feat(syscall): add msgget, msgsnd, msgrcv, and msgctl (#57)

Author: LHHL7

api/src/syscall/ipc/mod.rs

@@ -1,11 +1,48 @@
 use core::sync::atomic::{AtomicI32, Ordering};
 
+use starry_core::shm::IpcPerm;
+
 static IPC_ID: AtomicI32 = AtomicI32::new(0);
 
 fn next_ipc_id() -> i32 {
     IPC_ID.fetch_add(1, Ordering::Relaxed)
 }
 
+mod msg;
 mod shm;
+pub use self::{msg::*, shm::*};
+
+// IPC command constants
+const IPC_PRIVATE: i32 = 0;
+const IPC_CREAT: i32 = 0o1000;
+const IPC_EXCL: i32 = 0o2000;
+const IPC_RMID: i32 = 0;
+const IPC_SET: i32 = 1;
+const IPC_STAT: i32 = 2;
+const IPC_INFO: i32 = 3;
+const MSG_STAT: i32 = 11;
+const MSG_INFO: i32 = 12;
+
+// Permission bits
+const USER_READ: u32 = 0o400;
+const USER_WRITE: u32 = 0o200;
+const GROUP_READ: u32 = 0o040;
+const GROUP_WRITE: u32 = 0o020;
+const OTHER_READ: u32 = 0o004;
+const OTHER_WRITE: u32 = 0o002;
 
-pub use self::shm::*;
+// add a helper function to check IPC permissions
+fn has_ipc_permission(perm: &IpcPerm, current_uid: u32, current_gid: u32, is_write: bool) -> bool {
+    // root user has all permissions
+    if current_uid == 0 {
+        return true;
+    }
+
+    if perm.uid == current_uid {
+        (perm.mode & if is_write { USER_WRITE } else { USER_READ }) != 0
+    } else if perm.gid == current_gid {
+        (perm.mode & if is_write { GROUP_WRITE } else { GROUP_READ }) != 0
+    } else {
+        (perm.mode & if is_write { OTHER_WRITE } else { OTHER_READ }) != 0
+    }
+}