Added privilidges

docs/overview.md

@@ -157,7 +157,14 @@ void kmain(BootInfo *Boot)
     /* ---- Spawn Starling Terminal as its own task ---- */
     ctx = (StarlingContext *)kmalloc(sizeof(StarlingContext));
     ...
-    terminal_task = task_create(L"starling-term", starling_terminal_task, ctx);
+    ctx->Boot       = Boot;
+    ctx->depth      = 0;
+    ctx->shell_priv = TASK_PRIV_USER;
+
+    terminal_task = task_create_with_priv(L"starling-term",
+                                          starling_terminal_task,
+                                          ctx,
+                                          TASK_PRIV_USER);
     if (terminal_task == NULL) {
         ...
         starling_terminal_task(Boot);
@@ -180,7 +187,7 @@ void kmain(BootInfo *Boot)
    - `idt_init(Boot)` to install the kernel's Interrupt Descriptor Table and exception handlers.
    - `memory_init(Boot)` to bring up the physical allocator, paging helpers, and heap.
    - `task_init(Boot)` to bootstrap the cooperative scheduler and register the current thread as task 0.
-3. **User interface** – prints a banner and spawns the Starling Terminal as a separate task via `task_create`, then turns the core thread into an idle loop that continuously `task_yield`s to allow other tasks to run.
+3. **User interface** – prints a banner and spawns the Starling Terminal as a separate task via `task_create_with_priv` with `TASK_PRIV_USER` privilege, then turns the core thread into an idle loop that continuously `task_yield`s to allow other tasks to run.
 
 At this point, the system has:
 
@@ -206,10 +213,12 @@ static void starling_terminal_task(void *arg)
         return;
     }
 
-    Boot = ctx->Boot;
-    depth = ctx->depth;
+    Boot       = ctx->Boot;
+    depth      = ctx->depth;
+    shell_priv = ctx->shell_priv;
 
-    SAFE_PRINT(Boot, L"\n\r[Starling Terminal depth %d] ready.\n\r\n\r", depth);
+    SAFE_PRINT(Boot, L"\n\r[Starling Terminal depth %d, priv %d] ready.\n\r\n\r",
+               depth, (INT32)shell_priv);
     SAFE_PRINT(Boot, L"starling> ");
 
     while (TRUE) {
@@ -234,7 +243,7 @@ static void starling_terminal_task(void *arg)
             trim_spaces_inplace(line);
             ...
             } else {
-                Task *cmd_task = execute_command(Boot, line);
+                Task *cmd_task = execute_command(Boot, line, shell_priv);
 
                 /* If a command task was spawned, wait for it to finish. */
                 if (cmd_task != NULL) {
@@ -258,7 +267,7 @@ Key points:
 
 - **Non-blocking idle**: when `try_read_key` returns no key, the terminal calls `task_yield()` so other tasks can run while the user is idle.
 - **Line editing**: handles printable ASCII and backspace to maintain a simple line buffer (`line[128]`).
-- **Command execution**: on Enter, the line is trimmed and passed to `execute_command(Boot, line)` in `commands.c`. If that function spawns a dedicated command task, the terminal waits for it via `task_wait`.
+- **Command execution**: on Enter, the line is trimmed and passed to `execute_command(Boot, line, shell_priv)` in `commands.c`, propagating the shell's privilege level. If that function spawns a dedicated command task, the terminal waits for it via `task_wait`.
 - **Nested terminals**: entering `starling` recursively spawns another Starling Terminal task with increased `depth`, demonstrating multi-level shells.
 
 The command registry and dispatch path are documented in detail in `commands-and-terminal.md`.
@@ -278,15 +287,17 @@ The kernel is organised into focused subsystems, each in its own translation uni
 - **Tasks and scheduler** (`task.c` + `task.h`):
   - Static process control block (PCB) pool.
   - Cooperative round-robin scheduler.
+  - Software privilege levels (`TASK_PRIV_USER`, `TASK_PRIV_DRIVER`, `TASK_PRIV_KERNEL`) for access control.
   - Stack management and context switch support (via an external `context_switch` assembly routine).
 - **Interrupts and exceptions** (`idt.c` + `idt.h`):
   - IDT mirroring of firmware entries.
   - Replacement of CPU exception vectors 0–31 with kernel stubs.
   - Central `isr_handler` that prints diagnostics and halts on unrecoverable faults.
 - **Commands and shell** (`commands.c` + `commands.h`):
-  - Command registry and help/man system.
+  - Command registry with per-command minimum privilege levels and help/man system.
   - System control commands (`shutdown`, `about`, `mem`, `ps`).
   - Test commands (`memtest`, `tasktest`, `spawn`) that exercise memory and scheduler subsystems in isolation.
+  - Privilege escalation command (`kusr`) for running commands with elevated privilege.
 
 Each of these subsystems is covered in a dedicated document: