBRARIES := libbase
+LOCAL_SHARED_LIBRARIES := liblog
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_MULTILIB := both
+include $(BUILD_HOST_SHARED_LIBRARY)
+
+# Tests
+# ------------------------------------------------------------------------------
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbase_test
+LOCAL_CLANG := true
+LOCAL_SRC_FILES := $(libbase_test_src_files)
+LOCAL_CPPFLAGS := $(libbase_cppflags)
+LOCAL_SHARED_LIBRARIES := libbase
+LOCAL_MULTILIB := both
+LOCAL_MODULE_STEM_32 := $(LOCAL_MODULE)32
+LOCAL_MODULE_STEM_64 := $(LOCAL_MODULE)64
+include $(BUILD_NATIVE_TEST)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbase_test
+LOCAL_CLANG := true
+LOCAL_SRC_FILES := $(libbase_test_src_files)
+LOCAL_CPPFLAGS := $(libbase_cppflags)
+LOCAL_SHARED_LIBRARIES := libbase
+LOCAL_MULTILIB := both
+LOCAL_MODULE_STEM_32 := $(LOCAL_MODULE)32
+LOCAL_MODULE_STEM_64 := $(LOCAL_MODULE)64
+include $(BUILD_HOST_NATIVE_TEST)
diff --git a/base/CPPLINT.cfg b/base/CPPLINT.cfg
new file mode 100644
index 0000000..5ee068e
--- /dev/null
+++ b/base/CPPLINT.cfg
@@ -0,0 +1,2 @@
+set noparent
+filter=-build/header_guard
diff --git a/base/file.cpp b/base/file.cpp
new file mode 100644
index 0000000..773f33b
--- /dev/null
+++ b/base/file.cpp
@@ -0,0 +1,123 @@
+/*
+ * 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/file.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <string>
+
+#define LOG_TAG "base.file"
+#include "cutils/log.h"
+#include "utils/Compat.h"  // For TEMP_FAILURE_RETRY on Darwin.
+
+namespace android {
+namespace base {
+
+bool ReadFdToString(int fd, std::string* content) {
+  content->clear();
+
+  char buf[BUFSIZ];
+  ssize_t n;
+  while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)))) > 0) {
+    content->append(buf, n);
+  }
+  return (n == 0) ? true : false;
+}
+
+bool ReadFileToString(const std::string& path, std::string* content) {
+  content->clear();
+
+  int fd =
+      TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC | O_NOFOLLOW));
+  if (fd == -1) {
+    return false;
+  }
+  bool result = ReadFdToString(fd, content);
+  TEMP_FAILURE_RETRY(close(fd));
+  return result;
+}
+
+bool WriteStringToFd(const std::string& content, int fd) {
+  const char* p = content.data();
+  size_t left = content.size();
+  while (left > 0) {
+    ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, left));
+    if (n == -1) {
+      return false;
+    }
+    p += n;
+    left -= n;
+  }
+  return true;
+}
+
+static bool CleanUpAfterFailedWrite(const std::string& path) {
+  // Something went wrong. Let's not leave a corrupt file lying around.
+  int saved_errno = errno;
+  unlink(path.c_str());
+  errno = saved_errno;
+  return false;
+}
+
+#if !defined(_WIN32)
+bool WriteStringToFile(const std::string& content, const std::string& path,
+                       mode_t mode, uid_t owner, gid_t group) {
+  int fd = TEMP_FAILURE_RETRY(
+      open(path.c_str(), O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW,
+           mode));
+  if (fd == -1) {
+    ALOGE("android::WriteStringToFile open failed: %s", strerror(errno));
+    return false;
+  }
+
+  // We do an explicit fchmod here because we assume that the caller really
+  // meant what they said and doesn't want the umask-influenced mode.
+  if (fchmod(fd, mode) == -1) {
+    ALOGE("android::WriteStringToFile fchmod failed: %s", strerror(errno));
+    return CleanUpAfterFailedWrite(path);
+  }
+  if (fchown(fd, owner, group) == -1) {
+    ALOGE("android::WriteStringToFile fchown failed: %s", strerror(errno));
+    return CleanUpAfterFailedWrite(path);
+  }
+  if (!WriteStringToFd(content, fd)) {
+    ALOGE("android::WriteStringToFile write failed: %s", strerror(errno));
+    return CleanUpAfterFailedWrite(path);
+  }
+  TEMP_FAILURE_RETRY(close(fd));
+  return true;
+}
+#endif
+
+bool WriteStringToFile(const std::string& content, const std::string& path) {
+  int fd = TEMP_FAILURE_RETRY(
+      open(path.c_str(), O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW,
+           DEFFILEMODE));
+  if (fd == -1) {
+    return false;
+  }
+
+  bool result = WriteStringToFd(content, fd);
+  TEMP_FAILURE_RETRY(close(fd));
+  return result || CleanUpAfterFailedWrite(path);
+}
+
+}  // namespace base
+}  // namespace android
diff --git a/base/file_test.cpp b/base/file_test.cpp
new file mode 100644
index 0000000..34b8755
--- /dev/null
+++ b/base/file_test.cpp
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2013 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/file.h"
+
+#include <gtest/gtest.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#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);
+  }
+};
+
+TEST(file, ReadFileToString_ENOENT) {
+  std::string s("hello");
+  errno = 0;
+  ASSERT_FALSE(android::base::ReadFileToString("/proc/does-not-exist", &s));
+  EXPECT_EQ(ENOENT, errno);
+  EXPECT_EQ("", s);  // s was cleared.
+}
+
+TEST(file, ReadFileToString_success) {
+  std::string s("hello");
+  ASSERT_TRUE(android::base::ReadFileToString("/proc/version", &s)) << errno;
+  EXPECT_GT(s.length(), 6U);
+  EXPECT_EQ('\n', s[s.length() - 1]);
+  s[5] = 0;
+  EXPECT_STREQ("Linux", s.c_str());
+}
+
+TEST(file, WriteStringToFile) {
+  TemporaryFile tf;
+  ASSERT_TRUE(tf.fd != -1);
+  ASSERT_TRUE(android::base::WriteStringToFile("abc", tf.filename)) << errno;
+  std::string s;
+  ASSERT_TRUE(android::base::ReadFileToString(tf.filename, &s)) << errno;
+  EXPECT_EQ("abc", s);
+}
+
+TEST(file, WriteStringToFile2) {
+  TemporaryFile tf;
+  ASSERT_TRUE(tf.fd != -1);
+  ASSERT_TRUE(android::base::WriteStringToFile("abc", tf.filename, 0660,
+                                               getuid(), getgid()))
+      << errno;
+  struct stat sb;
+  ASSERT_EQ(0, stat(tf.filename, &sb));
+  ASSERT_EQ(0660U, (sb.st_mode & ~S_IFMT));
+  ASSERT_EQ(getuid(), sb.st_uid);
+  ASSERT_EQ(getgid(), sb.st_gid);
+  std::string s;
+  ASSERT_TRUE(android::base::ReadFileToString(tf.filename, &s)) << errno;
+  EXPECT_EQ("abc", s);
+}
+
+TEST(file, WriteStringToFd) {
+  TemporaryFile tf;
+  ASSERT_TRUE(tf.fd != -1);
+  ASSERT_TRUE(android::base::WriteStringToFd("abc", tf.fd));
+
+  ASSERT_EQ(0, lseek(tf.fd, 0, SEEK_SET)) << errno;
+
+  std::string s;
+  ASSERT_TRUE(android::base::ReadFdToString(tf.fd, &s)) << errno;
+  EXPECT_EQ("abc", s);
+}
diff --git a/base/include/base/file.h b/base/include/base/file.h
new file mode 100644
index 0000000..ef97742
--- /dev/null
+++ b/base/include/base/file.h
@@ -0,0 +1,40 @@
+/*
+ * 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_FILE_H
+#define BASE_FILE_H
+
+#include <sys/stat.h>
+#include <string>
+
+namespace android {
+namespace base {
+
+bool ReadFdToString(int fd, std::string* content);
+bool ReadFileToString(const std::string& path, std::string* content);
+
+bool WriteStringToFile(const std::string& content, const std::string& path);
+bool WriteStringToFd(const std::string& content, int fd);
+
+#if !defined(_WIN32)
+bool WriteStringToFile(const std::string& content, const std::string& path,
+                       mode_t mode, uid_t owner, gid_t group);
+#endif
+
+}  // namespace base
+}  // namespace android
+
+#endif  // BASE_FILE_H
diff --git a/base/include/base/stringprintf.h b/base/include/base/stringprintf.h
new file mode 100644
index 0000000..195c1de
--- /dev/null
+++ b/base/include/base/stringprintf.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2011 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_STRINGPRINTF_H
+#define BASE_STRINGPRINTF_H
+
+#include <stdarg.h>
+#include <string>
+
+namespace android {
+namespace base {
+
+// Returns a string corresponding to printf-like formatting of the arguments.
+std::string StringPrintf(const char* fmt, ...)
+    __attribute__((__format__(__printf__, 1, 2)));
+
+// Appends a printf-like formatting of the arguments to 'dst'.
+void StringAppendF(std::string* dst, const char* fmt, ...)
+    __attribute__((__format__(__printf__, 2, 3)));
+
+// Appends a printf-like formatting of the arguments to 'dst'.
+void StringAppendV(std::string* dst, const char* format, va_list ap);
+
+}  // namespace base
+}  // namespace android
+
+#endif  // BASE_STRINGPRINTF_H
diff --git a/base/stringprintf.cpp b/base/stringprintf.cpp
new file mode 100644
index 0000000..d55ff52
--- /dev/null
+++ b/base/stringprintf.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2011 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/stringprintf.h"
+
+#include <stdio.h>
+
+#include <string>
+
+namespace android {
+namespace base {
+
+void StringAppendV(std::string* dst, const char* format, va_list ap) {
+  // First try with a small fixed size buffer
+  char space[1024];
+
+  // It's possible for methods that use a va_list to invalidate
+  // the data in it upon use.  The fix is to make a copy
+  // of the structure before using it and use that copy instead.
+  va_list backup_ap;
+  va_copy(backup_ap, ap);
+  int result = vsnprintf(space, sizeof(space), format, backup_ap);
+  va_end(backup_ap);
+
+  if (result < static_cast<int>(sizeof(space))) {
+    if (result >= 0) {
+      // Normal case -- everything fit.
+      dst->append(space, result);
+      return;
+    }
+
+    if (result < 0) {
+      // Just an error.
+      return;
+    }
+  }
+
+  // Increase the buffer size to the size requested by vsnprintf,
+  // plus one for the closing \0.
+  int length = result + 1;
+  char* buf = new char[length];
+
+  // Restore the va_list before we use it again
+  va_copy(backup_ap, ap);
+  result = vsnprintf(buf, length, format, backup_ap);
+  va_end(backup_ap);
+
+  if (result >= 0 && result < length) {
+    // It fit
+    dst->append(buf, result);
+  }
+  delete[] buf;
+}
+
+std::string StringPrintf(const char* fmt, ...) {
+  va_list ap;
+  va_start(ap, fmt);
+  std::string result;
+  StringAppendV(&result, fmt, ap);
+  va_end(ap);
+  return result;
+}
+
+void StringAppendF(std::string* dst, const char* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  StringAppendV(dst, format, ap);
+  va_end(ap);
+}
+
+}  // namespace base
+}  // namespace android
diff --git a/base/stringprintf_test.cpp b/base/stringprintf_test.cpp
new file mode 100644
index 0000000..5cc2086
--- /dev/null
+++ b/base/stringprintf_test.cpp
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2011 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/stringprintf.h"
+
+#include <gtest/gtest.h>
+
+#include <string>
+
+TEST(StringPrintfTest, HexSizeT) {
+  size_t size = 0x00107e59;
+  EXPECT_EQ("00107e59", android::base::StringPrintf("%08zx", size));
+  EXPECT_EQ("0x00107e59", android::base::StringPrintf("0x%08zx", size));
+}
+
+TEST(StringPrintfTest, StringAppendF) {
+  std::string s("a");
+  android::base::StringAppendF(&s, "b");
+  EXPECT_EQ("ab", s);
+}
+
+TEST(StringPrintfTest, Errno) {
+  errno = 123;
+  android::base::StringPrintf("hello %s", "world");
+  EXPECT_EQ(123, errno);
+}
+
+void TestN(size_t n) {
+  char* buf = new char[n + 1];
+  memset(buf, 'x', n);
+  buf[n] = '\0';
+  std::string s(android::base::StringPrintf("%s", buf));
+  EXPECT_EQ(buf, s);
+  delete[] buf;
+}
+
+TEST(StringPrintfTest, At1023) {
+  TestN(1023);
+}
+
+TEST(StringPrintfTest, At1024) {
+  TestN(1024);
+}
+
+TEST(StringPrintfTest, At1025) {
+  TestN(1025);
+}