kernel: Add basic process groups

kernel/src/sys/exec.cpp

@@ -117,6 +117,8 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
         current->signal_handlers[i] = { .sa_handler = SIG_DFL, .sa_mask = 0, .sa_flags = 0 };
     }
 
+    current->has_called_exec = true;
+
     kinfoln("exec: thread %lu was replaced with %s", current->id, path.chars());
 
     return 0;

kernel/src/sys/id.cpp

@@ -95,6 +95,39 @@ Result<u64> sys_setegid(Registers*, SyscallArgs args)
     return 0;
 }
 
+Result<u64> sys_setpgid(Registers*, SyscallArgs args)
+{
+    pid_t pid = (pid_t)args[0];
+    pid_t pgid = (pid_t)args[1];
+
+    auto* current = Scheduler::current();
+    if (pid == 0) pid = (pid_t)current->id;
+    if (pgid == 0) pgid = (pid_t)current->id;
+
+    if (pgid < 0) return err(EINVAL);
+
+    auto* thread = TRY(Result<Thread*>::from_option(Scheduler::find_by_pid(pid), ESRCH));
+    if (thread != current && thread->parent != current) return err(ESRCH);
+
+    // FIXME: Weird session stuff, we don't have that currently.
+
+    if (thread->has_called_exec) return err(EPERM);
+
+    if (pgid != (pid_t)current->id)
+    {
+        bool pgid_exists = false;
+        Scheduler::for_each_in_process_group(pgid, [&pgid_exists](Thread*) {
+            pgid_exists = true;
+            return false;
+        });
+        if (!pgid_exists) return err(EPERM);
+    }
+
+    thread->pgid = (u64)pgid;
+
+    return 0;
+}
+
 Result<u64> sys_fchmodat(Registers*, SyscallArgs args)
 {
     int dirfd = (int)args[0];

kernel/src/thread/Scheduler.h

@@ -45,6 +45,19 @@ namespace Scheduler
         }
     }
 
+    template <typename Callback> void for_each_in_process_group(pid_t group, Callback callback)
+    {
+        for (Thread* current = g_threads.first().value_or(nullptr); current;
+             current = g_threads.next(current).value_or(nullptr))
+        {
+            if (current->pgid == (u64)group)
+            {
+                bool should_continue = callback(current);
+                if (!should_continue) return;
+            }
+        }
+    }
+
     void dump_state();
 
     bool has_children(Thread* thread);

kernel/src/thread/Thread.h

@@ -57,6 +57,7 @@ struct Thread : public LinkedListNode<Thread>
     Registers regs;
 
     u64 id;
+    u64 pgid { 0 };
 
     Credentials auth;
 
@@ -82,14 +83,14 @@ struct Thread : public LinkedListNode<Thread>
 
     struct sigaction signal_handlers[NSIG];
     sigset_t signal_mask { 0 };
-
+    sigset_t pending_signals { 0 };
-    int pending_signals { 0 };
 
     FPData fp_data;
 
     ThreadState state = ThreadState::Runnable;
 
     bool is_kernel { true };
+    bool has_called_exec { false };
 
     int status { 0 };
 

libc/src/unistd.cpp

@@ -144,6 +144,12 @@ extern "C"
         __errno_return(rc, int);
     }
 
+    int setpgid(pid_t pid, pid_t pgid)
+    {
+        long rc = syscall(SYS_setpgid, pid, pgid);
+        __errno_return(rc, int);
+    }
+
     int chown(const char* path, uid_t uid, gid_t gid)
     {
         long rc = syscall(SYS_fchownat, AT_FDCWD, path, uid, gid, 0);

libluna/include/luna/Syscall.h

@@ -6,7 +6,7 @@
             _e(getgid) _e(getegid) _e(setuid) _e(setgid) _e(seteuid) _e(setegid) _e(fchmodat) _e(fchownat) _e(ioctl)   \
                 _e(fstatat) _e(chdir) _e(getcwd) _e(unlinkat) _e(uname) _e(sethostname) _e(dup2) _e(pipe) _e(mount)    \
                     _e(umount) _e(pstat) _e(getrusage) _e(symlinkat) _e(readlinkat) _e(umask) _e(linkat) _e(faccessat) \
-                        _e(pivot_root) _e(sigreturn) _e(sigaction) _e(kill) _e(sigprocmask)
+                        _e(pivot_root) _e(sigreturn) _e(sigaction) _e(kill) _e(sigprocmask) _e(setpgid)
 
 enum Syscalls
 {