From ab1bb94805916f1d4141956713919071e787f648 Mon Sep 17 00:00:00 2001
From: Tulio A M Mendes <tadryanom@hotmail.com>
Date: Mon, 9 Feb 2026 22:01:09 -0300
Subject: [PATCH] user: add isatty smoke test via TCGETS

---
 user/init.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/user/init.c b/user/init.c
index 1288879..277faab 100644
--- a/user/init.c
+++ b/user/init.c
@@ -76,6 +76,10 @@ enum {
     TIOCSPGRP = 0x5410,
 };
 
+enum {
+    ENOTTY = 25,
+};
+
 enum {
     ICANON = 0x0001,
     ECHO   = 0x0002,
@@ -140,6 +144,17 @@ static int sys_write(int fd, const void* buf, uint32_t len) {
     return __syscall_fix(ret);
 }
 
+static int sys_ioctl(int fd, uint32_t cmd, void* arg);
+
+static int isatty_fd(int fd) {
+    struct termios t;
+    if (sys_ioctl(fd, TCGETS, &t) < 0) {
+        if (errno == ENOTTY) return 0;
+        return -1;
+    }
+    return 1;
+}
+
 static int sys_getdents(int fd, void* buf, uint32_t len) {
     int ret;
     __asm__ volatile(
@@ -1663,6 +1678,39 @@ void _start(void) {
                   (uint32_t)(sizeof("[init] diskfs getdents OK\n") - 1));
     }
 
+    // B5: isatty() POSIX-like smoke (via ioctl TCGETS)
+    {
+        int fd = sys_open("/dev/tty", 0);
+        if (fd < 0) {
+            sys_write(1, "[init] isatty open /dev/tty failed\n",
+                      (uint32_t)(sizeof("[init] isatty open /dev/tty failed\n") - 1));
+            sys_exit(1);
+        }
+        int r = isatty_fd(fd);
+        (void)sys_close(fd);
+        if (r != 1) {
+            sys_write(1, "[init] isatty(/dev/tty) failed\n",
+                      (uint32_t)(sizeof("[init] isatty(/dev/tty) failed\n") - 1));
+            sys_exit(1);
+        }
+
+        fd = sys_open("/dev/null", 0);
+        if (fd < 0) {
+            sys_write(1, "[init] isatty open /dev/null failed\n",
+                      (uint32_t)(sizeof("[init] isatty open /dev/null failed\n") - 1));
+            sys_exit(1);
+        }
+        r = isatty_fd(fd);
+        (void)sys_close(fd);
+        if (r != 0) {
+            sys_write(1, "[init] isatty(/dev/null) expected 0\n",
+                      (uint32_t)(sizeof("[init] isatty(/dev/null) expected 0\n") - 1));
+            sys_exit(1);
+        }
+
+        sys_write(1, "[init] isatty OK\n", (uint32_t)(sizeof("[init] isatty OK\n") - 1));
+    }
+
     enum { NCHILD = 100 };
     int children[NCHILD];
     for (int i = 0; i < NCHILD; i++) {
-- 
2.43.0