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time: Use 64-bit time values for time zone parsing

This commit is contained in:
Florian Weimer 2018-05-11 16:30:30 +02:00
parent 89aacb513e
commit fc79706a32
3 changed files with 55 additions and 80 deletions
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13
ChangeLog
View File

@ -1,3 +1,16 @@
2018-05-11 Florian Weimer <fweimer@redhat.com>
Use 64-bit epoch values in the time zone file parser.
* include/time.h (internal_time_t): Define.
(__tzfile_compute): Use it.
* time/tzfile.c (struct leap): Use internal_time_t for epoch
member.
(transitions): Switch to internal_time_t.
(__tzfile_read): Likewise. Remove code dealing with 4-byte time_t
types.
(__tzfile_compute): Use internal_time_t for timer argument. Check
for truncation before calling __offtime.
2018-05-11 Florian Weimer <fweimer@redhat.com>
[BZ #23166]

6
include/time.h
View File

@ -26,6 +26,10 @@ extern __typeof (clock_getcpuclockid) __clock_getcpuclockid;
/* Now define the internal interfaces. */
struct tm;
/* time_t variant for representing time zone data, independent of
time_t. */
typedef __int64_t internal_time_t;
/* Defined in mktime.c. */
extern const unsigned short int __mon_yday[2][13] attribute_hidden;
@ -39,7 +43,7 @@ extern int __use_tzfile attribute_hidden;
extern void __tzfile_read (const char *file, size_t extra,
char **extrap) attribute_hidden;
extern void __tzfile_compute (time_t timer, int use_localtime,
extern void __tzfile_compute (internal_time_t timer, int use_localtime,
long int *leap_correct, int *leap_hit,
struct tm *tp) attribute_hidden;
extern void __tzfile_default (const char *std, const char *dst,

116
time/tzfile.c
View File

@ -44,12 +44,12 @@ struct ttinfo
struct leap
{
time_t transition; /* Time the transition takes effect. */
internal_time_t transition; /* Time the transition takes effect. */
long int change; /* Seconds of correction to apply. */
};
static size_t num_transitions;
libc_freeres_ptr (static time_t *transitions);
libc_freeres_ptr (static internal_time_t *transitions);
static unsigned char *type_idxs;
static size_t num_types;
static struct ttinfo *types;
@ -113,8 +113,8 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
size_t tzspec_len;
char *new = NULL;
if (sizeof (time_t) != 4 && sizeof (time_t) != 8)
abort ();
_Static_assert (sizeof (internal_time_t) == 8,
"internal_time_t must be eight bytes");
__use_tzfile = 0;
@ -200,9 +200,7 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
if (__glibc_unlikely (num_isstd > num_types || num_isgmt > num_types))
goto lose;
/* 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')
if (trans_width == 4 && tzhead.tzh_version[0] != '\0')
{
/* We use the 8-byte format. */
trans_width = 8;
@ -222,9 +220,9 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
if (__builtin_expect (num_transitions
> ((SIZE_MAX - (__alignof__ (struct ttinfo) - 1))
/ (sizeof (time_t) + 1)), 0))
/ (sizeof (internal_time_t) + 1)), 0))
goto lose;
total_size = num_transitions * (sizeof (time_t) + 1);
total_size = num_transitions * (sizeof (internal_time_t) + 1);
total_size = ((total_size + __alignof__ (struct ttinfo) - 1)
& ~(__alignof__ (struct ttinfo) - 1));
types_idx = total_size;
@ -246,7 +244,7 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
goto lose;
total_size += num_leaps * sizeof (struct leap);
tzspec_len = 0;
if (sizeof (time_t) == 8 && trans_width == 8)
if (trans_width == 8)
{
off_t rem = st.st_size - __ftello (f);
if (__builtin_expect (rem < 0
@ -276,23 +274,23 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
/* Allocate enough memory including the extra block requested by the
caller. */
transitions = (time_t *) malloc (total_size + tzspec_len + extra);
transitions = malloc (total_size + tzspec_len + extra);
if (transitions == NULL)
goto lose;
type_idxs = (unsigned char *) transitions + (num_transitions
* sizeof (time_t));
* sizeof (internal_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)
if (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 (trans_width == 8, 1))
{
if (__builtin_expect (__fread_unlocked (transitions, trans_width + 1,
num_transitions, f)
@ -315,19 +313,17 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
if (__glibc_unlikely (type_idxs[i] >= num_types))
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))
if (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. */
network (big-endian) byte order. We work from the end of the
array so as not to clobber the next element to be
processed. */
i = num_transitions;
while (i-- > 0)
transitions[i] = decode ((char *) transitions + i * 4);
}
else if (BYTE_ORDER != BIG_ENDIAN && sizeof (time_t) == 8)
else if (BYTE_ORDER != BIG_ENDIAN)
{
/* Decode the transition times, stored as 8-byte integers in
network (big-endian) byte order. */
@ -364,10 +360,10 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
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);
if (trans_width == 4)
leaps[i].transition = decode (x);
else
leaps[i].transition = (time_t) decode64 (x);
leaps[i].transition = decode64 (x);
if (__glibc_unlikely (__fread_unlocked (x, 1, 4, f) != 4))
goto lose;
@ -395,7 +391,7 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
types[i++].isgmt = 0;
/* Read the POSIX TZ-style information if possible. */
if (sizeof (time_t) == 8 && tzspec != NULL)
if (tzspec != NULL)
{
/* Skip over the newline first. */
if (__getc_unlocked (f) != '\n'
@ -405,52 +401,6 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
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;
if (tzspec_len == 0)
goto lose;
char *tzstr = malloc (tzspec_len);
if (tzstr == NULL)
goto lose;
if (__getc_unlocked (f) != '\n'
|| (__fread_unlocked (tzstr, 1, tzspec_len - 1, f)
!= tzspec_len - 1))
{
free (tzstr);
goto lose;
}
tzstr[tzspec_len - 1] = '\0';
tzspec = __tzstring (tzstr);
free (tzstr);
}
/* Don't use an empty TZ string. */
if (tzspec != NULL && tzspec[0] == '\0')
@ -630,7 +580,7 @@ __tzfile_default (const char *std, const char *dst,
}
void
__tzfile_compute (time_t timer, int use_localtime,
__tzfile_compute (internal_time_t timer, int use_localtime,
long int *leap_correct, int *leap_hit,
struct tm *tp)
{
@ -685,10 +635,16 @@ __tzfile_compute (time_t timer, int use_localtime,
/* Convert to broken down structure. If this fails do not
use the string. */
if (__glibc_unlikely (! __offtime (&timer, 0, tp)))
goto use_last;
{
time_t truncated = timer;
if (__glibc_unlikely (truncated != timer
|| ! __offtime (&truncated, 0, tp)))
goto use_last;
}
/* Use the rules from the TZ string to compute the change. */
/* Use the rules from the TZ string to compute the change.
timer fits into time_t due to the truncation check
above. */
__tz_compute (timer, tp, 1);
/* If tzspec comes from posixrules loaded by __tzfile_default,
@ -709,10 +665,12 @@ __tzfile_compute (time_t timer, int use_localtime,
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. */
/* 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.
The value i can be truncated if size_t is smaller than
internal_time_t, but this is harmless because it is just
a guess. */
i = (transitions[num_transitions - 1] - timer) / 15778476;
if (i < num_transitions)
{