Add Google-style ReadFileToString and WriteStringToFile.

Bug: 19217569
Change-Id: I64789d3fa6777ee30a324cdf00fdc275c1230e1b

1 files changed, 68 insertions, 0 deletions

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;
+}