Add syscall accept4

docs/src/kernel/linux-compatibility.md

@@ -308,7 +308,7 @@ provided by Linux on x86-64 architecture.
 | 285     | fallocate        | ❌              |
 | 286     | timerfd_settime  | ❌              |
 | 287     | timerfd_gettime  | ❌              |
-| 288     | accept4          | ❌              |
+| 288     | accept4          | ✅              |
 | 289     | signalfd4        | ❌              |
 | 290     | eventfd2         | ✅              |
 | 291     | epoll_create1    | ✅              |

kernel/aster-nix/src/syscall/accept.rs

@@ -2,9 +2,13 @@
 
 use super::{SyscallReturn, SYS_ACCEPT};
 use crate::{
-    fs::file_table::{FdFlags, FileDesc},
+    fs::{
+        file_table::{FdFlags, FileDesc},
+        utils::{CreationFlags, StatusFlags},
+    },
     log_syscall_entry,
     prelude::*,
+    syscall::SYS_ACCEPT4,
     util::net::{get_socket_from_fd, write_socket_addr_to_user},
 };
 
@@ -16,15 +20,68 @@ pub fn sys_accept(
     log_syscall_entry!(SYS_ACCEPT);
     debug!("sockfd = {sockfd}, sockaddr_ptr = 0x{sockaddr_ptr:x}, addrlen_ptr = 0x{addrlen_ptr:x}");
 
-    let socket = get_socket_from_fd(sockfd)?;
+    let fd = do_accept(sockfd, sockaddr_ptr, addrlen_ptr, Flags::empty())?;
+    Ok(SyscallReturn::Return(fd as _))
+}
 
-    let (connected_socket, socket_addr) = socket.accept()?;
-    write_socket_addr_to_user(&socket_addr, sockaddr_ptr, addrlen_ptr)?;
+pub fn sys_accept4(
+    sockfd: FileDesc,
+    sockaddr_ptr: Vaddr,
+    addrlen_ptr: Vaddr,
+    flags: u32,
+) -> Result<SyscallReturn> {
+    log_syscall_entry!(SYS_ACCEPT4);
+    trace!("raw flags = 0x{:x}", flags);
+    let flags = Flags::from_bits_truncate(flags);
+    debug!(
+        "sockfd = {}, sockaddr_ptr = 0x{:x}, addrlen_ptr = 0x{:x}, flags = {:?}",
+        sockfd, sockaddr_ptr, addrlen_ptr, flags
+    );
 
-    let connected_fd = {
+    let fd = do_accept(sockfd, sockaddr_ptr, addrlen_ptr, flags)?;
+    Ok(SyscallReturn::Return(fd as _))
+}
+
+fn do_accept(
+    sockfd: FileDesc,
+    sockaddr_ptr: Vaddr,
+    addrlen_ptr: Vaddr,
+    flags: Flags,
+) -> Result<FileDesc> {
+    let (connected_socket, socket_addr) = {
+        let socket = get_socket_from_fd(sockfd)?;
+        socket.accept()?
+    };
+
+    if flags.contains(Flags::SOCK_NONBLOCK) {
+        connected_socket.set_status_flags(StatusFlags::O_NONBLOCK)?;
+    }
+
+    let fd_flags = if flags.contains(Flags::SOCK_CLOEXEC) {
+        FdFlags::CLOEXEC
+    } else {
+        FdFlags::empty()
+    };
+
+    if sockaddr_ptr != 0 {
+        write_socket_addr_to_user(&socket_addr, sockaddr_ptr, addrlen_ptr)?;
+    }
+
+    let fd = {
         let current = current!();
         let mut file_table = current.file_table().lock();
-        file_table.insert(connected_socket, FdFlags::empty())
+        file_table.insert(connected_socket, fd_flags)
     };
-    Ok(SyscallReturn::Return(connected_fd as _))
+
+    Ok(fd)
 }
+
+bitflags! {
+    struct Flags: u32 {
+        const SOCK_NONBLOCK = NONBLOCK;
+        const SOCK_CLOEXEC = CLOEXEC;
+    }
+}
+
+const NONBLOCK: u32 = StatusFlags::O_NONBLOCK.bits();
+const CLOEXEC: u32 = CreationFlags::O_CLOEXEC.bits();

kernel/aster-nix/src/syscall/mod.rs

@@ -5,7 +5,7 @@
 use aster_frame::cpu::UserContext;
 
 use self::{
-    accept::sys_accept,
+    accept::{sys_accept, sys_accept4},
     alarm::sys_alarm,
     bind::sys_bind,
     connect::sys_connect,
@@ -391,6 +391,7 @@ define_syscall_nums!(
     SYS_UTIMENSAT = 280,
     SYS_EPOLL_PWAIT = 281,
     SYS_EVENTFD = 284,
+    SYS_ACCEPT4 = 288,
     SYS_EVENTFD2 = 290,
     SYS_EPOLL_CREATE1 = 291,
     SYS_PIPE2 = 293,
@@ -584,6 +585,7 @@ pub fn syscall_dispatch(
         SYS_UTIMENSAT => syscall_handler!(4, sys_utimensat, args),
         SYS_EPOLL_PWAIT => syscall_handler!(5, sys_epoll_pwait, args),
         SYS_EVENTFD => syscall_handler!(1, sys_eventfd, args),
+        SYS_ACCEPT4 => syscall_handler!(4, sys_accept4, args),
         SYS_EVENTFD2 => syscall_handler!(2, sys_eventfd2, args),
         SYS_EPOLL_CREATE1 => syscall_handler!(1, sys_epoll_create1, args),
         SYS_PIPE2 => syscall_handler!(2, sys_pipe2, args),