2052 lines
71 KiB
C
2052 lines
71 KiB
C
/**************************************************************************
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hwclock
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***************************************************************************
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This is a program for reading and setting the Hardware Clock on an ISA
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family computer. This is the clock that is also known as the RTC,
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real time clock, or, unfortunately, the CMOS clock.
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See man page for details.
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By Bryan Henderson, 96.09.19. bryanh@giraffe-data.com
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Based on work by others; see history at end of source code.
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**************************************************************************/
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/**************************************************************************
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Maintenance notes
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To compile this, you must use GNU compiler optimization (-O option)
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in order to make the "extern inline" functions from asm/io.h (inb(),
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etc.) compile. If you don't optimize, which means the compiler
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will generate no inline functions, the references to these functions
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in this program will be compiled as external references. Since you
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probably won't be linking with any functions by these names, you will
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have unresolved external references when you link.
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The program is designed to run setuid superuser, since we need to be
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able to do direct I/O. (More to the point: we need permission to
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execute the iopl() system call). (However, if you use one of the
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methods other than direct ISA I/O to access the clock, no setuid is
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required).
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Here's some info on how we must deal with the time that elapses while
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this program runs: There are two major delays as we run:
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1) Waiting up to 1 second for a transition of the Hardware Clock so
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we are synchronized to the Hardware Clock.
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2) Running the "date" program to interpret the value of our --date
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option.
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Reading the /etc/adjtime file is the next biggest source of delay and
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uncertainty.
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The user wants to know what time it was at the moment he invoked us,
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not some arbitrary time later. And in setting the clock, he is
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giving us the time at the moment we are invoked, so if we set the
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clock some time later, we have to add some time to that.
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So we check the system time as soon as we start up, then run "date"
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and do file I/O if necessary, then wait to synchronize with a
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Hardware Clock edge, then check the system time again to see how
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much time we spent. We immediately read the clock then and (if
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appropriate) report that time, and additionally, the delay we measured.
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If we're setting the clock to a time given by the user, we wait some
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more so that the total delay is an integral number of seconds, then
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set the Hardware Clock to the time the user requested plus that
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integral number of seconds. N.B. The Hardware Clock can only be set
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in integral seconds.
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If we're setting the clock to the system clock value, we wait for
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the system clock to reach the top of a second, and then set the
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Hardware Clock to the system clock's value.
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Here's an interesting point about setting the Hardware Clock: On my
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machine, when you set it, it sets to that precise time. But one can
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imagine another clock whose update oscillator marches on a steady one
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second period, so updating the clock between any two oscillator ticks
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is the same as updating it right at the earlier tick. To avoid any
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complications that might cause, we set the clock as soon as possible
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after an oscillator tick.
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About synchronizing to the Hardware Clock when reading the time: The
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precision of the Hardware Clock counters themselves is one second.
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You can't read the counters and find out that is 12:01:02.5. But if
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you consider the location in time of the counter's ticks as part of
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its value, then its precision is as infinite as time is continuous!
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What I'm saying is this: To find out the _exact_ time in the
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hardware clock, we wait until the next clock tick (the next time the
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second counter changes) and measure how long we had to wait. We
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then read the value of the clock counters and subtract the wait time
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and we know precisely what time it was when we set out to query the
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time.
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hwclock uses this method, and considers the Hardware Clock to have
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infinite precision.
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Enhancements needed:
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- When waiting for whole second boundary in set_hardware_clock_exact,
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fail if we miss the goal by more than .1 second, as could happen if
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we get pre-empted (by the kernel dispatcher).
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****************************************************************************/
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#include <string.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <time.h>
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#include <sys/time.h>
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#include <sys/stat.h>
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#include <asm/io.h>
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#include <shhopt.h>
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#include "../version.h"
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#define MYNAME "hwclock"
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#define VERSION "2.2"
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#define FLOOR(arg) ((arg >= 0 ? (int) arg : ((int) arg) - 1));
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/* Here the information for time adjustments is kept. */
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#define ADJPATH "/etc/adjtime"
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/* Note that we must define the boolean type as int because we use the
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shhopt option processing library which, unfortunately, returns flag
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options as integers. It is customary to define bool as char, but
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then we would have to do a lot of conversion in order to interface
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with shhopt.
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*/
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typedef int bool;
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#define TRUE 1
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#define FALSE 0
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struct adjtime {
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/* This is information we keep in the adjtime file that tells us how
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to do drift corrections. Elements are all straight from the
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adjtime file, so see documentation of that file for details.
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Exception is <dirty>, which is an indication that what's in this
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structure is not what's in the disk file (because it has been
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updated since read from the disk file).
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*/
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bool dirty;
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float drift_factor;
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time_t last_adj_time;
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float not_adjusted;
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time_t last_calib_time;
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};
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enum clock_access_method {ISA, RTC_IOCTL, KD, NOCLOCK};
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/* A method for accessing (reading, writing) the hardware clock:
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ISA:
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via direct CPU I/O instructions that work on an ISA family
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machine (IBM PC compatible).
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RTC_IOCTL:
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via the rtc device driver, using device special file /dev/rtc.
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KD:
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via the console driver, using device special file /dev/tty1.
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This is the m68k ioctl interface, known as KDGHWCLK.
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NO_CLOCK:
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Unable to determine a usable access method for the system clock.
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*/
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#ifdef __i386__
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/* The following are just constants. Oddly, this program will not
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compile if the inb() and outb() functions use something even
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slightly different from these variables. This is probably at least
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partially related to the fact that __builtin_constant_p() doesn't
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work (is never true) in an inline function. See comment to this
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effect in asm/io.h.
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*/
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static unsigned short clock_ctl_addr = 0x70;
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static unsigned short clock_data_addr = 0x71;
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#endif
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bool debug;
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/* We are running in debug mode, wherein we put a lot of information about
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what we're doing to standard output. Because of the pervasive and yet
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background nature of this value, this is a global variable. */
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bool interrupts_enabled;
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/* Interrupts are enabled as normal. We, unfortunately, turn interrupts
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on the machine off in some places where we do the direct ISA accesses
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to the Hardware Clock. It is in extremely poor form for a user space
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program to do this, but that's the price we have to pay to run on an
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ISA machine without the rtc driver in the kernel.
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Code which turns interrupts off uses this value to determine if they
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need to be turned back on.
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*/
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#include <linux/version.h>
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/* Check if the /dev/rtc interface is available in this version of
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the system headers. 131072 is linux 2.0.0. Might need to make
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it conditional on i386 or something too -janl */
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#if LINUX_VERSION_CODE >= 131072
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#include <linux/mc146818rtc.h>
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#include <linux/kd.h>
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static const bool got_rtc = TRUE;
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#else
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static const bool got_rtc = FALSE;
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/* Dummy definitions to make it compile. If any lines containing these
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macros ever execute, there is a bug in the code.
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*/
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#define RTC_SET_TIME -1
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#define RTC_RD_TIME -1
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#define RTC_UIE_ON -1
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#define RTC_UIE_OFF -1
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#endif
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/* The RTC_EPOCH_READ and RTC_EPOCH_SET macros are supposed to be
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defined by linux/mc146818rtc.h, included above. However, these are
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recent inventions and at the time of this writing, not in any
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official Linux. Since these values aren't even necessary for most
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uses of hwclock, we don't want compilation to depend on the user
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having some arcane version of this header file on his system. Thus,
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we define the macros ourselves if the header file failed to do so.
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98.03.03.
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*/
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#ifndef RTC_EPOCH_READ
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#define RTC_EPOCH_READ _IOR('p', 0x0d, unsigned long) /* Read epoch */
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/* Not all kernels have this ioctl */
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#endif
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#ifndef RTC_EPOCH_SET
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#define RTC_EPOCH_SET _IOW('p', 0x0e, unsigned long) /* Set epoch */
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/* Not all kernels have this ioctl */
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#endif
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#if defined(KDGHWCLK)
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static const bool got_kdghwclk = TRUE;
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static const int kdghwclk_ioctl = KDGHWCLK;
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static const int kdshwclk_ioctl = KDSHWCLK;
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#else
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static const bool got_kdghwclk = FALSE;
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static const int kdghwclk_ioctl; /* Never used; just to make compile work */
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struct hwclk_time {int sec;};
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/* Never used; just to make compile work */
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#endif
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/* We're going to assume that if the CPU is in the Intel x86 family,
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this is an ISA family machine. For all practical purposes, this is
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the case at the time of this writing, especially after we assume a
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Linux kernel is running on it.
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*/
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const bool isa_machine =
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#ifdef __i386__
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TRUE
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#else
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FALSE;
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#endif
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;
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const bool alpha_machine =
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#ifdef __alpha__
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TRUE
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#else
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FALSE;
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#endif
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;
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static int
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i386_iopl(const int level) {
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/*----------------------------------------------------------------------------
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When compiled for an Intel target, this is just the iopl() kernel call.
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When compiled for any other target, this is a dummy function.
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We do it this way in order to keep the conditional compilation stuff
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out of the way so it doesn't mess up readability of the code.
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-----------------------------------------------------------------------------*/
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#ifdef __i386__
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extern int iopl(const int level);
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return iopl(level);
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#else
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return -1;
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#endif
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}
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static float
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time_diff(struct timeval subtrahend, struct timeval subtractor) {
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/*---------------------------------------------------------------------------
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The difference in seconds between two times in "timeval" format.
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----------------------------------------------------------------------------*/
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return( (subtrahend.tv_sec - subtractor.tv_sec)
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+ (subtrahend.tv_usec - subtractor.tv_usec) / 1E6 );
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}
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static struct timeval
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time_inc(struct timeval addend, float increment) {
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/*----------------------------------------------------------------------------
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The time, in "timeval" format, which is <increment> seconds after
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the time <addend>. Of course, <increment> may be negative.
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-----------------------------------------------------------------------------*/
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struct timeval newtime;
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newtime.tv_sec = addend.tv_sec + (int) increment;
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newtime.tv_usec = addend.tv_usec + (increment - (int) increment) * 1E6;
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/* Now adjust it so that the microsecond value is between 0 and 1 million */
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if (newtime.tv_usec < 0) {
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newtime.tv_usec += 1E6;
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newtime.tv_sec -= 1;
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} else if (newtime.tv_usec >= 1E6) {
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newtime.tv_usec -= 1E6;
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newtime.tv_sec += 1;
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}
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return(newtime);
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}
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static inline unsigned char
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hclock_read(unsigned char reg) {
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/*---------------------------------------------------------------------------
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Relative byte <reg> of the Hardware Clock value.
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On non-ISA machine, just return 0.
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---------------------------------------------------------------------------*/
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register unsigned char ret;
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#ifdef __i386__
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const bool interrupts_were_enabled = interrupts_enabled;
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__asm__ volatile ("cli");
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interrupts_enabled = FALSE;
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/* & 0x7f ensures that we are not disabling NMI while we read.
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Setting on Bit 7 here would disable NMI
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*/
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outb(reg & 0x7f, clock_ctl_addr);
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ret = inb(clock_data_addr);
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if (interrupts_were_enabled) {
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__asm__ volatile ("sti");
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interrupts_enabled = TRUE;
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}
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#else
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ret = 0;
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#endif
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return ret;
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}
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static inline void
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hclock_write(unsigned char reg, unsigned char val) {
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/*----------------------------------------------------------------------------
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Set relative byte <reg> of the Hardware Clock value to <val>.
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On non-ISA machine, do nothing.
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----------------------------------------------------------------------------*/
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#ifdef __i386__
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/* & 0x7f ensures that we are not disabling NMI while we read.
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Setting on Bit 7 here would disable NMI
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*/
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outb(reg & 0x7f, clock_ctl_addr);
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outb(val, clock_data_addr);
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#endif
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}
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static inline int
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hclock_read_bcd (int addr) {
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int b;
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b = hclock_read(addr);
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return (b & 15) + (b >> 4) * 10;
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}
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static inline void
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hclock_write_bcd(int addr, int value) {
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hclock_write(addr, ((value / 10) << 4) + value % 10);
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}
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static void
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read_adjtime(struct adjtime *adjtime_p, int *rc_p) {
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/*----------------------------------------------------------------------------
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Read the adjustment parameters out of the /etc/adjtime file.
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Return them as the adjtime structure <*adjtime_p>.
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If there is no /etc/adjtime file, return defaults.
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If values are missing from the file, return defaults for them.
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return *rc_p = 0 if all OK, !=0 otherwise.
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-----------------------------------------------------------------------------*/
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FILE *adjfile;
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int rc; /* local return code */
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struct stat statbuf; /* We don't even use the contents of this. */
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rc = stat(ADJPATH, &statbuf);
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if (rc < 0 && errno == ENOENT) {
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/* He doesn't have a adjtime file, so we'll use defaults. */
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adjtime_p->drift_factor = 0;
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adjtime_p->last_adj_time = 0;
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adjtime_p->not_adjusted = 0;
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adjtime_p->last_calib_time = 0;
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*rc_p = 0;
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} else {
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adjfile = fopen(ADJPATH, "r"); /* open file for reading */
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if (adjfile == NULL) {
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const int fopen_errno = errno;
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fprintf(stderr, MYNAME " is unable to open file " ADJPATH ". "
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"fopen() errno=%d:%s", fopen_errno, strerror(fopen_errno));
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*rc_p = 2;
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} else {
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char line1[81]; /* String: first line of adjtime file */
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char line2[81]; /* String: second line of adjtime file */
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line1[0] = '\0'; /* In case fgets fails */
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fgets(line1, sizeof(line1), adjfile);
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line2[0] = '\0'; /* In case fgets fails */
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fgets(line2, sizeof(line2), adjfile);
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fclose(adjfile);
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/* Set defaults in case values are missing from file */
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adjtime_p->drift_factor = 0;
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adjtime_p->last_adj_time = 0;
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adjtime_p->not_adjusted = 0;
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adjtime_p->last_calib_time = 0;
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sscanf(line1, "%f %d %f",
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&adjtime_p->drift_factor,
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(int *) &adjtime_p->last_adj_time,
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&adjtime_p->not_adjusted);
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sscanf(line2, "%d", (int *) &adjtime_p->last_calib_time);
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*rc_p = 0;
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}
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adjtime_p->dirty = FALSE;
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if (debug) {
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printf("Last drift adjustment done at %d seconds after 1969\n",
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(int) adjtime_p->last_adj_time);
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printf("Last calibration done at %d seconds after 1969\n",
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(int) adjtime_p->last_calib_time);
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}
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}
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}
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static void
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synchronize_to_clock_tick_ISA(int *retcode_p) {
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/*----------------------------------------------------------------------------
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Same as synchronize_to_clock_tick(), but just for ISA.
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-----------------------------------------------------------------------------*/
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int i; /* local loop index */
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/* Wait for rise. Should be within a second, but in case something
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weird happens, we have a limit on this loop to reduce the impact
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of this failure.
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*/
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for (i = 0; !(hclock_read(10) & 0x80) && (i < 10000000); i++);
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if (i >= 10000000) *retcode_p = 1;
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else {
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/* Wait for fall. Should be within 2.228 ms. */
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for (i = 0; (hclock_read(10) & 0x80) && (i < 1000000); i++);
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if (i >= 10000000) *retcode_p = 1;
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else *retcode_p = 0;
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}
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}
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static void
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busywait_for_rtc_clock_tick(const int rtc_fd, int *retcode_p) {
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/*----------------------------------------------------------------------------
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Wait for the top of a clock tick by reading /dev/rtc in a busy loop until
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we see it.
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-----------------------------------------------------------------------------*/
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struct tm start_time;
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/* The time when we were called (and started waiting) */
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int rc;
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if (debug)
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printf("Waiting in loop for time from /dev/rtc to change\n");
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rc = ioctl(rtc_fd, RTC_RD_TIME, &start_time);
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if (rc == -1) {
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fprintf(stderr, "ioctl() to /dev/rtc to read time failed, "
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"errno = %s (%d).\n", strerror(errno), errno);
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*retcode_p = 1;
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} else {
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/* Wait for change. Should be within a second, but in case something
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weird happens, we have a limit on this loop to reduce the impact
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of this failure.
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*/
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struct tm nowtime;
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int i; /* local loop index */
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int rc; /* Return code from ioctl */
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for (i = 0;
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(rc = ioctl(rtc_fd, RTC_RD_TIME, &nowtime)) != -1
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&& start_time.tm_sec == nowtime.tm_sec && i < 1000000;
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i++);
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if (i >= 1000000) {
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fprintf(stderr, "Timed out waiting for time change.\n");
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*retcode_p = 2;
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} else if (rc == -1) {
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fprintf(stderr, "ioctl() to /dev/rtc to read time failed, "
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"errno = %s (%d).\n", strerror(errno), errno);
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*retcode_p = 3;
|
|
} else *retcode_p = 0;
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
synchronize_to_clock_tick_RTC(int *retcode_p) {
|
|
/*----------------------------------------------------------------------------
|
|
Same as synchronize_to_clock_tick(), but just for /dev/rtc.
|
|
-----------------------------------------------------------------------------*/
|
|
int rtc_fd; /* File descriptor of /dev/rtc */
|
|
|
|
rtc_fd = open("/dev/rtc",O_RDONLY);
|
|
if (rtc_fd == -1) {
|
|
fprintf(stderr, "open() of /dev/rtc failed, errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
} else {
|
|
int rc; /* Return code from ioctl */
|
|
/* Turn on update interrupts (one per second) */
|
|
rc = ioctl(rtc_fd, RTC_UIE_ON, 0);
|
|
if (rc == -1 && errno == EINVAL) {
|
|
/* This rtc device doesn't have interrupt functions. This is typical
|
|
on an Alpha, where the Hardware Clock interrupts are used by the
|
|
kernel for the system clock, so aren't at the user's disposal.
|
|
*/
|
|
if (debug) printf("/dev/rtc does not have interrupt functions. ");
|
|
busywait_for_rtc_clock_tick(rtc_fd, retcode_p);
|
|
} else if (rc != -1) {
|
|
int rc; /* return code from ioctl */
|
|
unsigned long dummy;
|
|
|
|
/* this blocks until the next update interrupt */
|
|
rc = read(rtc_fd, &dummy, sizeof(dummy));
|
|
if (rc == -1) {
|
|
fprintf(stderr, "read() to /dev/rtc to wait for clock tick failed, "
|
|
"errno = %s (%d).\n", strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
} else {
|
|
*retcode_p = 0;
|
|
}
|
|
/* Turn off update interrupts */
|
|
rc = ioctl(rtc_fd, RTC_UIE_OFF, 0);
|
|
if (rc == -1) {
|
|
fprintf(stderr, "ioctl() to /dev/rtc to turn off update interrupts "
|
|
"failed, errno = %s (%d).\n", strerror(errno), errno);
|
|
}
|
|
} else {
|
|
fprintf(stderr, "ioctl() to /dev/rtc to turn on update interrupts "
|
|
"failed unexpectedly, errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
}
|
|
close(rtc_fd);
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
synchronize_to_clock_tick_KD(int *retcode_p) {
|
|
/*----------------------------------------------------------------------------
|
|
Wait for the top of a clock tick by calling KDGHWCLK in a busy loop until
|
|
we see it.
|
|
-----------------------------------------------------------------------------*/
|
|
int con_fd;
|
|
|
|
if (debug)
|
|
printf("Waiting in loop for time from KDGHWCLK to change\n");
|
|
|
|
con_fd = open("/dev/tty1", O_RDONLY);
|
|
if (con_fd < 0) {
|
|
fprintf(stderr, "open() failed to open /dev/tty1, errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
} else {
|
|
int rc; /* return code from ioctl() */
|
|
int i; /* local loop index */
|
|
/* The time when we were called (and started waiting) */
|
|
struct hwclk_time start_time, nowtime;
|
|
|
|
rc = ioctl(con_fd, kdghwclk_ioctl, &start_time);
|
|
if (rc == -1) {
|
|
fprintf(stderr, "KDGHWCLK to read time failed, "
|
|
"errno = %s (%d).\n", strerror(errno), errno);
|
|
*retcode_p = 3;
|
|
}
|
|
|
|
for (i = 0;
|
|
(rc = ioctl(con_fd, kdghwclk_ioctl, &nowtime)) != -1
|
|
&& start_time.sec == nowtime.sec && i < 1000000;
|
|
i++);
|
|
if (i >= 1000000) {
|
|
fprintf(stderr, "Timed out waiting for time change.\n");
|
|
*retcode_p = 2;
|
|
} else if (rc == -1) {
|
|
fprintf(stderr, "KDGHWCLK to read time failed, "
|
|
"errno = %s (%d).\n", strerror(errno), errno);
|
|
*retcode_p = 3;
|
|
} else *retcode_p = 0;
|
|
close(con_fd);
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
synchronize_to_clock_tick(enum clock_access_method clock_access,
|
|
int *retcode_p) {
|
|
/*-----------------------------------------------------------------------------
|
|
Wait until the falling edge of the Hardware Clock's update flag so
|
|
that any time that is read from the clock immediately after we
|
|
return will be exact.
|
|
|
|
The clock only has 1 second precision, so it gives the exact time only
|
|
once per second, right on the falling edge of the update flag.
|
|
|
|
We wait (up to one second) either blocked waiting for an rtc device
|
|
or in a CPU spin loop. The former is probably not very accurate.
|
|
|
|
For the KD clock access method, we have no way to synchronize, so we
|
|
just return immediately. This will mess some things up, but it's the
|
|
best we can do.
|
|
|
|
Return *retcode_p == 0 if it worked, nonzero if it didn't.
|
|
|
|
-----------------------------------------------------------------------------*/
|
|
if (debug) printf("Waiting for clock tick...\n");
|
|
|
|
switch (clock_access) {
|
|
case ISA: synchronize_to_clock_tick_ISA(retcode_p); break;
|
|
case RTC_IOCTL: synchronize_to_clock_tick_RTC(retcode_p); break;
|
|
case KD: synchronize_to_clock_tick_KD(retcode_p); break;
|
|
default:
|
|
fprintf(stderr, "Internal error in synchronize_to_clock_tick. Invalid "
|
|
"value for clock_access argument.\n");
|
|
*retcode_p = 1;
|
|
}
|
|
if (debug) printf("...got clock tick\n");
|
|
return;
|
|
}
|
|
|
|
|
|
|
|
static time_t
|
|
mktime_tz(struct tm tm, const bool universal) {
|
|
/*-----------------------------------------------------------------------------
|
|
Convert a time in broken down format (hours, minutes, etc.) into standard
|
|
unix time (seconds into epoch).
|
|
|
|
The broken down time is argument <tm>. This broken down time is either in
|
|
local time zone or UTC, depending on value of logical argument "universal".
|
|
True means it is in UTC.
|
|
-----------------------------------------------------------------------------*/
|
|
time_t systime; /* our eventual return value */
|
|
char *zone; /* Local time zone name */
|
|
|
|
/* We use the C library function mktime(), but since it only works on
|
|
local time zone input, we may have to fake it out by temporarily
|
|
changing the local time zone to UTC.
|
|
*/
|
|
zone = (char *) getenv("TZ"); /* remember original time zone */
|
|
|
|
if (universal) {
|
|
/* Set timezone to UTC */
|
|
setenv("TZ", "", TRUE);
|
|
/* Note: tzset() gets called implicitly by the time code, but only the
|
|
first time. When changing the environment variable, better call
|
|
tzset() explicitly.
|
|
*/
|
|
tzset();
|
|
}
|
|
systime = mktime(&tm);
|
|
if (systime == -1) {
|
|
/* We don't expect this to happen. Consider this a crash */
|
|
fprintf(stderr, "mktime() failed unexpectedly (rc -1). Aborting.\n");
|
|
exit(2);
|
|
}
|
|
|
|
/* now put back the original zone. */
|
|
if (zone) setenv("TZ", zone, TRUE);
|
|
else unsetenv("TZ");
|
|
tzset();
|
|
|
|
if (debug)
|
|
printf("Hw clock time : %.2d:%.2d:%.2d = %d seconds since 1969\n",
|
|
tm.tm_hour, tm.tm_min, tm.tm_sec, (int) systime);
|
|
|
|
return(systime);
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
read_hardware_clock_kd(struct tm *tm) {
|
|
/*----------------------------------------------------------------------------
|
|
Read the hardware clock and return the current time via <tm>
|
|
argument. Use ioctls to /dev/tty1 on what we assume is an m68k
|
|
machine.
|
|
|
|
Note that we don't use /dev/console here. That might be a serial
|
|
console.
|
|
-----------------------------------------------------------------------------*/
|
|
#ifdef KDGHWCLK
|
|
int con_fd;
|
|
struct hwclk_time t;
|
|
|
|
con_fd = open("/dev/tty1", O_RDONLY);
|
|
if (con_fd < 0) {
|
|
fprintf(stderr, "open() failed to open /dev/tty1, errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
exit(5);
|
|
} else {
|
|
int rc; /* return code from ioctl() */
|
|
|
|
rc = ioctl(con_fd, kdghwclk_ioctl, &t);
|
|
if (rc == -1) {
|
|
fprintf(stderr, "ioctl() failed to read time from /dev/tty1, "
|
|
"errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
exit(5);
|
|
}
|
|
close(con_fd);
|
|
}
|
|
|
|
tm->tm_sec = t.sec;
|
|
tm->tm_min = t.min;
|
|
tm->tm_hour = t.hour;
|
|
tm->tm_mday = t.day;
|
|
tm->tm_mon = t.mon;
|
|
tm->tm_year = t.year;
|
|
tm->tm_wday = t.wday;
|
|
tm->tm_isdst = -1; /* Don't know if it's Daylight Savings Time */
|
|
#else
|
|
/* This routine should never be invoked. It is here just to make the
|
|
program compile.
|
|
*/
|
|
#endif
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
read_hardware_clock_rtc_ioctl(struct tm *tm) {
|
|
/*----------------------------------------------------------------------------
|
|
Read the hardware clock and return the current time via <tm>
|
|
argument. Use ioctls to "rtc" device /dev/rtc.
|
|
-----------------------------------------------------------------------------*/
|
|
#if defined(_MC146818RTC_H)
|
|
int rc; /* Local return code */
|
|
int rtc_fd; /* File descriptor of /dev/rtc */
|
|
|
|
rtc_fd = open("/dev/rtc",O_RDONLY);
|
|
if (rtc_fd == -1) {
|
|
fprintf(stderr, "open() of /dev/rtc failed, errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
exit(5);
|
|
} else {
|
|
/* Read the RTC time/date */
|
|
rc = ioctl(rtc_fd, RTC_RD_TIME, tm);
|
|
if (rc == -1) {
|
|
fprintf(stderr, "ioctl() to /dev/rtc to read the time failed, "
|
|
"errno = %s (%d).\n", strerror(errno), errno);
|
|
exit(5);
|
|
}
|
|
close(rtc_fd);
|
|
}
|
|
tm->tm_isdst = -1; /* don't know whether it's daylight */
|
|
#else
|
|
/* This function should never be called. It exists just to make the
|
|
program compile.
|
|
*/
|
|
#endif
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
read_hardware_clock_isa(struct tm *tm) {
|
|
/*----------------------------------------------------------------------------
|
|
Read the hardware clock and return the current time via <tm> argument.
|
|
Assume we have an ISA machine and read the clock directly with CPU I/O
|
|
instructions.
|
|
|
|
This function is not totally reliable. It takes a finite and
|
|
unpredictable amount of time to execute the code below. During that
|
|
time, the clock may change and we may even read an invalid value in
|
|
the middle of an update. We do a few checks to minimize this
|
|
possibility, but only the kernel can actually read the clock
|
|
properly, since it can execute code in a short and predictable
|
|
amount of time (by turning of interrupts).
|
|
|
|
In practice, the chance of this function returning the wrong time is
|
|
extremely remote.
|
|
|
|
-----------------------------------------------------------------------------*/
|
|
bool got_time;
|
|
/* We've successfully read a time from the Hardware Clock */
|
|
|
|
got_time = FALSE;
|
|
while (!got_time) {
|
|
/* Bit 7 of Byte 10 of the Hardware Clock value is the Update In Progress
|
|
(UIP) bit, which is on while and 244 uS before the Hardware Clock
|
|
updates itself. It updates the counters individually, so reading
|
|
them during an update would produce garbage. The update takes 2mS,
|
|
so we could be spinning here that long waiting for this bit to turn
|
|
off.
|
|
|
|
Furthermore, it is pathologically possible for us to be in this
|
|
code so long that even if the UIP bit is not on at first, the
|
|
clock has changed while we were running. We check for that too,
|
|
and if it happens, we start over.
|
|
*/
|
|
|
|
if ((hclock_read(10) & 0x80) == 0) {
|
|
/* No clock update in progress, go ahead and read */
|
|
tm->tm_sec = hclock_read_bcd(0);
|
|
tm->tm_min = hclock_read_bcd(2);
|
|
tm->tm_hour = hclock_read_bcd(4);
|
|
tm->tm_wday = hclock_read_bcd(6) - 3;
|
|
tm->tm_mday = hclock_read_bcd(7);
|
|
tm->tm_mon = hclock_read_bcd(8) - 1;
|
|
tm->tm_year = hclock_read_bcd(9);
|
|
if (hclock_read_bcd(50) == 0) {
|
|
/* I suppose Linux could run on an old machine that doesn't implement
|
|
the Byte 50 century value, and that if it does, that machine puts
|
|
zero in Byte 50. If so, this could could be useful, in that it
|
|
makes values 70-99 -> 1970-1999 and 00-69 -> 2000-2069.
|
|
*/
|
|
if (hclock_read_bcd(9) >= 70) tm->tm_year = hclock_read_bcd(9);
|
|
else tm->tm_year = hclock_read_bcd(9) + 100;
|
|
} else {
|
|
tm->tm_year = hclock_read_bcd(50) * 100 + hclock_read_bcd(9) - 1900;
|
|
/* Note: Byte 50 contains centuries since A.D. Byte 9 contains
|
|
years since beginning of century. tm_year contains years
|
|
since 1900. At least we _assume_ that's what tm_year
|
|
contains. It is documented only as "year", and it could
|
|
conceivably be years since the beginning of the current
|
|
century. If so, this code won't work after 1999.
|
|
*/
|
|
}
|
|
/* Unless the clock changed while we were reading, consider this
|
|
a good clock read .
|
|
*/
|
|
if (tm->tm_sec == hclock_read_bcd (0)) got_time = TRUE;
|
|
/* Yes, in theory we could have been running for 60 seconds and
|
|
the above test wouldn't work!
|
|
*/
|
|
}
|
|
}
|
|
tm->tm_isdst = -1; /* don't know whether it's daylight */
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
read_hardware_clock(const enum clock_access_method method, struct tm *tm){
|
|
/*----------------------------------------------------------------------------
|
|
Read the hardware clock and return the current time via <tm> argument.
|
|
|
|
Use the method indicated by <method> argument to access the hardware clock.
|
|
-----------------------------------------------------------------------------*/
|
|
switch (method) {
|
|
case ISA:
|
|
read_hardware_clock_isa(tm);
|
|
break;
|
|
case RTC_IOCTL:
|
|
read_hardware_clock_rtc_ioctl(tm);
|
|
break;
|
|
case KD:
|
|
read_hardware_clock_kd(tm);
|
|
break;
|
|
default:
|
|
fprintf(stderr,
|
|
"Internal error: invalid value for clock access method.\n");
|
|
exit(5);
|
|
}
|
|
if (debug)
|
|
printf ("Time read from Hardware Clock: %02d:%02d:%02d\n",
|
|
tm->tm_hour, tm->tm_min, tm->tm_sec);
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
set_hardware_clock_kd(const struct tm new_broken_time,
|
|
const bool testing) {
|
|
/*----------------------------------------------------------------------------
|
|
Set the Hardware Clock to the time <new_broken_time>. Use ioctls to
|
|
/dev/tty1 on what we assume is an m68k machine.
|
|
|
|
Note that we don't use /dev/console here. That might be a serial console.
|
|
----------------------------------------------------------------------------*/
|
|
#ifdef KDGHWCLK
|
|
int con_fd; /* File descriptor of /dev/tty1 */
|
|
struct hwclk_time t;
|
|
|
|
con_fd = open("/dev/tty1", O_RDONLY);
|
|
if (con_fd < 0) {
|
|
fprintf(stderr, "Error opening /dev/tty1. Errno: %s (%d)\n",
|
|
strerror(errno), errno);
|
|
exit(1);
|
|
} else {
|
|
int rc; /* locally used return code */
|
|
|
|
t.sec = new_broken_time.tm_sec;
|
|
t.min = new_broken_time.tm_min;
|
|
t.hour = new_broken_time.tm_hour;
|
|
t.day = new_broken_time.tm_mday;
|
|
t.mon = new_broken_time.tm_mon;
|
|
t.year = new_broken_time.tm_year;
|
|
t.wday = new_broken_time.tm_wday;
|
|
|
|
if (testing)
|
|
printf("Not setting Hardware Clock because running in test mode.\n");
|
|
else {
|
|
rc = ioctl(con_fd, kdshwclk_ioctl, &t );
|
|
if (rc < 0) {
|
|
fprintf(stderr, "ioctl() to open /dev/tty1 failed. "
|
|
"Errno: %s (%d)\n",
|
|
strerror(errno), errno);
|
|
exit(1);
|
|
}
|
|
}
|
|
close(con_fd);
|
|
}
|
|
#else
|
|
/* This function should never be invoked. It is here just to make the
|
|
program compile.
|
|
*/
|
|
#endif
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
set_hardware_clock_rtc_ioctl(const struct tm new_broken_time,
|
|
const bool testing) {
|
|
/*----------------------------------------------------------------------------
|
|
Set the Hardware Clock to the broken down time <new_broken_time>.
|
|
Use ioctls to "rtc" device /dev/rtc.
|
|
----------------------------------------------------------------------------*/
|
|
int rc;
|
|
int rtc_fd;
|
|
|
|
rtc_fd = open("/dev/rtc", O_RDONLY);
|
|
if (rtc_fd < 0) {
|
|
fprintf(stderr, "Unable to open /dev/rtc, open() errno = %s (%d)\n",
|
|
strerror(errno), errno);
|
|
exit(5);
|
|
} else {
|
|
if (testing)
|
|
printf("Not setting Hardware Clock because running in test mode.\n");
|
|
else {
|
|
rc = ioctl(rtc_fd, RTC_SET_TIME, &new_broken_time);
|
|
if (rc == -1) {
|
|
fprintf(stderr,
|
|
"ioctl() (RTC_SET_TIME) to /dev/rtc to set time failed, "
|
|
"errno = %s (%d).\n", strerror(errno), errno);
|
|
exit(5);
|
|
} else {
|
|
if (debug)
|
|
printf("ioctl(RTC_SET_TIME) was successful.\n");
|
|
}
|
|
}
|
|
close(rtc_fd);
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
set_hardware_clock_isa(const struct tm new_broken_time,
|
|
const bool testing) {
|
|
/*----------------------------------------------------------------------------
|
|
Set the Hardware Clock to the time (in broken down format)
|
|
new_broken_time. Use direct I/O instructions to what we assume is
|
|
an ISA Hardware Clock.
|
|
----------------------------------------------------------------------------*/
|
|
unsigned char save_control, save_freq_select;
|
|
#ifdef __i386__
|
|
const bool interrupts_were_enabled = interrupts_enabled;
|
|
#endif
|
|
|
|
if (testing)
|
|
printf("Not setting Hardware Clock because running in test mode.\n");
|
|
else {
|
|
#ifdef __i386__
|
|
__asm__ volatile ("cli");
|
|
interrupts_enabled = FALSE;
|
|
#endif
|
|
save_control = hclock_read(11); /* tell the clock it's being set */
|
|
hclock_write(11, (save_control | 0x80));
|
|
save_freq_select = hclock_read(10); /* stop and reset prescaler */
|
|
hclock_write (10, (save_freq_select | 0x70));
|
|
|
|
hclock_write_bcd(0, new_broken_time.tm_sec);
|
|
hclock_write_bcd(2, new_broken_time.tm_min);
|
|
hclock_write_bcd(4, new_broken_time.tm_hour);
|
|
hclock_write_bcd(6, new_broken_time.tm_wday + 3);
|
|
hclock_write_bcd(7, new_broken_time.tm_mday);
|
|
hclock_write_bcd(8, new_broken_time.tm_mon + 1);
|
|
hclock_write_bcd(9, new_broken_time.tm_year%100);
|
|
hclock_write_bcd(50, (1900+new_broken_time.tm_year)/100);
|
|
|
|
/* The kernel sources, linux/arch/i386/kernel/time.c, have the
|
|
following comment:
|
|
|
|
The following flags have to be released exactly in this order,
|
|
otherwise the DS12887 (popular MC146818A clone with integrated
|
|
battery and quartz) will not reset the oscillator and will not
|
|
update precisely 500 ms later. You won't find this mentioned
|
|
in the Dallas Semiconductor data sheets, but who believes data
|
|
sheets anyway ... -- Markus Kuhn
|
|
|
|
Hence, they will also be done in this order here.
|
|
faith@cs.unc.edu, Thu Nov 9 08:26:37 1995
|
|
*/
|
|
|
|
hclock_write (11, save_control);
|
|
hclock_write (10, save_freq_select);
|
|
#ifdef __i386__
|
|
if (interrupts_were_enabled) {
|
|
__asm__ volatile ("sti");
|
|
interrupts_enabled = TRUE;
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
|
|
|
|
static void
|
|
set_hardware_clock(const enum clock_access_method method,
|
|
const time_t newtime,
|
|
const bool universal,
|
|
const bool testing) {
|
|
/*----------------------------------------------------------------------------
|
|
Set the Hardware Clock to the time <newtime>, in local time zone or UTC,
|
|
according to <universal>.
|
|
|
|
Use the method indicated by the <method> argument.
|
|
----------------------------------------------------------------------------*/
|
|
|
|
struct tm new_broken_time;
|
|
/* Time to which we will set Hardware Clock, in broken down format, in
|
|
the time zone of caller's choice
|
|
*/
|
|
|
|
if (universal) new_broken_time = *gmtime(&newtime);
|
|
else new_broken_time = *localtime(&newtime);
|
|
|
|
if (debug)
|
|
printf("Setting Hardware Clock to %.2d:%.2d:%.2d "
|
|
"= %d seconds since 1969\n",
|
|
new_broken_time.tm_hour, new_broken_time.tm_min,
|
|
new_broken_time.tm_sec, (int) newtime);
|
|
|
|
switch (method) {
|
|
case ISA:
|
|
set_hardware_clock_isa(new_broken_time, testing);
|
|
break;
|
|
case RTC_IOCTL:
|
|
set_hardware_clock_rtc_ioctl(new_broken_time, testing);
|
|
break;
|
|
case KD:
|
|
set_hardware_clock_kd(new_broken_time, testing);
|
|
break;
|
|
default:
|
|
fprintf(stderr,
|
|
"Internal error: invalid value for clock access method.\n");
|
|
exit(5);
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
set_hardware_clock_exact(const time_t settime,
|
|
const struct timeval ref_time,
|
|
const enum clock_access_method clock_access,
|
|
const bool universal,
|
|
const bool testing) {
|
|
/*----------------------------------------------------------------------------
|
|
Set the Hardware Clock to the time "settime", in local time zone or UTC,
|
|
according to "universal".
|
|
|
|
But correct "settime" and wait for a fraction of a second so that
|
|
"settime" is the value of the Hardware Clock as of system time
|
|
"ref_time", which is in the past. For example, if "settime" is
|
|
14:03:05 and "ref_time" is 12:10:04.5 and the current system
|
|
time is 12:10:06.0: Wait .5 seconds (to make exactly 2 seconds since
|
|
"ref_time") and then set the Hardware Clock to 14:03:07, thus
|
|
getting a precise and retroactive setting of the clock.
|
|
|
|
(Don't be confused by the fact that the system clock and the Hardware
|
|
Clock differ by two hours in the above example. That's just to remind
|
|
you that there are two independent time scales here).
|
|
|
|
This function ought to be able to accept set times as fractional times.
|
|
Idea for future enhancement.
|
|
|
|
-----------------------------------------------------------------------------*/
|
|
time_t newtime; /* Time to which we will set Hardware Clock */
|
|
struct timeval now_time; /* locally used time */
|
|
|
|
gettimeofday(&now_time, NULL);
|
|
newtime = settime + (int) time_diff(now_time, ref_time) + 1;
|
|
if (debug)
|
|
printf("Time elapsed since reference time has been %.6f seconds.\n"
|
|
"Delaying further to reach the next full second.\n",
|
|
time_diff(now_time, ref_time));
|
|
|
|
/* Now delay some more until Hardware Clock time newtime arrives */
|
|
do gettimeofday(&now_time, NULL);
|
|
while (time_diff(now_time, ref_time) < newtime - settime);
|
|
|
|
set_hardware_clock(clock_access, newtime, universal, testing);
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
get_epoch(unsigned long *epoch_p, int *retcode_p) {
|
|
/*----------------------------------------------------------------------------
|
|
Get the Hardware Clock epoch setting from the kernel.
|
|
----------------------------------------------------------------------------*/
|
|
int rtc_fd;
|
|
|
|
rtc_fd = open("/dev/rtc", O_RDONLY);
|
|
if (rtc_fd < 0) {
|
|
if (errno == ENOENT)
|
|
fprintf(stderr, "To manipulate the epoch value in the kernel, we must "
|
|
"access the Linux 'rtc' device driver via the device special "
|
|
"file /dev/rtc. This file does not exist on this system.\n");
|
|
else
|
|
fprintf(stderr, "Unable to open /dev/rtc, open() errno = %s (%d)\n",
|
|
strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
} else {
|
|
int rc; /* return code from ioctl */
|
|
rc = ioctl(rtc_fd, RTC_EPOCH_READ, epoch_p);
|
|
if (rc == -1) {
|
|
fprintf(stderr, "ioctl(RTC_EPOCH_READ) to /dev/rtc failed, "
|
|
"errno = %s (%d).\n", strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
} else {
|
|
*retcode_p = 0;
|
|
if (debug) printf("we have read epoch %ld from /dev/rtc "
|
|
"with RTC_EPOCH_READ ioctl.\n", *epoch_p);
|
|
}
|
|
close(rtc_fd);
|
|
}
|
|
return;
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
set_epoch(unsigned long epoch, const bool testing, int *retcode_p) {
|
|
/*----------------------------------------------------------------------------
|
|
Set the Hardware Clock epoch in the kernel.
|
|
----------------------------------------------------------------------------*/
|
|
if (epoch < 1900)
|
|
/* kernel would not accept this epoch value */
|
|
fprintf(stderr, "The epoch value may not be less than 1900. "
|
|
"You requested %ld\n", epoch);
|
|
else {
|
|
int rtc_fd;
|
|
|
|
rtc_fd = open("/dev/rtc", O_RDONLY);
|
|
if (rtc_fd < 0) {
|
|
if (errno == ENOENT)
|
|
fprintf(stderr, "To manipulate the epoch value in the kernel, we must "
|
|
"access the Linux 'rtc' device driver via the device special "
|
|
"file /dev/rtc. This file does not exist on this system.\n");
|
|
fprintf(stderr, "Unable to open /dev/rtc, open() errno = %s (%d)\n",
|
|
strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
} else {
|
|
if (debug) printf("setting epoch to %ld "
|
|
"with RTC_EPOCH_SET ioctl to /dev/rtc.\n", epoch);
|
|
if (testing) {
|
|
printf("Not setting epoch because running in test mode.\n");
|
|
*retcode_p = 0;
|
|
} else {
|
|
int rc; /* return code from ioctl */
|
|
rc = ioctl(rtc_fd, RTC_EPOCH_SET, epoch);
|
|
if (rc == -1) {
|
|
if (errno == EINVAL)
|
|
fprintf(stderr, "The kernel (specifically, the device driver "
|
|
"for /dev/rtc) does not have the RTC_EPOCH_SET ioctl. "
|
|
"Get a newer driver.\n");
|
|
else
|
|
fprintf(stderr, "ioctl(RTC_EPOCH_SET) to /dev/rtc failed, "
|
|
"errno = %s (%d).\n", strerror(errno), errno);
|
|
*retcode_p = 1;
|
|
} else *retcode_p = 0;
|
|
}
|
|
close(rtc_fd);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
display_time(const time_t systime, const float sync_duration) {
|
|
/*----------------------------------------------------------------------------
|
|
Put the time "systime" on standard output in display format.
|
|
|
|
Include in the output the adjustment "sync_duration".
|
|
-----------------------------------------------------------------------------*/
|
|
char *ctime_now; /* Address of static storage containing time string */
|
|
|
|
/* For some strange reason, ctime() is designed to include a newline
|
|
character at the end. We have to remove that.
|
|
*/
|
|
ctime_now = ctime(&systime); /* Compute display value for time */
|
|
*(ctime_now+strlen(ctime_now)-1) = '\0'; /* Cut off trailing newline */
|
|
|
|
printf("%s %.6f seconds\n", ctime_now, -(sync_duration));
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
interpret_date_string(const char *date_opt, time_t * const time_p) {
|
|
/*----------------------------------------------------------------------------
|
|
Interpret the value of the --date option, which is something like
|
|
"13:05:01". In fact, it can be any of the myriad ASCII strings that specify
|
|
a time which the "date" program can understand. The date option value in
|
|
question is our "dateopt" argument.
|
|
|
|
The specified time is in the local time zone.
|
|
|
|
Our output, "*time_p", is a seconds-into-epoch time.
|
|
|
|
We use the "date" program to interpret the date string. "date" must be
|
|
runnable by issuing the command "date" to the /bin/sh shell. That means
|
|
in must be in the current PATH.
|
|
|
|
If anything goes wrong (and many things can), we return return code
|
|
10 and arbitrary *time_p. Otherwise, return code is 0 and *time_p
|
|
is valid.
|
|
----------------------------------------------------------------------------*/
|
|
FILE *date_child_fp;
|
|
char date_resp[100];
|
|
const char magic[]="seconds-into-epoch=";
|
|
char date_command[100];
|
|
int retcode; /* our eventual return code */
|
|
int rc; /* local return code */
|
|
|
|
if (date_opt == NULL) {
|
|
fprintf(stderr, "No --date option specified.\n");
|
|
retcode = 14;
|
|
} else if (strchr(date_opt, '"') != NULL) {
|
|
/* Quotation marks in date_opt would ruin the date command we construct.
|
|
*/
|
|
fprintf(stderr, "The value of the --date option is not a valid date.\n"
|
|
"In particular, it contains quotation marks.\n");
|
|
retcode = 12;
|
|
} else {
|
|
sprintf(date_command, "date --date=\"%s\" +seconds-into-epoch=%%s",
|
|
date_opt);
|
|
if (debug) printf("Issuing date command: %s\n", date_command);
|
|
|
|
date_child_fp = popen(date_command, "r");
|
|
if (date_child_fp == NULL) {
|
|
fprintf(stderr, "Unable to run 'date' program in /bin/sh shell. "
|
|
"popen() failed with errno=%d:%s\n", errno, strerror(errno));
|
|
retcode = 10;
|
|
} else {
|
|
date_resp[0] = '\0'; /* in case fgets fails */
|
|
fgets(date_resp, sizeof(date_resp), date_child_fp);
|
|
if (debug) printf("response from date command = %s\n", date_resp);
|
|
if (strncmp(date_resp, magic, sizeof(magic)-1) != 0) {
|
|
fprintf(stderr, "The date command issued by " MYNAME " returned "
|
|
"unexpected results.\n"
|
|
"The command was:\n %s\nThe response was:\n %s\n",
|
|
date_command, date_resp);
|
|
retcode = 8;
|
|
} else {
|
|
int seconds_since_epoch;
|
|
rc = sscanf(date_resp + sizeof(magic)-1, "%d", &seconds_since_epoch);
|
|
if (rc < 1) {
|
|
fprintf(stderr, "The date command issued by " MYNAME " returned"
|
|
"something other than an integer where the converted"
|
|
"time value was expected.\n"
|
|
"The command was:\n %s\nThe response was:\n %s\n",
|
|
date_command, date_resp);
|
|
retcode = 6;
|
|
} else {
|
|
retcode = 0;
|
|
*time_p = seconds_since_epoch;
|
|
if (debug)
|
|
printf("date string %s equates to %d seconds since 1969.\n",
|
|
date_opt, (int) *time_p);
|
|
}
|
|
}
|
|
fclose(date_child_fp);
|
|
}
|
|
}
|
|
return(retcode);
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
set_system_clock(const time_t newtime, const bool testing) {
|
|
|
|
struct timeval tv;
|
|
int retcode; /* our eventual return code */
|
|
int rc; /* local return code */
|
|
|
|
tv.tv_sec = newtime;
|
|
tv.tv_usec = 0;
|
|
|
|
if (debug) {
|
|
printf( "Calling settimeofday:\n" );
|
|
printf( "\ttv.tv_sec = %ld, tv.tv_usec = %ld\n",
|
|
(long) tv.tv_sec, (long) tv.tv_usec );
|
|
}
|
|
if (testing) {
|
|
printf("Not setting system clock because running in test mode.\n");
|
|
retcode = 0;
|
|
} else {
|
|
rc = settimeofday(&tv, NULL);
|
|
if (rc != 0) {
|
|
if (errno == EPERM)
|
|
fprintf(stderr, "Must be superuser to set system clock.\n");
|
|
else
|
|
fprintf(stderr,
|
|
"settimeofday() failed, errno=%d:%s\n",
|
|
errno, strerror(errno));
|
|
retcode = 1;
|
|
} else retcode = 0;
|
|
}
|
|
return(retcode);
|
|
}
|
|
|
|
|
|
static void
|
|
adjust_drift_factor(struct adjtime *adjtime_p,
|
|
const time_t nowtime,
|
|
const time_t hclocktime ) {
|
|
/*---------------------------------------------------------------------------
|
|
Update the drift factor in <*adjtime_p> to reflect the fact that the
|
|
Hardware Clock was calibrated to <nowtime> and before that was set
|
|
to <hclocktime>.
|
|
|
|
We assume that the user has been doing regular drift adjustments
|
|
using the drift factor in the adjtime file, so if <nowtime> and
|
|
<clocktime> are different, that means the adjustment factor isn't
|
|
quite right.
|
|
|
|
We record in the adjtime file the time at which we last calibrated
|
|
the clock so we can compute the drift rate each time we calibrate.
|
|
|
|
----------------------------------------------------------------------------*/
|
|
if ((hclocktime - adjtime_p->last_calib_time) >= 24 * 60 * 60) {
|
|
const float factor_adjust =
|
|
((float) (nowtime - hclocktime)
|
|
/ (hclocktime - adjtime_p->last_calib_time))
|
|
* 24 * 60 * 60;
|
|
|
|
if (debug)
|
|
printf("Clock drifted %d seconds in the past %d seconds "
|
|
"in spite of a drift factor of %f seconds/day.\n"
|
|
"Adjusting drift factor by %f seconds/day\n",
|
|
(int) (nowtime - hclocktime),
|
|
(int) (hclocktime - adjtime_p->last_calib_time),
|
|
adjtime_p->drift_factor,
|
|
factor_adjust );
|
|
|
|
adjtime_p->drift_factor += factor_adjust;
|
|
} else if (debug)
|
|
printf("Not adjusting drift factor because it has been less than a "
|
|
"day since the last calibration.\n");
|
|
|
|
adjtime_p->last_calib_time = nowtime;
|
|
|
|
adjtime_p->last_adj_time = nowtime;
|
|
|
|
adjtime_p->not_adjusted = 0;
|
|
|
|
adjtime_p->dirty = TRUE;
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
calculate_adjustment(
|
|
const float factor,
|
|
const time_t last_time,
|
|
const float not_adjusted,
|
|
const time_t systime,
|
|
int *adjustment_p,
|
|
float *retro_p,
|
|
const int debug ) {
|
|
/*----------------------------------------------------------------------------
|
|
Do the drift adjustment calculation.
|
|
|
|
The way we have to set the clock, we need the adjustment in two parts:
|
|
|
|
1) an integer number of seconds (return as *adjustment_p)
|
|
|
|
2) a positive fraction of a second (less than 1) (return as *retro_p)
|
|
|
|
The sum of these two values is the adjustment needed. Positive means to
|
|
advance the clock or insert seconds. Negative means to retard the clock
|
|
or remove seconds.
|
|
----------------------------------------------------------------------------*/
|
|
float exact_adjustment;
|
|
|
|
exact_adjustment = ((float) (systime - last_time)) * factor / (24 * 60 * 60)
|
|
+ not_adjusted;
|
|
*adjustment_p = FLOOR(exact_adjustment);
|
|
|
|
*retro_p = exact_adjustment - (float) *adjustment_p;
|
|
if (debug) {
|
|
printf ("Time since last adjustment is %d seconds\n",
|
|
(int) (systime - last_time));
|
|
printf ("Need to insert %d seconds and refer time back "
|
|
"%.6f seconds ago\n",
|
|
*adjustment_p, *retro_p);
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
save_adjtime(const struct adjtime adjtime, const bool testing) {
|
|
/*-----------------------------------------------------------------------------
|
|
Write the contents of the <adjtime> structure to its disk file.
|
|
|
|
But if the contents are clean (unchanged since read from disk), don't
|
|
bother.
|
|
-----------------------------------------------------------------------------*/
|
|
FILE *adjfile;
|
|
char newfile[405]; /* Stuff to write to disk file */
|
|
|
|
int rc; /* locally used: return code from a function */
|
|
|
|
if (adjtime.dirty) {
|
|
/* snprintf is not always available, but this is safe
|
|
as long as libc does not use more than 100 positions for %ld or %f */
|
|
sprintf(newfile, "%f %ld %f\n%ld\n",
|
|
adjtime.drift_factor,
|
|
(long) adjtime.last_adj_time,
|
|
adjtime.not_adjusted,
|
|
(long) adjtime.last_calib_time );
|
|
|
|
if (testing) {
|
|
printf("Not updating adjtime file because of testing mode.\n");
|
|
printf("Would have written the following to %s:\n%s",
|
|
ADJPATH, newfile);
|
|
} else {
|
|
adjfile = fopen(ADJPATH, "w");
|
|
if (adjfile == NULL) {
|
|
const int fopen_errno = errno;
|
|
printf("Could not open file with the clock adjustment parameters "
|
|
"in it (%s) for output.\n"
|
|
"fopen() returned errno %d: %s.\n"
|
|
"Drift adjustment parameters not updated.\n",
|
|
ADJPATH, fopen_errno, strerror(errno));
|
|
} else {
|
|
rc = fprintf(adjfile, newfile);
|
|
if (rc < 0) {
|
|
const int fprintf_errno = errno;
|
|
printf("Could not update file with the clock adjustment parameters "
|
|
"(%s) in it.\n"
|
|
"fprintf() returned errno %d: %s.\n"
|
|
"Drift adjustment parameters not updated.\n",
|
|
ADJPATH, fprintf_errno, strerror(errno));
|
|
}
|
|
rc = fclose(adjfile);
|
|
if (rc < 0) {
|
|
const int fclose_errno = errno;
|
|
printf("Could not update file with the clock adjustment parameters "
|
|
"(%s) in it.\n"
|
|
"fclose() returned errno %d: %s.\n"
|
|
"Drift adjustment parameters not updated.\n",
|
|
ADJPATH, fclose_errno, strerror(errno));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
do_adjustment(struct adjtime *adjtime_p,
|
|
const time_t hclocktime, const struct timeval read_time,
|
|
const enum clock_access_method clock_access,
|
|
const bool universal, const bool testing) {
|
|
/*---------------------------------------------------------------------------
|
|
Do the adjustment requested, by 1) setting the Hardware Clock (if
|
|
necessary), and 2) updating the last-adjusted time in the adjtime
|
|
structure.
|
|
|
|
arguments <factor> and <last_time> are current values from the adjtime
|
|
file.
|
|
|
|
<hclocktime> is the current time set in the Hardware Clock.
|
|
|
|
<read_time> is the current system time (to be precise, it is the system
|
|
time at the time <hclocktime> was read, which due to computational delay
|
|
could be a short time ago).
|
|
|
|
<universal>: the Hardware Clock is kept in UTC.
|
|
|
|
<testing>: We are running in test mode (no updating of clock).
|
|
|
|
We do not bother to update the clock if the adjustment would be less than
|
|
one second. This is to avoid cumulative error and needless CPU hogging
|
|
(remember we use an infinite loop for some timing) if the user runs us
|
|
frequently.
|
|
|
|
----------------------------------------------------------------------------*/
|
|
int adjustment;
|
|
/* Number of seconds we must insert in the Hardware Clock */
|
|
float retro;
|
|
/* Fraction of second we have to remove from clock after inserting
|
|
<adjustment> whole seconds.
|
|
*/
|
|
calculate_adjustment(adjtime_p->drift_factor,
|
|
adjtime_p->last_adj_time,
|
|
adjtime_p->not_adjusted,
|
|
hclocktime,
|
|
&adjustment, &retro,
|
|
debug );
|
|
if (adjustment > 0 || adjustment < -1) {
|
|
set_hardware_clock_exact(hclocktime + adjustment,
|
|
time_inc(read_time, -retro),
|
|
clock_access, universal, testing);
|
|
adjtime_p->last_adj_time = hclocktime + adjustment;
|
|
adjtime_p->not_adjusted = 0;
|
|
adjtime_p->dirty = TRUE;
|
|
} else
|
|
if (debug)
|
|
printf("Needed adjustment is less than one second, "
|
|
"so not setting clock.\n");
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
determine_clock_access_method(const bool user_requests_ISA,
|
|
enum clock_access_method *clock_access_p) {
|
|
/*----------------------------------------------------------------------------
|
|
Figure out how we're going to access the hardware clock, by seeing
|
|
what facilities are available, looking at invocation options, and
|
|
using compile-time constants.
|
|
|
|
<user_requests_ISA> means the user explicitly asked for the ISA method.
|
|
Even if he did, we will not select the ISA method if this is not an
|
|
ISA machine.
|
|
-----------------------------------------------------------------------------*/
|
|
bool rtc_works;
|
|
/* The /dev/rtc method is available and seems to work on this machine */
|
|
|
|
if (got_rtc) {
|
|
int rtc_fd = open("/dev/rtc", O_RDONLY);
|
|
if (rtc_fd > 0) {
|
|
rtc_works = TRUE;
|
|
close(rtc_fd);
|
|
} else {
|
|
rtc_works = FALSE;
|
|
if (debug)
|
|
printf("Open of /dev/rtc failed, errno = %s (%d). "
|
|
"falling back to more primitive clock access method.\n",
|
|
strerror(errno), errno);
|
|
}
|
|
} else {
|
|
if (debug)
|
|
printf("The Linux kernel for which this copy of hwclock() was built "
|
|
"is too old to have /dev/rtc\n");
|
|
rtc_works = FALSE;
|
|
}
|
|
|
|
if (user_requests_ISA && isa_machine) *clock_access_p = ISA;
|
|
else if (rtc_works) *clock_access_p = RTC_IOCTL;
|
|
else if (got_kdghwclk) {
|
|
int con_fd;
|
|
struct hwclk_time t;
|
|
|
|
con_fd = open("/dev/tty1", O_RDONLY);
|
|
if (con_fd >= 0) {
|
|
if (ioctl( con_fd, kdghwclk_ioctl, &t ) >= 0)
|
|
*clock_access_p = KD;
|
|
else {
|
|
if (errno == EINVAL) {
|
|
/* KDGHWCLK not implemented in this kernel... */
|
|
*clock_access_p = ISA;
|
|
} else {
|
|
*clock_access_p = KD;
|
|
fprintf(stderr,
|
|
"KDGHWCLK ioctl failed, errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
}
|
|
}
|
|
} else {
|
|
*clock_access_p = KD;
|
|
fprintf(stderr,
|
|
"Can't open /dev/tty1. open() errno = %s (%d).\n",
|
|
strerror(errno), errno);
|
|
}
|
|
close(con_fd);
|
|
} else if (isa_machine) {
|
|
*clock_access_p = ISA;
|
|
} else
|
|
*clock_access_p = NOCLOCK;
|
|
if (debug) {
|
|
switch (*clock_access_p) {
|
|
case ISA: printf("Using direct I/O instructions to ISA clock.\n"); break;
|
|
case KD: printf("Using KDGHWCLK interface to m68k clock.\n"); break;
|
|
case RTC_IOCTL: printf("Using /dev/rtc interface to clock.\n"); break;
|
|
default:
|
|
printf("determine_clock_access_method() returned invalid value: %d.\n",
|
|
*clock_access_p);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
manipulate_clock(const bool show, const bool adjust,
|
|
const bool set, const time_t set_time,
|
|
const bool hctosys, const bool systohc,
|
|
const struct timeval startup_time,
|
|
const enum clock_access_method clock_access,
|
|
const bool universal, const bool testing,
|
|
int *retcode_p
|
|
) {
|
|
/*---------------------------------------------------------------------------
|
|
Do all the normal work of hwclock - read, set clock, etc.
|
|
|
|
Issue output to stdout and error message to stderr where appropriate.
|
|
|
|
Return rc == 0 if everything went OK, rc != 0 if not.
|
|
----------------------------------------------------------------------------*/
|
|
struct adjtime adjtime;
|
|
/* Contents of the adjtime file, or what they should be. */
|
|
struct tm tm;
|
|
time_t hclocktime;
|
|
/* The time the hardware clock had just after we synchronized to its
|
|
next clock tick when we started up.
|
|
*/
|
|
struct timeval read_time;
|
|
/* The time at which we read the Hardware Clock */
|
|
|
|
int rc; /* local return code */
|
|
bool no_auth; /* User lacks necessary authorization to access the clock */
|
|
|
|
if (clock_access == ISA) {
|
|
rc = i386_iopl(3);
|
|
if (rc != 0) {
|
|
fprintf(stderr, MYNAME " is unable to get I/O port access. "
|
|
"I.e. iopl(2) returned nonzero return code %d.\n"
|
|
"This is often because the program isn't running "
|
|
"with superuser privilege, which it needs.\n",
|
|
rc);
|
|
no_auth = TRUE;
|
|
} else no_auth = FALSE;
|
|
} else no_auth = FALSE;
|
|
|
|
if (no_auth) *retcode_p = 1;
|
|
else {
|
|
if (adjust || set || systohc)
|
|
read_adjtime(&adjtime, &rc);
|
|
else {
|
|
/* A little trick to avoid reading the file if we don't have to */
|
|
adjtime.dirty = FALSE;
|
|
rc = 0;
|
|
}
|
|
if (rc != 0) *retcode_p = 2;
|
|
else {
|
|
synchronize_to_clock_tick(clock_access, retcode_p);
|
|
/* this takes up to 1 second */
|
|
if (*retcode_p == 0) {
|
|
/* Get current time from Hardware Clock, in case we need it */
|
|
gettimeofday(&read_time, NULL);
|
|
read_hardware_clock(clock_access, &tm);
|
|
hclocktime = mktime_tz(tm, universal);
|
|
|
|
if (show) {
|
|
display_time(hclocktime, time_diff(read_time, startup_time));
|
|
*retcode_p = 0;
|
|
} else if (set) {
|
|
set_hardware_clock_exact(set_time, startup_time,
|
|
clock_access, universal, testing);
|
|
adjust_drift_factor(&adjtime, set_time, hclocktime);
|
|
*retcode_p = 0;
|
|
} else if (adjust) {
|
|
do_adjustment(&adjtime, hclocktime, read_time, clock_access,
|
|
universal, testing);
|
|
*retcode_p = 0;
|
|
} else if (systohc) {
|
|
struct timeval nowtime, reftime;
|
|
/* We can only set_hardware_clock_exact to a whole seconds
|
|
time, so we set it with reference to the most recent
|
|
whole seconds time.
|
|
*/
|
|
gettimeofday(&nowtime, NULL);
|
|
reftime.tv_sec = nowtime.tv_sec;
|
|
reftime.tv_usec = 0;
|
|
|
|
set_hardware_clock_exact((time_t) reftime.tv_sec, reftime,
|
|
clock_access, universal, testing);
|
|
*retcode_p = 0;
|
|
adjust_drift_factor(&adjtime, (time_t) reftime.tv_sec, hclocktime);
|
|
} else if (hctosys) {
|
|
rc = set_system_clock(hclocktime, testing);
|
|
if (rc != 0) {
|
|
printf("Unable to set system clock.\n");
|
|
*retcode_p = 1;
|
|
} else *retcode_p = 0;
|
|
}
|
|
save_adjtime(adjtime, testing);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
manipulate_epoch(const bool getepoch, const bool setepoch,
|
|
const int epoch_opt, const bool testing) {
|
|
/*----------------------------------------------------------------------------
|
|
Get or set the Hardware Clock epoch value in the kernel, as appropriate.
|
|
<getepoch>, <setepoch>, and <epoch> are hwclock invocation options.
|
|
|
|
<epoch> == -1 if the user did not specify an "epoch" option.
|
|
|
|
-----------------------------------------------------------------------------*/
|
|
/*
|
|
Maintenance note: This should work on non-Alpha machines, but the
|
|
evidence today (98.03.04) indicates that the kernel only keeps the
|
|
epoch value on Alphas. If that is ever fixed, this function should be
|
|
changed.
|
|
*/
|
|
|
|
if (!alpha_machine)
|
|
fprintf(stderr, "The kernel keeps an epoch value for the Hardware Clock "
|
|
"only on an Alpha machine.\nThis copy of hwclock was built for "
|
|
"a machine other than Alpha\n(and thus is presumably not running "
|
|
"on an Alpha now). No action taken.\n");
|
|
else {
|
|
if (getepoch) {
|
|
unsigned long epoch;
|
|
int retcode;
|
|
|
|
get_epoch(&epoch, &retcode);
|
|
if (retcode != 0)
|
|
printf("Unable to get the epoch value from the kernel.\n");
|
|
else
|
|
printf("Kernel is assuming an epoch value of %lu\n", epoch);
|
|
} else if (setepoch) {
|
|
if (epoch_opt == -1)
|
|
fprintf(stderr, "To set the epoch value, you must use the 'epoch' "
|
|
"option to tell to what value to set it.\n");
|
|
else {
|
|
int rc;
|
|
set_epoch(epoch_opt, testing, &rc);
|
|
if (rc != 0)
|
|
printf("Unable to set the epoch value in the kernel.\n");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
int
|
|
main(int argc, char **argv, char **envp) {
|
|
/*----------------------------------------------------------------------------
|
|
MAIN
|
|
-----------------------------------------------------------------------------*/
|
|
struct timeval startup_time;
|
|
/* The time we started up, in seconds into the epoch, including fractions.
|
|
*/
|
|
time_t set_time; /* Time to which user said to set Hardware Clock */
|
|
|
|
enum clock_access_method clock_access;
|
|
/* The method that we determine is best for accessing Hardware Clock
|
|
on this system.
|
|
*/
|
|
|
|
bool permitted; /* User is permitted to do the function */
|
|
int retcode; /* Our eventual return code */
|
|
|
|
int rc; /* local return code */
|
|
|
|
/* option_def is the control table for the option parser. These other
|
|
variables are the results of parsing the options and their meanings
|
|
are given by the option_def. The only exception is <show>, which
|
|
may be modified after parsing is complete to effect an implied option.
|
|
*/
|
|
bool show, set, systohc, hctosys, adjust, getepoch, setepoch, version;
|
|
bool universal, testing, directisa;
|
|
char *date_opt;
|
|
int epoch_opt;
|
|
|
|
const optStruct option_def[] = {
|
|
{ 'r', (char *) "show", OPT_FLAG, &show, 0 },
|
|
{ 0, (char *) "set", OPT_FLAG, &set, 0 },
|
|
{ 'w', (char *) "systohc", OPT_FLAG, &systohc, 0 },
|
|
{ 's', (char *) "hctosys", OPT_FLAG, &hctosys, 0 },
|
|
{ 0, (char *) "getepoch", OPT_FLAG, &getepoch, 0 },
|
|
{ 0, (char *) "setepoch", OPT_FLAG, &setepoch, 0 },
|
|
{ 'a', (char *) "adjust", OPT_FLAG, &adjust, 0 },
|
|
{ 'v', (char *) "version", OPT_FLAG, &version, 0 },
|
|
{ 0, (char *) "date", OPT_STRING, &date_opt, 0 },
|
|
{ 0, (char *) "epoch", OPT_UINT, &epoch_opt, 0 },
|
|
{ 'u', (char *) "utc", OPT_FLAG, &universal, 0 },
|
|
{ 0, (char *) "directisa", OPT_FLAG, &directisa, 0 },
|
|
{ 0, (char *) "test", OPT_FLAG, &testing, 0 },
|
|
{ 'D', (char *) "debug", OPT_FLAG, &debug, 0 },
|
|
{ 0, (char *) NULL, OPT_END, NULL, 0 }
|
|
};
|
|
int argc_parse; /* argc, except we modify it as we parse */
|
|
char **argv_parse; /* argv, except we modify it as we parse */
|
|
|
|
interrupts_enabled = TRUE; /* Since we haven't messed with them yet */
|
|
|
|
gettimeofday(&startup_time, NULL); /* Remember what time we were invoked */
|
|
|
|
/* set option defaults */
|
|
show = set = systohc = hctosys = adjust = getepoch = setepoch =
|
|
version = universal =
|
|
directisa = testing = debug = FALSE;
|
|
date_opt = NULL;
|
|
epoch_opt = -1;
|
|
|
|
argc_parse = argc; argv_parse = argv;
|
|
optParseOptions(&argc_parse, argv_parse, option_def, 0);
|
|
/* Uses and sets argc_parse, argv_parse.
|
|
Sets show, systohc, hctosys, adjust, universal, version, testing,
|
|
debug, set, date_opt, getepoch, setepoch, epoch_opt
|
|
*/
|
|
|
|
if (argc_parse - 1 > 0) {
|
|
fprintf(stderr, MYNAME " takes no non-option arguments. "
|
|
"You supplied %d.\n",
|
|
argc_parse - 1);
|
|
exit(100);
|
|
}
|
|
|
|
if (show + set + systohc + hctosys + adjust +
|
|
getepoch + setepoch + version > 1) {
|
|
fprintf(stderr, "You have specified multiple function options.\n"
|
|
"You can only perform one function at a time.\n");
|
|
exit(100);
|
|
}
|
|
|
|
if (set) {
|
|
rc = interpret_date_string(date_opt, &set_time); /* (time-consuming) */
|
|
if (rc != 0) {
|
|
fprintf(stderr, "No usable set-to time. Cannot set clock.\n");
|
|
exit(100);
|
|
}
|
|
}
|
|
|
|
if (directisa && !isa_machine) {
|
|
fprintf(stderr, "You have requested direct access to the ISA Hardware "
|
|
"Clock using machine instructions from the user process. "
|
|
"But this method only works on an ISA machine with an x86 "
|
|
"CPU, and this is not one!\n");
|
|
exit(100);
|
|
}
|
|
|
|
if (!(show | set | systohc | hctosys | adjust | getepoch | setepoch |
|
|
version))
|
|
show = 1; /* default to show */
|
|
|
|
|
|
if (getuid() == 0) permitted = TRUE;
|
|
else {
|
|
/* program is designed to run setuid (in some situations) -- be secure! */
|
|
if (set || hctosys || systohc || adjust) {
|
|
fprintf(stderr,
|
|
"Sorry, only the superuser can change the Hardware Clock.\n");
|
|
permitted = FALSE;
|
|
} else if (setepoch) {
|
|
fprintf(stderr,
|
|
"Sorry, only the superuser can change "
|
|
"the Hardware Clock epoch in the kernel.\n");
|
|
permitted = FALSE;
|
|
} else permitted = TRUE;
|
|
}
|
|
|
|
if (!permitted) retcode = 2;
|
|
else {
|
|
retcode = 0;
|
|
if (version) {
|
|
printf(MYNAME " " VERSION "/%s\n",util_linux_version);
|
|
} else if (getepoch || setepoch) {
|
|
manipulate_epoch(getepoch, setepoch, epoch_opt, testing);
|
|
} else {
|
|
determine_clock_access_method(directisa, &clock_access);
|
|
if (clock_access == NOCLOCK)
|
|
fprintf(stderr, "Cannot access the Hardware Clock via any known "
|
|
"method. Use --debug option to see the details of our "
|
|
"search for an access method.\n");
|
|
else
|
|
manipulate_clock(show, adjust, set, set_time, hctosys, systohc,
|
|
startup_time, clock_access, universal, testing, &rc);
|
|
}
|
|
}
|
|
exit(retcode);
|
|
}
|
|
|
|
|
|
/****************************************************************************
|
|
|
|
History of this program:
|
|
|
|
98.03.05 BJH. Version 2.2.
|
|
|
|
Add --getepoch and --setepoch.
|
|
|
|
Fix some word length things so it works on Alpha.
|
|
|
|
Make it work when /dev/rtc doesn't have the interrupt functions.
|
|
In this case, busywait for the top of a second instead of blocking and
|
|
waiting for the update complete interrupt.
|
|
|
|
Fix a bunch of bugs too numerous to mention.
|
|
|
|
97.06.01: BJH. Version 2.1. Read and write the century byte (Byte
|
|
50) of the ISA Hardware Clock when using direct ISA I/O. Problem
|
|
discovered by job (jei@iclnl.icl.nl).
|
|
|
|
Use the rtc clock access method in preference to the KDGHWCLK method.
|
|
Problem discovered by Andreas Schwab <schwab@LS5.informatik.uni-dortmund.de>.
|
|
|
|
November 1996: Version 2.0.1. Modifications by Nicolai Langfeldt
|
|
(janl@math.uio.no) to make it compile on linux 1.2 machines as well
|
|
as more recent versions of the kernel. Introduced the NO_CLOCK
|
|
access method and wrote feature test code to detect absense of rtc
|
|
headers.
|
|
|
|
|
|
Bryan Henderson based hwclock on the program "clock", in September
|
|
1996. While remaining mostly backward compatible with clock,
|
|
hwclock added the following:
|
|
|
|
- You can set the hardware clock without also modifying the Linux
|
|
system clock.
|
|
|
|
- You can read and set the clock with finer than 1 second precision.
|
|
|
|
- When you set the clock, hwclock automatically refigures the drift
|
|
rate, based on how far off the clock was before you set it. (This
|
|
is the drift rate that is used with the --adjust function to
|
|
automatically adjust the clock periodically to compensate for drift).
|
|
|
|
- More mnemonic GNU-style command line options.
|
|
|
|
- Comments describing how the clock and program work to improve
|
|
maintainability.
|
|
|
|
- Removed the old dead I/O code that worked without the inb/outb
|
|
instructions and without the asm/io.h definitions.
|
|
|
|
The first version of hwclock was Version 2.
|
|
|
|
Here is the history section from the "clock" program at the time it was
|
|
used as a basis for hwclock:
|
|
|
|
V1.0
|
|
|
|
|
|
V1.0 by Charles Hedrick, hedrick@cs.rutgers.edu, April 1992.
|
|
|
|
********************
|
|
V1.1
|
|
Modified for clock adjustments - Rob Hooft, hooft@chem.ruu.nl, Nov 1992
|
|
Also moved error messages to stderr. The program now uses getopt.
|
|
Changed some exit codes. Made 'gcc 2.3 -Wall' happy.
|
|
|
|
*****
|
|
V1.2
|
|
|
|
Applied patches by Harald Koenig (koenig@nova.tat.physik.uni-tuebingen.de)
|
|
Patched and indented by Rob Hooft (hooft@EMBL-Heidelberg.DE)
|
|
|
|
A free quote from a MAIL-message (with spelling corrections):
|
|
|
|
"I found the explanation and solution for the CMOS reading 0xff problem
|
|
in the 0.99pl13c (ALPHA) kernel: the RTC goes offline for a small amount
|
|
of time for updating. Solution is included in the kernel source
|
|
(linux/kernel/time.c)."
|
|
|
|
"I modified clock.c to fix this problem and added an option (now default,
|
|
look for USE_INLINE_ASM_IO) that I/O instructions are used as inline
|
|
code and not via /dev/port (still possible via #undef ...)."
|
|
|
|
With the new code, which is partially taken from the kernel sources,
|
|
the CMOS clock handling looks much more "official".
|
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Thanks Harald (and Torsten for the kernel code)!
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*****
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V1.3
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Canges from alan@spri.levels.unisa.edu.au (Alan Modra):
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a) Fix a few typos in comments and remove reference to making
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clock -u a cron job. The kernel adjusts cmos time every 11
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minutes - see kernel/sched.c and kernel/time.c set_rtc_mmss().
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This means we should really have a cron job updating
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/etc/adjtime every 11 mins (set last_time to the current time
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and not_adjusted to ???).
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b) Swapped arguments of outb() to agree with asm/io.h macro of the
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same name. Use outb() from asm/io.h as it's slightly better.
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c) Changed CMOS_READ and CMOS_WRITE to inline functions. Inserted
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cli()..sti() pairs in appropriate places to prevent possible
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errors, and changed ioperm() call to iopl() to allow cli.
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d) Moved some variables around to localise them a bit.
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e) Fixed bug with clock -ua or clock -us that cleared environment
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variable TZ. This fix also cured the annoying display of bogus
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day of week on a number of machines. (Use mktime(), ctime()
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rather than asctime() )
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f) Use settimeofday() rather than stime(). This one is important
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as it sets the kernel's timezone offset, which is returned by
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gettimeofday(), and used for display of MSDOS and OS2 file
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times.
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g) faith@cs.unc.edu added -D flag for debugging
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V1.4: alan@SPRI.Levels.UniSA.Edu.Au (Alan Modra)
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Wed Feb 8 12:29:08 1995, fix for years > 2000.
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faith@cs.unc.edu added -v option to print version. */
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