5 files changed, 138 insertions, 10 deletions
diff --git a/include/utils/file.h b/include/utils/file.h
new file mode 100644
index 0000000..108cabc
--- /dev/null
+++ b/include/utils/file.h
@@ -0,0 +1,29 @@
+/*
+ * 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 UTILS_FILE_H
+#define UTILS_FILE_H
+
+#include <string>
+
+namespace android {
+
+bool ReadFileToString(const std::string& path, std::string* content);
+bool WriteStringToFile(const std::string& content, const std::string& path);
+
+} // namespace android
+
+#endif
diff --git a/libutils/Android.mk b/libutils/Android.mk
index 52de910..701fe0e 100644
--- a/libutils/Android.mk
+++ b/libutils/Android.mk
@@ -14,9 +14,6 @@
 
 LOCAL_PATH:= $(call my-dir)
 
-# libutils is a little unique: It's built twice, once for the host
-# and once for the device.
-
 commonSources:= \
 	BasicHashtable.cpp \
 	BlobCache.cpp \
@@ -42,7 +39,8 @@ commonSources:= \
 	Tokenizer.cpp \
 	Unicode.cpp \
 	VectorImpl.cpp \
-	misc.cpp
+	file.cpp \
+	misc.cpp \
 
 host_commonCflags := -DLIBUTILS_NATIVE=1 $(TOOL_CFLAGS) -Werror
 
@@ -111,11 +109,6 @@ LOCAL_CFLAGS := -Werror
 
 include $(BUILD_SHARED_LIBRARY)
 
-# Include subdirectory makefiles
-# ============================================================
 
-# If we're building with ONE_SHOT_MAKEFILE (mm, mmm), then what the framework
-# team really wants is to build the stuff defined by this makefile.
-ifeq (,$(ONE_SHOT_MAKEFILE))
+# Build the tests in the tests/ subdirectory.
 include $(call first-makefiles-under,$(LOCAL_PATH))
-endif
diff --git a/libutils/file.cpp b/libutils/file.cpp
new file mode 100644
index 0000000..15bda7f
--- /dev/null
+++ b/libutils/file.cpp
@@ -0,0 +1,68 @@
+/*
+ * 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 "utils/file.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+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;
+  }
+
+  while (true) {
+    char buf[BUFSIZ];
+    ssize_t n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)));
+    if (n == -1) {
+      TEMP_FAILURE_RETRY(close(fd));
+      return false;
+    }
+    if (n == 0) {
+      TEMP_FAILURE_RETRY(close(fd));
+      return true;
+    }
+    content->append(buf, n);
+  }
+}
+
+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;
+  }
+
+  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) {
+      TEMP_FAILURE_RETRY(close(fd));
+      return false;
+    }
+    p += n;
+    left -= n;
+  }
+  TEMP_FAILURE_RETRY(close(fd));
+  return true;
+}
diff --git a/libutils/tests/Android.mk b/libutils/tests/Android.mk
index 634f44f..03d5342 100644
--- a/libutils/tests/Android.mk
+++ b/libutils/tests/Android.mk
@@ -26,6 +26,7 @@ LOCAL_SRC_FILES := \
     BasicHashtable_test.cpp \
     BlobCache_test.cpp \
     BitSet_test.cpp \
+    file_test.cpp \
     Looper_test.cpp \
     LruCache_test.cpp \
     String8_test.cpp \
diff --git a/libutils/tests/file_test.cpp b/libutils/tests/file_test.cpp
new file mode 100644
index 0000000..acf66a6
--- /dev/null
+++ b/libutils/tests/file_test.cpp
@@ -0,0 +1,37 @@
+/*
+ * 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 <gtest/gtest.h>
+
+TEST(file, ReadFileToString_ENOENT) {
+  std::string s("hello");
+  errno = 0;
+  EXPECT_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");
+  EXPECT_TRUE(android::ReadFileToString("/proc/version", &s));
+  EXPECT_GT(s.length(), 6U);
+  EXPECT_EQ('\n', s[s.length() - 1]);
+  s[5] = 0;
+  EXPECT_STREQ("Linux", s.c_str());
+}