tickadj.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

				      ktick,
#ifdef K_TICK_NAME
				      K_TICK_NAME
#else
				      "<this can't happen>"
#endif			
				      );
		}
#ifdef PRESET_TICK
		(void) printf("PRESET tick = %d usec\n", tick);
#endif /* PRESET_TICK */
		if (tickadj_offset != 0)
		{
			(void) printf("KERNEL tickadj = %d usec (from %s kernel variable)\n",
				      ktickadj,
#ifdef K_TICKADJ_NAME
				      K_TICKADJ_NAME
#else
				      "<this can't happen>"
#endif
				      );
		}
#ifdef PRESET_TICKADJ
		(void) printf("PRESET tickadj = %d usec\n", tickadj);
#endif /* PRESET_TICKADJ */
		if (dosync_offset != 0)
		{
			(void) printf("dosynctodr is %s\n", dosynctodr ? "on" : "off");
		}
		if (noprintf_offset != 0)
		{
			(void) printf("kernel level printf's: %s\n",
				      noprintf ? "off" : "on");
		}
	}

	if (tick <= 0)
	{
		(void) fprintf(stderr, "%s: the value of tick is silly!\n",
			       progname);
		exit(1);
	}

	hz_int = (int)(1000000L / (long)tick);
	hz_hundredths = (int)((100000000L / (long)tick) - ((long)hz_int * 100L));
	if (!quiet)
	{
		(void) printf("KERNEL hz = %d\n", hz);
		(void) printf("calculated hz = %d.%02d Hz\n", hz_int,
			      hz_hundredths);
	}

#if defined SCO5_CLOCK
	recommend_tickadj = 100;
#else /* SCO5_CLOCK */
	tmp = (long) tick * 500L;
	recommend_tickadj = (int)(tmp / 1000000L);
	if (tmp % 1000000L > 0)
	{
		recommend_tickadj++;
	}

#ifdef MIN_REC_TICKADJ
	if (recommend_tickadj < MIN_REC_TICKADJ)
	{
		recommend_tickadj = MIN_REC_TICKADJ;
	}
#endif /* MIN_REC_TICKADJ */
#endif /* SCO5_CLOCK */
  

	if ((!quiet) && (tickadj_offset != 0))
	{
		(void) printf("recommended value of tickadj = %d us\n",
			      recommend_tickadj);
	}

	if (   writetickadj == 0
	       && !writeopttickadj
	       && !unsetdosync
	       && writetick == 0
	       && !setnoprintf)
	{
		exit(errflg ? 1 : 0);
	}

	if (writetickadj == 0 && writeopttickadj)
	{
		writetickadj = recommend_tickadj;
	}

	fd = openfile(file, O_WRONLY);

	if (setnoprintf && (noprintf_offset != 0))
	{
		if (!quiet)
		{
			(void) fprintf(stderr, "setting noprintf: ");
			(void) fflush(stderr);
		}
		writevar(fd, noprintf_offset, 1);
		if (!quiet)
		{
			(void) fprintf(stderr, "done!\n");
		}
	}

	if ((writetick > 0) && (tick_offset != 0))
	{
		if (!quiet)
		{
			(void) fprintf(stderr, "writing tick, value %d: ",
				       writetick);
			(void) fflush(stderr);
		}
		writevar(fd, tick_offset, writetick);
		if (!quiet)
		{
			(void) fprintf(stderr, "done!\n");
		}
	}

	if ((writetickadj > 0) && (tickadj_offset != 0))
	{
		if (!quiet)
		{
			(void) fprintf(stderr, "writing tickadj, value %d: ",
				       writetickadj);
			(void) fflush(stderr);
		}

#ifdef SCO5_CLOCK
		/* scale from usec/tick to nsec/sec */
		writetickadj *= (1000L * HZ);
#endif /* SCO5_CLOCK */

		writevar(fd, tickadj_offset, writetickadj);
		if (!quiet)
		{
			(void) fprintf(stderr, "done!\n");
		}
	}

	if (unsetdosync && (dosync_offset != 0))
	{
		if (!quiet)
		{
			(void) fprintf(stderr, "zeroing dosynctodr: ");
			(void) fflush(stderr);
		}
		writevar(fd, dosync_offset, 0);
		if (!quiet)
		{
			(void) fprintf(stderr, "done!\n");
		}
	}
	(void) close(fd);
	return(errflg ? 1 : 0);
}

/*
 * getoffsets - read the magic offsets from the specified file
 */
static void
getoffsets(
	off_t *tick_off,
	off_t *tickadj_off,
	off_t *dosync_off,
	off_t *noprintf_off
	)
{

#ifndef NOKMEM
# ifndef HAVE_KVM_OPEN
	const char **kname;
# endif
#endif

#ifndef NOKMEM
# ifdef NLIST_NAME_UNION
#  define NL_B {{
#  define NL_E }}
# else
#  define NL_B {
#  define NL_E }
# endif
#endif

#define K_FILLER_NAME "DavidLetterman"

#ifdef NLIST_EXTRA_INDIRECTION
	int i;
#endif

#ifndef NOKMEM
	static struct nlist nl[] =
	{
		NL_B
#ifdef K_TICKADJ_NAME
#define N_TICKADJ	0
		K_TICKADJ_NAME
#else
		K_FILLER_NAME
#endif
		NL_E,
		NL_B
#ifdef K_TICK_NAME
#define N_TICK		1
		K_TICK_NAME
#else
		K_FILLER_NAME
#endif
		NL_E,
		NL_B
#ifdef K_DOSYNCTODR_NAME
#define N_DOSYNC	2
		K_DOSYNCTODR_NAME
#else
		K_FILLER_NAME
#endif
		NL_E,
		NL_B
#ifdef K_NOPRINTF_NAME
#define N_NOPRINTF	3
		K_NOPRINTF_NAME
#else
		K_FILLER_NAME
#endif
		NL_E,
		NL_B "" NL_E,
	};

#ifndef HAVE_KVM_OPEN
	static const char *kernels[] =
	{
#ifdef HAVE_GETBOOTFILE
		NULL,			/* *** SEE BELOW! *** */
#endif
		"/kernel/unix",
		"/kernel",
		"/vmunix",
		"/unix",
		"/mach",
		"/hp-ux",
		"/386bsd",
		"/netbsd",
		"/stand/vmunix",
		"/bsd",
		NULL
	};
#endif /* not HAVE_KVM_OPEN */

#ifdef HAVE_KVM_OPEN
	/*
	 * Solaris > 2.5 doesn't have a kernel file.  Use the kvm_* interface
	 * to read the kernel name list. -- stolcke 3/4/96
	 */
	kvm_t *kvm_handle = kvm_open(NULL, NULL, NULL, O_RDONLY, progname);

	if (kvm_handle == NULL)
	{
		(void) fprintf(stderr,
			       "%s: kvm_open failed\n",
			       progname);
		exit(1);
	}
	if (kvm_nlist(kvm_handle, nl) == -1)
	{
		(void) fprintf(stderr,
			       "%s: kvm_nlist failed\n",
			       progname);
		exit(1);
	}
	kvm_close(kvm_handle);
#else /* not HAVE_KVM_OPEN */
#ifdef HAVE_GETBOOTFILE		/* *** SEE HERE! *** */
	if (kernels[0] == NULL)
	{
		char * cp = (char *)getbootfile();

		if (cp)
		{
			kernels[0] = cp;
		}
		else
		{
			kernels[0] = "/Placeholder";
		}
	}
#endif /* HAVE_GETBOOTFILE */
	for (kname = kernels; *kname != NULL; kname++)
	{
		struct stat stbuf;

		if (stat(*kname, &stbuf) == -1)
		{
			continue;
		}
		if (nlist(*kname, nl) >= 0)
		{
			break;
		}
		else
		{
			(void) fprintf(stderr,
				       "%s: nlist didn't find needed symbols from <%s>: %s\n",
				       progname, *kname, strerror(errno));
		}
	}
	if (*kname == NULL)
	{
		(void) fprintf(stderr,
			       "%s: Couldn't find the kernel\n",
			       progname);
		exit(1);
	}
#endif /* HAVE_KVM_OPEN */

	if (dokmem)
	{
		file = kmem;

		fd = openfile(file, O_RDONLY);
#ifdef NLIST_EXTRA_INDIRECTION
		/*
		 * Go one more round of indirection.
		 */
		for (i = 0; i < (sizeof(nl) / sizeof(struct nlist)); i++)
		{
			if ((nl[i].n_value) && (nl[i].n_sclass == 0x6b))
			{
				readvar(fd, nl[i].n_value, &nl[i].n_value);
			}
		}
#endif /* NLIST_EXTRA_INDIRECTION */
	}
#endif /* not NOKMEM */

	*tickadj_off  = 0;
	*tick_off     = 0;
	*dosync_off   = 0;
	*noprintf_off = 0;

#if defined(N_TICKADJ)
	*tickadj_off = nl[N_TICKADJ].n_value;
#endif

#if defined(N_TICK)
	*tick_off = nl[N_TICK].n_value;
#endif

#if defined(N_DOSYNC)
	*dosync_off = nl[N_DOSYNC].n_value;
#endif

#if defined(N_NOPRINTF)
	*noprintf_off = nl[N_NOPRINTF].n_value;
#endif
	return;
}

#undef N_TICKADJ
#undef N_TICK
#undef N_DOSYNC
#undef N_NOPRINTF


/*
 * openfile - open the file, check for errors
 */
static int
openfile(
	const char *name,
	int mode
	)
{
	int ifd;

	ifd = open(name, mode);
	if (ifd < 0)
	{
		(void) fprintf(stderr, "%s: open %s: ", progname, name);
		perror("");
		exit(1);
	}
	return ifd;
}


/*
 * writevar - write a variable into the file
 */
static void
writevar(
	int ofd,
	off_t off,
	int var
	)
{
	
	if (lseek(ofd, off, L_SET) == -1)
	{
		(void) fprintf(stderr, "%s: lseek fails: ", progname);
		perror("");
		exit(1);
	}
	if (write(ofd, (char *)&var, sizeof(int)) != sizeof(int))
	{
		(void) fprintf(stderr, "%s: write fails: ", progname);
		perror("");
		exit(1);
	}
	return;
}


/*
 * readvar - read a variable from the file
 */
static void
readvar(
	int ifd,
	off_t off,
	int *var
	)
{
	int i;
	
	if (lseek(ifd, off, L_SET) == -1)
	{
		(void) fprintf(stderr, "%s: lseek fails: ", progname);
		perror("");
		exit(1);
	}
	i = read(ifd, (char *)var, sizeof(int));
	if (i < 0)
	{
		(void) fprintf(stderr, "%s: read fails: ", progname);
		perror("");
		exit(1);
	}
	if (i != sizeof(int))
	{
		(void) fprintf(stderr, "%s: read expected %d, got %d\n",
			       progname, (int)sizeof(int), i);
		exit(1);
	}
	return;
}
#endif /* not Linux */