Implement semget syscall

docs/src/kernel/linux-compatibility.md

@@ -84,7 +84,7 @@ provided by Linux on x86-64 architecture.
 | 61      | wait4            | ✅              |
 | 62      | kill             | ✅              |
 | 63      | uname            | ✅              |
-| 64      | semget           | ❌              |
+| 64      | semget           | ✅              |
 | 65      | semop            | ❌              |
 | 66      | semctl           | ❌              |
 | 67      | shmdt            | ❌              |

kernel/aster-nix/src/syscall/arch/x86.rs

@@ -89,6 +89,7 @@ use crate::syscall::{
     sched_getaffinity::sys_sched_getaffinity,
     sched_yield::sys_sched_yield,
     select::sys_select,
+    semget::sys_semget,
     sendfile::sys_sendfile,
     sendmsg::sys_sendmsg,
     sendto::sys_sendto,
@@ -190,6 +191,7 @@ impl_syscall_nums_and_dispatch_fn! {
     SYS_WAIT4 = 61             => sys_wait4(args[..4]);
     SYS_KILL = 62              => sys_kill(args[..2]);
     SYS_UNAME = 63             => sys_uname(args[..1]);
+    SYS_SEMGET = 64            => sys_semget(args[..3]);
     SYS_FCNTL = 72             => sys_fcntl(args[..3]);
     SYS_FLOCK = 73             => sys_flock(args[..2]);
     SYS_FSYNC = 74             => sys_fsync(args[..1]);

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

@@ -96,6 +96,7 @@ mod rt_sigsuspend;
 mod sched_getaffinity;
 mod sched_yield;
 mod select;
+mod semget;
 mod sendfile;
 mod sendmsg;
 mod sendto;

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

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::SyscallReturn;
+use crate::{
+    ipc::{
+        semaphore::system_v::{
+            sem_set::{check_sem, create_sem_set, create_sem_set_with_id, SEMMSL},
+            PermissionMode,
+        },
+        IpcFlags,
+    },
+    prelude::*,
+};
+
+pub fn sys_semget(key: i32, nsems: i32, semflags: i32, ctx: &Context) -> Result<SyscallReturn> {
+    if nsems < 0 || nsems as usize > SEMMSL {
+        return_errno!(Errno::EINVAL);
+    }
+
+    let flags = IpcFlags::from_bits_truncate(semflags as u32);
+    let mode: u16 = (semflags as u32 & 0x1FF) as u16;
+    let nsems = nsems as usize;
+    let credentials = ctx.posix_thread.credentials();
+
+    debug!(
+        "[sys_semget] key = {}, nsems = {}, flags = {:?}",
+        key, nsems, semflags
+    );
+
+    // Create a new semaphore set directly
+    const IPC_NEW: i32 = 0;
+    if key == IPC_NEW {
+        if nsems == 0 {
+            return_errno!(Errno::EINVAL);
+        }
+        return Ok(SyscallReturn::Return(
+            create_sem_set(nsems, mode, credentials)? as isize,
+        ));
+    }
+
+    // Get a semaphore set, and create if necessary
+    match check_sem(
+        key,
+        Some(nsems),
+        PermissionMode::ALTER | PermissionMode::READ,
+    ) {
+        Ok(_) => {
+            if flags.contains(IpcFlags::IPC_CREAT | IpcFlags::IPC_EXCL) {
+                return_errno!(Errno::EEXIST);
+            }
+        }
+        Err(err) => {
+            let need_create = err.error() == Errno::ENOENT && flags.contains(IpcFlags::IPC_CREAT);
+            if !need_create {
+                return Err(err);
+            }
+            if nsems == 0 {
+                return_errno!(Errno::EINVAL);
+            }
+
+            create_sem_set_with_id(key, nsems, mode, credentials)?
+        }
+    };
+
+    Ok(SyscallReturn::Return(key as isize))
+}