Merge from gnulib.

1 files changed, 263 insertions, 35 deletions

diff --git a/lib/intprops.h b/lib/intprops.h
index 58b1b3fbf44..a84bd6af531 100644
--- a/lib/intprops.h
+++ b/lib/intprops.h
@@ -17,70 +17,298 @@
 
 /* Written by Paul Eggert.  */
 
-#ifndef GL_INTPROPS_H
-# define GL_INTPROPS_H
+#ifndef _GL_INTPROPS_H
+#define _GL_INTPROPS_H
 
-# include <limits.h>
+#include <limits.h>
+
+/* Return a integer value, converted to the same type as the integer
+   expression E after integer type promotion.  V is the unconverted value.
+   E should not have side effects.  */
+#define _GL_INT_CONVERT(e, v) ((e) - (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)
+#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
 
 /* True if negative values of the signed integer type T use two's
    complement, ones' complement, or signed magnitude representation,
    respectively.  Much GNU code assumes two's complement, but some
    people like to be portable to all possible C hosts.  */
-# define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
-# define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
-# define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
+#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
+#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
+#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
+
+/* True if the signed integer expression E uses two's complement.  */
+#define _GL_INT_TWOS_COMPLEMENT(e) (~ _GL_INT_CONVERT (e, 0) == -1)
 
 /* True if the arithmetic type T is signed.  */
-# define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+
+/* Return 1 if the integer expression E, after integer promotion, has
+   a signed type.  E should not have side effects.  */
+#define _GL_INT_SIGNED(e) (_GL_INT_CONVERT (e, -1) < 0)
 
-/* The maximum and minimum values for the integer type T.  These
+
+/* Minimum and maximum values for integer types and expressions.  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_SIGNED_MAGNITUDE (t) \
-        ? ~ (t) 0 \
+
+/* The maximum and minimum values for the integer type T.  */
+#define TYPE_MINIMUM(t)                                                 \
+  ((t) (! TYPE_SIGNED (t)                                               \
+        ? (t) 0                                                         \
+        : TYPE_SIGNED_MAGNITUDE (t)                                     \
+        ? ~ (t) 0                                                       \
         : ~ TYPE_MAXIMUM (t)))
-# define TYPE_MAXIMUM(t) \
-  ((t) (! TYPE_SIGNED (t) \
-        ? (t) -1 \
+#define TYPE_MAXIMUM(t)                                                 \
+  ((t) (! TYPE_SIGNED (t)                                               \
+        ? (t) -1                                                        \
         : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1)))
 
-/* Return zero if T can be determined to be an unsigned type.
-   Otherwise, return 1.
-   When compiling with GCC, INT_STRLEN_BOUND uses this macro to obtain a
-   tighter bound.  Otherwise, it overestimates the true bound by one byte
-   when applied to unsigned types of size 2, 4, 16, ... bytes.
-   The symbol signed_type_or_expr__ is private to this header file.  */
-# if __GNUC__ >= 2
-#  define signed_type_or_expr__(t) TYPE_SIGNED (__typeof__ (t))
-# else
-#  define signed_type_or_expr__(t) 1
-# endif
+/* The maximum and minimum values for the type of the expression E,
+   after integer promotion.  E should not have side effects.  */
+#define _GL_INT_MINIMUM(e)                                              \
+  (_GL_INT_SIGNED (e)                                                   \
+   ? - _GL_INT_TWOS_COMPLEMENT (e) - _GL_SIGNED_INT_MAXIMUM (e)         \
+   : _GL_INT_CONVERT (e, 0))
+#define _GL_INT_MAXIMUM(e)                                              \
+  (_GL_INT_SIGNED (e)                                                   \
+   ? _GL_SIGNED_INT_MAXIMUM (e)                                         \
+   : _GL_INT_CONVERT (e, -1))
+#define _GL_SIGNED_INT_MAXIMUM(e)                                       \
+  (((_GL_INT_CONVERT (e, 1) << (sizeof ((e) + 0) * CHAR_BIT - 2)) - 1) * 2 + 1)
+
+
+/* Return 1 if the __typeof__ keyword works.  This could be done by
+   'configure', but for now it's easier to do it by hand.  */
+#if 2 <= __GNUC__ || 0x5110 <= __SUNPRO_C
+# 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)
+#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.  */
-# define INT_STRLEN_BOUND(t) \
-  (INT_BITS_STRLEN_BOUND (sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) \
-   + signed_type_or_expr__ (t))
+   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 (sizeof (t) * CHAR_BIT                 \
+                          - _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)
+#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.  */
+#define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max)     \
+  ((b) < 0                                              \
+   ? ((a) < 0                                           \
+      ? (a) < (max) / (b)                               \
+      : (b) < -1 && (min) / (b) < (a))                  \
+   : (0 < (b)                                           \
+      && ((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))
+
+
+/* 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.  */
+#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))
+#define _GL_DIVIDE_OVERFLOW(a, b, min, max)                             \
+  ((min) < 0 ? (b) == _GL_INT_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_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)
+
+
+/* Integer overflow checks.
+
+   The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
+   might not yield numerically correct answers due to arithmetic overflow.
+   They work correctly on all known practical hosts, and do not rely
+   on undefined behavior due to signed arithmetic overflow.
+
+   Example usage:
+
+     long int i = ...;
+     long int j = ...;
+     if (INT_MULTIPLY_OVERFLOW (i, j))
+       printf ("multiply would overflow");
+     else
+       printf ("product is %ld", i * j);
+
+   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.
+
+   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)
+#define INT_NEGATE_OVERFLOW(a) \
+  INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
+#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.
+
+   This macro assumes that A | B is a valid integer if both A and B are,
+   which is true of all known practical hosts.  If this is a problem
+   for you, please let us know how to fix it for your host.  */
+#define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow)        \
+  op_result_overflow (a, b,                                     \
+                      _GL_INT_MINIMUM ((a) | (b)),              \
+                      _GL_INT_MAXIMUM ((a) | (b)))
 
-#endif /* GL_INTPROPS_H */
+#endif /* _GL_INTPROPS_H */