From 3c7b85d8355c64dec5b4ce011753196d53774103 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Sat, 11 Jan 2025 10:36:20 +0100
Subject: Added PIDFile

---
 PIDFile.cpp | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 PIDFile.cpp

(limited to 'PIDFile.cpp')

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;
+}
+
-- 
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