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authorPaul Eggert <eggert@cs.ucla.edu>2018-09-19 13:16:14 -0700
committerPaul Eggert <eggert@cs.ucla.edu>2018-09-19 17:09:08 -0700
commit8e6fd2bdb21efe2cc1ae7571ff8fb2599db6a05a (patch)
tree16623453ad42c7ad61408a410c312aae747cc4d6
parent83a552b0bb9fc2a5e80a0ab3723c0a80ce1db9f2 (diff)
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Merge mktime, timegm from upstream Gnulib
[BZ #23603][BZ #16346] This fixes some obscure problems with integer overflow. Although it looks scary, it is almost all a byte-for-byte copy from Gnulib, and the Gnulib code has been tested reasonably well. * include/intprops.h: New file, copied from Gnulib. * include/verify.h, time/mktime-internal.h: New tiny files, simplified 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. Include mktime-internal.h. (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 it’s 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 needn’t 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. (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. Access *OFFSET only once, to avoid an unlikely race if the compiler delays a load and if this cascades into a signed integer overflow. (mktime): Move tzsettish code to my_tzset, and move localtime_offset to within mktime so that it doesn’t 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: Include mktime-internal.h. [!_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.
-rw-r--r--ChangeLog70
-rw-r--r--include/intprops.h455
-rw-r--r--include/verify.h2
-rw-r--r--time/mktime-internal.h2
-rw-r--r--time/mktime.c545
-rw-r--r--time/timegm.c23
6 files changed, 781 insertions, 316 deletions
diff --git a/ChangeLog b/ChangeLog
index 69ee9d08ca5..a49dba34eac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,73 @@
+2018-09-19 Paul Eggert <eggert@cs.ucla.edu>
+
+ Merge mktime, timegm from upstream Gnulib
+ [BZ #23603][BZ #16346]
+ This fixes some obscure problems with integer overflow.
+ Although it looks scary, it is almost all a byte-for-byte copy
+ from Gnulib, and the Gnulib code has been tested reasonably well.
+ * include/intprops.h: New file, copied from Gnulib.
+ * include/verify.h, time/mktime-internal.h:
+ New tiny files, simplified 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.
+ Include mktime-internal.h.
+ (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 it’s 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 needn’t 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.
+ (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.
+ Access *OFFSET only once, to avoid an unlikely race if the
+ compiler delays a load and if this cascades into a signed integer
+ overflow.
+ (mktime): Move tzsettish code to my_tzset, and move
+ localtime_offset to within mktime so that it doesn’t
+ 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:
+ Include mktime-internal.h.
+ [!_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.
+
2018-09-19 Wilco Dijkstra <wdijkstr@arm.com>
[BZ #23637]
diff --git a/include/intprops.h b/include/intprops.h
new file mode 100644
index 00000000000..9702aec4c6e
--- /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 (_GL_INT_CONVERT (a, b)), \
+ _GL_INT_MAXIMUM (_GL_INT_CONVERT (a, b)))
+
+/* 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 00000000000..00e78d3f8c8
--- /dev/null
+++ b/include/verify.h
@@ -0,0 +1,2 @@
+/* Gnulib <verify.h>, simplified by assuming GCC 4.6 or later. */
+#define verify(R) _Static_assert (R, "verify (" #R ")")
diff --git a/time/mktime-internal.h b/time/mktime-internal.h
new file mode 100644
index 00000000000..01671285fce
--- /dev/null
+++ b/time/mktime-internal.h
@@ -0,0 +1,2 @@
+/* Gnulib mktime-internal.h, tailored for glibc. */
+typedef time_t mktime_offset_t;
diff --git a/time/mktime.c b/time/mktime.c
index 5f038a212f8..1404ee9f1ff 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 +52,128 @@
#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
+
+#include "mktime-internal.h"
+
+#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 +197,9 @@ 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 +207,68 @@ 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 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)
{
- 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)
-{
- 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 +276,51 @@ 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 +331,7 @@ 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 +348,9 @@ 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 +380,7 @@ __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 +390,8 @@ __mktime_internal (struct tm *tp,
long_int lmday = mday;
long_int yday = mon_yday + lmday;
- time_t guessed_offset = *offset;
+ mktime_offset_t off = *offset;
+ int negative_offset_guess;
int sec_requested = sec;
@@ -410,71 +408,14 @@ __mktime_internal (struct tm *tp,
/* Invert CONVERT by probing. First assume the same offset as last
time. */
+ INT_SUBTRACT_WRAPV (0, off, &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.
- (ghazi@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 +472,70 @@ __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))
- return -1;
- t2 = t1 + sec_adjustment;
- if (! convert (&t2, &tm))
+ 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;
- 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 +546,7 @@ 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 +598,14 @@ 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 +619,7 @@ 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 +634,16 @@ 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 +654,16 @@ 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 fb720e2d7df..229fff23c6a 100644
--- a/time/timegm.c
+++ b/time/timegm.c
@@ -17,31 +17,18 @@
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
-#ifdef _LIBC
-# include <time.h>
-#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 *);
-#endif
+#include <time.h>
+
+#include "mktime-internal.h"
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);
}