From: Tulio A M Mendes <tadryanom@hotmail.com>
Date: Sun, 19 Apr 2026 21:05:46 +0000 (-0300)
Subject: libgloss: fix isatty() and ttyname() — use TCGETS instead of TIOCGPGRP with NULL
X-Git-Url: https://projects.tadryanom.me/?a=commitdiff_plain;h=a1771488db7a7e3b587e93ca661b7128fbfaa07e;p=AdrOS.git

libgloss: fix isatty() and ttyname() — use TCGETS instead of TIOCGPGRP with NULL

isatty() in syscalls.c used ioctl(TIOCGPGRP, 0) which always failed
because the kernel rejects NULL user_arg with -EFAULT. This caused
bash to think stdin was not a terminal, running in non-interactive
mode (no prompt, no line editing).

Fix: use TCGETS (0x5401) with a stack-allocated termios struct instead.
TCGETS succeeds on any tty regardless of process group state — this
is the standard POSIX way to test for a terminal.

Also fix ttyname() in posix_stubs.c which had the same bug.
---

diff --git a/newlib/libgloss/adros/posix_stubs.c b/newlib/libgloss/adros/posix_stubs.c
index ea391696..db32cadd 100644
--- a/newlib/libgloss/adros/posix_stubs.c
+++ b/newlib/libgloss/adros/posix_stubs.c
@@ -431,7 +431,8 @@ int cfsetospeed(struct termios *t, speed_t speed) { (void)t; (void)speed; return
 
 char *ttyname(int fd) {
     /* Minimal: check if fd is a tty, return generic name */
-    int r = _sc3(SYS_IOCTL, fd, TTY_TIOCGPGRP, 0);
+    struct { uint32_t a, b, c, d; uint8_t e[8]; } t;
+    int r = _sc3(SYS_IOCTL, fd, TTY_TCGETS, (int)&t);
     if (r < 0) { errno = ENOTTY; return 0; }
     return "/dev/tty";
 }
diff --git a/newlib/libgloss/adros/syscalls.c b/newlib/libgloss/adros/syscalls.c
index 949592b9..a68a9e65 100644
--- a/newlib/libgloss/adros/syscalls.c
+++ b/newlib/libgloss/adros/syscalls.c
@@ -162,8 +162,12 @@ int mkdir(const char *path, mode_t mode) {
 }
 
 int isatty(int fd) {
-    /* Use ioctl TIOCGPGRP (0x540F) — if it succeeds, fd is a tty */
-    int r = _sc3(SYS_IOCTL, fd, 0x540F, 0);
+    /* Use ioctl TCGETS (0x5401) — if it succeeds, fd is a tty.
+     * TCGETS is the standard test: it succeeds on any terminal device
+     * regardless of process group state. TIOCGPGRP was unreliable because
+     * it requires a valid output pointer and a foreground pgrp to be set. */
+    struct { uint32_t a, b, c, d; uint8_t e[8]; } t;
+    int r = _sc3(SYS_IOCTL, fd, 0x5401, (int)&t);
     if (r < 0) {
         errno = ENOTTY;
         return 0;