kernel: Use pid_t internally for process IDs

This removes a bunch of casts between pid_t and u64, and makes more sense since pid_t is literally the data type for process IDs.

kernel/src/arch/x86_64/Thread.cpp

@@ -106,7 +106,7 @@ bool Thread::deliver_signal(int signo, Registers* current_regs)
 
     memcpy(&regs, current_regs, sizeof(regs));
 
-    kinfoln("signal: delivering signal %d for thread %ld, ip=%p, sp=%p, handler=%p, sigreturn=%p", signo, id,
+    kinfoln("signal: delivering signal %d for thread %d, ip=%p, sp=%p, handler=%p, sigreturn=%p", signo, id,
             (void*)regs.rip, (void*)regs.rsp, (void*)handler.sa_handler, (void*)handler.__sa_sigreturn);
 
     regs.rsp -= 128; // Skip the red zone

kernel/src/fs/devices/ConsoleDevice.cpp

@@ -31,7 +31,7 @@ Result<void> ConsoleDevice::handle_background_process_group(bool can_succeed, in
     auto foreground_pgrp = m_foreground_process_group.value();
 
     auto* current = Scheduler::current();
-    if ((pid_t)current->pgid == foreground_pgrp) return {};
+    if (current->pgid == foreground_pgrp) return {};
 
     if ((current->signal_mask & (1 << (signo - 1))) || (current->signal_handlers[signo - 1].sa_handler == SIG_IGN))
     {

kernel/src/sys/exec.cpp

@@ -119,7 +119,7 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
 
     current->has_called_exec = true;
 
-    kinfoln("exec: thread %lu was replaced with %s", current->id, path.chars());
+    kinfoln("exec: thread %d was replaced with %s", current->id, path.chars());
 
     return 0;
 }

kernel/src/sys/id.cpp

@@ -101,8 +101,8 @@ Result<u64> sys_setpgid(Registers*, SyscallArgs args)
     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 (pid == 0) pid = current->id;
+    if (pgid == 0) pgid = current->id;
 
     if (pgid < 0) return err(EINVAL);
 
@@ -113,7 +113,7 @@ Result<u64> sys_setpgid(Registers*, SyscallArgs args)
 
     if (thread->has_called_exec) return err(EPERM);
 
-    if (pgid != (pid_t)current->id)
+    if (pgid != current->id)
     {
         bool pgid_exists = false;
         Scheduler::for_each_in_process_group(pgid, [&pgid_exists](Thread*) {
@@ -133,7 +133,7 @@ Result<u64> sys_getpgid(Registers*, SyscallArgs args)
     pid_t pid = (pid_t)args[0];
 
     auto* current = Scheduler::current();
-    if (pid == 0) pid = (pid_t)current->id;
+    if (pid == 0) pid = current->id;
 
     if (pid < 0) return err(EINVAL);
 

kernel/src/sys/pstat.cpp

@@ -20,8 +20,8 @@ Result<u64> sys_pstat(Registers*, SyscallArgs args)
     auto* thread = TRY(Result<Thread*>::from_option(Scheduler::find_by_pid(pid), ESRCH));
 
     struct process proc;
-    proc.ps_pid = (pid_t)thread->id;
-    proc.ps_ppid = thread->parent ? (pid_t)thread->parent->id : 0;
+    proc.ps_pid = thread->id;
+    proc.ps_ppid = thread->parent ? thread->parent->id : 0;
     proc.ps_uid = thread->auth.uid;
     proc.ps_gid = thread->auth.gid;
     proc.ps_euid = thread->auth.euid;

kernel/src/thread/Scheduler.cpp

@@ -40,7 +40,7 @@ namespace Scheduler
 
         g_idle.stack = idle_stack;
 
-        kinfoln("Created idle thread: id %lu with ip %#lx and sp %#lx", g_idle.id, g_idle.ip(), g_idle.sp());
+        kinfoln("Created idle thread: id %d with ip %#lx and sp %#lx", g_idle.id, g_idle.ip(), g_idle.sp());
 
         g_current = &g_idle;
     }
@@ -95,7 +95,7 @@ namespace Scheduler
 
         thread->state = ThreadState::Runnable;
 
-        kinfoln("Created kernel thread: id %lu with ip %#lx and sp %#lx", thread->id, thread->ip(), thread->sp());
+        kinfoln("Created kernel thread: id %d with ip %#lx and sp %#lx", thread->id, thread->ip(), thread->sp());
 
         return thread;
     }
@@ -161,7 +161,7 @@ namespace Scheduler
             thread->signal_handlers[i] = { .sa_handler = SIG_DFL, .sa_mask = 0, .sa_flags = 0 };
         }
 
-        kinfoln("Created userspace thread: id %lu with ip %#.16lx and sp %#.16lx (ksp %#lx)", thread->id, thread->ip(),
+        kinfoln("Created userspace thread: id %d with ip %#.16lx and sp %#.16lx (ksp %#lx)", thread->id, thread->ip(),
                 thread->sp(), thread->kernel_stack.top());
 
         g_threads.append(thread);
@@ -308,7 +308,7 @@ namespace Scheduler
     {
         for (auto* const thread : g_threads)
         {
-            if (thread->id == (u64)pid && thread->state != ThreadState::Dying) return thread;
+            if (thread->id == pid && thread->state != ThreadState::Dying) return thread;
         }
 
         return {};
@@ -347,11 +347,11 @@ namespace Scheduler
         CPU::disable_interrupts();
 
         kdbgln("--- BEGIN SCHEDULER DUMP ---");
-        kdbgln("current at %p, id = %zu", g_current, g_current->id);
+        kdbgln("current at %p, id = %d", g_current, g_current->id);
 
         for (const auto* thread : g_threads)
         {
-            kdbgln("%p %c [%-20s] %4zu, parent = (%-18p,%zu), state = %d, ticks: (k:%04zu,u:%04zu), status = "
+            kdbgln("%p %c [%-20s] %4d, parent = (%-18p,%d), state = %d, ticks: (k:%04zu,u:%04zu), status = "
                    "%d, cwd = %s",
                    thread, thread->is_kernel ? 'k' : 'u', thread->name.chars(), thread->id, thread->parent,
                    thread->parent ? thread->parent->id : 0, (int)thread->state, thread->kernel_ticks_self,

kernel/src/thread/Scheduler.h

@@ -50,7 +50,7 @@ namespace Scheduler
         for (Thread* current = g_threads.first().value_or(nullptr); current;
              current = g_threads.next(current).value_or(nullptr))
         {
-            if (current->pgid == (u64)group)
+            if (current->pgid == group)
             {
                 bool should_continue = callback(current);
                 if (!should_continue) return;

kernel/src/thread/Thread.cpp

@@ -11,7 +11,7 @@
 #include <luna/Atomic.h>
 #include <luna/PathParser.h>
 
-static Atomic<u64> g_next_id;
+static Atomic<pid_t> g_next_id;
 
 LinkedList<Thread> g_threads;
 
@@ -29,7 +29,7 @@ Result<Thread*> new_thread()
     return thread;
 }
 
-u64 next_thread_id()
+pid_t next_thread_id()
 {
     return g_next_id.load();
 }
@@ -98,9 +98,9 @@ Result<SharedPtr<VFS::Inode>> Thread::resolve_atfile(int dirfd, const String& pa
             if (parent->state == ThreadState::Waiting)
             {
                 auto child = *parent->child_being_waited_for;
-                if (child == -1 || child == (pid_t)id)
+                if (child == -1 || child == id)
                 {
-                    parent->child_being_waited_for = (pid_t)id;
+                    parent->child_being_waited_for = id;
                     parent->wake_up();
                 }
             }
@@ -151,7 +151,7 @@ void Thread::process_pending_signals(Registers* current_regs)
         if (pending_signals & (1 << i))
         {
             pending_signals &= ~(1 << i);
-            kinfoln("signal: executing signal %d for thread %ld", signo, id);
+            kinfoln("signal: executing signal %d for thread %d", signo, id);
             auto handler = signal_handlers[i];
             if (signo != SIGKILL && signo != SIGSTOP && handler.sa_handler == SIG_IGN)
             {

kernel/src/thread/Thread.h

@@ -56,8 +56,8 @@ struct Thread : public LinkedListNode<Thread>
 {
     Registers regs;
 
-    u64 id;
-    u64 pgid { 0 };
+    pid_t id;
+    pid_t pgid { 0 };
 
     Credentials auth;
 
@@ -159,6 +159,6 @@ bool is_in_kernel(Registers* regs);
 
 Result<Thread*> new_thread();
 
-u64 next_thread_id();
+pid_t next_thread_id();
 
 extern LinkedList<Thread> g_threads;