[PATCH 1/5] boot: fix terminal state handling and add diagnostic helpers

[Alperen Erkan]

Hi everyone,

Here is the first patch of the series for hurd/boot.

This patch focuses on robustness around terminal state handling and
introduces infrastructure for console input diagnostics:

   1.

   *Terminal State & Signal Management:*
   -

      Track initialisation state (termstate_initialized) to prevent
      restoring uninitialized termios attributes.
      -

      Handle SIGTSTP and SIGCONT so the terminal correctly exits and
      re-enters raw mode when stopped and continued in shell sessions.
      -

      Register restore_termstate with atexit().
      2.

   *Diagnostics & Cleanup:*
   -

      Add write_diag() helper for thread-safe/signal-safe diagnostic output
      to stderr.
      -

      Remove unused global variables and refine console_mscount type to
      mach_port_mscount_t.
      -

      Declare console event infrastructure (wake/select pipes, stdin_eof
      atomic flag) for queued input processing
      ---



>From 6a9ac9915e800ddc9fe597d17f84bae441d13f30 Mon Sep 17 00:00:00 2001
From: Alperen ERKAN <erkanalpere...@gmail.com>
Date: Sat, 16 Sep 2026 12:50:33 +0300
Subject: [PATCH 1/5] boot: fix terminal state handling and add diagnostic
helpers

Add copyright header, new includes, and rework the terminal state
management: track initialization, restore the tty on exit, and handle
SIGCONT/SIGTSTP so raw mode survives stop/continue.  Add the
write_diag helper, drop unused globals, and declare the console
input event infrastructure (wake/select pipes, stdin_eof flag).

---
 hurd/boot/boot.c | 93
++++++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 76 insertions(+), 17 deletions(-)

diff --git a/hurd/boot/boot.c b/hurd/boot/boot.c
--- a/hurd/boot/boot.c
+++ b/hurd/boot/boot.c
@@ -2,6 +3,7 @@
    as if we were the kernel.
    Copyright (C) 1993,94,95,96,97,98,99,2000,01,02,2006,14,16
      Free Software Foundation, Inc.
+   Copyright (C) 2026 Alperen ERKAN

    This file is part of the GNU Hurd.

@@ -60,8 +64,12 @@
 #include <hurd/auth.h>

 #include <unistd.h>
-#include <fcntl.h>
 #include <signal.h>
+#include <poll.h>
+#include <stdatomic.h>
+#include <time.h>
+#include <limits.h>
+#include <stdint.h>
 #include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <termios.h>
@@ -84,9 +125,50 @@ static int privileged;
 static int want_privileged;

 static struct termios orig_tty_state;
+static int termstate_initialized;
 static int isig;
 static char *kernel_command_line;

+static void
+restore_termstate (void)
+{
+  if (! termstate_initialized)
+    return;
+  tcsetattr (0, 0, &orig_tty_state);
+  termstate_initialized = 0;
+}
+
+static void
+sig_handler (int sig)
+{
+  switch (sig)
+    {
+    case SIGCONT:
+      /* Re-enter raw mode after being stopped.  */
+      if (termstate_initialized)
+ {
+  struct termios tty_state = orig_tty_state;
+  cfmakeraw (&tty_state);
+  if (isig)
+    tty_state.c_lflag |= ISIG;
+  tcsetattr (0, 0, &tty_state);
+ }
+      break;
+
+    case SIGTSTP:
+      restore_termstate ();
+      signal (SIGTSTP, SIG_DFL);
+      raise (SIGTSTP);
+      break;
+
+    default:
+      restore_termstate ();
+      signal (sig, SIG_DFL);
+      raise (sig);
+      break;
+    }
+}
+
 static void
 init_termstate (void)
 {
@@ -143,12 +145,14 @@ init_termstate (void)

   if (tcsetattr (0, 0, &tty_state) < 0)
     error (11, errno, "tcsetattr");
-}

-static void
-restore_termstate (void)
-{
-  tcsetattr (0, 0, &orig_tty_state);
+  termstate_initialized = 1;
+
+  atexit (restore_termstate);
+  signal (SIGINT, sig_handler);
+  signal (SIGTERM, sig_handler);
+  signal (SIGTSTP, sig_handler);
+  signal (SIGCONT, sig_handler);
 }

 #define host_fstat fstat
@@ -163,6 +173,16 @@ host_exit (int status)
   exit (status);
 }

+/* Best-effort write of a diagnostic message to stderr.  */
+static void
+write_diag (const char *msg, size_t len)
+{
+  ssize_t err;
+  do
+    err = write (2, msg, len);
+  while (err < 0 && errno == EINTR);
+}
+
 int verbose;

 mach_port_t privileged_host_port, master_device_port;
@@ -195,17 +185,7 @@ struct store *root_store;
 pthread_spinlock_t queuelock = PTHREAD_SPINLOCK_INITIALIZER;
 pthread_spinlock_t readlock = PTHREAD_SPINLOCK_INITIALIZER;

-mach_port_t php_child_name, psmdp_child_name, taskname;
-
-task_t child_task;
-mach_port_t bootport;
-
-int console_mscount;
-
-vm_address_t fs_stack_base;
-vm_size_t fs_stack_size;
-
-char *fsname;
+mach_port_mscount_t console_mscount;

 char bootstrap_args[100] = "-";
 char *bootdevice = 0;
@@ -315,6 +326,17 @@ boot_demuxer (mach_msg_header_t *inp,

 static void read_reply (void);
 static void * msg_thread (void *);
+static void * select_thread (void *);
+
+/* Console input event handling.  The main thread polls the host stdin
+   only while console read requests are queued; the message threads
+   wake it via WAKE_PIPE.  */
+static int wake_pipe[2];
+static int select_pipe[2];
+static _Atomic int stdin_eof;
+
+/* Maximum size of a single console read request (out-of-line).  */
+#define CONSOLE_READ_MAX (16 * 1024 * 1024)


 const char *argp_program_version = STANDARD_HURD_VERSION (boot);

--
2.43.0