fix fork() issues on linux and MacOS (#910)

- Improvement: Hub child process spawning on macOS now uses `posix_spawn` in line with Apple recommendations
- Bugfix: Hub child process spawning on Linux now uses `vfork` instead of `fork`, preventing ENOMEM failures on systems with strict memory overcommit (`vm.overcommit_memory=2`)
- Bugfix: Fixed process group management on POSIX; child processes were not placed into the correct process group, breaking group-wide signal delivery

3 files changed, 7 insertions, 3 deletions

diff --git a/src/zenutil/cloud/minioprocess.cpp b/src/zenutil/cloud/minioprocess.cpp
index 457453bd8..e146f6677 100644
--- a/src/zenutil/cloud/minioprocess.cpp
+++ b/src/zenutil/cloud/minioprocess.cpp
@@ -45,7 +45,7 @@ struct MinioProcess::Impl
 		}
 
 		CreateProcOptions Options;
-		Options.Flags |= CreateProcOptions::Flag_Windows_NewProcessGroup;
+		Options.Flags |= CreateProcOptions::Flag_NewProcessGroup;
 		Options.Environment.emplace_back("MINIO_ROOT_USER", m_Options.RootUser);
 		Options.Environment.emplace_back("MINIO_ROOT_PASSWORD", m_Options.RootPassword);
 
diff --git a/src/zenutil/consul/consul.cpp b/src/zenutil/consul/consul.cpp
index ad1b92b38..c0cea20c0 100644
--- a/src/zenutil/consul/consul.cpp
+++ b/src/zenutil/consul/consul.cpp
@@ -31,7 +31,7 @@ struct ConsulProcess::Impl
 		}
 
 		CreateProcOptions Options;
-		Options.Flags |= CreateProcOptions::Flag_Windows_NewProcessGroup;
+		Options.Flags |= CreateProcOptions::Flag_NewProcessGroup;
 
 		const std::filesystem::path ConsulExe = GetRunningExecutablePath().parent_path() / ("consul" ZEN_EXE_SUFFIX_LITERAL);
 		CreateProcResult			Result	  = CreateProc(ConsulExe, "consul" ZEN_EXE_SUFFIX_LITERAL " agent -dev", Options);
diff --git a/src/zenutil/process/subprocessmanager.cpp b/src/zenutil/process/subprocessmanager.cpp
index b053ac6bd..e908dd63a 100644
--- a/src/zenutil/process/subprocessmanager.cpp
+++ b/src/zenutil/process/subprocessmanager.cpp
@@ -903,7 +903,11 @@ ProcessGroup::Impl::Spawn(const std::filesystem::path& Executable,
 		Options.AssignToJob = &m_JobObject;
 	}
 #else
-	if (m_Pgid > 0)
+	if (m_Pgid == 0)
+	{
+		Options.Flags |= CreateProcOptions::Flag_NewProcessGroup;
+	}
+	else
 	{
 		Options.ProcessGroupId = m_Pgid;
 	}