Merge pull request #288 from ue-foundation/lm/zen-service-command

Implementation of service commands for Linux.

1 files changed, 13 insertions, 1 deletions

diff --git a/src/zenutil/zenserverprocess.cpp b/src/zenutil/zenserverprocess.cpp
index 11fcce02f..0409cb976 100644
--- a/src/zenutil/zenserverprocess.cpp
+++ b/src/zenutil/zenserverprocess.cpp
@@ -168,10 +168,22 @@ ZenServerState::Initialize()
 	}
 #else
 	ZEN_INFO("{}", S_IRUSR | S_IWUSR | S_IXUSR);
+	ZEN_INFO("{}", geteuid());
 	int Fd = shm_open("/UnrealEngineZen", O_RDWR | O_CREAT | O_CLOEXEC, geteuid() == 0 ? 0766 : 0666);
 	if (Fd < 0)
 	{
-		ThrowLastError("Could not open a shared memory object");
+		// Work around a potential issue if the service user is changed in certain configurations.
+		// If the sysctl 'fs.protected_regular' is set to 1 or 2 (default on many distros),
+		// we will be unable to open an existing shared memory object created by another user using O_CREAT,
+		// even if we have the correct permissions, or are running as root. If we destroy the existing
+		// shared memory object and retry, we'll be able to get past shm_open() so long as we have
+		// the appropriate permissions to create the shared memory object.
+		shm_unlink("/UnrealEngineZen");
+		Fd = shm_open("/UnrealEngineZen", O_RDWR | O_CREAT | O_CLOEXEC, geteuid() == 0 ? 0766 : 0666);
+		if (Fd < 0)
+		{
+			ThrowLastError("Could not open a shared memory object");
+		}
 	}
 	fchmod(Fd, 0666);
 	void* hMap = (void*)intptr_t(Fd);