Albert ARIBAUD wrote:
https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/aaribaud/y2038
Thanks for the heads-up. I would like to look at these patches sequentially.
Let's start with the first three:
Y2038: Add 64-bit time for all architectures
Y2038: make __tz_convert compatible with 64-bit-time
Y2038: make __mktime_internal compatible with 64-bit-time
The first two look OK. The third patch has some problems, some of which I've
mentioned before, some which I haven't:
1. It changes __mktime_internal's offset argument from time_t to __time64_t. But
that offset argument is the difference between localtime and gmtime, which
comfortably fits into long int everywhere; it would even fit into int, for that
matter (the only reason it's a long is that the API was designed for platforms
with 16-bit int). So let's not make that integer wider; let's keep it 'long' (we
could even make it 'int' if we wanted to, since it's private), as that will be
one less thing to hassle with when we change time_t width.
2. It's better to avoid casts when possible, and there are some opportunities
for doing that in the code.
3. The most serious problem is that the patch continues in the tradition of
hoping that integers won't overflow instead of checking for overflow properly.
The upstream code in Gnulib fixed this a couple of years ago, and it's time to
merge that back in now since the old way is likely to be even creakier in the
combined 32-and-64-bit world.
To fix these problems, let's replace this third patch with the attached patchset
0001, 0002, and 0003 instead. I merged the glibc mktime changes upstream into
Gnulib, and 0001 (which may look a little scary due to its size) simply copies
the merged Gnulib code back down to glibc unchanged; this fixes problem (3).
0002 fixes problem (1). 0003 reworks your third patch, except without the casts
so it fixes problem (2).
0001 and 0002 are so straightforward that I've installed their equivalents into
Gnulib on Savannah, so they're properly merged into Gnulib now. (They could be
installed into Glibc now too, as they are independent of your Y2038 changes,
though a review would certainly be nice.) I'd like your opinion on 0003 before
installing its equivalent into Gnulib.
>From 6791005ffaea865e27584d0442f0262fb557aa17 Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Fri, 31 Aug 2018 15:03:05 -0700
Subject: [PATCH 1/3] Merge mktime, timegm from upstream Gnulib
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
This fixes some obscure problems with integer overflow.
Although it looks scary, it is a byte-for-byte copy from Gnulib,
and the Gnulib code has been tested reasonably well.
* include/intprops.h, include/verify.h: New files, copied from Gnulib.
* time/mktime.c: Copy from Gnulib. This has the following changes:
Do not include config.h if DEBUG_MKTIME is nonzero.
Include stdbool.h, intprops.h, verify.h.
Include string.h only if needed.
Include stdlib.h on MS-Windows.
(DEBUG_MKTIME): Default to 0, and simplify later uses.
(NEED_MKTIME_INTERNAL, NEED_MKTIME_WINDOWS)
(NEED_MKTIME_WORKING): Give default values to pacify -Wundef,
which glibc uses. Default NEED_MKTIME_WORKING to DEBUG_MKTIME, to
simplify later conditionals; default the others to zero. Use
these conditionals to express only the code needed on the current
platform. In uses of these conditionals, explicitly spell out how
_LIBC affects things, so itâs easier to review from a glibc
viewpoint.
(WRAPV): Remove; no longer needed now that we have
systematic overflow checking.
(my_tzset, __tzset) [!_LIBC]: New function and macro, to better
compartmentalize tzset issues. Move system-dependent tzsettish
code here from mktime.
(verify): Remove; now done by verify.h. All uses changed.
(long_int): Use a more-conservative definition, to avoid
integer overflow.
(SHR): Remove, replacing with ...
(shr): New function, which means we neednât worry about side
effects in args, and conversion analysis is simpler.
(TYPE_IS_INTEGER, TYPE_TWOS_COMPLEMENT, TYPE_SIGNED, TYPE_MINIMUM)
(TYPE_MAXIMUM, TIME_T_MIN, TIME_T_MAX, TIME_T_MIDPOINT)
(time_t_avg, time_t_add_ok): Remove.
(mktime_min, mktime_max): New constants.
(leapyear, isdst_differ): Use bool for booleans.
(mktime_offset_t) [_LIBC]: New type.
(ydhms_diff, guess_time_tm, ranged_convert, __mktime_internal):
Use long_int, not time_t, for mktime differences.
(long_int_avg): New function, replacing time_t_avg.
INT_ADD_WRAPV replaces time_t_add_ok.
(guess_time_tm): 6th arg is now long_int, not time_t const *.
All uses changed.
(convert_time): New function.
(ranged_convert): Use it.
(__mktime_internal): Last arg now points to mktime_offset_t, not
time_t. All uses changed. This is a no-op on glibc, where
mktime_offset_t is always time_t. Use int, not time_t, for UTC
offset guess. Directly check for integer overflow instead of
using a heuristic that works only 99.9...% of the time.
(mktime): Move tzsettish code to my_tzset, and move
localtime_offset to within mktime so that it doesnât
need a separate ifdef.
(main) [DEBUG_MKTIME]: Speed up by using localtime_r
instead of localtime.
* time/timegm.c: Copy from Gnulib. This has the following changes:
(mktime_offset_t) [_LIBC]: New typedef.
[!_LIBC]: Include config.h and time.h. Do not include
timegm.h or time_r.h. Make __mktime_internal a macro,
and include mktime-internal.h to get its declaration.
(timegm): Temporary is now mktime_offset_t, not time_t.
This affects only Gnulib.
---
ChangeLog | 64 ++++++
include/intprops.h | 455 +++++++++++++++++++++++++++++++++++++
include/verify.h | 285 +++++++++++++++++++++++
time/mktime.c | 548 +++++++++++++++++++++------------------------
time/timegm.c | 21 +-
5 files changed, 1060 insertions(+), 313 deletions(-)
create mode 100644 include/intprops.h
create mode 100644 include/verify.h
diff --git a/ChangeLog b/ChangeLog
index 21d914141c..d1ab1b0718 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,67 @@
+2018-08-31 Paul Eggert <egg...@cs.ucla.edu>
+
+ Merge mktime, timegm from upstream Gnulib
+ This fixes some obscure problems with integer overflow.
+ Although it looks scary, it is a byte-for-byte copy from Gnulib,
+ and the Gnulib code has been tested reasonably well.
+ * include/intprops.h, include/verify.h: New files, copied from Gnulib.
+ * time/mktime.c: Copy from Gnulib. This has the following changes:
+ Do not include config.h if DEBUG_MKTIME is nonzero.
+ Include stdbool.h, intprops.h, verify.h.
+ Include string.h only if needed.
+ Include stdlib.h on MS-Windows.
+ (DEBUG_MKTIME): Default to 0, and simplify later uses.
+ (NEED_MKTIME_INTERNAL, NEED_MKTIME_WINDOWS)
+ (NEED_MKTIME_WORKING): Give default values to pacify -Wundef,
+ which glibc uses. Default NEED_MKTIME_WORKING to DEBUG_MKTIME, to
+ simplify later conditionals; default the others to zero. Use
+ these conditionals to express only the code needed on the current
+ platform. In uses of these conditionals, explicitly spell out how
+ _LIBC affects things, so itâs easier to review from a glibc
+ viewpoint.
+ (WRAPV): Remove; no longer needed now that we have
+ systematic overflow checking.
+ (my_tzset, __tzset) [!_LIBC]: New function and macro, to better
+ compartmentalize tzset issues. Move system-dependent tzsettish
+ code here from mktime.
+ (verify): Remove; now done by verify.h. All uses changed.
+ (long_int): Use a more-conservative definition, to avoid
+ integer overflow.
+ (SHR): Remove, replacing with ...
+ (shr): New function, which means we neednât worry about side
+ effects in args, and conversion analysis is simpler.
+ (TYPE_IS_INTEGER, TYPE_TWOS_COMPLEMENT, TYPE_SIGNED, TYPE_MINIMUM)
+ (TYPE_MAXIMUM, TIME_T_MIN, TIME_T_MAX, TIME_T_MIDPOINT)
+ (time_t_avg, time_t_add_ok): Remove.
+ (mktime_min, mktime_max): New constants.
+ (leapyear, isdst_differ): Use bool for booleans.
+ (mktime_offset_t) [_LIBC]: New type.
+ (ydhms_diff, guess_time_tm, ranged_convert, __mktime_internal):
+ Use long_int, not time_t, for mktime differences.
+ (long_int_avg): New function, replacing time_t_avg.
+ INT_ADD_WRAPV replaces time_t_add_ok.
+ (guess_time_tm): 6th arg is now long_int, not time_t const *.
+ All uses changed.
+ (convert_time): New function.
+ (ranged_convert): Use it.
+ (__mktime_internal): Last arg now points to mktime_offset_t, not
+ time_t. All uses changed. This is a no-op on glibc, where
+ mktime_offset_t is always time_t. Use int, not time_t, for UTC
+ offset guess. Directly check for integer overflow instead of
+ using a heuristic that works only 99.9...% of the time.
+ (mktime): Move tzsettish code to my_tzset, and move
+ localtime_offset to within mktime so that it doesnât
+ need a separate ifdef.
+ (main) [DEBUG_MKTIME]: Speed up by using localtime_r
+ instead of localtime.
+ * time/timegm.c: Copy from Gnulib. This has the following changes:
+ (mktime_offset_t) [_LIBC]: New typedef.
+ [!_LIBC]: Include config.h and time.h. Do not include
+ timegm.h or time_r.h. Make __mktime_internal a macro,
+ and include mktime-internal.h to get its declaration.
+ (timegm): Temporary is now mktime_offset_t, not time_t.
+ This affects only Gnulib.
+
2018-08-30 Carlos O'Donell <car...@redhat.com>
* elf/tst-dlopen-aout.c: Include support/xthread.h. Use
diff --git a/include/intprops.h b/include/intprops.h
new file mode 100644
index 0000000000..a4be30b8d0
--- /dev/null
+++ b/include/intprops.h
@@ -0,0 +1,455 @@
+/* intprops.h -- properties of integer types
+
+ Copyright (C) 2001-2018 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by Paul Eggert. */
+
+#ifndef _GL_INTPROPS_H
+#define _GL_INTPROPS_H
+
+#include <limits.h>
+
+/* Return a value with the common real type of E and V and the value of V.
+ Do not evaluate E. */
+#define _GL_INT_CONVERT(e, v) ((1 ? 0 : (e)) + (v))
+
+/* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see
+ <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00406.html>. */
+#define _GL_INT_NEGATE_CONVERT(e, v) ((1 ? 0 : (e)) - (v))
+
+/* The extra casts in the following macros work around compiler bugs,
+ e.g., in Cray C 5.0.3.0. */
+
+/* True if the arithmetic type T is an integer type. bool counts as
+ an integer. */
+#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
+
+/* True if the real type T is signed. */
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+
+/* Return 1 if the real expression E, after promotion, has a
+ signed or floating type. Do not evaluate E. */
+#define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
+
+
+/* Minimum and maximum values for integer types and expressions. */
+
+/* The width in bits of the integer type or expression T.
+ Do not evaluate T.
+ Padding bits are not supported; this is checked at compile-time below. */
+#define TYPE_WIDTH(t) (sizeof (t) * CHAR_BIT)
+
+/* The maximum and minimum values for the integer type T. */
+#define TYPE_MINIMUM(t) ((t) ~ TYPE_MAXIMUM (t))
+#define TYPE_MAXIMUM(t) \
+ ((t) (! TYPE_SIGNED (t) \
+ ? (t) -1 \
+ : ((((t) 1 << (TYPE_WIDTH (t) - 2)) - 1) * 2 + 1)))
+
+/* The maximum and minimum values for the type of the expression E,
+ after integer promotion. E is not evaluated. */
+#define _GL_INT_MINIMUM(e) \
+ (EXPR_SIGNED (e) \
+ ? ~ _GL_SIGNED_INT_MAXIMUM (e) \
+ : _GL_INT_CONVERT (e, 0))
+#define _GL_INT_MAXIMUM(e) \
+ (EXPR_SIGNED (e) \
+ ? _GL_SIGNED_INT_MAXIMUM (e) \
+ : _GL_INT_NEGATE_CONVERT (e, 1))
+#define _GL_SIGNED_INT_MAXIMUM(e) \
+ (((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH ((e) + 0) - 2)) - 1) * 2 + 1)
+
+/* Work around OpenVMS incompatibility with C99. */
+#if !defined LLONG_MAX && defined __INT64_MAX
+# define LLONG_MAX __INT64_MAX
+# define LLONG_MIN __INT64_MIN
+#endif
+
+/* This include file assumes that signed types are two's complement without
+ padding bits; the above macros have undefined behavior otherwise.
+ If this is a problem for you, please let us know how to fix it for your host.
+ This assumption is tested by the intprops-tests module. */
+
+/* Does the __typeof__ keyword work? This could be done by
+ 'configure', but for now it's easier to do it by hand. */
+#if (2 <= __GNUC__ \
+ || (1210 <= __IBMC__ && defined __IBM__TYPEOF__) \
+ || (0x5110 <= __SUNPRO_C && !__STDC__))
+# define _GL_HAVE___TYPEOF__ 1
+#else
+# define _GL_HAVE___TYPEOF__ 0
+#endif
+
+/* Return 1 if the integer type or expression T might be signed. Return 0
+ if it is definitely unsigned. This macro does not evaluate its argument,
+ and expands to an integer constant expression. */
+#if _GL_HAVE___TYPEOF__
+# define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t))
+#else
+# define _GL_SIGNED_TYPE_OR_EXPR(t) 1
+#endif
+
+/* Bound on length of the string representing an unsigned integer
+ value representable in B bits. log10 (2.0) < 146/485. The
+ smallest value of B where this bound is not tight is 2621. */
+#define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485)
+
+/* Bound on length of the string representing an integer type or expression T.
+ Subtract 1 for the sign bit if T is signed, and then add 1 more for
+ a minus sign if needed.
+
+ Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 0 when its argument is
+ signed, this macro may overestimate the true bound by one byte when
+ applied to unsigned types of size 2, 4, 16, ... bytes. */
+#define INT_STRLEN_BOUND(t) \
+ (INT_BITS_STRLEN_BOUND (TYPE_WIDTH (t) - _GL_SIGNED_TYPE_OR_EXPR (t)) \
+ + _GL_SIGNED_TYPE_OR_EXPR (t))
+
+/* Bound on buffer size needed to represent an integer type or expression T,
+ including the terminating null. */
+#define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
+
+
+/* Range overflow checks.
+
+ The INT_<op>_RANGE_OVERFLOW macros return 1 if the corresponding C
+ operators might not yield numerically correct answers due to
+ arithmetic overflow. They do not rely on undefined or
+ implementation-defined behavior. Their implementations are simple
+ and straightforward, but they are a bit harder to use than the
+ INT_<op>_OVERFLOW macros described below.
+
+ Example usage:
+
+ long int i = ...;
+ long int j = ...;
+ if (INT_MULTIPLY_RANGE_OVERFLOW (i, j, LONG_MIN, LONG_MAX))
+ printf ("multiply would overflow");
+ else
+ printf ("product is %ld", i * j);
+
+ Restrictions on *_RANGE_OVERFLOW macros:
+
+ These macros do not check for all possible numerical problems or
+ undefined or unspecified behavior: they do not check for division
+ by zero, for bad shift counts, or for shifting negative numbers.
+
+ These macros may evaluate their arguments zero or multiple times,
+ so the arguments should not have side effects. The arithmetic
+ arguments (including the MIN and MAX arguments) must be of the same
+ integer type after the usual arithmetic conversions, and the type
+ must have minimum value MIN and maximum MAX. Unsigned types should
+ use a zero MIN of the proper type.
+
+ These macros are tuned for constant MIN and MAX. For commutative
+ operations such as A + B, they are also tuned for constant B. */
+
+/* Return 1 if A + B would overflow in [MIN,MAX] arithmetic.
+ See above for restrictions. */
+#define INT_ADD_RANGE_OVERFLOW(a, b, min, max) \
+ ((b) < 0 \
+ ? (a) < (min) - (b) \
+ : (max) - (b) < (a))
+
+/* Return 1 if A - B would overflow in [MIN,MAX] arithmetic.
+ See above for restrictions. */
+#define INT_SUBTRACT_RANGE_OVERFLOW(a, b, min, max) \
+ ((b) < 0 \
+ ? (max) + (b) < (a) \
+ : (a) < (min) + (b))
+
+/* Return 1 if - A would overflow in [MIN,MAX] arithmetic.
+ See above for restrictions. */
+#define INT_NEGATE_RANGE_OVERFLOW(a, min, max) \
+ ((min) < 0 \
+ ? (a) < - (max) \
+ : 0 < (a))
+
+/* Return 1 if A * B would overflow in [MIN,MAX] arithmetic.
+ See above for restrictions. Avoid && and || as they tickle
+ bugs in Sun C 5.11 2010/08/13 and other compilers; see
+ <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00401.html>. */
+#define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max) \
+ ((b) < 0 \
+ ? ((a) < 0 \
+ ? (a) < (max) / (b) \
+ : (b) == -1 \
+ ? 0 \
+ : (min) / (b) < (a)) \
+ : (b) == 0 \
+ ? 0 \
+ : ((a) < 0 \
+ ? (a) < (min) / (b) \
+ : (max) / (b) < (a)))
+
+/* Return 1 if A / B would overflow in [MIN,MAX] arithmetic.
+ See above for restrictions. Do not check for division by zero. */
+#define INT_DIVIDE_RANGE_OVERFLOW(a, b, min, max) \
+ ((min) < 0 && (b) == -1 && (a) < - (max))
+
+/* Return 1 if A % B would overflow in [MIN,MAX] arithmetic.
+ See above for restrictions. Do not check for division by zero.
+ Mathematically, % should never overflow, but on x86-like hosts
+ INT_MIN % -1 traps, and the C standard permits this, so treat this
+ as an overflow too. */
+#define INT_REMAINDER_RANGE_OVERFLOW(a, b, min, max) \
+ INT_DIVIDE_RANGE_OVERFLOW (a, b, min, max)
+
+/* Return 1 if A << B would overflow in [MIN,MAX] arithmetic.
+ See above for restrictions. Here, MIN and MAX are for A only, and B need
+ not be of the same type as the other arguments. The C standard says that
+ behavior is undefined for shifts unless 0 <= B < wordwidth, and that when
+ A is negative then A << B has undefined behavior and A >> B has
+ implementation-defined behavior, but do not check these other
+ restrictions. */
+#define INT_LEFT_SHIFT_RANGE_OVERFLOW(a, b, min, max) \
+ ((a) < 0 \
+ ? (a) < (min) >> (b) \
+ : (max) >> (b) < (a))
+
+/* True if __builtin_add_overflow (A, B, P) works when P is non-null. */
+#if 5 <= __GNUC__ && !defined __ICC
+# define _GL_HAS_BUILTIN_OVERFLOW 1
+#else
+# define _GL_HAS_BUILTIN_OVERFLOW 0
+#endif
+
+/* True if __builtin_add_overflow_p (A, B, C) works. */
+#define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__)
+
+/* The _GL*_OVERFLOW macros have the same restrictions as the
+ *_RANGE_OVERFLOW macros, except that they do not assume that operands
+ (e.g., A and B) have the same type as MIN and MAX. Instead, they assume
+ that the result (e.g., A + B) has that type. */
+#if _GL_HAS_BUILTIN_OVERFLOW_P
+# define _GL_ADD_OVERFLOW(a, b, min, max) \
+ __builtin_add_overflow_p (a, b, (__typeof__ ((a) + (b))) 0)
+# define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \
+ __builtin_sub_overflow_p (a, b, (__typeof__ ((a) - (b))) 0)
+# define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \
+ __builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0)
+#else
+# define _GL_ADD_OVERFLOW(a, b, min, max) \
+ ((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max) \
+ : (a) < 0 ? (b) <= (a) + (b) \
+ : (b) < 0 ? (a) <= (a) + (b) \
+ : (a) + (b) < (b))
+# define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \
+ ((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max) \
+ : (a) < 0 ? 1 \
+ : (b) < 0 ? (a) - (b) <= (a) \
+ : (a) < (b))
+# define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \
+ (((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a)))) \
+ || INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max))
+#endif
+#define _GL_DIVIDE_OVERFLOW(a, b, min, max) \
+ ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \
+ : (a) < 0 ? (b) <= (a) + (b) - 1 \
+ : (b) < 0 && (a) + (b) <= (a))
+#define _GL_REMAINDER_OVERFLOW(a, b, min, max) \
+ ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \
+ : (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b) \
+ : (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max))
+
+/* Return a nonzero value if A is a mathematical multiple of B, where
+ A is unsigned, B is negative, and MAX is the maximum value of A's
+ type. A's type must be the same as (A % B)'s type. Normally (A %
+ -B == 0) suffices, but things get tricky if -B would overflow. */
+#define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max) \
+ (((b) < -_GL_SIGNED_INT_MAXIMUM (b) \
+ ? (_GL_SIGNED_INT_MAXIMUM (b) == (max) \
+ ? (a) \
+ : (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1)) \
+ : (a) % - (b)) \
+ == 0)
+
+/* Check for integer overflow, and report low order bits of answer.
+
+ The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
+ might not yield numerically correct answers due to arithmetic overflow.
+ The INT_<op>_WRAPV macros also store the low-order bits of the answer.
+ These macros work correctly on all known practical hosts, and do not rely
+ on undefined behavior due to signed arithmetic overflow.
+
+ Example usage, assuming A and B are long int:
+
+ if (INT_MULTIPLY_OVERFLOW (a, b))
+ printf ("result would overflow\n");
+ else
+ printf ("result is %ld (no overflow)\n", a * b);
+
+ Example usage with WRAPV flavor:
+
+ long int result;
+ bool overflow = INT_MULTIPLY_WRAPV (a, b, &result);
+ printf ("result is %ld (%s)\n", result,
+ overflow ? "after overflow" : "no overflow");
+
+ Restrictions on these macros:
+
+ These macros do not check for all possible numerical problems or
+ undefined or unspecified behavior: they do not check for division
+ by zero, for bad shift counts, or for shifting negative numbers.
+
+ These macros may evaluate their arguments zero or multiple times, so the
+ arguments should not have side effects.
+
+ The WRAPV macros are not constant expressions. They support only
+ +, binary -, and *. The result type must be signed.
+
+ These macros are tuned for their last argument being a constant.
+
+ Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B,
+ A % B, and A << B would overflow, respectively. */
+
+#define INT_ADD_OVERFLOW(a, b) \
+ _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW)
+#define INT_SUBTRACT_OVERFLOW(a, b) \
+ _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW)
+#if _GL_HAS_BUILTIN_OVERFLOW_P
+# define INT_NEGATE_OVERFLOW(a) INT_SUBTRACT_OVERFLOW (0, a)
+#else
+# define INT_NEGATE_OVERFLOW(a) \
+ INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
+#endif
+#define INT_MULTIPLY_OVERFLOW(a, b) \
+ _GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW)
+#define INT_DIVIDE_OVERFLOW(a, b) \
+ _GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW)
+#define INT_REMAINDER_OVERFLOW(a, b) \
+ _GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW)
+#define INT_LEFT_SHIFT_OVERFLOW(a, b) \
+ INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \
+ _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
+
+/* Return 1 if the expression A <op> B would overflow,
+ where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test,
+ assuming MIN and MAX are the minimum and maximum for the result type.
+ Arguments should be free of side effects. */
+#define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow) \
+ op_result_overflow (a, b, \
+ _GL_INT_MINIMUM ((1 ? 0 : (b)) + (a)), \
+ _GL_INT_MAXIMUM ((1 ? 0 : (b)) + (a)))
+
+/* Store the low-order bits of A + B, A - B, A * B, respectively, into *R.
+ Return 1 if the result overflows. See above for restrictions. */
+#define INT_ADD_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, +, __builtin_add_overflow, INT_ADD_OVERFLOW)
+#define INT_SUBTRACT_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, -, __builtin_sub_overflow, INT_SUBTRACT_OVERFLOW)
+#define INT_MULTIPLY_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, *, __builtin_mul_overflow, INT_MULTIPLY_OVERFLOW)
+
+/* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390. See:
+ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193
+ https://llvm.org/bugs/show_bug.cgi?id=25390
+ For now, assume all versions of GCC-like compilers generate bogus
+ warnings for _Generic. This matters only for older compilers that
+ lack __builtin_add_overflow. */
+#if __GNUC__
+# define _GL__GENERIC_BOGUS 1
+#else
+# define _GL__GENERIC_BOGUS 0
+#endif
+
+/* Store the low-order bits of A <op> B into *R, where OP specifies
+ the operation. BUILTIN is the builtin operation, and OVERFLOW the
+ overflow predicate. Return 1 if the result overflows. See above
+ for restrictions. */
+#if _GL_HAS_BUILTIN_OVERFLOW
+# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) builtin (a, b, r)
+#elif 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS
+# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+ (_Generic \
+ (*(r), \
+ signed char: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ signed char, SCHAR_MIN, SCHAR_MAX), \
+ short int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ short int, SHRT_MIN, SHRT_MAX), \
+ int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ int, INT_MIN, INT_MAX), \
+ long int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ long int, LONG_MIN, LONG_MAX), \
+ long long int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ long long int, LLONG_MIN, LLONG_MAX)))
+#else
+# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+ (sizeof *(r) == sizeof (signed char) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ signed char, SCHAR_MIN, SCHAR_MAX) \
+ : sizeof *(r) == sizeof (short int) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ short int, SHRT_MIN, SHRT_MAX) \
+ : sizeof *(r) == sizeof (int) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ int, INT_MIN, INT_MAX) \
+ : _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow))
+# ifdef LLONG_MAX
+# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
+ (sizeof *(r) == sizeof (long int) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ long int, LONG_MIN, LONG_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ long long int, LLONG_MIN, LLONG_MAX))
+# else
+# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ long int, LONG_MIN, LONG_MAX)
+# endif
+#endif
+
+/* Store the low-order bits of A <op> B into *R, where the operation
+ is given by OP. Use the unsigned type UT for calculation to avoid
+ overflow problems. *R's type is T, with extrema TMIN and TMAX.
+ T must be a signed integer type. Return 1 if the result overflows. */
+#define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \
+ (sizeof ((a) op (b)) < sizeof (t) \
+ ? _GL_INT_OP_CALC1 ((t) (a), (t) (b), r, op, overflow, ut, t, tmin, tmax) \
+ : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax))
+#define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \
+ ((overflow (a, b) \
+ || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \
+ || (tmax) < ((a) op (b))) \
+ ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 1) \
+ : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 0))
+
+/* Return the low-order bits of A <op> B, where the operation is given
+ by OP. Use the unsigned type UT for calculation to avoid undefined
+ behavior on signed integer overflow, and convert the result to type T.
+ UT is at least as wide as T and is no narrower than unsigned int,
+ T is two's complement, and there is no padding or trap representations.
+ Assume that converting UT to T yields the low-order bits, as is
+ done in all known two's-complement C compilers. E.g., see:
+ https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html
+
+ According to the C standard, converting UT to T yields an
+ implementation-defined result or signal for values outside T's
+ range. However, code that works around this theoretical problem
+ runs afoul of a compiler bug in Oracle Studio 12.3 x86. See:
+ https://lists.gnu.org/r/bug-gnulib/2017-04/msg00049.html
+ As the compiler bug is real, don't try to work around the
+ theoretical problem. */
+
+#define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t) \
+ ((t) ((ut) (a) op (ut) (b)))
+
+#endif /* _GL_INTPROPS_H */
diff --git a/include/verify.h b/include/verify.h
new file mode 100644
index 0000000000..3b57ddee0a
--- /dev/null
+++ b/include/verify.h
@@ -0,0 +1,285 @@
+/* Compile-time assert-like macros.
+
+ Copyright (C) 2005-2006, 2009-2018 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */
+
+#ifndef _GL_VERIFY_H
+#define _GL_VERIFY_H
+
+
+/* Define _GL_HAVE__STATIC_ASSERT to 1 if _Static_assert works as per C11.
+ This is supported by GCC 4.6.0 and later, in C mode, and its use
+ here generates easier-to-read diagnostics when verify (R) fails.
+
+ Define _GL_HAVE_STATIC_ASSERT to 1 if static_assert works as per C++11.
+ This will likely be supported by future GCC versions, in C++ mode.
+
+ Use this only with GCC. If we were willing to slow 'configure'
+ down we could also use it with other compilers, but since this
+ affects only the quality of diagnostics, why bother? */
+#if (4 < __GNUC__ + (6 <= __GNUC_MINOR__) \
+ && (201112L <= __STDC_VERSION__ || !defined __STRICT_ANSI__) \
+ && !defined __cplusplus)
+# define _GL_HAVE__STATIC_ASSERT 1
+#endif
+/* The condition (99 < __GNUC__) is temporary, until we know about the
+ first G++ release that supports static_assert. */
+#if (99 < __GNUC__) && defined __cplusplus
+# define _GL_HAVE_STATIC_ASSERT 1
+#endif
+
+/* FreeBSD 9.1 <sys/cdefs.h>, included by <stddef.h> and lots of other
+ system headers, defines a conflicting _Static_assert that is no
+ better than ours; override it. */
+#ifndef _GL_HAVE_STATIC_ASSERT
+# include <stddef.h>
+# undef _Static_assert
+#endif
+
+/* Each of these macros verifies that its argument R is nonzero. To
+ be portable, R should be an integer constant expression. Unlike
+ assert (R), there is no run-time overhead.
+
+ If _Static_assert works, verify (R) uses it directly. Similarly,
+ _GL_VERIFY_TRUE works by packaging a _Static_assert inside a struct
+ that is an operand of sizeof.
+
+ The code below uses several ideas for C++ compilers, and for C
+ compilers that do not support _Static_assert:
+
+ * The first step is ((R) ? 1 : -1). Given an expression R, of
+ integral or boolean or floating-point type, this yields an
+ expression of integral type, whose value is later verified to be
+ constant and nonnegative.
+
+ * Next this expression W is wrapped in a type
+ struct _gl_verify_type {
+ unsigned int _gl_verify_error_if_negative: W;
+ }.
+ If W is negative, this yields a compile-time error. No compiler can
+ deal with a bit-field of negative size.
+
+ One might think that an array size check would have the same
+ effect, that is, that the type struct { unsigned int dummy[W]; }
+ would work as well. However, inside a function, some compilers
+ (such as C++ compilers and GNU C) allow local parameters and
+ variables inside array size expressions. With these compilers,
+ an array size check would not properly diagnose this misuse of
+ the verify macro:
+
+ void function (int n) { verify (n < 0); }
+
+ * For the verify macro, the struct _gl_verify_type will need to
+ somehow be embedded into a declaration. To be portable, this
+ declaration must declare an object, a constant, a function, or a
+ typedef name. If the declared entity uses the type directly,
+ such as in
+
+ struct dummy {...};
+ typedef struct {...} dummy;
+ extern struct {...} *dummy;
+ extern void dummy (struct {...} *);
+ extern struct {...} *dummy (void);
+
+ two uses of the verify macro would yield colliding declarations
+ if the entity names are not disambiguated. A workaround is to
+ attach the current line number to the entity name:
+
+ #define _GL_CONCAT0(x, y) x##y
+ #define _GL_CONCAT(x, y) _GL_CONCAT0 (x, y)
+ extern struct {...} * _GL_CONCAT (dummy, __LINE__);
+
+ But this has the problem that two invocations of verify from
+ within the same macro would collide, since the __LINE__ value
+ would be the same for both invocations. (The GCC __COUNTER__
+ macro solves this problem, but is not portable.)
+
+ A solution is to use the sizeof operator. It yields a number,
+ getting rid of the identity of the type. Declarations like
+
+ extern int dummy [sizeof (struct {...})];
+ extern void dummy (int [sizeof (struct {...})]);
+ extern int (*dummy (void)) [sizeof (struct {...})];
+
+ can be repeated.
+
+ * Should the implementation use a named struct or an unnamed struct?
+ Which of the following alternatives can be used?
+
+ extern int dummy [sizeof (struct {...})];
+ extern int dummy [sizeof (struct _gl_verify_type {...})];
+ extern void dummy (int [sizeof (struct {...})]);
+ extern void dummy (int [sizeof (struct _gl_verify_type {...})]);
+ extern int (*dummy (void)) [sizeof (struct {...})];
+ extern int (*dummy (void)) [sizeof (struct _gl_verify_type {...})];
+
+ In the second and sixth case, the struct type is exported to the
+ outer scope; two such declarations therefore collide. GCC warns
+ about the first, third, and fourth cases. So the only remaining
+ possibility is the fifth case:
+
+ extern int (*dummy (void)) [sizeof (struct {...})];
+
+ * GCC warns about duplicate declarations of the dummy function if
+ -Wredundant-decls is used. GCC 4.3 and later have a builtin
+ __COUNTER__ macro that can let us generate unique identifiers for
+ each dummy function, to suppress this warning.
+
+ * This implementation exploits the fact that older versions of GCC,
+ which do not support _Static_assert, also do not warn about the
+ last declaration mentioned above.
+
+ * GCC warns if -Wnested-externs is enabled and verify() is used
+ within a function body; but inside a function, you can always
+ arrange to use verify_expr() instead.
+
+ * In C++, any struct definition inside sizeof is invalid.
+ Use a template type to work around the problem. */
+
+/* Concatenate two preprocessor tokens. */
+#define _GL_CONCAT(x, y) _GL_CONCAT0 (x, y)
+#define _GL_CONCAT0(x, y) x##y
+
+/* _GL_COUNTER is an integer, preferably one that changes each time we
+ use it. Use __COUNTER__ if it works, falling back on __LINE__
+ otherwise. __LINE__ isn't perfect, but it's better than a
+ constant. */
+#if defined __COUNTER__ && __COUNTER__ != __COUNTER__
+# define _GL_COUNTER __COUNTER__
+#else
+# define _GL_COUNTER __LINE__
+#endif
+
+/* Generate a symbol with the given prefix, making it unique if
+ possible. */
+#define _GL_GENSYM(prefix) _GL_CONCAT (prefix, _GL_COUNTER)
+
+/* Verify requirement R at compile-time, as an integer constant expression
+ that returns 1. If R is false, fail at compile-time, preferably
+ with a diagnostic that includes the string-literal DIAGNOSTIC. */
+
+#define _GL_VERIFY_TRUE(R, DIAGNOSTIC) \
+ (!!sizeof (_GL_VERIFY_TYPE (R, DIAGNOSTIC)))
+
+#ifdef __cplusplus
+# if !GNULIB_defined_struct__gl_verify_type
+template <int w>
+ struct _gl_verify_type {
+ unsigned int _gl_verify_error_if_negative: w;
+ };
+# define GNULIB_defined_struct__gl_verify_type 1
+# endif
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+ _gl_verify_type<(R) ? 1 : -1>
+#elif defined _GL_HAVE__STATIC_ASSERT
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+ struct { \
+ _Static_assert (R, DIAGNOSTIC); \
+ int _gl_dummy; \
+ }
+#else
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+ struct { unsigned int _gl_verify_error_if_negative: (R) ? 1 : -1; }
+#endif
+
+/* Verify requirement R at compile-time, as a declaration without a
+ trailing ';'. If R is false, fail at compile-time, preferably
+ with a diagnostic that includes the string-literal DIAGNOSTIC.
+
+ Unfortunately, unlike C11, this implementation must appear as an
+ ordinary declaration, and cannot appear inside struct { ... }. */
+
+#ifdef _GL_HAVE__STATIC_ASSERT
+# define _GL_VERIFY _Static_assert
+#else
+# define _GL_VERIFY(R, DIAGNOSTIC) \
+ extern int (*_GL_GENSYM (_gl_verify_function) (void)) \
+ [_GL_VERIFY_TRUE (R, DIAGNOSTIC)]
+#endif
+
+/* _GL_STATIC_ASSERT_H is defined if this code is copied into assert.h. */
+#ifdef _GL_STATIC_ASSERT_H
+# if !defined _GL_HAVE__STATIC_ASSERT && !defined _Static_assert
+# define _Static_assert(R, DIAGNOSTIC) _GL_VERIFY (R, DIAGNOSTIC)
+# endif
+# if !defined _GL_HAVE_STATIC_ASSERT && !defined static_assert
+# define static_assert _Static_assert /* C11 requires this #define. */
+# endif
+#endif
+
+/* @assert.h omit start@ */
+
+/* Each of these macros verifies that its argument R is nonzero. To
+ be portable, R should be an integer constant expression. Unlike
+ assert (R), there is no run-time overhead.
+
+ There are two macros, since no single macro can be used in all
+ contexts in C. verify_true (R) is for scalar contexts, including
+ integer constant expression contexts. verify (R) is for declaration
+ contexts, e.g., the top level. */
+
+/* Verify requirement R at compile-time, as an integer constant expression.
+ Return 1. This is equivalent to verify_expr (R, 1).
+
+ verify_true is obsolescent; please use verify_expr instead. */
+
+#define verify_true(R) _GL_VERIFY_TRUE (R, "verify_true (" #R ")")
+
+/* Verify requirement R at compile-time. Return the value of the
+ expression E. */
+
+#define verify_expr(R, E) \
+ (_GL_VERIFY_TRUE (R, "verify_expr (" #R ", " #E ")") ? (E) : (E))
+
+/* Verify requirement R at compile-time, as a declaration without a
+ trailing ';'. */
+
+#ifdef __GNUC__
+# define verify(R) _GL_VERIFY (R, "verify (" #R ")")
+#else
+/* PGI barfs if R is long. Play it safe. */
+# define verify(R) _GL_VERIFY (R, "verify (...)")
+#endif
+
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
+/* Assume that R always holds. This lets the compiler optimize
+ accordingly. R should not have side-effects; it may or may not be
+ evaluated. Behavior is undefined if R is false. */
+
+#if (__has_builtin (__builtin_unreachable) \
+ || 4 < __GNUC__ + (5 <= __GNUC_MINOR__))
+# define assume(R) ((R) ? (void) 0 : __builtin_unreachable ())
+#elif 1200 <= _MSC_VER
+# define assume(R) __assume (R)
+#elif ((defined GCC_LINT || defined lint) \
+ && (__has_builtin (__builtin_trap) \
+ || 3 < __GNUC__ + (3 < __GNUC_MINOR__ + (4 <= __GNUC_PATCHLEVEL__))))
+ /* Doing it this way helps various packages when configured with
+ --enable-gcc-warnings, which compiles with -Dlint. It's nicer
+ when 'assume' silences warnings even with older GCCs. */
+# define assume(R) ((R) ? (void) 0 : __builtin_trap ())
+#else
+ /* Some tools grok NOTREACHED, e.g., Oracle Studio 12.6. */
+# define assume(R) ((R) ? (void) 0 : /*NOTREACHED*/ (void) 0)
+#endif
+
+/* @assert.h omit end@ */
+
+#endif
diff --git a/time/mktime.c b/time/mktime.c
index 5f038a212f..2858764792 100644
--- a/time/mktime.c
+++ b/time/mktime.c
@@ -15,13 +15,30 @@
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
+ <https://www.gnu.org/licenses/>. */
-/* Define this to have a standalone program to test this implementation of
+/* Define this to 1 to have a standalone program to test this implementation of
mktime. */
-/* #define DEBUG_MKTIME 1 */
+#ifndef DEBUG_MKTIME
+# define DEBUG_MKTIME 0
+#endif
-#ifndef _LIBC
+/* The following macros influence what gets defined when this file is compiled:
+
+ Macro/expression Which gnulib module This compilation unit
+ should define
+
+ _LIBC (glibc proper) mktime
+
+ NEED_MKTIME_WORKING mktime rpl_mktime
+ || NEED_MKTIME_WINDOWS
+
+ NEED_MKTIME_INTERNAL mktime-internal mktime_internal
+
+ DEBUG_MKTIME (defined manually) my_mktime, main
+ */
+
+#if !defined _LIBC && !DEBUG_MKTIME
# include <config.h>
#endif
@@ -35,114 +52,132 @@
#include <time.h>
#include <limits.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
-#include <string.h> /* For the real memcpy prototype. */
+#include <intprops.h>
+#include <verify.h>
-#if defined DEBUG_MKTIME && DEBUG_MKTIME
+#if DEBUG_MKTIME
# include <stdio.h>
-# include <stdlib.h>
/* Make it work even if the system's libc has its own mktime routine. */
# undef mktime
# define mktime my_mktime
#endif /* DEBUG_MKTIME */
-/* Some of the code in this file assumes that signed integer overflow
- silently wraps around. This assumption can't easily be programmed
- around, nor can it be checked for portably at compile-time or
- easily eliminated at run-time.
-
- Define WRAPV to 1 if the assumption is valid and if
- #pragma GCC optimize ("wrapv")
- does not trigger GCC bug 51793
- <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51793>.
- Otherwise, define it to 0; this forces the use of slower code that,
- while not guaranteed by the C Standard, works on all production
- platforms that we know about. */
-#ifndef WRAPV
-# if (((__GNUC__ == 4 && 4 <= __GNUC_MINOR__) || 4 < __GNUC__) \
- && defined __GLIBC__)
-# pragma GCC optimize ("wrapv")
-# define WRAPV 1
-# else
-# define WRAPV 0
+#ifndef NEED_MKTIME_INTERNAL
+# define NEED_MKTIME_INTERNAL 0
+#endif
+#ifndef NEED_MKTIME_WINDOWS
+# define NEED_MKTIME_WINDOWS 0
+#endif
+#ifndef NEED_MKTIME_WORKING
+# define NEED_MKTIME_WORKING DEBUG_MKTIME
+#endif
+
+#ifdef _LIBC
+typedef time_t mktime_offset_t;
+#else
+# include "mktime-internal.h"
+#endif
+
+#ifndef _LIBC
+static void
+my_tzset (void)
+{
+# if NEED_MKTIME_WINDOWS
+ /* Rectify the value of the environment variable TZ.
+ There are four possible kinds of such values:
+ - Traditional US time zone names, e.g. "PST8PDT". Syntax: see
+ <https://msdn.microsoft.com/en-us/library/90s5c885.aspx>
+ - Time zone names based on geography, that contain one or more
+ slashes, e.g. "Europe/Moscow".
+ - Time zone names based on geography, without slashes, e.g.
+ "Singapore".
+ - Time zone names that contain explicit DST rules. Syntax: see
+ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>
+ The Microsoft CRT understands only the first kind. It produces incorrect
+ results if the value of TZ is of the other kinds.
+ But in a Cygwin environment, /etc/profile.d/tzset.sh sets TZ to a value
+ of the second kind for most geographies, or of the first kind in a few
+ other geographies. If it is of the second kind, neutralize it. For the
+ Microsoft CRT, an absent or empty TZ means the time zone that the user
+ has set in the Windows Control Panel.
+ If the value of TZ is of the third or fourth kind -- Cygwin programs
+ understand these syntaxes as well --, it does not matter whether we
+ neutralize it or not, since these values occur only when a Cygwin user
+ has set TZ explicitly; this case is 1. rare and 2. under the user's
+ responsibility. */
+ const char *tz = getenv ("TZ");
+ if (tz != NULL && strchr (tz, '/') != NULL)
+ _putenv ("TZ=");
+# elif HAVE_TZSET
+ tzset ();
# endif
+}
+# undef __tzset
+# define __tzset() my_tzset ()
#endif
-/* Verify a requirement at compile-time (unlike assert, which is runtime). */
-#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
+#if defined _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL
+
+/* A signed type that can represent an integer number of years
+ multiplied by three times the number of seconds in a year. It is
+ needed when converting a tm_year value times the number of seconds
+ in a year. The factor of three comes because these products need
+ to be subtracted from each other, and sometimes with an offset
+ added to them, without worrying about overflow.
+
+ Much of the code uses long_int to represent time_t values, to
+ lessen the hassle of dealing with platforms where time_t is
+ unsigned, and because long_int should suffice to represent all
+ time_t values that mktime can generate even on platforms where
+ time_t is excessively wide. */
-/* A signed type that is at least one bit wider than int. */
-#if INT_MAX <= LONG_MAX / 2
+#if INT_MAX <= LONG_MAX / 3 / 366 / 24 / 60 / 60
typedef long int long_int;
#else
typedef long long int long_int;
#endif
-verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2);
+verify (INT_MAX <= TYPE_MAXIMUM (long_int) / 3 / 366 / 24 / 60 / 60);
/* Shift A right by B bits portably, by dividing A by 2**B and
- truncating towards minus infinity. A and B should be free of side
- effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
- INT_BITS is the number of useful bits in an int. GNU code can
- assume that INT_BITS is at least 32.
+ truncating towards minus infinity. B should be in the range 0 <= B
+ <= LONG_INT_BITS - 2, where LONG_INT_BITS is the number of useful
+ bits in a long_int. LONG_INT_BITS is at least 32.
ISO C99 says that A >> B is implementation-defined if A < 0. Some
implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
right in the usual way when A < 0, so SHR falls back on division if
ordinary A >> B doesn't seem to be the usual signed shift. */
-#define SHR(a, b) \
- ((-1 >> 1 == -1 \
- && (long_int) -1 >> 1 == -1 \
- && ((time_t) -1 >> 1 == -1 || ! TYPE_SIGNED (time_t))) \
- ? (a) >> (b) \
- : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
-
-/* The extra casts in the following macros work around compiler bugs,
- e.g., in Cray C 5.0.3.0. */
-
-/* True if the arithmetic type T is an integer type. bool counts as
- an integer. */
-#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
-
-/* True if negative values of the signed integer type T use two's
- complement, or if T is an unsigned integer type. */
-#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
-
-/* True if the arithmetic type T is signed. */
-#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
-
-/* The maximum and minimum values for the integer type T. These
- macros have undefined behavior if T is signed and has padding bits.
- If this is a problem for you, please let us know how to fix it for
- your host. */
-#define TYPE_MINIMUM(t) \
- ((t) (! TYPE_SIGNED (t) \
- ? (t) 0 \
- : ~ TYPE_MAXIMUM (t)))
-#define TYPE_MAXIMUM(t) \
- ((t) (! TYPE_SIGNED (t) \
- ? (t) -1 \
- : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1)))
-
-#ifndef TIME_T_MIN
-# define TIME_T_MIN TYPE_MINIMUM (time_t)
-#endif
-#ifndef TIME_T_MAX
-# define TIME_T_MAX TYPE_MAXIMUM (time_t)
-#endif
-#define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)
-verify (time_t_is_integer, TYPE_IS_INTEGER (time_t));
-verify (twos_complement_arithmetic,
- (TYPE_TWOS_COMPLEMENT (int)
- && TYPE_TWOS_COMPLEMENT (long_int)
- && TYPE_TWOS_COMPLEMENT (time_t)));
+static long_int
+shr (long_int a, int b)
+{
+ long_int one = 1;
+ return (-one >> 1 == -1
+ ? a >> b
+ : a / (one << b) - (a % (one << b) < 0));
+}
+
+/* Bounds for the intersection of time_t and long_int. */
+
+static long_int const mktime_min
+ = ((TYPE_SIGNED (time_t) && TYPE_MINIMUM (time_t) < TYPE_MINIMUM (long_int))
+ ? TYPE_MINIMUM (long_int) : TYPE_MINIMUM (time_t));
+static long_int const mktime_max
+ = (TYPE_MAXIMUM (long_int) < TYPE_MAXIMUM (time_t)
+ ? TYPE_MAXIMUM (long_int) : TYPE_MAXIMUM (time_t));
+
+verify (TYPE_IS_INTEGER (time_t));
#define EPOCH_YEAR 1970
#define TM_YEAR_BASE 1900
-verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0);
+verify (TM_YEAR_BASE % 100 == 0);
-/* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */
-static int
+/* Is YEAR + TM_YEAR_BASE a leap year? */
+static bool
leapyear (long_int year)
{
/* Don't add YEAR to TM_YEAR_BASE, as that might overflow.
@@ -166,20 +201,9 @@ const unsigned short int __mon_yday[2][13] =
};
-#ifndef _LIBC
-/* Portable standalone applications should supply a <time.h> that
- declares a POSIX-compliant localtime_r, for the benefit of older
- implementations that lack localtime_r or have a nonstandard one.
- See the gnulib time_r module for one way to implement this. */
-# undef __localtime_r
-# define __localtime_r localtime_r
-# define __mktime_internal mktime_internal
-# include "mktime-internal.h"
-#endif
-
-/* Return 1 if the values A and B differ according to the rules for
- tm_isdst: A and B differ if one is zero and the other positive. */
-static int
+/* Do the values A and B differ according to the rules for tm_isdst?
+ A and B differ if one is zero and the other positive. */
+static bool
isdst_differ (int a, int b)
{
return (!a != !b) && (0 <= a) && (0 <= b);
@@ -187,107 +211,68 @@ isdst_differ (int a, int b)
/* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) -
(YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks
- were not adjusted between the time stamps.
+ were not adjusted between the timestamps.
The YEAR values uses the same numbering as TP->tm_year. Values
- need not be in the usual range. However, YEAR1 must not be less
- than 2 * INT_MIN or greater than 2 * INT_MAX.
-
- The result may overflow. It is the caller's responsibility to
- detect overflow. */
+ need not be in the usual range. However, YEAR1 must not overflow
+ when multiplied by three times the number of seconds in a year, and
+ likewise for YDAY1 and three times the number of seconds in a day. */
-static time_t
+static long_int
ydhms_diff (long_int year1, long_int yday1, int hour1, int min1, int sec1,
int year0, int yday0, int hour0, int min0, int sec0)
{
- verify (C99_integer_division, -1 / 2 == 0);
+ verify (-1 / 2 == 0);
/* Compute intervening leap days correctly even if year is negative.
Take care to avoid integer overflow here. */
- int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3);
- int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3);
+ int a4 = shr (year1, 2) + shr (TM_YEAR_BASE, 2) - ! (year1 & 3);
+ int b4 = shr (year0, 2) + shr (TM_YEAR_BASE, 2) - ! (year0 & 3);
int a100 = a4 / 25 - (a4 % 25 < 0);
int b100 = b4 / 25 - (b4 % 25 < 0);
- int a400 = SHR (a100, 2);
- int b400 = SHR (b100, 2);
+ int a400 = shr (a100, 2);
+ int b400 = shr (b100, 2);
int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
- /* Compute the desired time in time_t precision. Overflow might
- occur here. */
- time_t tyear1 = year1;
- time_t years = tyear1 - year0;
- time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
- time_t hours = 24 * days + hour1 - hour0;
- time_t minutes = 60 * hours + min1 - min0;
- time_t seconds = 60 * minutes + sec1 - sec0;
+ /* Compute the desired time without overflowing. */
+ long_int years = year1 - year0;
+ long_int days = 365 * years + yday1 - yday0 + intervening_leap_days;
+ long_int hours = 24 * days + hour1 - hour0;
+ long_int minutes = 60 * hours + min1 - min0;
+ long_int seconds = 60 * minutes + sec1 - sec0;
return seconds;
}
-/* Return the average of A and B, even if A + B would overflow. */
-static time_t
-time_t_avg (time_t a, time_t b)
-{
- return SHR (a, 1) + SHR (b, 1) + (a & b & 1);
-}
-
-/* Return 1 if A + B does not overflow. If time_t is unsigned and if
- B's top bit is set, assume that the sum represents A - -B, and
- return 1 if the subtraction does not wrap around. */
-static int
-time_t_add_ok (time_t a, time_t b)
+/* Return the average of A and B, even if A + B would overflow.
+ Round toward positive infinity. */
+static long_int
+long_int_avg (long_int a, long_int b)
{
- if (! TYPE_SIGNED (time_t))
- {
- time_t sum = a + b;
- return (sum < a) == (TIME_T_MIDPOINT <= b);
- }
- else if (WRAPV)
- {
- time_t sum = a + b;
- return (sum < a) == (b < 0);
- }
- else
- {
- time_t avg = time_t_avg (a, b);
- return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2;
- }
-}
-
-/* Return 1 if A + B does not overflow. */
-static int
-time_t_int_add_ok (time_t a, int b)
-{
- verify (int_no_wider_than_time_t, INT_MAX <= TIME_T_MAX);
- if (WRAPV)
- {
- time_t sum = a + b;
- return (sum < a) == (b < 0);
- }
- else
- {
- int a_odd = a & 1;
- time_t avg = SHR (a, 1) + (SHR (b, 1) + (a_odd & b));
- return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2;
- }
+ return shr (a, 1) + shr (b, 1) + ((a | b) & 1);
}
/* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
- assuming that *T corresponds to *TP and that no clock adjustments
+ assuming that T corresponds to *TP and that no clock adjustments
occurred between *TP and the desired time.
- If TP is null, return a value not equal to *T; this avoids false matches.
- If overflow occurs, yield the minimal or maximal value, except do not
- yield a value equal to *T. */
-static time_t
+ Although T and the returned value are of type long_int,
+ they represent time_t values and must be in time_t range.
+ If TP is null, return a value not equal to T; this avoids false matches.
+ YEAR and YDAY must not be so large that multiplying them by three times the
+ number of seconds in a year (or day, respectively) would overflow long_int.
+ If the returned value would be out of range, yield the minimal or
+ maximal in-range value, except do not yield a value equal to T. */
+static long_int
guess_time_tm (long_int year, long_int yday, int hour, int min, int sec,
- const time_t *t, const struct tm *tp)
+ long_int t, const struct tm *tp)
{
if (tp)
{
- time_t d = ydhms_diff (year, yday, hour, min, sec,
- tp->tm_year, tp->tm_yday,
- tp->tm_hour, tp->tm_min, tp->tm_sec);
- if (time_t_add_ok (*t, d))
- return *t + d;
+ long_int result;
+ long_int d = ydhms_diff (year, yday, hour, min, sec,
+ tp->tm_year, tp->tm_yday,
+ tp->tm_hour, tp->tm_min, tp->tm_sec);
+ if (! INT_ADD_WRAPV (t, d, &result))
+ return result;
}
/* Overflow occurred one way or another. Return the nearest result
@@ -295,32 +280,51 @@ guess_time_tm (long_int year, long_int yday, int hour, int min, int sec,
if the actual difference is nonzero, as that would cause a false
match; and don't oscillate between two values, as that would
confuse the spring-forward gap detector. */
- return (*t < TIME_T_MIDPOINT
- ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN)
- : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX));
+ return (t < long_int_avg (mktime_min, mktime_max)
+ ? (t <= mktime_min + 1 ? t + 1 : mktime_min)
+ : (mktime_max - 1 <= t ? t - 1 : mktime_max));
+}
+
+/* Use CONVERT to convert T to a struct tm value in *TM. T must be in
+ range for time_t. Return TM if successful, NULL if T is out of
+ range for CONVERT. */
+static struct tm *
+convert_time (struct tm *(*convert) (const time_t *, struct tm *),
+ long_int t, struct tm *tm)
+{
+ time_t x = t;
+ return convert (&x, tm);
}
/* Use CONVERT to convert *T to a broken down time in *TP.
If *T is out of range for conversion, adjust it so that
- it is the nearest in-range value and then convert that. */
+ it is the nearest in-range value and then convert that.
+ A value is in range if it fits in both time_t and long_int. */
static struct tm *
ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
- time_t *t, struct tm *tp)
+ long_int *t, struct tm *tp)
{
- struct tm *r = convert (t, tp);
+ struct tm *r;
+ if (*t < mktime_min)
+ *t = mktime_min;
+ else if (mktime_max < *t)
+ *t = mktime_max;
+ r = convert_time (convert, *t, tp);
if (!r && *t)
{
- time_t bad = *t;
- time_t ok = 0;
+ long_int bad = *t;
+ long_int ok = 0;
- /* BAD is a known unconvertible time_t, and OK is a known good one.
+ /* BAD is a known unconvertible value, and OK is a known good one.
Use binary search to narrow the range between BAD and OK until
they differ by 1. */
- while (bad != ok + (bad < 0 ? -1 : 1))
+ while (true)
{
- time_t mid = *t = time_t_avg (ok, bad);
- r = convert (t, tp);
+ long_int mid = long_int_avg (ok, bad);
+ if (mid != ok && mid != bad)
+ break;
+ r = convert_time (convert, mid, tp);
if (r)
ok = mid;
else
@@ -331,8 +335,7 @@ ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
{
/* The last conversion attempt failed;
revert to the most recent successful attempt. */
- *t = ok;
- r = convert (t, tp);
+ r = convert_time (convert, ok, tp);
}
}
@@ -349,9 +352,9 @@ ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
time_t
__mktime_internal (struct tm *tp,
struct tm *(*convert) (const time_t *, struct tm *),
- time_t *offset)
+ mktime_offset_t *offset)
{
- time_t t, gt, t0, t1, t2;
+ long_int t, gt, t0, t1, t2, dt;
struct tm tm;
/* The maximum number of probes (calls to CONVERT) should be enough
@@ -381,9 +384,7 @@ __mktime_internal (struct tm *tp,
long_int year = lyear_requested + mon_years;
/* The other values need not be in range:
- the remaining code handles minor overflows correctly,
- assuming int and time_t arithmetic wraps around.
- Major overflows are caught at the end. */
+ the remaining code handles overflows correctly. */
/* Calculate day of year from year, month, and day of month.
The result need not be in range. */
@@ -393,7 +394,7 @@ __mktime_internal (struct tm *tp,
long_int lmday = mday;
long_int yday = mon_yday + lmday;
- time_t guessed_offset = *offset;
+ int negative_offset_guess;
int sec_requested = sec;
@@ -410,71 +411,14 @@ __mktime_internal (struct tm *tp,
/* Invert CONVERT by probing. First assume the same offset as last
time. */
+ INT_SUBTRACT_WRAPV (0, *offset, &negative_offset_guess);
t0 = ydhms_diff (year, yday, hour, min, sec,
- EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
-
- if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
- {
- /* time_t isn't large enough to rule out overflows, so check
- for major overflows. A gross check suffices, since if t0
- has overflowed, it is off by a multiple of TIME_T_MAX -
- TIME_T_MIN + 1. So ignore any component of the difference
- that is bounded by a small value. */
-
- /* Approximate log base 2 of the number of time units per
- biennium. A biennium is 2 years; use this unit instead of
- years to avoid integer overflow. For example, 2 average
- Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
- which is 63113904 seconds, and rint (log2 (63113904)) is
- 26. */
- int ALOG2_SECONDS_PER_BIENNIUM = 26;
- int ALOG2_MINUTES_PER_BIENNIUM = 20;
- int ALOG2_HOURS_PER_BIENNIUM = 14;
- int ALOG2_DAYS_PER_BIENNIUM = 10;
- int LOG2_YEARS_PER_BIENNIUM = 1;
-
- int approx_requested_biennia =
- (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM)
- - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM)
- + SHR (mday, ALOG2_DAYS_PER_BIENNIUM)
- + SHR (hour, ALOG2_HOURS_PER_BIENNIUM)
- + SHR (min, ALOG2_MINUTES_PER_BIENNIUM)
- + (LEAP_SECONDS_POSSIBLE
- ? 0
- : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM)));
-
- int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
- int diff = approx_biennia - approx_requested_biennia;
- int approx_abs_diff = diff < 0 ? -1 - diff : diff;
-
- /* IRIX 4.0.5 cc miscalculates TIME_T_MIN / 3: it erroneously
- gives a positive value of 715827882. Setting a variable
- first then doing math on it seems to work.
- (gh...@caip.rutgers.edu) */
- time_t time_t_max = TIME_T_MAX;
- time_t time_t_min = TIME_T_MIN;
- time_t overflow_threshold =
- (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
-
- if (overflow_threshold < approx_abs_diff)
- {
- /* Overflow occurred. Try repairing it; this might work if
- the time zone offset is enough to undo the overflow. */
- time_t repaired_t0 = -1 - t0;
- approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
- diff = approx_biennia - approx_requested_biennia;
- approx_abs_diff = diff < 0 ? -1 - diff : diff;
- if (overflow_threshold < approx_abs_diff)
- return -1;
- guessed_offset += repaired_t0 - t0;
- t0 = repaired_t0;
- }
- }
+ EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, negative_offset_guess);
/* Repeatedly use the error to improve the guess. */
for (t = t1 = t2 = t0, dst2 = 0;
- (gt = guess_time_tm (year, yday, hour, min, sec, &t,
+ (gt = guess_time_tm (year, yday, hour, min, sec, t,
ranged_convert (convert, &t, &tm)),
t != gt);
t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
@@ -531,65 +475,70 @@ __mktime_internal (struct tm *tp,
for (delta = stride; delta < delta_bound; delta += stride)
for (direction = -1; direction <= 1; direction += 2)
- if (time_t_int_add_ok (t, delta * direction))
- {
- time_t ot = t + delta * direction;
- struct tm otm;
- ranged_convert (convert, &ot, &otm);
- if (! isdst_differ (isdst, otm.tm_isdst))
- {
- /* We found the desired tm_isdst.
- Extrapolate back to the desired time. */
- t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
- ranged_convert (convert, &t, &tm);
- goto offset_found;
- }
- }
+ {
+ long_int ot;
+ if (! INT_ADD_WRAPV (t, delta * direction, &ot))
+ {
+ struct tm otm;
+ ranged_convert (convert, &ot, &otm);
+ if (! isdst_differ (isdst, otm.tm_isdst))
+ {
+ /* We found the desired tm_isdst.
+ Extrapolate back to the desired time. */
+ t = guess_time_tm (year, yday, hour, min, sec, ot, &otm);
+ ranged_convert (convert, &t, &tm);
+ goto offset_found;
+ }
+ }
+ }
}
offset_found:
- *offset = guessed_offset + t - t0;
+ /* Set *OFFSET to the low-order bits of T - T0 - NEGATIVE_OFFSET_GUESS.
+ This is just a heuristic to speed up the next mktime call, and
+ correctness is unaffected if integer overflow occurs here. */
+ INT_SUBTRACT_WRAPV (t, t0, &dt);
+ INT_SUBTRACT_WRAPV (dt, negative_offset_guess, offset);
if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
{
/* Adjust time to reflect the tm_sec requested, not the normalized value.
Also, repair any damage from a false match due to a leap second. */
- int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
- if (! time_t_int_add_ok (t, sec_requested))
- return -1;
- t1 = t + sec_requested;
- if (! time_t_int_add_ok (t1, sec_adjustment))
+ long_int sec_adjustment = sec == 0 && tm.tm_sec == 60;
+ sec_adjustment -= sec;
+ sec_adjustment += sec_requested;
+ if (INT_ADD_WRAPV (t, sec_adjustment, &t)
+ || ! (mktime_min <= t && t <= mktime_max)
+ || ! convert_time (convert, t, &tm))
return -1;
- t2 = t1 + sec_adjustment;
- if (! convert (&t2, &tm))
- return -1;
- t = t2;
}
*tp = tm;
return t;
}
+#endif /* _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_INTERNAL */
-/* FIXME: This should use a signed type wide enough to hold any UTC
- offset in seconds. 'int' should be good enough for GNU code. We
- can't fix this unilaterally though, as other modules invoke
- __mktime_internal. */
-static time_t localtime_offset;
+#if defined _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS
/* Convert *TP to a time_t value. */
time_t
mktime (struct tm *tp)
{
-#ifdef _LIBC
/* POSIX.1 8.1.1 requires that whenever mktime() is called, the
time zone names contained in the external variable 'tzname' shall
be set as if the tzset() function had been called. */
__tzset ();
-#endif
+# if defined __LIBC || NEED_MKTIME_WORKING
+ static mktime_offset_t localtime_offset;
return __mktime_internal (tp, __localtime_r, &localtime_offset);
+# else
+# undef mktime
+ return mktime (tp);
+# endif
}
+#endif /* _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS */
#ifdef weak_alias
weak_alias (mktime, timelocal)
@@ -600,7 +549,7 @@ libc_hidden_def (mktime)
libc_hidden_weak (timelocal)
#endif
-#if defined DEBUG_MKTIME && DEBUG_MKTIME
+#if DEBUG_MKTIME
static int
not_equal_tm (const struct tm *a, const struct tm *b)
@@ -652,6 +601,14 @@ main (int argc, char **argv)
time_t tk, tl, tl1;
char trailer;
+ /* Sanity check, plus call tzset. */
+ tl = 0;
+ if (! localtime (&tl))
+ {
+ printf ("localtime (0) fails\n");
+ status = 1;
+ }
+
if ((argc == 3 || argc == 4)
&& (sscanf (argv[1], "%d-%d-%d%c",
&tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer)
@@ -665,12 +622,7 @@ main (int argc, char **argv)
tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
tmk = tm;
tl = mktime (&tmk);
- lt = localtime (&tl);
- if (lt)
- {
- tml = *lt;
- lt = &tml;
- }
+ lt = localtime_r (&tl, &tml);
printf ("mktime returns %ld == ", (long int) tl);
print_tm (&tmk);
printf ("\n");
@@ -685,16 +637,16 @@ main (int argc, char **argv)
if (argc == 4)
for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
{
- lt = localtime (&tl);
+ lt = localtime_r (&tl, &tml);
if (lt)
{
- tmk = tml = *lt;
+ tmk = tml;
tk = mktime (&tmk);
status |= check_result (tk, tmk, tl, &tml);
}
else
{
- printf ("localtime (%ld) yields 0\n", (long int) tl);
+ printf ("localtime_r (%ld) yields 0\n", (long int) tl);
status = 1;
}
tl1 = tl + by;
@@ -705,16 +657,16 @@ main (int argc, char **argv)
for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
{
/* Null benchmark. */
- lt = localtime (&tl);
+ lt = localtime_r (&tl, &tml);
if (lt)
{
- tmk = tml = *lt;
+ tmk = tml;
tk = tl;
status |= check_result (tk, tmk, tl, &tml);
}
else
{
- printf ("localtime (%ld) yields 0\n", (long int) tl);
+ printf ("localtime_r (%ld) yields 0\n", (long int) tl);
status = 1;
}
tl1 = tl + by;
diff --git a/time/timegm.c b/time/timegm.c
index fb720e2d7d..275a7a2eca 100644
--- a/time/timegm.c
+++ b/time/timegm.c
@@ -17,31 +17,22 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#ifdef HAVE_CONFIG_H
+#ifndef _LIBC
# include <config.h>
#endif
+#include <time.h>
+
#ifdef _LIBC
-# include <time.h>
+typedef time_t mktime_offset_t;
#else
-# include "timegm.h"
-
-/* Portable standalone applications should supply a "time_r.h" that
- declares a POSIX-compliant gmtime_r, for the benefit of older
- implementations that lack gmtime_r or have a nonstandard one.
- See the gnulib time_r module for one way to implement this. */
-# include <time_r.h>
-# undef __gmtime_r
-# define __gmtime_r gmtime_r
-time_t __mktime_internal (struct tm *,
- struct tm * (*) (time_t const *, struct tm *),
- time_t *);
+# include "mktime-internal.h"
#endif
time_t
timegm (struct tm *tmp)
{
- static time_t gmtime_offset;
+ static mktime_offset_t gmtime_offset;
tmp->tm_isdst = 0;
return __mktime_internal (tmp, __gmtime_r, &gmtime_offset);
}
--
2.17.1
>From ab45ee41d8165913c805cdd7c7de2e6060db24ec Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Fri, 31 Aug 2018 16:17:06 -0700
Subject: [PATCH 2/3] Fix mktime localtime offset confusion
* include/time.h (__mktime_internal): The localtime offset is now
of type long int instead of time_t. This is the longstanding type
in glibc, and it is more than enough to represent difference
between localtime and gmtime even if it is 32 bits and time_t is
64. Changing it now will let us avoid an unnecessary change when
time_t is widened to 64 bits on 32-bit platforms.
* time/mktime.c, time/timegm.c (mktime_offset_t) [_LIBC]: Now long int.
---
ChangeLog | 9 +++++++++
include/time.h | 4 ++--
time/mktime.c | 2 +-
time/timegm.c | 2 +-
4 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index d1ab1b0718..9f31582e19 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
2018-08-31 Paul Eggert <egg...@cs.ucla.edu>
+ Fix mktime localtime offset confusion
+ * include/time.h (__mktime_internal): The localtime offset is now
+ of type long int instead of time_t. This is the longstanding type
+ in glibc, and it is more than enough to represent difference
+ between localtime and gmtime even if it is 32 bits and time_t is
+ 64. Changing it now will let us avoid an unnecessary change when
+ time_t is widened to 64 bits on 32-bit platforms.
+ * time/mktime.c, time/timegm.c (mktime_offset_t) [_LIBC]: Now long int.
+
Merge mktime, timegm from upstream Gnulib
This fixes some obscure problems with integer overflow.
Although it looks scary, it is a byte-for-byte copy from Gnulib,
diff --git a/include/time.h b/include/time.h
index f562f681c3..114d0f7da6 100644
--- a/include/time.h
+++ b/include/time.h
@@ -52,11 +52,11 @@ extern void __tz_compute (__time64_t timer, struct tm *tm, int use_localtime)
/* Subroutine of `mktime'. Return the `time_t' representation of TP and
normalize TP, given that a `struct tm *' maps to a `time_t' as performed
- by FUNC. Keep track of next guess for time_t offset in *OFFSET. */
+ by FUNC. Record next guess for localtime-gmtime offset in *OFFSET. */
extern time_t __mktime_internal (struct tm *__tp,
struct tm *(*__func) (const time_t *,
struct tm *),
- time_t *__offset) attribute_hidden;
+ long int *__offset) attribute_hidden;
/* nis/nis_print.c needs ctime, so even if ctime is not declared here,
we define __ctime64 as ctime so that nis/nis_print.c can get linked
diff --git a/time/mktime.c b/time/mktime.c
index 2858764792..a307671feb 100644
--- a/time/mktime.c
+++ b/time/mktime.c
@@ -77,7 +77,7 @@
#endif
#ifdef _LIBC
-typedef time_t mktime_offset_t;
+typedef long int mktime_offset_t;
#else
# include "mktime-internal.h"
#endif
diff --git a/time/timegm.c b/time/timegm.c
index 275a7a2eca..71276bbe0b 100644
--- a/time/timegm.c
+++ b/time/timegm.c
@@ -24,7 +24,7 @@
#include <time.h>
#ifdef _LIBC
-typedef time_t mktime_offset_t;
+typedef long int mktime_offset_t;
#else
# include "mktime-internal.h"
#endif
--
2.17.1
>From edeaac0060e9fbe4e1aa094e4ad6b58398a75f9d Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Fri, 31 Aug 2018 23:45:31 -0700
Subject: [PATCH 3/3] Add support for __time64_t to mktime, timegm
* include/time.h, time/mktime.c, time/timegm.c:
Change externally-visible names to their __xxx64yyy version.
* include/time.h (fits_in_time_t): New static function.
* time/mktime.c (mktime) [_LIBC]: New wrapper function.
* time/timegm.c (timegm) [_LIBC]: New wrapper function.
---
ChangeLog | 7 ++++++
include/time.h | 20 ++++++++++-----
time/mktime.c | 66 +++++++++++++++++++++++++++++++-------------------
time/timegm.c | 22 ++++++++++++++---
4 files changed, 81 insertions(+), 34 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 9f31582e19..3b20dafde1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
2018-08-31 Paul Eggert <egg...@cs.ucla.edu>
+ Add support for __time64_t to mktime, timegm
+ * include/time.h, time/mktime.c, time/timegm.c:
+ Change externally-visible names to their __xxx64yyy version.
+ * include/time.h (fits_in_time_t): New static function.
+ * time/mktime.c (mktime) [_LIBC]: New wrapper function.
+ * time/timegm.c (timegm) [_LIBC]: New wrapper function.
+
Fix mktime localtime offset confusion
* include/time.h (__mktime_internal): The localtime offset is now
of type long int instead of time_t. This is the longstanding type
diff --git a/include/time.h b/include/time.h
index 114d0f7da6..05a7372285 100644
--- a/include/time.h
+++ b/include/time.h
@@ -50,13 +50,13 @@ extern void __tzset_parse_tz (const char *tz) attribute_hidden;
extern void __tz_compute (__time64_t timer, struct tm *tm, int use_localtime)
__THROW attribute_hidden;
-/* Subroutine of `mktime'. Return the `time_t' representation of TP and
- normalize TP, given that a `struct tm *' maps to a `time_t' as performed
+/* Subroutine of mktime. Return the __time64_t representation of TP and
+ normalize TP, given that a struct tm * maps to a __time64_t as performed
by FUNC. Record next guess for localtime-gmtime offset in *OFFSET. */
-extern time_t __mktime_internal (struct tm *__tp,
- struct tm *(*__func) (const time_t *,
- struct tm *),
- long int *__offset) attribute_hidden;
+extern __time64_t __mktime_internal (struct tm *__tp,
+ struct tm *(*__func) (const __time64_t *,
+ struct tm *),
+ long int *__offset) attribute_hidden;
/* nis/nis_print.c needs ctime, so even if ctime is not declared here,
we define __ctime64 as ctime so that nis/nis_print.c can get linked
@@ -131,5 +131,13 @@ extern double __difftime (time_t time1, time_t time0);
actual clock ID. */
#define CLOCK_IDFIELD_SIZE 3
+/* Check whether a time64_t value fits in a time_t. */
+static inline bool
+fits_in_time_t (__time64_t t64)
+{
+ time_t t = t64;
+ return t == t64;
+}
+
#endif
#endif
diff --git a/time/mktime.c b/time/mktime.c
index a307671feb..fcef7ee3ca 100644
--- a/time/mktime.c
+++ b/time/mktime.c
@@ -51,6 +51,7 @@
#include <time.h>
+#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stdlib.h>
@@ -129,11 +130,11 @@ my_tzset (void)
to be subtracted from each other, and sometimes with an offset
added to them, without worrying about overflow.
- Much of the code uses long_int to represent time_t values, to
- lessen the hassle of dealing with platforms where time_t is
- unsigned, and because long_int should suffice to represent all
- time_t values that mktime can generate even on platforms where
- time_t is excessively wide. */
+ Much of the code uses long_int to represent __time64_t values, to
+ lessen the hassle of dealing with Gnulib-using platforms where
+ __time64_t is time_t and time_t is unsigned, and because long_int
+ should suffice to represent all __time64_t values that mktime can
+ generate even on platforms where __time64_t is excessively wide. */
#if INT_MAX <= LONG_MAX / 3 / 366 / 24 / 60 / 60
typedef long int long_int;
@@ -161,16 +162,17 @@ shr (long_int a, int b)
: a / (one << b) - (a % (one << b) < 0));
}
-/* Bounds for the intersection of time_t and long_int. */
+/* Bounds for the intersection of __time64_t and long_int. */
static long_int const mktime_min
- = ((TYPE_SIGNED (time_t) && TYPE_MINIMUM (time_t) < TYPE_MINIMUM (long_int))
- ? TYPE_MINIMUM (long_int) : TYPE_MINIMUM (time_t));
+ = ((TYPE_SIGNED (__time64_t)
+ && TYPE_MINIMUM (__time64_t) < TYPE_MINIMUM (long_int))
+ ? TYPE_MINIMUM (long_int) : TYPE_MINIMUM (__time64_t));
static long_int const mktime_max
- = (TYPE_MAXIMUM (long_int) < TYPE_MAXIMUM (time_t)
- ? TYPE_MAXIMUM (long_int) : TYPE_MAXIMUM (time_t));
+ = (TYPE_MAXIMUM (long_int) < TYPE_MAXIMUM (__time64_t)
+ ? TYPE_MAXIMUM (long_int) : TYPE_MAXIMUM (__time64_t));
-verify (TYPE_IS_INTEGER (time_t));
+verify (TYPE_IS_INTEGER (__time64_t));
#define EPOCH_YEAR 1970
#define TM_YEAR_BASE 1900
@@ -251,11 +253,11 @@ long_int_avg (long_int a, long_int b)
return shr (a, 1) + shr (b, 1) + ((a | b) & 1);
}
-/* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
+/* Return a __time64_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
assuming that T corresponds to *TP and that no clock adjustments
occurred between *TP and the desired time.
Although T and the returned value are of type long_int,
- they represent time_t values and must be in time_t range.
+ they represent __time64_t values and must be in __time64_t range.
If TP is null, return a value not equal to T; this avoids false matches.
YEAR and YDAY must not be so large that multiplying them by three times the
number of seconds in a year (or day, respectively) would overflow long_int.
@@ -286,22 +288,22 @@ guess_time_tm (long_int year, long_int yday, int hour, int min, int sec,
}
/* Use CONVERT to convert T to a struct tm value in *TM. T must be in
- range for time_t. Return TM if successful, NULL if T is out of
+ range for __time64_t. Return TM if successful, NULL if T is out of
range for CONVERT. */
static struct tm *
-convert_time (struct tm *(*convert) (const time_t *, struct tm *),
+convert_time (struct tm *(*convert) (const __time64_t *, struct tm *),
long_int t, struct tm *tm)
{
- time_t x = t;
+ __time64_t x = t;
return convert (&x, tm);
}
/* Use CONVERT to convert *T to a broken down time in *TP.
If *T is out of range for conversion, adjust it so that
it is the nearest in-range value and then convert that.
- A value is in range if it fits in both time_t and long_int. */
+ A value is in range if it fits in both __time64_t and long_int. */
static struct tm *
-ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
+ranged_convert (struct tm *(*convert) (const __time64_t *, struct tm *),
long_int *t, struct tm *tp)
{
struct tm *r;
@@ -343,15 +345,15 @@ ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
}
-/* Convert *TP to a time_t value, inverting
+/* Convert *TP to a __time64_t value, inverting
the monotonic and mostly-unit-linear conversion function CONVERT.
Use *OFFSET to keep track of a guess at the offset of the result,
compared to what the result would be for UTC without leap seconds.
If *OFFSET's guess is correct, only one CONVERT call is needed.
This function is external because it is used also by timegm.c. */
-time_t
+__time64_t
__mktime_internal (struct tm *tp,
- struct tm *(*convert) (const time_t *, struct tm *),
+ struct tm *(*convert) (const __time64_t *, struct tm *),
mktime_offset_t *offset)
{
long_int t, gt, t0, t1, t2, dt;
@@ -521,9 +523,9 @@ __mktime_internal (struct tm *tp,
#if defined _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS
-/* Convert *TP to a time_t value. */
-time_t
-mktime (struct tm *tp)
+/* Convert *TP to a __time64_t value. */
+__time64_t
+__mktime64 (struct tm *tp)
{
/* POSIX.1 8.1.1 requires that whenever mktime() is called, the
time zone names contained in the external variable 'tzname' shall
@@ -532,7 +534,7 @@ mktime (struct tm *tp)
# if defined __LIBC || NEED_MKTIME_WORKING
static mktime_offset_t localtime_offset;
- return __mktime_internal (tp, __localtime_r, &localtime_offset);
+ return __mktime_internal (tp, __localtime64_r, &localtime_offset);
# else
# undef mktime
return mktime (tp);
@@ -540,8 +542,22 @@ mktime (struct tm *tp)
}
#endif /* _LIBC || NEED_MKTIME_WORKING || NEED_MKTIME_WINDOWS */
+#ifdef _LIBC
+/* The 32-bit-time wrapper. */
+time_t
+mktime (struct tm *tp)
+{
+ __time64_t t64 = __mktime64 (tp);
+ if (fits_in_time_t (t64))
+ return t64;
+ __set_errno (EOVERFLOW);
+ return -1;
+}
+#endif
+
#ifdef weak_alias
weak_alias (mktime, timelocal)
+weak_alias (__mktime64, __timelocal64)
#endif
#ifdef _LIBC
diff --git a/time/timegm.c b/time/timegm.c
index 71276bbe0b..104f206086 100644
--- a/time/timegm.c
+++ b/time/timegm.c
@@ -23,16 +23,32 @@
#include <time.h>
+#include <errno.h>
+
#ifdef _LIBC
typedef long int mktime_offset_t;
#else
# include "mktime-internal.h"
#endif
+__time64_t
+__timegm64 (struct tm *tmp)
+{
+ static long int gmtime_offset;
+ tmp->tm_isdst = 0;
+ return __mktime_internal (tmp, __gmtime64_r, &gmtime_offset);
+}
+
+#ifdef _LIBC
+
time_t
timegm (struct tm *tmp)
{
- static mktime_offset_t gmtime_offset;
- tmp->tm_isdst = 0;
- return __mktime_internal (tmp, __gmtime_r, &gmtime_offset);
+ __time64_t t64 = __timegm64 (tmp);
+ if (fits_in_time_t (t64))
+ return t64;
+ __set_errno (EOVERFLOW);
+ return -1;
}
+
+#endif
--
2.17.1
