Hi Linus, Alan,
some applications do need to know where the console (/dev/console)
actually maps to. For processes with a controlling terminal, you may see
it in /proc/$$/stat. However, daemons are supposed to run detached (they
don't want to get killed by ^C) and some processes like init or bootlogd
do still need to be able to find out.
The kernel provides this information -- sort of:
It contains the TIOCTTYGSTRUCT syscall which returns a struct. Of course,
it changes between different kernel archs and revisions, so using it is
an ugly hack. Grab for TIOCTTYGSTRUCT_HACK in the bootlogd.c file of the
sysvinit sources. Shudder!
Having a new ioctl, just returning the device no is a much cleaner solution,
IMHO. So, I created the TIOCGDEV, which Miquel suggests in his sysvinit
sources. It makes querying the actual console device as easy as
int tty; ioctl (0, TIOCGDEV, &tty);
Patches against 2.2.18 and 2.4.0-testX are attached.
Please apply.
--
Kurt Garloff <[EMAIL PROTECTED]> Eindhoven, NL
GPG key: See mail header, key servers Linux kernel development
SuSE GmbH, Nuernberg, FRG SCSI, Security
diff -uNr linux-2.4.0_test10.SuSE/drivers/char/tty_io.c
linux-2.4.0_test10.TIOCGDEV/drivers/char/tty_io.c
--- linux-2.4.0_test10.SuSE/drivers/char/tty_io.c Mon Oct 16 21:58:51 2000
+++ linux-2.4.0_test10.TIOCGDEV/drivers/char/tty_io.c Fri Dec 15 19:35:23 2000
@@ -1766,7 +1766,8 @@
#endif
case TIOCTTYGSTRUCT:
return tiocttygstruct(tty, (struct tty_struct *) arg);
-
+ case TIOCGDEV:
+ return put_user (kdev_to_nr (real_tty->device, (unsigned int*)
+arg);
/*
* Break handling
*/
diff -uNr linux-2.4.0_test10.SuSE/include/asm/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm/ioctls.h Fri Jul 24 20:10:16 1998
+++ linux-2.4.0_test10.TIOCGDEV/include/asm/ioctls.h Fri Dec 15 19:39:17 2000
@@ -49,6 +49,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.4.0_test10.SuSE/include/asm-alpha/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-alpha/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-alpha/ioctls.h Fri Jan 28 01:40:09 2000
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-alpha/ioctls.h Fri Dec 15 19:41:45
+2000
@@ -91,6 +91,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
diff -uNr linux-2.4.0_test10.SuSE/include/asm-arm/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-arm/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-arm/ioctls.h Fri Feb 13 01:25:04 1998
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-arm/ioctls.h Fri Dec 15 19:42:39
+2000
@@ -49,6 +49,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.4.0_test10.SuSE/include/asm-i386/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-i386/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-i386/ioctls.h Fri Jul 24 20:10:16 1998
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-i386/ioctls.h Fri Dec 15 19:39:17
+2000
@@ -49,6 +49,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.4.0_test10.SuSE/include/asm-ia64/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-ia64/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-ia64/ioctls.h Mon Feb 7 03:42:40 2000
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-ia64/ioctls.h Fri Dec 15 19:41:31
+2000
@@ -54,6 +54,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.4.0_test10.SuSE/include/asm-m68k/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-m68k/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-m68k/ioctls.h Fri Feb 13 01:25:04 1998
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-m68k/ioctls.h Fri Dec 15 19:40:58
+2000
@@ -49,6 +49,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.4.0_test10.SuSE/include/asm-mips/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-mips/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-mips/ioctls.h Sat May 13 17:31:25 2000
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-mips/ioctls.h Fri Dec 15 19:42:54
+2000
@@ -100,6 +100,7 @@
#define TIOCGSID 0x7416 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5488
#define TIOCSERGWILD 0x5489
diff -uNr linux-2.4.0_test10.SuSE/include/asm-mips64/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-mips64/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-mips64/ioctls.h Sat May 13 17:31:25 2000
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-mips64/ioctls.h Fri Dec 15 19:37:24
+2000
@@ -100,6 +100,7 @@
#define TIOCGSID 0x7416 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5488
#define TIOCSERGWILD 0x5489
diff -uNr linux-2.4.0_test10.SuSE/include/asm-ppc/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-ppc/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-ppc/ioctls.h Sun Nov 28 00:42:33 1999
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-ppc/ioctls.h Fri Dec 15 19:42:28
+2000
@@ -88,6 +88,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
diff -uNr linux-2.4.0_test10.SuSE/include/asm-s390/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-s390/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-s390/ioctls.h Fri May 12 20:41:44 2000
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-s390/ioctls.h Fri Dec 15 19:44:04
+2000
@@ -57,6 +57,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.4.0_test10.SuSE/include/asm-sh/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-sh/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-sh/ioctls.h Sat Nov 6 19:40:31 1999
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-sh/ioctls.h Fri Dec 15 19:41:20 2000
@@ -80,6 +80,7 @@
#define TIOCGSID _IOR('T', 41, pid_t) /* 0x5429 */ /* Return the session ID of
FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG _IO('T', 83) /* 0x5453 */
#define TIOCSERGWILD _IOR('T', 84, int) /* 0x5454 */
diff -uNr linux-2.4.0_test10.SuSE/include/asm-sparc/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-sparc/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-sparc/ioctls.h Sun Oct 4 19:22:44 1998
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-sparc/ioctls.h Fri Dec 15 19:39:50
+2000
@@ -99,6 +99,7 @@
#define TIOCSSERIAL 0x541F
#define TCSBRKP 0x5425
#define TIOCTTYGSTRUCT 0x5426
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
#define TIOCSERSWILD 0x5455
diff -uNr linux-2.4.0_test10.SuSE/include/asm-sparc64/ioctls.h
linux-2.4.0_test10.TIOCGDEV/include/asm-sparc64/ioctls.h
--- linux-2.4.0_test10.SuSE/include/asm-sparc64/ioctls.h Wed Apr 15 02:44:24
1998
+++ linux-2.4.0_test10.TIOCGDEV/include/asm-sparc64/ioctls.h Fri Dec 15 19:40:18
+2000
@@ -100,6 +100,7 @@
#define TIOCSSERIAL 0x541F
#define TCSBRKP 0x5425
#define TIOCTTYGSTRUCT 0x5426
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
#define TIOCSERSWILD 0x5455
diff -uNr linux-2.2.18.SuSE/drivers/char/tty_io.c
linux-2.2.18.TIOCGDEV/drivers/char/tty_io.c
--- linux-2.2.18.SuSE/drivers/char/tty_io.c Thu Dec 14 22:38:30 2000
+++ linux-2.2.18.TIOCGDEV/drivers/char/tty_io.c Fri Dec 15 17:39:05 2000
@@ -1768,6 +1768,9 @@
case TIOCTTYGSTRUCT:
return tiocttygstruct(tty, (struct tty_struct *) arg);
+ case TIOCGDEV:
+ return put_user (kdev_t_to_nr (real_tty->device), (unsigned
+int *) arg);
+
/*
* Break handling
*/
diff -uNr linux-2.2.18.SuSE/include/asm-alpha/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-alpha/ioctls.h
--- linux-2.2.18.SuSE/include/asm-alpha/ioctls.h Fri Feb 13 01:25:04 1998
+++ linux-2.2.18.TIOCGDEV/include/asm-alpha/ioctls.h Fri Dec 15 19:51:59 2000
@@ -88,6 +88,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
diff -uNr linux-2.2.18.SuSE/include/asm-arm/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-arm/ioctls.h
--- linux-2.2.18.SuSE/include/asm-arm/ioctls.h Fri Feb 13 01:25:04 1998
+++ linux-2.2.18.TIOCGDEV/include/asm-arm/ioctls.h Fri Dec 15 19:53:09 2000
@@ -49,6 +49,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.2.18.SuSE/include/asm-i386/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-i386/ioctls.h
--- linux-2.2.18.SuSE/include/asm-i386/ioctls.h Fri Jul 24 20:10:16 1998
+++ linux-2.2.18.TIOCGDEV/include/asm-i386/ioctls.h Fri Dec 15 19:50:35 2000
@@ -49,6 +49,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.2.18.SuSE/include/asm-m68k/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-m68k/ioctls.h
--- linux-2.2.18.SuSE/include/asm-m68k/ioctls.h Fri Feb 13 01:25:04 1998
+++ linux-2.2.18.TIOCGDEV/include/asm-m68k/ioctls.h Fri Dec 15 19:51:48 2000
@@ -49,6 +49,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.2.18.SuSE/include/asm-mips/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-mips/ioctls.h
--- linux-2.2.18.SuSE/include/asm-mips/ioctls.h Mon Aug 9 21:04:41 1999
+++ linux-2.2.18.TIOCGDEV/include/asm-mips/ioctls.h Fri Dec 15 19:53:23 2000
@@ -100,6 +100,7 @@
#define TIOCGSID 0x7416 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5488
#define TIOCSERGWILD 0x5489
diff -uNr linux-2.2.18.SuSE/include/asm-ppc/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-ppc/ioctls.h
--- linux-2.2.18.SuSE/include/asm-ppc/ioctls.h Fri Feb 13 01:25:04 1998
+++ linux-2.2.18.TIOCGDEV/include/asm-ppc/ioctls.h Fri Dec 15 19:52:49 2000
@@ -88,6 +88,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
diff -uNr linux-2.2.18.SuSE/include/asm-s390/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-s390/ioctls.h
--- linux-2.2.18.SuSE/include/asm-s390/ioctls.h Tue Jan 4 19:12:24 2000
+++ linux-2.2.18.TIOCGDEV/include/asm-s390/ioctls.h Fri Dec 15 19:53:34 2000
@@ -57,6 +57,7 @@
#define TIOCGSID 0x5429 /* Return the session ID of FD */
#define TIOCGPTN _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux
device) */
#define TIOCSPTLCK _IOW('T',0x31, int) /* Lock/unlock Pty */
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff -uNr linux-2.2.18.SuSE/include/asm-sparc/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-sparc/ioctls.h
--- linux-2.2.18.SuSE/include/asm-sparc/ioctls.h Sun Oct 4 19:22:44 1998
+++ linux-2.2.18.TIOCGDEV/include/asm-sparc/ioctls.h Fri Dec 15 19:51:00 2000
@@ -99,6 +99,7 @@
#define TIOCSSERIAL 0x541F
#define TCSBRKP 0x5425
#define TIOCTTYGSTRUCT 0x5426
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
#define TIOCSERSWILD 0x5455
diff -uNr linux-2.2.18.SuSE/include/asm-sparc64/ioctls.h
linux-2.2.18.TIOCGDEV/include/asm-sparc64/ioctls.h
--- linux-2.2.18.SuSE/include/asm-sparc64/ioctls.h Wed Apr 15 02:44:24 1998
+++ linux-2.2.18.TIOCGDEV/include/asm-sparc64/ioctls.h Fri Dec 15 19:53:43 2000
@@ -100,6 +100,7 @@
#define TIOCSSERIAL 0x541F
#define TCSBRKP 0x5425
#define TIOCTTYGSTRUCT 0x5426
+#define TIOCGDEV _IOR('T',0x32, unsigned int) /* Get real dev no below
+/dev/console */
#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
#define TIOCSERSWILD 0x5455
