terminal fixes

src/kernel/cmd.c

@@ -871,10 +871,12 @@ void cmd_screen_clear() {
         for(int c=0; c<terminal_cols; c++) {
             screen_buffer[r * terminal_cols + c].c = ' ';
             screen_buffer[r * terminal_cols + c].color = COLOR_DARK_TEXT;
+            screen_buffer[r * terminal_cols + c].attrs = 0;
         }
     }
     cursor_row = 0;
     cursor_col = 0;
+    wm_mark_dirty(win_cmd.x, win_cmd.y, win_cmd.w, win_cmd.h);
 }
 
 // Public for CLI apps to use - exit/close the terminal window
@@ -1159,8 +1161,6 @@ void cmd_process_finished(void) {
             return;
         }
 
-        extern int cursor_col;
-        void cmd_putchar(char c);
         if (cursor_col > 0) {
             cmd_putchar('\n');
         }
@@ -2000,6 +2000,21 @@ void cmd_handle_click(Window *win, int x, int y) {
     }
 }
 
+static void cmd_handle_close(Window *win) {
+    if (!win) return;
+    
+    extern process_t* process_get_by_ui_window(void *win);
+    extern void process_terminate(process_t *proc);
+    
+    // Find any process associated with this terminal window and terminate it
+    process_t *proc = process_get_by_ui_window(win);
+    if (proc) {
+        process_terminate(proc);
+    }
+    
+    win->visible = false;
+}
+
 void cmd_set_raw_mode(bool enabled) {
     terminal_raw_mode = enabled;
 }
@@ -2470,6 +2485,7 @@ void cmd_init(void) {
     win_cmd.handle_key = cmd_key;
     win_cmd.handle_click = cmd_handle_click;
     win_cmd.handle_right_click = NULL;
+    win_cmd.handle_close = cmd_handle_close;
     win_cmd.handle_resize = cmd_handle_resize;
     win_cmd.resizable = true;
     

src/kernel/network.c

@@ -272,6 +272,27 @@ int network_tcp_recv(void *buf, size_t max_len) {
     return (int)copied;
 }
 
+int network_tcp_recv_nb(void *buf, size_t max_len) {
+    if (network_processing) return -1;
+    network_processing = 1;
+
+    if (!tcp_recv_queue) {
+        network_processing = 0;
+        return 0;
+    }
+    
+    size_t to_copy = max_len;
+    if (to_copy > tcp_recv_queue->tot_len) to_copy = tcp_recv_queue->tot_len;
+    if (to_copy > 0xFFFF) to_copy = 0xFFFF; // pbuf_copy_partial limit
+
+    size_t copied = pbuf_copy_partial(tcp_recv_queue, buf, (u16_t)to_copy, 0);
+    struct pbuf *remainder = pbuf_free_header(tcp_recv_queue, (u16_t)copied);
+    if (current_tcp_pcb) tcp_recved(current_tcp_pcb, (u16_t)copied);
+    tcp_recv_queue = remainder;
+    network_processing = 0;
+    return (int)copied;
+}
+
 int network_tcp_close(void) {
     if (network_processing) return 0;
     network_processing = 1;

src/kernel/network.h

@@ -89,6 +89,13 @@ int network_dhcp_acquire(void);
 int network_get_gateway_ip(ipv4_address_t* ip);
 int network_get_dns_ip(ipv4_address_t *ip);
 int network_icmp_single_ping(ipv4_address_t *dest);
+int network_tcp_connect(const ipv4_address_t *ip, uint16_t port);
+int network_tcp_send(const void *data, size_t len);
+int network_tcp_recv(void *buf, size_t max_len);
+int network_tcp_recv_nb(void *buf, size_t max_len);
+int network_tcp_close(void);
+int network_dns_lookup(const char *name, ipv4_address_t *out_ip);
+int network_set_dns_server(const ipv4_address_t *ip);
 void network_cleanup(void);
 void network_force_unlock(void);
 

src/kernel/process.c

@@ -329,6 +329,72 @@ uint64_t process_schedule(uint64_t current_rsp) {
     return current_process->rsp;
 }
 
+static void process_cleanup_inner(process_t *proc) {
+    if (!proc || proc->pid == 0xFFFFFFFF) return;
+
+    // 1. Cleanup side effects
+    extern Window win_cmd;
+    if (proc->ui_window && (proc->ui_window != &win_cmd)) {
+        wm_remove_window((Window *)proc->ui_window);
+        proc->ui_window = NULL;
+    }
+    
+    extern void fat32_close(struct FAT32_FileHandle *fh);
+    for (int i = 0; i < MAX_PROCESS_FDS; i++) {
+        if (proc->fds[i]) {
+            fat32_close(proc->fds[i]);
+            proc->fds[i] = NULL;
+        }
+    }
+    
+    extern void cmd_process_finished(void);
+    cmd_process_finished();
+    
+    extern void network_cleanup_pcb(void *pcb);
+    // TODO: We need per-process PCB tracking to call this safely
+    // For now, let's NOT call global network_cleanup
+}
+
+void process_terminate(process_t *to_delete) {
+    if (!to_delete || to_delete->pid == 0xFFFFFFFF) return;
+
+    uint64_t rflags;
+    asm volatile("pushfq; pop %0; cli" : "=r"(rflags));
+
+    process_cleanup_inner(to_delete);
+
+    // 2. Find previous process in circular list
+    process_t *prev = to_delete;
+    while (prev->next != to_delete) {
+        prev = prev->next;
+    }
+
+    if (prev == to_delete) {
+        // Only one process (should be kernel), cannot terminate.
+        asm volatile("push %0; popfq" : : "r"(rflags));
+        return;
+    }
+
+    // 3. Remove current from list
+    prev->next = to_delete->next;
+    
+    if (to_delete == current_process) {
+        current_process = to_delete->next;
+        // WARNING: If this was called as a regular function and not via a task switch,
+        // the stack might be in a weird state. But usually we call this via window manager
+        // or other external triggers.
+    }
+
+    // Mark slot as free
+    to_delete->pid = 0xFFFFFFFF; 
+
+    if (to_delete->user_stack_alloc) kfree(to_delete->user_stack_alloc);
+    to_delete->user_stack_alloc = NULL;
+    to_delete->kernel_stack_alloc = NULL; 
+
+    asm volatile("push %0; popfq" : : "r"(rflags));
+}
+
 uint64_t process_terminate_current(void) {
     uint64_t rflags;
     asm volatile("pushfq; pop %0; cli" : "=r"(rflags));
@@ -338,26 +404,7 @@ uint64_t process_terminate_current(void) {
         return 0;
     }
     
-    // 1. Cleanup side effects
-    extern Window win_cmd;
-    if (current_process->ui_window && (current_process->ui_window != &win_cmd)) {
-        wm_remove_window((Window *)current_process->ui_window);
-        current_process->ui_window = NULL;
-    }
-    
-    extern void fat32_close(struct FAT32_FileHandle *fh);
-    for (int i = 0; i < MAX_PROCESS_FDS; i++) {
-        if (current_process->fds[i]) {
-            fat32_close(current_process->fds[i]);
-            current_process->fds[i] = NULL;
-        }
-    }
-    
-    extern void cmd_process_finished(void);
-    cmd_process_finished();
-
-    extern void network_cleanup(void);
-    network_cleanup();
+    process_cleanup_inner(current_process);
 
     // 2. Find previous process in circular list
     process_t *prev = current_process;

src/kernel/process.h

@@ -55,6 +55,7 @@ process_t* process_create_elf(const char* filepath, const char* args_str);
 process_t* process_get_current(void);
 uint64_t process_schedule(uint64_t current_rsp);
 uint64_t process_terminate_current(void);
+void process_terminate(process_t *proc);
 
 void process_push_gui_event(process_t *proc, gui_event_t *ev);
 process_t* process_get_by_ui_window(void* win);

src/kernel/syscall.c

@@ -153,7 +153,14 @@ static void user_window_resize(Window *win, int w, int h) {
 }
 
 
-static uint64_t syscall_handler_inner(uint64_t syscall_num, uint64_t arg1, uint64_t arg2, uint64_t arg3, uint64_t arg4, uint64_t arg5) {
+static uint64_t syscall_handler_inner(registers_t *regs) {
+    uint64_t syscall_num = regs->rax;
+    uint64_t arg1 = regs->rdi;
+    uint64_t arg2 = regs->rsi;
+    uint64_t arg3 = regs->rdx;
+    uint64_t arg4 = regs->r10;
+    uint64_t arg5 = regs->r8;
+
     extern void cmd_write(const char *str);
     extern void serial_write(const char *str);
     
@@ -561,7 +568,7 @@ static uint64_t syscall_handler_inner(uint64_t syscall_num, uint64_t arg1, uint6
         } else if (cmd == GUI_CMD_GET_EVENT) {
             Window *win = (Window *)arg2;
             gui_event_t *ev_out = (gui_event_t *)arg3;
-            if (!win || !ev_out) return 0;
+            if (!ev_out) return 0;
             if (proc->gui_event_head != proc->gui_event_tail) {
                 *ev_out = proc->gui_events[proc->gui_event_head];
                 proc->gui_event_head = (proc->gui_event_head + 1) % MAX_GUI_EVENTS;
@@ -1056,6 +1063,11 @@ static uint64_t syscall_handler_inner(uint64_t syscall_num, uint64_t arg1, uint6
             extern void cmd_set_raw_mode(bool enabled);
             cmd_set_raw_mode((bool)arg2);
             return 0;
+        } else if (cmd == 42) { // SYSTEM_CMD_TCP_RECV_NB
+            void *buf = (void *)arg2;
+            size_t max_len = (size_t)arg3;
+            extern int network_tcp_recv_nb(void *buf, size_t max_len);
+            return (uint64_t)network_tcp_recv_nb(buf, max_len);
         }
         return -1;
     }
@@ -1071,8 +1083,14 @@ uint64_t syscall_handler_c(registers_t *regs) {
         return process_terminate_current();
     }
     
+    if (syscall_num == 5 && regs->rdi == 43) { // SYSTEM_CMD_YIELD
+        extern uint64_t process_schedule(uint64_t current_rsp);
+        regs->rax = 0;
+        return process_schedule((uint64_t)regs);
+    }
+    
     // Normal syscalls
-    regs->rax = syscall_handler_inner(regs->rax, regs->rdi, regs->rsi, regs->rdx, regs->r10, regs->r8);
+    regs->rax = syscall_handler_inner(regs);
     
     // Return current RSP to assembly wrapper
     return (uint64_t)regs;

src/kernel/userland/libc/syscall.c

@@ -207,6 +207,10 @@ int sys_tcp_recv(void *buf, size_t max_len) {
     return (int)syscall3(SYS_SYSTEM, SYSTEM_CMD_TCP_RECV, (uint64_t)buf, (uint64_t)max_len);
 }
 
+int sys_tcp_recv_nb(void *buf, size_t max_len) {
+    return (int)syscall3(SYS_SYSTEM, SYSTEM_CMD_TCP_RECV_NB, (uint64_t)buf, (uint64_t)max_len);
+}
+
 int sys_tcp_close(void) {
     return (int)syscall2(SYS_SYSTEM, SYSTEM_CMD_TCP_CLOSE, 0);
 }
@@ -223,3 +227,7 @@ void sys_network_force_unlock(void) {
     syscall2(SYS_SYSTEM, SYSTEM_CMD_NET_UNLOCK, 0);
 }
 
+void sys_yield(void) {
+    syscall1(SYS_SYSTEM, SYSTEM_CMD_YIELD);
+}
+

src/kernel/userland/libc/syscall.h

@@ -69,6 +69,8 @@
 #define SYSTEM_CMD_SET_DNS 38
 #define SYSTEM_CMD_NET_UNLOCK 39
 #define SYSTEM_CMD_SET_RAW_MODE 41
+#define SYSTEM_CMD_TCP_RECV_NB 42
+#define SYSTEM_CMD_YIELD 43
 
 // Internal assembly entry into Ring 0
 extern uint64_t syscall0(uint64_t sys_num);
@@ -133,10 +135,12 @@ void sys_set_text_color(uint32_t color);
 int sys_tcp_connect(const net_ipv4_address_t *ip, uint16_t port);
 int sys_tcp_send(const void *data, size_t len);
 int sys_tcp_recv(void *buf, size_t max_len);
+int sys_tcp_recv_nb(void *buf, size_t max_len);
 int sys_tcp_close(void);
 int sys_dns_lookup(const char *name, net_ipv4_address_t *out_ip);
 int sys_set_dns_server(const net_ipv4_address_t *ip);
 void sys_network_force_unlock(void);
+void sys_yield(void);
 
 
 #endif

src/kernel/userland/telnet.c

@@ -363,7 +363,7 @@ int main(int argc, char **argv) {
         }
         if (!connected) break;
 
-        int len = sys_tcp_recv(recv_buf, sizeof(recv_buf) - 1);
+        int len = sys_tcp_recv_nb(recv_buf, sizeof(recv_buf) - 1);
         if (len < 0) {
             printf("\r\n[Connection error]\r\n");
             connected = 0;
@@ -377,8 +377,7 @@ int main(int argc, char **argv) {
                 connected = 0;
                 break;
             }
-            // Brief spin
-            for (volatile int d = 0; d < 100; d++);
+            sys_yield();
             continue;
         }