Clean up reading and writing in init.

This isn't particularly useful in and of itself, but it does introduce the
first (trivial) unit test, improves the documentation (including details
about how to debug init crashes), and made me aware of how unpleasant the
existing parser is.

I also fixed a bug in passing --- unless you thought the "peboot" and "pm"
commands were features...

Bug: 19217569
Change-Id: I6ab76129a543ce3ed3dab52ef2c638009874c3de

1 files changed, 37 insertions, 0 deletions

diff --git a/init/util_test.cpp b/init/util_test.cpp
new file mode 100644
index 0000000..e9a1581
--- /dev/null
+++ b/init/util_test.cpp
@@ -0,0 +1,37 @@
+/*
+ * 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 "util.h"
+
+#include <errno.h>
+#include <gtest/gtest.h>
+
+TEST(util, read_file_ENOENT) {
+  std::string s("hello");
+  errno = 0;
+  EXPECT_FALSE(read_file("/proc/does-not-exist", &s));
+  EXPECT_EQ(ENOENT, errno);
+  EXPECT_EQ("", s); // s was cleared.
+}
+
+TEST(util, read_file_success) {
+  std::string s("hello");
+  EXPECT_TRUE(read_file("/proc/version", &s));
+  EXPECT_GT(s.length(), 6U);
+  EXPECT_EQ('\n', s[s.length() - 1]);
+  s[5] = 0;
+  EXPECT_STREQ("Linux", s.c_str());
+}