diff --git a/libutils/Android.mk b/libutils/Android.mk
index e9c5f89..7bff14e 100644
--- a/libutils/Android.mk
+++ b/libutils/Android.mk
@@ -39,7 +39,9 @@
 	Tokenizer.cpp \
 	Unicode.cpp \
 	VectorImpl.cpp \
+	file.cpp \
 	misc.cpp \
+	stringprintf.cpp \
 
 host_commonCflags := -DLIBUTILS_NATIVE=1 $(TOOL_CFLAGS) -Werror
 
diff --git a/libutils/file.cpp b/libutils/file.cpp
new file mode 100644
index 0000000..0690bc2
--- /dev/null
+++ b/libutils/file.cpp
@@ -0,0 +1,115 @@
+/*
+ * 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.
+ */
+
+#define LOG_TAG "utils.file"
+#include <cutils/log.h>
+
+#include "utils/file.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <utils/Compat.h> // For TEMP_FAILURE_RETRY on Darwin.
+
+bool android::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 android::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 android::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 android::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 android::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);
+}
diff --git a/libutils/stringprintf.cpp b/libutils/stringprintf.cpp
new file mode 100644
index 0000000..5eaa293
--- /dev/null
+++ b/libutils/stringprintf.cpp
@@ -0,0 +1,77 @@
+/*
+ * 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 <utils/stringprintf.h>
+
+#include <stdio.h>
+
+void android::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 android::StringPrintf(const char* fmt, ...) {
+  va_list ap;
+  va_start(ap, fmt);
+  std::string result;
+  StringAppendV(&result, fmt, ap);
+  va_end(ap);
+  return result;
+}
+
+void android::StringAppendF(std::string* dst, const char* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  StringAppendV(dst, format, ap);
+  va_end(ap);
+}
diff --git a/libutils/tests/Android.mk b/libutils/tests/Android.mk
index 634f44f..ce288ca 100644
--- a/libutils/tests/Android.mk
+++ b/libutils/tests/Android.mk
@@ -26,9 +26,11 @@
     BasicHashtable_test.cpp \
     BlobCache_test.cpp \
     BitSet_test.cpp \
+    file_test.cpp \
     Looper_test.cpp \
     LruCache_test.cpp \
     String8_test.cpp \
+    stringprintf_test.cpp \
     Unicode_test.cpp \
     Vector_test.cpp \
 
diff --git a/libutils/tests/file_test.cpp b/libutils/tests/file_test.cpp
new file mode 100644
index 0000000..cea18b6
--- /dev/null
+++ b/libutils/tests/file_test.cpp
@@ -0,0 +1,98 @@
+/*
+ * 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 "utils/file.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <gtest/gtest.h>
+
+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::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::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::WriteStringToFile("abc", tf.filename)) << errno;
+  std::string s;
+  ASSERT_TRUE(android::ReadFileToString(tf.filename, &s)) << errno;
+  EXPECT_EQ("abc", s);
+}
+
+TEST(file, WriteStringToFile2) {
+  TemporaryFile tf;
+  ASSERT_TRUE(tf.fd != -1);
+  ASSERT_TRUE(android::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::ReadFileToString(tf.filename, &s)) << errno;
+  EXPECT_EQ("abc", s);
+}
+
+TEST(file, WriteStringToFd) {
+  TemporaryFile tf;
+  ASSERT_TRUE(tf.fd != -1);
+  ASSERT_TRUE(android::WriteStringToFd("abc", tf.fd));
+
+  ASSERT_EQ(0, lseek(tf.fd, 0, SEEK_SET)) << errno;
+
+  std::string s;
+  ASSERT_TRUE(android::ReadFdToString(tf.fd, &s)) << errno;
+  EXPECT_EQ("abc", s);
+}
diff --git a/libutils/tests/stringprintf_test.cpp b/libutils/tests/stringprintf_test.cpp
new file mode 100644
index 0000000..f995452
--- /dev/null
+++ b/libutils/tests/stringprintf_test.cpp
@@ -0,0 +1,58 @@
+/*
+ * 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 <utils/stringprintf.h>
+
+#include <gtest/gtest.h>
+
+TEST(StringPrintfTest, HexSizeT) {
+  size_t size = 0x00107e59;
+  EXPECT_EQ("00107e59", android::StringPrintf("%08zx", size));
+  EXPECT_EQ("0x00107e59", android::StringPrintf("0x%08zx", size));
+}
+
+TEST(StringPrintfTest, StringAppendF) {
+  std::string s("a");
+  android::StringAppendF(&s, "b");
+  EXPECT_EQ("ab", s);
+}
+
+TEST(StringPrintfTest, Errno) {
+  errno = 123;
+  android::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::StringPrintf("%s", buf));
+  EXPECT_EQ(buf, s);
+  delete[] buf;
+}
+
+TEST(StringPrintfTest, At1023) {
+  TestN(1023);
+}
+
+TEST(StringPrintfTest, At1024) {
+  TestN(1024);
+}
+
+TEST(StringPrintfTest, At1025) {
+  TestN(1025);
+}