Set Setpgid on child git processes (#19865)

When Gitea is running as PID 1 git will occassionally orphan child processes leading
to (defunct) processes. This PR simply sets Setpgid to true on these child processes
meaning that these defunct processes will also be correctly reaped.

Fix #19077

Signed-off-by: Andrew Thornton <art27@cantab.net>

3 files changed, 35 insertions, 0 deletions

diff --git a/modules/process/manager_exec.go b/modules/process/manager_exec.go
index 61ddae646f..77e3d3193a 100644
--- a/modules/process/manager_exec.go
+++ b/modules/process/manager_exec.go
@@ -58,6 +58,7 @@ func (pm *Manager) ExecDirEnvStdIn(ctx context.Context, timeout time.Duration, d
 	if stdIn != nil {
 		cmd.Stdin = stdIn
 	}
+	SetSysProcAttribute(cmd)
 
 	if err := cmd.Start(); err != nil {
 		return "", "", err
diff --git a/modules/process/manager_unix.go b/modules/process/manager_unix.go
new file mode 100644
index 0000000000..1e7c77fdbf
--- /dev/null
+++ b/modules/process/manager_unix.go
@@ -0,0 +1,18 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build !windows
+
+package process
+
+import (
+	"os/exec"
+	"syscall"
+)
+
+// SetSysProcAttribute sets the common SysProcAttrs for commands
+func SetSysProcAttribute(cmd *exec.Cmd) {
+	// When Gitea runs SubProcessA -> SubProcessB and SubProcessA gets killed by context timeout, use setpgid to make sure the sub processes can be reaped instead of leaving defunct(zombie) processes.
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+}
diff --git a/modules/process/manager_windows.go b/modules/process/manager_windows.go
new file mode 100644
index 0000000000..35f66d9fa5
--- /dev/null
+++ b/modules/process/manager_windows.go
@@ -0,0 +1,16 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+
+package process
+
+import (
+	"os/exec"
+)
+
+// SetSysProcAttribute sets the common SysProcAttrs for commands
+func SetSysProcAttribute(cmd *exec.Cmd) {
+	// Do nothing
+}