syscalls: continue making brk syscall

src/kernel/kernel.c

@@ -218,7 +218,7 @@ void kmain(unsigned int magic, unsigned int info)
 	printf("huy1 points to: 0x%X huy2 points to:0x%X\n", huy, huy2);
 	printf("huy1: %s\nhuy2: %s", huy, huy2);
 
-	exec_from_file("/ebalo/aye", "/ebalo/");
+	exec_from_file("/ebalo/main", "/ebalo/");
 
 	while(1)
 	{

src/tasking/syscalls.c

@@ -263,6 +263,38 @@ int sys_getpid(TrapFrame *tf)
     return current->pid;
 }
 
+#define DivRoundUp(number, divisor) ((number + divisor - 1) / divisor)
+
+uint32_t sys_brk(TrapFrame *tf)
+{
+    if(!tf->ebx)
+    {
+        debug_log("current brk is %X\n", (uint32_t)current->brk);
+        return (uint32_t)current->brk;
+    }
+    if(tf->ebx < (uint32_t)current->brk)
+    {
+        debug_log("PIZDETS!!!! new brk less than current brk\n");
+        while(1){}
+    }
+
+    uint32_t old_brk_page = DivRoundUp((uint32_t)current->brk, 0x1000);
+    uint32_t new_brk_page = DivRoundUp(tf->ebx, 0x1000);
+
+    uint32_t pages_needed = new_brk_page - old_brk_page;
+    for(uint32_t i = 0; i < pages_needed; i++)
+    {
+        void* phys_addr = alloc_page();
+        void* virt_addr = (void*)(old_brk_page * 0x1000 + i * 0x1000);
+        map_page(phys_addr, virt_addr, 0x7);
+        debug_log("mapping page %X to %X\n", phys_addr, virt_addr);
+        memset(virt_addr, 0, 0x1000);
+        current->brk = (void*)tf->ebx;
+        debug_log("new brk is %X\n", (uint32_t)current->brk);
+    }
+    return (uint32_t)current->brk;
+}
+
 void handle_syscall(TrapFrame *tf)
 {
     /*
@@ -308,6 +340,10 @@ void handle_syscall(TrapFrame *tf)
             tf->eax = sys_getcwd(tf);
             break;
         
+        case 0x2d://brk
+            tf->eax = sys_brk(tf);
+            break;
+
         default:
             debug_log("unknown syscall: %X\n", tf->eax);
             tf->eax = -1;