Back to index

glibc  2.9
Classes | Defines | Functions | Variables
tzfile.c File Reference
#include <assert.h>
#include <limits.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
#include <timezone/tzfile.h>
#include <endian.h>
#include <byteswap.h>

Go to the source code of this file.

Classes

struct  ttinfo
struct  leap

Defines

#define NOID

Functions

static void compute_tzname_max (size_t)
static int64_t __attribute ((always_inline))
void __tzfile_read (const char *file, size_t extra, char **extrap)
void __tzfile_default (const char *std, const char *dst, long int stdoff, long int dstoff)
void __tzfile_compute (time_t timer, int use_localtime, long int *leap_correct, int *leap_hit, struct tm *tp)

Variables

int __use_tzfile
static dev_t tzfile_dev
static ino64_t tzfile_ino
static time_t tzfile_mtime

Class Documentation

struct ttinfo

Definition at line 38 of file tzfile.c.

Class Members
unsigned char idx
unsigned char isdst
unsigned char isgmt
unsigned char isstd
long int offset
struct leap

Definition at line 47 of file tzfile.c.

Class Members
long int change
time_t transition

Define Documentation

#define NOID

Definition at line 30 of file tzfile.c.


Function Documentation

static int64_t __attribute ( (always_inline)  ) [inline, static]

Definition at line 93 of file tzfile.c.

{
  if ((BYTE_ORDER == BIG_ENDIAN))
    return *(const int64_t *) ptr;

  return bswap_64 (*(const int64_t *) ptr);
}
void __tzfile_compute ( time_t  timer,
int  use_localtime,
long int leap_correct,
int leap_hit,
struct tm tp 
)

Definition at line 591 of file tzfile.c.

{
  register size_t i;

  if (use_localtime)
    {
      __tzname[0] = NULL;
      __tzname[1] = NULL;

      if (__builtin_expect (num_transitions == 0 || timer < transitions[0], 0))
       {
         /* TIMER is before any transition (or there are no transitions).
            Choose the first non-DST type
            (or the first if they're all DST types).  */
         i = 0;
         while (i < num_types && types[i].isdst)
           {
             if (__tzname[1] == NULL)
              __tzname[1] = __tzstring (&zone_names[types[i].idx]);

             ++i;
           }

         if (i == num_types)
           i = 0;
         __tzname[0] = __tzstring (&zone_names[types[i].idx]);
         if (__tzname[1] == NULL)
           {
             size_t j = i;
             while (j < num_types)
              if (types[j].isdst)
                {
                  __tzname[1] = __tzstring (&zone_names[types[j].idx]);
                  break;
                }
              else
                ++j;
           }
       }
      else if (__builtin_expect (timer >= transitions[num_transitions - 1], 0))
       {
         if (__builtin_expect (tzspec == NULL, 0))
           {
           use_last:
             i = num_transitions;
             goto found;
           }

         /* Parse the POSIX TZ-style string.  */
         __tzset_parse_tz (tzspec);

         /* Convert to broken down structure.  If this fails do not
            use the string.  */
         if (__builtin_expect (! __offtime (&timer, 0, tp), 0))
           goto use_last;

         /* Use the rules from the TZ string to compute the change.  */
         __tz_compute (timer, tp, 1);

         /* If tzspec comes from posixrules loaded by __tzfile_default,
            override the STD and DST zone names with the ones user
            requested in TZ envvar.  */
         if (__builtin_expect (zone_names == (char *) &leaps[num_leaps], 0))
           {
             assert (num_types == 2);
             __tzname[0] = __tzstring (zone_names);
             __tzname[1] = __tzstring (&zone_names[strlen (zone_names) + 1]);
           }

         *leap_correct = 0L;
         *leap_hit = 0;
         return;
       }
      else
       {
         /* Find the first transition after TIMER, and
            then pick the type of the transition before it.  */
         size_t lo = 0;
         size_t hi = num_transitions - 1;
         /* Assume that DST is changing twice a year and guess initial
            search spot from it.
            Half of a gregorian year has on average 365.2425 * 86400 / 2
            = 15778476 seconds.  */
         i = (transitions[num_transitions - 1] - timer) / 15778476;
         if (i < num_transitions)
           {
             i = num_transitions - 1 - i;
             if (timer < transitions[i])
              {
                if (i < 10 || timer >= transitions[i - 10])
                  {
                    /* Linear search.  */
                    while (timer < transitions[i - 1])
                     --i;
                    goto found;
                  }
                hi = i - 10;
              }
             else
              {
                if (i + 10 >= num_transitions || timer < transitions[i + 10])
                  {
                    /* Linear search.  */
                    while (timer >= transitions[i])
                     ++i;
                    goto found;
                  }
                lo = i + 10;
              }
           }

         /* Binary search.  */
         /* assert (timer >= transitions[lo] && timer < transitions[hi]); */
         while (lo + 1 < hi)
           {
             i = (lo + hi) / 2;
             if (timer < transitions[i])
              hi = i;
             else
              lo = i;
           }
         i = hi;

       found:
         /* assert (timer >= transitions[i - 1]
            && (i == num_transitions || timer < transitions[i])); */
         __tzname[types[type_idxs[i - 1]].isdst]
           = __tzstring (&zone_names[types[type_idxs[i - 1]].idx]);
         size_t j = i;
         while (j < num_transitions)
           {
             int type = type_idxs[j];
             int dst = types[type].isdst;
             int idx = types[type].idx;

             if (__tzname[dst] == NULL)
              {
                __tzname[dst] = __tzstring (&zone_names[idx]);

                if (__tzname[1 - dst] != NULL)
                  break;
              }

             ++j;
           }

         if (__builtin_expect (__tzname[0] == NULL, 0))
           __tzname[0] = __tzname[1];

         i = type_idxs[i - 1];
       }

      struct ttinfo *info = &types[i];
      __daylight = rule_stdoff != rule_dstoff;
      __timezone = -rule_stdoff;

      if (__tzname[0] == NULL)
       {
         /* This should only happen if there are no transition rules.
            In this case there should be only one single type.  */
         assert (num_types == 1);
         __tzname[0] = __tzstring (zone_names);
       }
      if (__tzname[1] == NULL)
       /* There is no daylight saving time.  */
       __tzname[1] = __tzname[0];
      tp->tm_isdst = info->isdst;
      assert (strcmp (&zone_names[info->idx], __tzname[tp->tm_isdst]) == 0);
      tp->tm_zone = __tzname[tp->tm_isdst];
      tp->tm_gmtoff = info->offset;
    }

  *leap_correct = 0L;
  *leap_hit = 0;

  /* Find the last leap second correction transition time before TIMER.  */
  i = num_leaps;
  do
    if (i-- == 0)
      return;
  while (timer < leaps[i].transition);

  /* Apply its correction.  */
  *leap_correct = leaps[i].change;

  if (timer == leaps[i].transition && /* Exactly at the transition time.  */
      ((i == 0 && leaps[i].change > 0) ||
       leaps[i].change > leaps[i - 1].change))
    {
      *leap_hit = 1;
      while (i > 0
            && leaps[i].transition == leaps[i - 1].transition + 1
            && leaps[i].change == leaps[i - 1].change + 1)
       {
         ++*leap_hit;
         --i;
       }
    }
}

Here is the call graph for this function:

Here is the caller graph for this function:

void __tzfile_default ( const char *  std,
const char *  dst,
long int  stdoff,
long int  dstoff 
)

Definition at line 507 of file tzfile.c.

{
  size_t stdlen = strlen (std) + 1;
  size_t dstlen = strlen (dst) + 1;
  size_t i;
  int isdst;
  char *cp;

  __tzfile_read (TZDEFRULES, stdlen + dstlen, &cp);
  if (!__use_tzfile)
    return;

  if (num_types < 2)
    {
      __use_tzfile = 0;
      return;
    }

  /* Ignore the zone names read from the file and use the given ones
     instead.  */
  __mempcpy (__mempcpy (cp, std, stdlen), dst, dstlen);
  zone_names = cp;

  /* Now there are only two zones, regardless of what the file contained.  */
  num_types = 2;

  /* Now correct the transition times for the user-specified standard and
     daylight offsets from GMT.  */
  isdst = 0;
  for (i = 0; i < num_transitions; ++i)
    {
      struct ttinfo *trans_type = &types[type_idxs[i]];

      /* We will use only types 0 (standard) and 1 (daylight).
        Fix up this transition to point to whichever matches
        the flavor of its original type.  */
      type_idxs[i] = trans_type->isdst;

      if (trans_type->isgmt)
       /* The transition time is in GMT.  No correction to apply.  */ ;
      else if (isdst && !trans_type->isstd)
       /* The type says this transition is in "local wall clock time", and
          wall clock time as of the previous transition was DST.  Correct
          for the difference between the rule's DST offset and the user's
          DST offset.  */
       transitions[i] += dstoff - rule_dstoff;
      else
       /* This transition is in "local wall clock time", and wall clock
          time as of this iteration is non-DST.  Correct for the
          difference between the rule's standard offset and the user's
          standard offset.  */
       transitions[i] += stdoff - rule_stdoff;

      /* The DST state of "local wall clock time" for the next iteration is
        as specified by this transition.  */
      isdst = trans_type->isdst;
    }

  /* Now that we adjusted the transitions to the requested offsets,
     reset the rule_stdoff and rule_dstoff values appropriately.  They
     are used elsewhere.  */
  rule_stdoff = stdoff;
  rule_dstoff = dstoff;

  /* Reset types 0 and 1 to describe the user's settings.  */
  types[0].idx = 0;
  types[0].offset = stdoff;
  types[0].isdst = 0;
  types[1].idx = stdlen;
  types[1].offset = dstoff;
  types[1].isdst = 1;

  /* Reset the zone names to point to the user's names.  */
  __tzname[0] = (char *) std;
  __tzname[1] = (char *) dst;

  /* Set the timezone.  */
  __timezone = -types[0].offset;

  compute_tzname_max (stdlen + dstlen);
}

Here is the call graph for this function:

Here is the caller graph for this function:

void __tzfile_read ( const char *  file,
size_t  extra,
char **  extrap 
)

Definition at line 104 of file tzfile.c.

{
  static const char default_tzdir[] = TZDIR;
  size_t num_isstd, num_isgmt;
  register FILE *f;
  struct tzhead tzhead;
  size_t chars;
  register size_t i;
  size_t total_size;
  size_t types_idx;
  size_t leaps_idx;
  int was_using_tzfile = __use_tzfile;
  int trans_width = 4;
  size_t tzspec_len;

  if (sizeof (time_t) != 4 && sizeof (time_t) != 8)
    abort ();

  __use_tzfile = 0;

  if (file == NULL)
    /* No user specification; use the site-wide default.  */
    file = TZDEFAULT;
  else if (*file == '\0')
    /* User specified the empty string; use UTC with no leap seconds.  */
    goto ret_free_transitions;
  else
    {
      /* We must not allow to read an arbitrary file in a setuid
        program.  So we fail for any file which is not in the
        directory hierachy starting at TZDIR
        and which is not the system wide default TZDEFAULT.  */
      if (__libc_enable_secure
         && ((*file == '/'
              && memcmp (file, TZDEFAULT, sizeof TZDEFAULT)
              && memcmp (file, default_tzdir, sizeof (default_tzdir) - 1))
             || strstr (file, "../") != NULL))
       /* This test is certainly a bit too restrictive but it should
          catch all critical cases.  */
       goto ret_free_transitions;
    }

  if (*file != '/')
    {
      const char *tzdir;
      unsigned int len, tzdir_len;
      char *new, *tmp;

      tzdir = getenv ("TZDIR");
      if (tzdir == NULL || *tzdir == '\0')
       {
         tzdir = default_tzdir;
         tzdir_len = sizeof (default_tzdir) - 1;
       }
      else
       tzdir_len = strlen (tzdir);
      len = strlen (file) + 1;
      new = (char *) __alloca (tzdir_len + 1 + len);
      tmp = __mempcpy (new, tzdir, tzdir_len);
      *tmp++ = '/';
      memcpy (tmp, file, len);
      file = new;
    }

  /* If we were already using tzfile, check whether the file changed.  */
  struct stat64 st;
  if (was_using_tzfile
      && stat64 (file, &st) == 0
      && tzfile_ino == st.st_ino && tzfile_dev == st.st_dev
      && tzfile_mtime == st.st_mtime)
    {
      /* Nothing to do.  */
      __use_tzfile = 1;
      return;
    }

  /* Note the file is opened with cancellation in the I/O functions
     disabled.  */
  f = fopen (file, "rc");
  if (f == NULL)
    goto ret_free_transitions;

  /* Get information about the file we are actually using.  */
  if (fstat64 (fileno (f), &st) != 0)
    {
      fclose (f);
      goto ret_free_transitions;
    }

  free ((void *) transitions);
  transitions = NULL;

  /* Remember the inode and device number and modification time.  */
  tzfile_dev = st.st_dev;
  tzfile_ino = st.st_ino;
  tzfile_mtime = st.st_mtime;

  /* No threads reading this stream.  */
  __fsetlocking (f, FSETLOCKING_BYCALLER);

 read_again:
  if (__builtin_expect (fread_unlocked ((void *) &tzhead, sizeof (tzhead),
                                   1, f) != 1, 0)
      || memcmp (tzhead.tzh_magic, TZ_MAGIC, sizeof (tzhead.tzh_magic)) != 0)
    goto lose;

  num_transitions = (size_t) decode (tzhead.tzh_timecnt);
  num_types = (size_t) decode (tzhead.tzh_typecnt);
  chars = (size_t) decode (tzhead.tzh_charcnt);
  num_leaps = (size_t) decode (tzhead.tzh_leapcnt);
  num_isstd = (size_t) decode (tzhead.tzh_ttisstdcnt);
  num_isgmt = (size_t) decode (tzhead.tzh_ttisgmtcnt);

  /* For platforms with 64-bit time_t we use the new format if available.  */
  if (sizeof (time_t) == 8 && trans_width == 4
      && tzhead.tzh_version[0] != '\0')
    {
      /* We use the 8-byte format.  */
      trans_width = 8;

      /* Position the stream before the second header.  */
      size_t to_skip = (num_transitions * (4 + 1)
                     + num_types * 6
                     + chars
                     + num_leaps * 8
                     + num_isstd
                     + num_isgmt);
      if (fseek (f, to_skip, SEEK_CUR) != 0)
       goto lose;

      goto read_again;
    }

  total_size = num_transitions * (sizeof (time_t) + 1);
  total_size = ((total_size + __alignof__ (struct ttinfo) - 1)
              & ~(__alignof__ (struct ttinfo) - 1));
  types_idx = total_size;
  total_size += num_types * sizeof (struct ttinfo) + chars;
  total_size = ((total_size + __alignof__ (struct leap) - 1)
              & ~(__alignof__ (struct leap) - 1));
  leaps_idx = total_size;
  total_size += num_leaps * sizeof (struct leap);
  tzspec_len = (sizeof (time_t) == 8 && trans_width == 8
              ? st.st_size - (ftello (f)
                            + num_transitions * (8 + 1)
                            + num_types * 6
                            + chars
                            + num_leaps * 8
                            + num_isstd
                            + num_isgmt) - 1 : 0);

  /* Allocate enough memory including the extra block requested by the
     caller.  */
  transitions = (time_t *) malloc (total_size + tzspec_len + extra);
  if (transitions == NULL)
    goto lose;

  type_idxs = (unsigned char *) transitions + (num_transitions
                                          * sizeof (time_t));
  types = (struct ttinfo *) ((char *) transitions + types_idx);
  zone_names = (char *) types + num_types * sizeof (struct ttinfo);
  leaps = (struct leap *) ((char *) transitions + leaps_idx);
  if (sizeof (time_t) == 8 && trans_width == 8)
    tzspec = (char *) leaps + num_leaps * sizeof (struct leap) + extra;
  else
    tzspec = NULL;
  if (extra > 0)
    *extrap = (char *) &leaps[num_leaps];

  if (sizeof (time_t) == 4 || __builtin_expect (trans_width == 8, 1))
    {
      if (__builtin_expect (fread_unlocked (transitions, trans_width + 1,
                                       num_transitions, f)
                         != num_transitions, 0))
       goto lose;
    }
  else
    {
      if (__builtin_expect (fread_unlocked (transitions, 4, num_transitions, f)
                         != num_transitions, 0)
         || __builtin_expect (fread_unlocked (type_idxs, 1, num_transitions,
                                          f) != num_transitions, 0))
       goto lose;
    }

  /* Check for bogus indices in the data file, so we can hereafter
     safely use type_idxs[T] as indices into `types' and never crash.  */
  for (i = 0; i < num_transitions; ++i)
    if (__builtin_expect (type_idxs[i] >= num_types, 0))
      goto lose;

  if ((BYTE_ORDER != BIG_ENDIAN && (sizeof (time_t) == 4 || trans_width == 4))
      || (BYTE_ORDER == BIG_ENDIAN && sizeof (time_t) == 8
         && trans_width == 4))
    {
      /* Decode the transition times, stored as 4-byte integers in
        network (big-endian) byte order.  We work from the end of
        the array so as not to clobber the next element to be
        processed when sizeof (time_t) > 4.  */
      i = num_transitions;
      while (i-- > 0)
       transitions[i] = decode ((char *) transitions + i * 4);
    }
  else if (BYTE_ORDER != BIG_ENDIAN && sizeof (time_t) == 8)
    {
      /* Decode the transition times, stored as 8-byte integers in
        network (big-endian) byte order.  */
      for (i = 0; i < num_transitions; ++i)
       transitions[i] = decode64 ((char *) transitions + i * 8);
    }

  for (i = 0; i < num_types; ++i)
    {
      unsigned char x[4];
      int c;
      if (__builtin_expect (fread_unlocked (x, 1, sizeof (x), f) != sizeof (x),
                         0))
       goto lose;
      c = getc_unlocked (f);
      if (__builtin_expect ((unsigned int) c > 1u, 0))
       goto lose;
      types[i].isdst = c;
      c = getc_unlocked (f);
      if (__builtin_expect ((size_t) c > chars, 0))
       /* Bogus index in data file.  */
       goto lose;
      types[i].idx = c;
      types[i].offset = (long int) decode (x);
    }

  if (__builtin_expect (fread_unlocked (zone_names, 1, chars, f) != chars, 0))
    goto lose;

  for (i = 0; i < num_leaps; ++i)
    {
      unsigned char x[8];
      if (__builtin_expect (fread_unlocked (x, 1, trans_width, f)
                         != trans_width, 0))
       goto lose;
      if (sizeof (time_t) == 4 || trans_width == 4)
       leaps[i].transition = (time_t) decode (x);
      else
       leaps[i].transition = (time_t) decode64 (x);

      if (__builtin_expect (fread_unlocked (x, 1, 4, f) != 4, 0))
       goto lose;
      leaps[i].change = (long int) decode (x);
    }

  for (i = 0; i < num_isstd; ++i)
    {
      int c = getc_unlocked (f);
      if (__builtin_expect (c == EOF, 0))
       goto lose;
      types[i].isstd = c != 0;
    }
  while (i < num_types)
    types[i++].isstd = 0;

  for (i = 0; i < num_isgmt; ++i)
    {
      int c = getc_unlocked (f);
      if (__builtin_expect (c == EOF, 0))
       goto lose;
      types[i].isgmt = c != 0;
    }
  while (i < num_types)
    types[i++].isgmt = 0;

  /* Read the POSIX TZ-style information if possible.  */
  if (sizeof (time_t) == 8 && tzspec != NULL)
    {
      /* Skip over the newline first.  */
      if (getc_unlocked (f) != '\n'
         || (fread_unlocked (tzspec, 1, tzspec_len - 1, f)
             != tzspec_len - 1))
       tzspec = NULL;
      else
       tzspec[tzspec_len - 1] = '\0';
    }
  else if (sizeof (time_t) == 4 && tzhead.tzh_version[0] != '\0')
    {
      /* Get the TZ string.  */
      if (__builtin_expect (fread_unlocked ((void *) &tzhead, sizeof (tzhead),
                                       1, f) != 1, 0)
         || (memcmp (tzhead.tzh_magic, TZ_MAGIC, sizeof (tzhead.tzh_magic))
             != 0))
       goto lose;

      size_t num_transitions2 = (size_t) decode (tzhead.tzh_timecnt);
      size_t num_types2 = (size_t) decode (tzhead.tzh_typecnt);
      size_t chars2 = (size_t) decode (tzhead.tzh_charcnt);
      size_t num_leaps2 = (size_t) decode (tzhead.tzh_leapcnt);
      size_t num_isstd2 = (size_t) decode (tzhead.tzh_ttisstdcnt);
      size_t num_isgmt2 = (size_t) decode (tzhead.tzh_ttisgmtcnt);

      /* Position the stream before the second header.  */
      size_t to_skip = (num_transitions2 * (8 + 1)
                     + num_types2 * 6
                     + chars2
                     + num_leaps2 * 12
                     + num_isstd2
                     + num_isgmt2);
      off_t off;
      if (fseek (f, to_skip, SEEK_CUR) != 0
         || (off = ftello (f)) < 0
         || st.st_size < off + 2)
       goto lose;

      tzspec_len = st.st_size - off - 1;
      char *tzstr = alloca (tzspec_len);
      if (getc_unlocked (f) != '\n'
         || (fread_unlocked (tzstr, 1, tzspec_len - 1, f) != tzspec_len - 1))
       goto lose;
      tzstr[tzspec_len - 1] = '\0';
      tzspec = __tzstring (tzstr);
    }

  fclose (f);

  /* First "register" all timezone names.  */
  for (i = 0; i < num_types; ++i)
    (void) __tzstring (&zone_names[types[i].idx]);

  /* Find the standard and daylight time offsets used by the rule file.
     We choose the offsets in the types of each flavor that are
     transitioned to earliest in time.  */
  __tzname[0] = NULL;
  __tzname[1] = NULL;
  for (i = num_transitions; i > 0; )
    {
      int type = type_idxs[--i];
      int dst = types[type].isdst;

      if (__tzname[dst] == NULL)
       {
         int idx = types[type].idx;

         __tzname[dst] = __tzstring (&zone_names[idx]);

         if (__tzname[1 - dst] != NULL)
           break;
       }
    }
  if (__tzname[0] == NULL)
    {
      /* This should only happen if there are no transition rules.
        In this case there should be only one single type.  */
      assert (num_types == 1);
      __tzname[0] = __tzstring (zone_names);
    }
  if (__tzname[1] == NULL)
    __tzname[1] = __tzname[0];

  compute_tzname_max (chars);

  if (num_transitions == 0)
    /* Use the first rule (which should also be the only one).  */
    rule_stdoff = rule_dstoff = types[0].offset;
  else
    {
      int stdoff_set = 0, dstoff_set = 0;
      rule_stdoff = rule_dstoff = 0;
      i = num_transitions - 1;
      do
       {
         if (!stdoff_set && !types[type_idxs[i]].isdst)
           {
             stdoff_set = 1;
             rule_stdoff = types[type_idxs[i]].offset;
           }
         else if (!dstoff_set && types[type_idxs[i]].isdst)
           {
             dstoff_set = 1;
             rule_dstoff = types[type_idxs[i]].offset;
           }
         if (stdoff_set && dstoff_set)
           break;
       }
      while (i-- > 0);

      if (!dstoff_set)
       rule_dstoff = rule_stdoff;
    }

  __daylight = rule_stdoff != rule_dstoff;
  __timezone = -rule_stdoff;

  __use_tzfile = 1;
  return;

 lose:
  fclose (f);
 ret_free_transitions:
  free ((void *) transitions);
  transitions = NULL;
}

Here is the call graph for this function:

Here is the caller graph for this function:

static void internal_function compute_tzname_max ( size_t  chars) [static]

Definition at line 53 of file tzfile.c.

{
  if (BYTE_ORDER == BIG_ENDIAN && sizeof (int) == 4)
    return *(const int *) ptr;
  if (sizeof (int) == 4)
    return bswap_32 (*(const int *) ptr);

  const unsigned char *p = ptr;
  int result = *p & (1 << (CHAR_BIT - 1)) ? ~0 : 0;

  result = (result << 8) | *p++;
  result = (result << 8) | *p++;
  result = (result << 8) | *p++;
  result = (result << 8) | *p++;

  return result;
}

Here is the caller graph for this function:


Variable Documentation

Definition at line 33 of file tzfile.c.

dev_t tzfile_dev [static]

Definition at line 34 of file tzfile.c.

ino64_t tzfile_ino [static]

Definition at line 35 of file tzfile.c.

time_t tzfile_mtime [static]

Definition at line 36 of file tzfile.c.