Added PIDFile

6 files changed, 89 insertions, 1 deletions

diff --git a/MainLoop.h b/MainLoop.h
index 9cd19a1..bfa0084 100644
--- a/MainLoop.h
+++ b/MainLoop.h
@@ -6,6 +6,7 @@
 #include "MIDI.h"
 #include "PCM.h"
 #include "UI.h"
+#include "PIDFile.h"
 
 #include <boost/signals2.hpp>
 
@@ -22,6 +23,8 @@ private:
 
   Config m_config;
 
+  PIDFile m_pid_file{m_config.get_programname()};
+
   NoteClick m_note_click;
   ClockClick m_clock_click;
   InternalClick m_internal_click;
diff --git a/Makefile b/Makefile
index f48b8b2..991d020 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,8 @@ SRCS= \
   ClockClick.cpp \
   InternalClick.cpp \
   BPMDetect.cpp \
-  Touchpad.cpp
+  Touchpad.cpp \
+  PIDFile.cpp
 
 HEADERS=$(SRCS:.cpp=.h)
 
diff --git a/PIDFile.cpp b/PIDFile.cpp
new file mode 100644
index 0000000..85f30d3
--- /dev/null
+++ b/PIDFile.cpp
@@ -0,0 +1,54 @@
+#include "PIDFile.h"
+
+#include "log.h"
+
+#include <libreichwein/file.h>
+#include <libreichwein/process.h>
+#include <fmt/format.h>
+
+#include <stdexcept>
+
+#include "unistd.h"
+
+namespace fs = std::filesystem;
+
+PIDFile::PIDFile(const std::string& programname): m_programname{programname}
+{
+  pid_t pid{getpid()};
+
+  std::string contents{std::to_string(static_cast<int>(pid))};
+
+  fs::path filename{get_filename()};
+
+  if (fs::exists(filename)) {
+    pid_t existing_pid{get_pid_from_file()};
+    if (Reichwein::Process::is_running(existing_pid)) {
+      throw std::runtime_error(fmt::format("Program already running at PID {}", existing_pid));
+    } else {
+      log_cout << fmt::format("Found stale PID file {}, removing.\n", filename.string());
+    }
+  }
+
+  try {
+    Reichwein::File::setFile(filename, contents);
+  } catch (const std::exception& ex) {
+    log_cout << fmt::format("Warning: Not able to write to file{}, ignoring.\n", filename.string());
+  }
+}
+
+PIDFile::~PIDFile()
+{
+  fs::remove(get_filename());
+}
+
+int PIDFile::get_pid_from_file() const
+{
+  std::string contents{Reichwein::File::getFile(get_filename())};
+  return std::stoul(contents);
+}
+
+fs::path PIDFile::get_filename() const
+{
+  return fs::path{"/var/run"} / m_programname;
+}
+
diff --git a/PIDFile.h b/PIDFile.h
new file mode 100644
index 0000000..3278b0e
--- /dev/null
+++ b/PIDFile.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <filesystem>
+#include <string>
+
+class PIDFile
+{
+public:
+  PIDFile(const std::string& programname);
+  ~PIDFile();
+
+private:
+  int get_pid_from_file() const;
+
+  std::filesystem::path get_filename() const;
+
+  std::string m_programname;
+};
+
diff --git a/config.cpp b/config.cpp
index f8bf89c..d0a7671 100644
--- a/config.cpp
+++ b/config.cpp
@@ -19,6 +19,8 @@ std::string config_filename = "click.cfg";
 
 fs::path click_data_filename = "media/click.s16le";
 
+const std::string programname = "click";
+
 Config::Config(int argc, char** argv):
   m_argv(argc)
 {
@@ -161,3 +163,9 @@ std::filesystem::path Config::get_click_data_filename() const
 {
   return fs::path{m_argv[0]}.parent_path() / click_data_filename;
 }
+
+std::string Config::get_programname() const
+{
+  return programname;
+}
+
diff --git a/config.h b/config.h
index 062989d..2262223 100644
--- a/config.h
+++ b/config.h
@@ -20,6 +20,7 @@ const int click_latency_frames = 10000;
 const int default_mode = 0; // 0 = note, 1 = clock, 2 = internal
 const int default_output = 1; // 0 = off, 1 = on
 extern std::filesystem::path click_data_filename;
+extern const std::string programname;
 
 class Config
 {
@@ -56,6 +57,8 @@ public:
 
   std::filesystem::path get_click_data_filename() const;
 
+  std::string get_programname() const;
+
 private:
   std::string get_config_filename() const;