Remove the shim kernel crate

kernel/src/syscall/setpgid.rs

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::SyscallReturn;
+use crate::{
+    prelude::*,
+    process::{process_table, Pgid, Pid},
+};
+
+pub fn sys_setpgid(pid: Pid, pgid: Pgid, ctx: &Context) -> Result<SyscallReturn> {
+    let current = ctx.process;
+    // if pid is 0, pid should be the pid of current process
+    let pid = if pid == 0 { current.pid() } else { pid };
+    // if pgid is 0, pgid should be pid
+    let pgid = if pgid == 0 { pid } else { pgid };
+    debug!("pid = {}, pgid = {}", pid, pgid);
+
+    if pid != current.pid() && !current.has_child(&pid) {
+        return_errno_with_message!(
+            Errno::ESRCH,
+            "cannot set pgid for process other than current or children of current"
+        );
+    }
+    // FIXME: If pid is child process of current and already calls execve, should return error.
+    // How can we determine a child process has called execve?
+
+    // only can move process to an existing group or self
+    if pgid != pid && !process_table::contain_process_group(&pgid) {
+        return_errno_with_message!(Errno::EPERM, "process group must exist");
+    }
+
+    let process = process_table::get_process(pid)
+        .ok_or(Error::with_message(Errno::ESRCH, "process does not exist"))?;
+
+    process.to_other_group(pgid)?;
+
+    Ok(SyscallReturn::Return(0))
+}