Implements flags checking for fork1 implementation (#1081)

kernel/src/main.rs

@@ -22,6 +22,7 @@ mod malloc;
 mod panic;
 mod proc;
 mod sched;
+mod signal;
 mod trap;
 mod uma;
 
@@ -87,6 +88,8 @@ fn create_init() {
     let flags = Fork::new().with_copy_fd(true);
 
     pmgr.fork(flags).unwrap();
+
+    todo!()
 }
 
 /// See `scheduler` function on the PS4 for a reference.

kernel/src/proc/mod.rs

@@ -4,6 +4,7 @@ pub use self::process::*;
 pub use self::thread::*;
 
 use crate::lock::{MappedMutex, Mutex, MutexGuard};
+use crate::signal::Signal;
 use alloc::sync::{Arc, Weak};
 use bitfield_struct::bitfield;
 use core::error::Error;
@@ -35,12 +36,15 @@ impl ProcMgr {
 
     /// Our implementation imply `RFPROC` since it is always specified on the PS4.
     ///
-    /// We also imply `FSTOPPED` to make [`ProcMgr`] not depend on a scheduler.
+    /// We also imply `RFSTOPPED` to make [`ProcMgr`] not depend on a scheduler.
     ///
     /// See `fork1` on the PS4 for a reference.
     pub fn fork(&self, flags: Fork) -> Result<Arc<Proc>, ForkError> {
         // TODO: Refactor this for readability.
-        if (flags.into_bits() & 0x60008f8b) != 0 {
+        if (flags.into_bits() & 0x60008f8b) != 0
+            || flags.copy_fd() && flags.clear_fd()
+            || flags.parent_signal().into_bits() != 0 && !flags.custom_signal()
+        {
             return Err(ForkError::InvalidFlags);
         }
 
@@ -51,14 +55,47 @@ impl ProcMgr {
 /// Flags to control behavior of [`ProcMgr::fork()`].
 #[bitfield(u32)]
 pub struct Fork {
-    #[bits(2)]
-    __: u8,
-    /// Duplicate file descriptor table to the child instead of sharing it with the parent.
+    __: bool,
+    __: bool,
+    /// Duplicate file descriptor table to the child instead of sharing it with the parent. Cannot
+    /// used together with [`Self::clear_fd()`].
     ///
     /// This has the same value as `RFFDG`.
     pub copy_fd: bool,
-    #[bits(29)]
-    __: u32,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    /// Create an empty file descriptor table for the child. Cannot used together with
+    /// [`Self::copy_fd()`].
+    ///
+    /// This has the same value as `RFCFDG`.
+    pub clear_fd: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
+    /// Enable [`Self::parent_signal()`].
+    ///
+    /// This has the same value as `RFTSIGZMB`.
+    pub custom_signal: bool,
+    /// Use this signal instead of `SIGCHLD` to notify the parent. Requires
+    /// [`Self::custom_signal()`] to be enabled.
+    ///
+    /// This has the same value produced by `RFTSIGNUM` macro.
+    #[bits(8)]
+    pub parent_signal: Signal,
+    __: bool,
+    __: bool,
+    __: bool,
+    __: bool,
 }
 
 /// Represents an error when [`ProcMgr::fork()`] fails.

kernel/src/signal/mod.rs

@@ -0,0 +1,18 @@
+/// Value of *nix signal.
+#[derive(Debug, Clone, Copy)]
+pub struct Signal(u8);
+
+impl Signal {
+    const MAX: u8 = 128; // _SIG_MAXSIG
+
+    /// # Panics
+    /// If `v` is not a valid signal number.
+    pub const fn from_bits(v: u8) -> Self {
+        assert!(v <= Self::MAX);
+        Self(v)
+    }
+
+    pub const fn into_bits(self) -> u8 {
+        self.0
+    }
+}

src/kernel/src/signal/mod.rs

@@ -82,9 +82,6 @@ impl SignalManager {
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub struct Signal(NonZeroI32);
-
 impl Signal {
     pub const fn new(raw: i32) -> Option<Self> {
         match raw {
@@ -159,7 +156,6 @@ pub fn strsignal(sig: Signal) -> Cow<'static, str> {
     strsignal_impl(sig)
 }
 
-pub const SIG_MAXSIG: i32 = 128;
 pub const SIG_IGN: usize = 1;
 pub const SIG_DFL: usize = 0;