From eb1b8a1488712b75562515f39c6ac44a086fec9c Mon Sep 17 00:00:00 2001
From: Martin Pecka <peci1@seznam.cz>
Date: Wed, 2 Sep 2020 04:09:17 +0200
Subject: [PATCH] Use random name for manager semaphore

Fixes #56.

Signed-off-by: Martin Pecka <peckama2@fel.cvut.cz>
---
 src/Manager.cc | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/Manager.cc b/src/Manager.cc
index 36451f93..219f2b27 100644
--- a/src/Manager.cc
+++ b/src/Manager.cc
@@ -36,6 +36,7 @@
 #include <ignition/common/Console.hh>
 #include <ignition/common/SignalHandler.hh>
 #include <ignition/common/SystemPaths.hh>
+#include <ignition/common/Uuid.hh>
 #include <ignition/plugin/Loader.hh>
 
 #include "ignition/launch/config.hh"
@@ -47,8 +48,6 @@
 using namespace ignition::launch;
 using namespace std::chrono_literals;
 
-static constexpr const char* kSemaphoreName = "/child_semaphore";
-
 /// \brief A class to encapsulate an executable (program) to run.
 class Executable
 {
@@ -177,6 +176,9 @@ class ignition::launch::ManagerPrivate
 
   /// \brief Semaphore to prevent restartThread from being a spinlock
   private: sem_t *stoppedChildSem;
+  
+  /// \brief Name of the semaphore created by stoppedChildSem.
+  private: std::string stoppedChildSemName;
 
   /// \brief Thread containing the restart loop
   private: std::thread restartThread;
@@ -295,9 +297,11 @@ ManagerPrivate::ManagerPrivate()
       std::bind(&ManagerPrivate::OnSigIntTerm, this, std::placeholders::_1));
 
   // Initialize semaphore
-  this->stoppedChildSem = sem_open(kSemaphoreName, O_CREAT, 0644, 1);
+  this->stoppedChildSemName = std::string("ign-launch-") + common::Uuid().String();
+  this->stoppedChildSem = sem_open(this->stoppedChildSemName.c_str(), O_CREAT, 0644, 1);
   if (this->stoppedChildSem == SEM_FAILED) {
-    ignerr << "Error initializing semaphore: " << strerror(errno) << std::endl;
+    ignerr << "Error initializing semaphore " << this->stoppedChildSemName << ": " <<
+      strerror(errno) << std::endl;
   }
 
   // Register a signal handler to capture child process death events.
@@ -329,12 +333,14 @@ ManagerPrivate::~ManagerPrivate()
   {
     if (sem_close(this->stoppedChildSem) == -1)
     {
-      ignerr << "Failed to close semaphore: " << strerror(errno) << std::endl;
+      ignerr << "Failed to close semaphore " << this->stoppedChildSemName << ": " <<
+        strerror(errno) << std::endl;
     }
 
-    if (sem_unlink(kSemaphoreName) == -1)
+    if (sem_unlink(this->stoppedChildSemName.c_str()) == -1)
     {
-      ignerr << "Failed to unlink semaphore: " << strerror(errno) << std::endl;
+      ignerr << "Failed to unlink semaphore " << this->stoppedChildSemName << ": " <<
+        strerror(errno) << std::endl;
     }
   }
 }