On Thu, Dec 07, 2023 at 01:17:15PM +1100, patrick.oppenlan...@gmail.com wrote:
> This patch adds support for getting leap second information from the
> leap-seconds.list file included with tzdata and adds a new configuration
> directive leapseclist to switch on the feature.

Finally getting back to this patch set.

> diff --git a/doc/chrony.conf.adoc b/doc/chrony.conf.adoc

> +[[leapseclist]]*leapseclist* _file_::
> +This directive specifies the path to a file containing a list of leap 
> seconds.

Can you please add few words about the file format, maybe simply
describe it as the NIST format? It contains not just the leap seconds,
but also the TAI-UTC offset.

> diff --git a/leapdb.c b/leapdb.c

> +enum {
> +  SRC_NONE,
> +  SRC_TZ,
> +  SRC_LEAP_SEC_LIST,
> +} leap_src;

The enum naming seems inconsistent. Maybe "SRC_TIMEZONE" and
"SRC_LIST" would look better?

> +
> +/* Offset between leap-seconds.list timestamp epoch and Unix epoch.
> +   leap-seconds.list epoch is 1 Jan 1900, 00:00:00 */
> +static const long long LEAP_SEC_LIST_OFFSET = 2208988800;

This should be a macro.

> @@ -93,6 +102,78 @@ get_tz_leap(time_t when, int *tai_offset)
>  
>  /* ================================================== */
>  
> +static NTP_Leap
> +get_leap_sec_list_leap(time_t when, int *tai_offset)

Or shorter get_list_leap()?

> +{
> +  FILE *f;
> +  char *line = NULL;
> +  size_t linelen = 0;
> +  NTP_Leap lsl_leap = LEAP_Normal;
> +  int prev_lsl_tai_offset = 10;
> +  long long lsl_updated = 0, lsl_expiry = 0;

I think these should be int64_t and SCNd64 format in sscanf.

> +  if (!(f = fopen(CNF_GetLeapSecList(), "r"))) {

Use UTI_OpenFile() here. It will print an error message. And maybe
add a variable to save the return value of CNF_GetLeapSecList(), so it
doesn't have to be called multiple times in the same function?

> +  while (getline(&line, &linelen, f) > 0) {

Please use fgets() as used in all other file parsing.

> +    long long lsl_when;

int64_t

> +    int lsl_tai_offset;
> +
> +    if (*line == '#') {
> +      /* Update time line starts with #$ */
> +      if (line[1] == '$' && sscanf(line + 2, "%lld", &lsl_updated) != 1)
> +        goto error;
> +      /* Expiration time line starts with #@ */
> +      if (line[1] == '@' && sscanf(line + 2, "%lld", &lsl_expiry) != 1)
> +        goto error;
> +      /* Comment or a special comment we don't care about */
> +      continue;
> +    }
> +
> +    /* Leap entry */
> +    if (sscanf(line, "%lld %d", &lsl_when, &lsl_tai_offset) != 2)
> +      goto error;
> +
> +    if (when == lsl_when) {
> +      if (lsl_tai_offset > prev_lsl_tai_offset)
> +        lsl_leap = LEAP_InsertSecond;
> +      else if (lsl_tai_offset < prev_lsl_tai_offset)
> +        lsl_leap = LEAP_DeleteSecond;
> +      /* When is rounded to the end of the day, so offset hasn't changed 
> yet! */
> +      *tai_offset = prev_lsl_tai_offset;
> +    } else if (when > lsl_when)
> +      *tai_offset = lsl_tai_offset;
> +
> +    prev_lsl_tai_offset = lsl_tai_offset;
> +  }
> +
> +  /* Make sure the file looks sensible */
> +  if (!feof(f) || !lsl_updated || !lsl_expiry)
> +    goto error;
> +
> +  if (when >= lsl_expiry)
> +    LOG(LOGS_WARN, "Leap second list %s needs update", CNF_GetLeapSecList());
> +
> +  goto out;
> +
> +error:
> +  LOG(LOGS_ERR, "Failed to parse leap seconds list %s", 
> CNF_GetLeapSecList());
> +out:
> +  if (f)
> +    fclose(f);
> +  return lsl_leap;
> +}
> +
> +/* ================================================== */
> +
>  static int
>  check_leap_source(NTP_Leap (*src)(time_t when, int *tai_offset))
>  {
> @@ -111,14 +192,30 @@ check_leap_source(NTP_Leap (*src)(time_t when, int 
> *tai_offset))
>  void
>  LDB_Initialise(void)
>  {
> -  leap_tzname = CNF_GetLeapSecTimezone();
> +  const char *leap_tzname = CNF_GetLeapSecTimezone();
>    if (leap_tzname && !check_leap_source(get_tz_leap)) {
>      LOG(LOGS_WARN, "Timezone %s failed leap second check, ignoring", 
> leap_tzname);
>      leap_tzname = NULL;
>    }
>  
> -  if (leap_tzname)
> +  const char *leap_sec_list = CNF_GetLeapSecList();

Declarations should be at the beginning of the function.

> +  if (leap_sec_list && !check_leap_source(get_leap_sec_list_leap)) {
> +    LOG(LOGS_WARN, "Leap second list %s failed check, ignoring", 
> leap_sec_list);
> +    leap_sec_list = NULL;
> +  }
> +
> +  if (leap_sec_list && leap_tzname) {
> +    LOG(LOGS_WARN, "Multiple leap second sources, ignoring leapsectz");
> +    leap_tzname = NULL;

This warning doesn't seem necessary to me. Info message for the first
working source is fine. It doesn't have to check both.

Thanks,

-- 
Miroslav Lichvar


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