libchromeos: add process control library, syslog logging capability, and run unit tests

chromeos/process.h

Index: chromeos/process.h
diff --git a/chromeos/process.h b/chromeos/process.h
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+// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMEOS_PROCESS_H_
+#define CHROMEOS_PROCESS_H_
+
+#include <sys/types.h>
+
+#include <string>
+#include <vector>
+
+#include <base/string_util.h>
+
+namespace chromeos {
+// Manages a process.  Can create the process, attach to an existing
+// process by pid or pid file, and kill the process.  Upon destruction
+// any managed process is killed with SIGKILL.  Use Release() to
+// release the process from management.  A given system process may
+// only be managed by one Process at a time.
+class Process {
+ public:
+  Process();
+  virtual ~Process();
+
+  // Adds |arg| to the executable command-line to be run.  The
+  // executable name itself is the first argument.
+  virtual void AddArg(const std::string& arg) = 0;
+
+  // Adds |option| and |value| as an option with a string value to the
+  // command line to be run.
+  inline void AddStringOption(const std::string& option,
+                              const std::string& value) {
+    AddArg(option);
+    AddArg(value);
+  }
+
+  // Adds |option| and |value| as an option which takes an integer
+  // value to the command line to be run.
+  inline void AddIntOption(const std::string& option, int value) {
+    AddArg(option);
+    AddArg(StringPrintf("%d", value));
+  }
+
+  // Redirects stderr and stdout to |output_file|.
+  virtual void RedirectOutput(const std::string& output_file) = 0;
+
+  // Starts this process, returning true if successful.
+  virtual bool Start() = 0;
+
+  // Waits for this process to finish.  Returns the process's exit
+  // status if it exited normally, or otherwise returns -1.
+  virtual int Wait() = 0;
+
+  // Start and wait for this process to finish.  Returns same value as
+  // Wait().
+  virtual int Run() = 0;
+
+  // Returns the pid of this process or else returns 0 if there is no
+  // corresponding process (either because it has not yet been started
+  // or has since exited).
+  virtual pid_t pid() = 0;
+
+  // Kills this process with |signal|.  If process is not a child,
+  // returns immediately with a value based on whether kill was
+  // successful.  If the process is a child and |timeout| is non-zero,
+  // returns true if the process is able to be reaped within the given
+  // |timeout| in seconds.
+  virtual bool Kill(int signal, int timeout) = 0;
+
+  // Resets this Process object to refer to the process with |pid|.
+  // If |pid| is zero, this object no longer refers to a process.
+  virtual void Reset(pid_t new_pid) = 0;
+
+  // Same as Reset but reads the pid from |pid_file|.  Returns false
+  // only when the file cannot be read/parsed.
+  virtual bool ResetPidByFile(const std::string& pid_file) = 0;
+
+  // Releases the process so that on destruction, the process is not killed.
+  virtual pid_t Release() = 0;
+
+  // Returns if |pid| is a currently running process.
+  static bool ProcessExists(pid_t pid);
+};
+
+class ProcessImpl : public Process {
+ public:
+  ProcessImpl();
+  virtual ~ProcessImpl();
+
+  virtual void AddArg(const std::string& arg);
+  virtual void RedirectOutput(const std::string& output_file);
+  virtual bool Start();
+  virtual int Wait();
+  virtual int Run();
+  virtual pid_t pid();
+  virtual bool Kill(int signal, int timeout);
+  virtual void Reset(pid_t pid);
+  virtual bool ResetPidByFile(const std::string& pid_file);
+  virtual pid_t Release();
+
+ protected:
+  std::string output_file_;
+  std::vector<std::string> arguments_;
+
+  void UpdatePid(pid_t new_pid);
+
+ private:
+  // Pid of currently managed process or 0 if no currently managed
+  // process.  pid must not be modified except by calling
+  // UpdatePid(new_pid).
+  pid_t pid_;
+};
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_PROCESS_H