Remove the shim kernel crate

kernel/src/process/signal/sig_disposition.rs

@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::{constants::*, sig_action::SigAction, sig_num::SigNum};
+
+#[derive(Copy, Clone)]
+pub struct SigDispositions {
+    // SigNum -> SigAction
+    map: [SigAction; COUNT_ALL_SIGS],
+}
+
+impl Default for SigDispositions {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl SigDispositions {
+    pub fn new() -> Self {
+        Self {
+            map: [SigAction::default(); COUNT_ALL_SIGS],
+        }
+    }
+
+    pub fn get(&self, num: SigNum) -> SigAction {
+        let idx = Self::num_to_idx(num);
+        self.map[idx]
+    }
+
+    pub fn set(&mut self, num: SigNum, sa: SigAction) {
+        let idx = Self::num_to_idx(num);
+        self.map[idx] = sa;
+    }
+
+    pub fn set_default(&mut self, num: SigNum) {
+        let idx = Self::num_to_idx(num);
+        self.map[idx] = SigAction::Dfl;
+    }
+
+    /// man 7 signal:
+    /// When execve, the handled signals are reset to the default; the dispositions of
+    /// ignored signals are left unchanged.
+    /// This function should be used when execve.
+    pub fn inherit(&mut self) {
+        for sigaction in &mut self.map {
+            if let SigAction::User { .. } = sigaction {
+                *sigaction = SigAction::Dfl;
+            }
+        }
+    }
+
+    fn num_to_idx(num: SigNum) -> usize {
+        (num.as_u8() - MIN_STD_SIG_NUM) as usize
+    }
+}