Remove the shim kernel crate

kernel/src/fs/utils/access_mode.rs

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use aster_rights::Rights;
+
+use crate::prelude::*;
+
+#[allow(non_camel_case_types)]
+#[derive(Clone, Copy, Debug)]
+#[repr(u8)]
+pub enum AccessMode {
+    /// read only
+    O_RDONLY = 0,
+    /// write only
+    O_WRONLY = 1,
+    /// read write
+    O_RDWR = 2,
+}
+
+impl AccessMode {
+    pub fn is_readable(&self) -> bool {
+        matches!(*self, AccessMode::O_RDONLY | AccessMode::O_RDWR)
+    }
+
+    pub fn is_writable(&self) -> bool {
+        matches!(*self, AccessMode::O_WRONLY | AccessMode::O_RDWR)
+    }
+}
+
+impl AccessMode {
+    pub fn from_u32(flags: u32) -> Result<Self> {
+        let bits = (flags & 0b11) as u8;
+        if bits > Self::O_RDWR as u8 {
+            return_errno_with_message!(Errno::EINVAL, "invalid bits for access mode");
+        }
+        Ok(match bits {
+            0 => Self::O_RDONLY,
+            1 => Self::O_WRONLY,
+            2 => Self::O_RDWR,
+            _ => unreachable!(),
+        })
+    }
+}
+
+impl From<Rights> for AccessMode {
+    fn from(rights: Rights) -> AccessMode {
+        if rights.contains(Rights::READ) && rights.contains(Rights::WRITE) {
+            AccessMode::O_RDWR
+        } else if rights.contains(Rights::READ) {
+            AccessMode::O_RDONLY
+        } else if rights.contains(Rights::WRITE) {
+            AccessMode::O_WRONLY
+        } else {
+            panic!("invalid rights");
+        }
+    }
+}
+
+impl From<AccessMode> for Rights {
+    fn from(access_mode: AccessMode) -> Rights {
+        match access_mode {
+            AccessMode::O_RDONLY => Rights::READ,
+            AccessMode::O_WRONLY => Rights::WRITE,
+            AccessMode::O_RDWR => Rights::READ | Rights::WRITE,
+        }
+    }
+}