syscalls: start adding exit syscall, not done yet

include/paging.h

@@ -39,6 +39,7 @@ uint32_t* get_page_dir();
 void set_page_dir(uint32_t new_page_dir);
 uint32_t phys_to_virt(uint32_t phys);
 uint32_t* create_page_dir();
+void destroy_page_dir(uint32_t* page_dir);
 
 //page_alloc.c
 void set_bit(uint32_t page_index);

include/stdio.h

@@ -14,7 +14,7 @@ int printf(const char* __restrict, ...);
 int putchar(int);
 int puts(const char*);
 
-//#define KATAU_DEBUG
+#define KATAU_DEBUG
 
 #ifdef KATAU_DEBUG
 #define debug_log printf

include/task.h

@@ -68,10 +68,12 @@ typedef struct Process
 extern Process* current;
 
 Process* task_create(uint32_t func, uint32_t user_esp, uint32_t ring, uint32_t* pagedir);
+void     task_kill(Process* proc);
+void     task_exit();
+
 void     scheduler_init();
 void     schedule();
 void     scheduler_lock();
 void     scheduler_unlock();
-void     handle_syscall(TrapFrame *tf);
 
 #endif

src/mm/paging.c

@@ -146,3 +146,27 @@ uint32_t* create_page_dir()
 
     return new_pd;
 }
+
+void destroy_page_dir(uint32_t* page_dir) {
+    // Iterate through all page directory entries
+    for (int i = 0; i < 1024; i++) {
+        if (page_dir[i] & 1) {  // If page table exists
+            uint32_t* page_table = (uint32_t*)(page_dir[i] & 0xFFFFF000);
+            
+            // Free all user pages (0-767)
+            if (i < 768) {
+                for (int j = 0; j < 1024; j++) {
+                    if (page_table[j] & 1) {
+                        free_page((void*)(page_table[j] & 0xFFFFF000));
+                    }
+                }
+            }
+            
+            // Free the page table itself
+            free_page(page_table);
+        }
+    }
+    
+    // Free the page directory
+    free_page(page_dir);
+}

src/tasking/syscalls.c

@@ -46,6 +46,14 @@ const char* flags_to_mode_str(int flags) {
     return mode;
 }
 
+int sys_exit(TrapFrame *tf)
+{
+    int error_code = tf->ebx;
+
+    task_kill(current);
+    return error_code;
+}
+
 int sys_read(TrapFrame *tf)
 {
     if(tf->ebx < 3)
@@ -72,7 +80,7 @@ int sys_write(TrapFrame *tf)
             debug_log("\n=================SYS_WRITE output to stdout=====================\n");
             print((char*)tf->ecx, tf->edx);
             debug_log("\n=================END OF THAT SHIT=====================\n");
-            tf->ecx++;
+            return tf->edx;
         }
     }
     else
@@ -141,6 +149,12 @@ void handle_syscall(TrapFrame *tf)
     debug_log("ECX: %s ", tf->ecx);
     debug_log("EDX: %X\n", tf->edx);
 
+    if(tf->eax == 1)//exit
+    {
+        int r = sys_exit(tf);
+        tf->eax = r;
+    }
+    
     if(tf->eax == 3)//read
     {
         int r = sys_read(tf);

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>
 
@@ -147,3 +148,60 @@ void scheduler_init()
 
     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();
+}