Add syscall getpgid

docs/src/kernel/linux-compatibility.md

@@ -141,7 +141,7 @@ provided by Linux on x86-64 architecture.
 | 118     | getresuid        | ✅              |
 | 119     | setresgid        | ✅              |
 | 120     | getresgid        | ✅              |
-| 121     | getpgid          | ❌              |
+| 121     | getpgid          | ✅              |
 | 122     | setfsuid         | ✅              |
 | 123     | setfsgid         | ✅              |
 | 124     | getsid           | ✅              |

kernel/src/syscall/arch/riscv.rs

@@ -33,7 +33,7 @@ use crate::syscall::{
     getgid::sys_getgid,
     getgroups::sys_getgroups,
     getpeername::sys_getpeername,
-    getpgrp::sys_getpgrp,
+    getpgid::sys_getpgid,
     getpid::sys_getpid,
     getppid::sys_getppid,
     getrandom::sys_getrandom,
@@ -214,7 +214,7 @@ impl_syscall_nums_and_dispatch_fn! {
     SYS_SETFSUID = 151           => sys_setfsuid(args[..1]);
     SYS_SETFSGID = 152           => sys_setfsgid(args[..1]);
     SYS_SETPGID = 154            => sys_setpgid(args[..2]);
-    SYS_GETPGRP = 155            => sys_getpgrp(args[..0]);
+    SYS_GETPGID = 155            => sys_getpgid(args[..1]);
     SYS_GETSID = 156             => sys_getsid(args[..1]);
     SYS_SETSID = 157             => sys_setsid(args[..0]);
     SYS_GETGROUPS = 158          => sys_getgroups(args[..2]);

kernel/src/syscall/arch/x86.rs

@@ -36,6 +36,7 @@ use crate::syscall::{
     getgid::sys_getgid,
     getgroups::sys_getgroups,
     getpeername::sys_getpeername,
+    getpgid::sys_getpgid,
     getpgrp::sys_getpgrp,
     getpid::sys_getpid,
     getppid::sys_getppid,
@@ -241,6 +242,7 @@ impl_syscall_nums_and_dispatch_fn! {
     SYS_GETRESUID = 118        => sys_getresuid(args[..3]);
     SYS_SETRESGID = 119        => sys_setresgid(args[..3]);
     SYS_GETRESGID = 120        => sys_getresgid(args[..3]);
+    SYS_GETPGID = 121          => sys_getpgid(args[..1]);
     SYS_SETFSUID = 122         => sys_setfsuid(args[..1]);
     SYS_SETFSGID = 123         => sys_setfsgid(args[..1]);
     SYS_GETSID = 124           => sys_getsid(args[..1]);

kernel/src/syscall/getpgid.rs

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::SyscallReturn;
+use crate::{
+    prelude::*,
+    process::{process_table, Pid},
+};
+
+pub fn sys_getpgid(pid: Pid, ctx: &Context) -> Result<SyscallReturn> {
+    debug!("pid = {}", pid);
+    // type Pid = u32, pid would never less than 0.
+    // if pid < 0 {
+    //     return_errno_with_message!(Errno::EINVAL, "pid cannot be negative");
+    // }
+
+    // if pid is 0, should return the pgid of current process
+    if pid == 0 {
+        return Ok(SyscallReturn::Return(ctx.process.pgid() as _));
+    }
+
+    let process = process_table::get_process(pid)
+        .ok_or(Error::with_message(Errno::ESRCH, "process does not exist"))?;
+
+    if !Arc::ptr_eq(&ctx.process.session().unwrap(), &process.session().unwrap()) {
+        return_errno_with_message!(
+            Errno::EPERM,
+            "the process and current process does not belong to the same session"
+        );
+    }
+
+    Ok(SyscallReturn::Return(process.pgid() as _))
+}

kernel/src/syscall/mod.rs

@@ -44,6 +44,7 @@ mod geteuid;
 mod getgid;
 mod getgroups;
 mod getpeername;
+mod getpgid;
 mod getpgrp;
 mod getpid;
 mod getppid;