Moved some functions to DumpstateUtil.h.

dumpstate_board() is been refactored into a HIDL interface, and the HIDL
implementations will need help functions to dump files and run commands into
a file descriptor.

BUG: 31982882
Test: dumpstate_test passes
Test: manual verification

Change-Id: I7a32f0ac236dae34fd85abe47bed0e52a34c5f36
diff --git a/cmds/dumpstate/DumpstateUtil.h b/cmds/dumpstate/DumpstateUtil.h
new file mode 100644
index 0000000..9c60f0d
--- /dev/null
+++ b/cmds/dumpstate/DumpstateUtil.h
@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2008 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 FRAMEWORK_NATIVE_CMD_DUMPSTATE_UTIL_H_
+#define FRAMEWORK_NATIVE_CMD_DUMPSTATE_UTIL_H_
+
+/*
+ * Defines the Linux user that should be executing a command.
+ */
+enum RootMode {
+    /* Explicitly change the `uid` and `gid` to be `shell`.*/
+    DROP_ROOT,
+    /* Don't change the `uid` and `gid`. */
+    DONT_DROP_ROOT,
+    /* Prefix the command with `/PATH/TO/su root`. Won't work non user builds. */
+    SU_ROOT
+};
+
+/*
+ * Defines what should happen with the `stdout` stream of a command.
+ */
+enum StdoutMode {
+    /* Don't change `stdout`. */
+    NORMAL_STDOUT,
+    /* Redirect `stdout` to `stderr`. */
+    REDIRECT_TO_STDERR
+};
+
+/*
+ * Value object used to set command options.
+ *
+ * Typically constructed using a builder with chained setters. Examples:
+ *
+ *  CommandOptions::WithTimeout(20).AsRoot().Build();
+ *  CommandOptions::WithTimeout(10).Always().RedirectStderr().Build();
+ *
+ * Although the builder could be used to dynamically set values. Example:
+ *
+ *  CommandOptions::CommandOptionsBuilder options =
+ *  CommandOptions::WithTimeout(10);
+ *  if (!is_user_build()) {
+ *    options.AsRoot();
+ *  }
+ *  RunCommand("command", {"args"}, options.Build());
+ */
+class CommandOptions {
+  private:
+    class CommandOptionsValues {
+      private:
+        CommandOptionsValues(int64_t timeout);
+
+        int64_t timeout_;
+        bool always_;
+        RootMode root_mode_;
+        StdoutMode stdout_mode_;
+        std::string logging_message_;
+
+        friend class CommandOptions;
+        friend class CommandOptionsBuilder;
+    };
+
+    CommandOptions(const CommandOptionsValues& values);
+
+    const CommandOptionsValues values;
+
+  public:
+    class CommandOptionsBuilder {
+      public:
+        /* Sets the command to always run, even on `dry-run` mode. */
+        CommandOptionsBuilder& Always();
+        /* Sets the command's RootMode as `SU_ROOT` */
+        CommandOptionsBuilder& AsRoot();
+        /* Sets the command's RootMode as `DROP_ROOT` */
+        CommandOptionsBuilder& DropRoot();
+        /* Sets the command's StdoutMode `REDIRECT_TO_STDERR` */
+        CommandOptionsBuilder& RedirectStderr();
+        /* When not empty, logs a message before executing the command.
+         * Must contain a `%s`, which will be replaced by the full command line, and end on `\n`. */
+        CommandOptionsBuilder& Log(const std::string& message);
+        /* Builds the command options. */
+        CommandOptions Build();
+
+      private:
+        CommandOptionsBuilder(int64_t timeout);
+        CommandOptionsValues values;
+        friend class CommandOptions;
+    };
+
+    /** Gets the command timeout, in seconds. */
+    int64_t Timeout() const;
+    /* Checks whether the command should always be run, even on dry-run mode. */
+    bool Always() const;
+    /** Gets the RootMode of the command. */
+    RootMode RootMode() const;
+    /** Gets the StdoutMode of the command. */
+    StdoutMode StdoutMode() const;
+    /** Gets the logging message header, it any. */
+    std::string LoggingMessage() const;
+
+    /** Creates a builder with the requied timeout. */
+    static CommandOptionsBuilder WithTimeout(int64_t timeout);
+
+    // Common options.
+    static CommandOptions DEFAULT;
+    static CommandOptions AS_ROOT_5;
+    static CommandOptions AS_ROOT_10;
+    static CommandOptions AS_ROOT_20;
+};
+
+/*
+ * Forks a command, waits for it to finish, and returns its status.
+ *
+ * |fd| file descriptor that receives the command's 'stdout'.
+ * |full_command| array containing the command (first entry) and its arguments.
+ * Must contain at least one element.
+ * |options| optional argument defining the command's behavior.
+ * |description| optional description of the command to be used on log messages. If empty,
+ * the command path (without arguments) will be used instead.
+ */
+int RunCommandToFd(int fd, const std::vector<const char*>& full_command,
+                   const CommandOptions& options = CommandOptions::DEFAULT,
+                   const std::string& description = "");
+
+/*
+ * Dumps the contents of a file into a file descriptor.
+ *
+ * |fd| file descriptor where the file is dumped into.
+ * |path| location of the file to be dumped.
+ */
+int DumpFileToFd(int fd, const std::string& path);
+
+#endif  // FRAMEWORK_NATIVE_CMD_DUMPSTATE_UTIL_H_