The init process now writes the current runlevel to /var/run/runlevel.

This information can be read by the "runlevel" command as well as "halt"
and "reboot". Having the information logged in /var/run/runlevel as
well as the utmp file means systems without utmp (like those running
the musl C library) can still check the current runlevel. This is
useful when running halt/reboot as these programs want to check the
runlevel.

Updated the changelog, and manual pages for halt and runlevel.

doc/Changelog

@@ -9,7 +9,13 @@ sysvinit (2.91) UNRELEASED; urgency=low
       Updated manual page for init.8 to match.
     * Version information is now fetched and defined by the Makefile.
       No more need to update the version manually in the init.c source.
-
+    * The init process now writes the current runlevel to /var/run/runlevel.
+      This information can be read by the "runlevel" command as well as "halt"
+      and "reboot". Having the information logged in /var/run/runlevel as
+      well as the utmp file means systems without utmp (like those running
+      the musl C library) can still check the current runlevel. This is
+      useful when running halt/reboot as these programs want to check the
+      runlevel.
 
 sysvinit (2.90) world; urgency=low
 

man/halt.8

@@ -95,7 +95,8 @@ never be called directly. From release 2.74 on \fBhalt\fP and \fBreboot\fP
 invoke \fBshutdown\fP(8) if the system is not in runlevel 0 or 6. This
 means that if \fBhalt\fP or \fBreboot\fP cannot find out the current
 runlevel (for example, when \fI/var/run/utmp\fP hasn't been initialized
-correctly) \fBshutdown\fP will be called, which might not be what you want.
+correctly and /var/run/runlevel does not exist) \fBshutdown\fP will be called, 
+which might not be what you want.
 Use the \fB-f\fP flag if you want to do a hard \fBhalt\fP or \fBreboot\fP.
 .PP
 The \fB-h\fP flag puts all hard disks in standby mode just before halt

man/runlevel.8

@@ -34,7 +34,9 @@ runlevel, the letter \fBN\fP will be printed instead.
 .PP
 If no
 .I utmp
-file exists, or if no runlevel record can be found,
+file exists, and if no runlevel record can be found in the
+.I /var/run/runlevel
+file,
 .B runlevel
 prints the word \fBunknown\fP and exits with an error.
 .PP

src/Makefile

@@ -107,10 +107,10 @@ all:		$(BIN) $(SBIN) $(USRBIN)
 #	$(CC) $(CFLAGS) $(CPPFLAGS) -c $^ -o $@
 
 init:		LDLIBS += $(INITLIBS) $(STATIC)
-init:		init.o init_utmp.o
+init:		init.o init_utmp.o runlevellog.o
 
 halt:		LDLIBS += $(STATIC)
-halt:		halt.o ifdown.o hddown.o utmp.o
+halt:		halt.o ifdown.o hddown.o utmp.o runlevellog.o
 
 last:		LDLIBS += $(STATIC)
 last:		last.o
@@ -148,7 +148,7 @@ sulogin.o:	sulogin.c
 runlevellog.o:	runlevellog.h runlevellog.c paths.h
 
 init.o:		CPPFLAGS += $(SELINUX_DEF)
-init.o:		init.c init.h initreq.h paths.h reboot.h set.h
+init.o:		init.c init.h initreq.h paths.h reboot.h runlevellog.h runlevellog.c set.h paths.h
 
 utmp.o:		
 
@@ -160,7 +160,7 @@ utmpdump.o:	utmpdump.c oldutmp.h
 
 shutdown.o:	shutdown.c paths.h reboot.h initreq.h init.h
 
-halt.o:		halt.c reboot.h
+halt.o:		halt.c reboot.h paths.h runlevellog.c runlevellog.h
 
 last.o:		last.c oldutmp.h
 

src/halt.c

@@ -57,6 +57,7 @@
 #include <stdio.h>
 #include <getopt.h>
 #include "reboot.h"
+#include "runlevellog.h"
 
 char *Version = "@(#)halt  2.86  31-Jul-2004 miquels@cistron.nl";
 char *progname;
@@ -90,11 +91,14 @@ void usage(void)
 /*
  *	See if we were started directly from init.
  *	Get the runlevel from /var/run/utmp or the environment.
+ *      Or the /var/run/runlevel log.
  */
 int get_runlevel(void)
 {
 	struct utmp *ut;
 	char *r;
+        int runlevel, status;
+
 #if RUNLVL_PICKY
 	time_t boottime;
 #endif
@@ -134,6 +138,11 @@ int get_runlevel(void)
 	}
 	endutent();
 
+        /* Did not find utmp entry, try to read from log file */
+        status = Read_Runlevel_Log(&runlevel);
+        if (status)
+           return runlevel;
+
 	/* This should not happen but warn the user! */
 	fprintf(stderr, "WARNING: could not determine runlevel"
 		" - doing soft %s\n", progname);

src/init.c

@@ -80,6 +80,7 @@ Version information is not placed in the top-level Makefile by default
 #include "initreq.h"
 #include "paths.h"
 #include "reboot.h"
+#include "runlevellog.h"
 #include "set.h"
 
 #ifndef SIGPWR
@@ -1905,6 +1906,7 @@ int get_init_default(void)
 	/*
 	 *	Log the fact that we have a runlevel now.
 	 */
+        Write_Runlevel_Log(lvl);
 	return lvl;
 }
 
@@ -2020,6 +2022,7 @@ int read_level(int arg)
 	write_utmp_wtmp("runlevel", "~~", foo + 256*runlevel, RUN_LVL, "~");
 	thislevel = foo;
 	prevlevel = runlevel;
+        Write_Runlevel_Log(runlevel);
 	return foo;
 }
 
@@ -2284,6 +2287,7 @@ void fifo_new_level(int level)
 			setproctitle("init [%c]", (int)runlevel);
 		}
 	}
+        Write_Runlevel_Log(runlevel);
 }
 
 
@@ -2572,6 +2576,7 @@ void boot_transitions()
 		prevlevel = oldlevel;
 		setproctitle("init [%c]", (int)runlevel);
 	}
+        Write_Runlevel_Log(runlevel);
   }
 }
 
@@ -2683,6 +2688,7 @@ void process_signals()
 			setproctitle("init [%c]", (int)runlevel);
 			DELSET(got_signals, SIGHUP);
 		}
+                Write_Runlevel_Log(runlevel);
 	}
   }
   if (ISMEMBER(got_signals, SIGUSR1)) {

src/runlevel.c

@@ -52,10 +52,10 @@ char **argv;
   status = Read_Runlevel_Log(&runlevel);
   if (status)
   {
-     printf("%c\n", runlevel);
+     printf("N %c\n", runlevel);
      return 0;
   }
-  printf("Unknown.\n");
+  printf("unknown\n");
   return(1);
 }
 

src/runlevellog.c

@@ -42,7 +42,7 @@ int Write_Runlevel_Log(int new_runlevel)
    if (status < 1)
       return FALSE;
    return TRUE;
-}   // end of writing to log function
+}
 
 
 /*
@@ -60,12 +60,11 @@ int Read_Runlevel_Log(int *runlevel)
    if (! log_file)
      return FALSE;
 
-   status = fscanf(log_file, "%c", runlevel);
+   status = fscanf(log_file, "%c", (char *) runlevel);
    fclose(log_file);
-   if (status == EOF)
+   if (status < 1)
       return FALSE;
    return TRUE;
 
-}   // end of reading from log function
-
+}