syscalls: start adding exit syscall, not done yet

src/tasking/task.c

@@ -2,6 +2,7 @@
 #include "../include/stdio.h"
 #include "../include/paging.h"
 #include "../include/string.h"
+#include "../include/liballoc.h"
 
 #include <stddef.h>
 
@@ -146,4 +147,61 @@ void scheduler_init()
     uint32_t* kernel_tasks_pagedir = (uint32_t*)create_page_dir();
 
     task_create((uint32_t)idle, 0, 0, kernel_tasks_pagedir);
+}
+
+void task_exit()
+{
+    task_kill(current);
+}
+
+void task_kill(Process* proc)
+{
+    scheduler_lock();
+
+    // Remove process from scheduler queue
+    Process* prev = NULL;
+    Process* curr = queue;
+    
+    while (curr) {
+        if (curr == proc) {
+            if (prev) {
+                prev->next = curr->next;
+            } else {
+                queue = curr->next;
+            }
+            break;
+        }
+        prev = curr;
+        curr = curr->next;
+    }
+
+    for (int i = 0; i < MAX_OPEN_FILES; i++) {
+        if (proc->file_descriptors[i] != NULL) {
+            fat_fclose(proc->file_descriptors[i]);
+            free(proc->file_descriptors[i]);
+            proc->file_descriptors[i] = NULL;
+        }
+    }
+
+    // Free kernel stack
+    if (proc->kstack) {
+        uint32_t kstack_phys = (uint32_t)proc->kstack - 0xC0000000;
+        free_page((void*)kstack_phys);
+    }
+    
+    // Free process structure
+    uint32_t proc_phys = (uint32_t)proc - 0xC0000000;
+    free_page((void*)proc_phys);
+
+    // Destroy page directory and free user pages
+    destroy_page_dir(proc->pagedir);
+    
+    // Update task count and current process if needed
+    task_count--;
+    if (proc == current) {
+        current = NULL;
+        schedule();  // Switch to another process
+    }
+
+    scheduler_unlock();
 }