vasnprintf: fix x86/glibc regression on printf("%La", 0.0L)
[gnulib.git] / lib / vasnprintf.c
index d6b012a..421e445 100644 (file)
@@ -1,5 +1,5 @@
 /* vsprintf with automatic memory allocation.
-   Copyright (C) 1999, 2002-2007 Free Software Foundation, Inc.
+   Copyright (C) 1999, 2002-2008 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
@@ -95,7 +95,7 @@
 
 #if (NEED_PRINTF_DOUBLE || NEED_PRINTF_INFINITE_DOUBLE) && !defined IN_LIBINTL
 # include <math.h>
-# include "isnan.h"
+# include "isnand-nolibm.h"
 #endif
 
 #if (NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_INFINITE_LONG_DOUBLE) && !defined IN_LIBINTL
 
 #if (NEED_PRINTF_DIRECTIVE_A || NEED_PRINTF_DOUBLE) && !defined IN_LIBINTL
 # include <math.h>
-# include "isnan.h"
+# include "isnand-nolibm.h"
 # include "printf-frexp.h"
 #endif
 
 # include "fpucw.h"
 #endif
 
-/* Some systems, like OSF/1 4.0 and Woe32, don't have EOVERFLOW.  */
-#ifndef EOVERFLOW
-# define EOVERFLOW E2BIG
-#endif
-
 #if HAVE_WCHAR_T
 # if HAVE_WCSLEN
 #  define local_wcslen wcslen
@@ -182,10 +177,12 @@ local_wcslen (const wchar_t *s)
 # endif
 #else
   /* TCHAR_T is char.  */
-# /* Use snprintf if it exists under the name 'snprintf' or '_snprintf'.
+  /* Use snprintf if it exists under the name 'snprintf' or '_snprintf'.
      But don't use it on BeOS, since BeOS snprintf produces no output if the
-     size argument is >= 0x3000000.  */
-# if (HAVE_DECL__SNPRINTF || HAVE_SNPRINTF) && !defined __BEOS__
+     size argument is >= 0x3000000.
+     Also don't use it on Linux libc5, since there snprintf with size = 1
+     writes any output without bounds, like sprintf.  */
+# if (HAVE_DECL__SNPRINTF || HAVE_SNPRINTF) && !defined __BEOS__ && !(__GNU_LIBRARY__ == 1)
 #  define USE_SNPRINTF 1
 # else
 #  define USE_SNPRINTF 0
@@ -203,7 +200,22 @@ local_wcslen (const wchar_t *s)
 /* Here we need to call the native sprintf, not rpl_sprintf.  */
 #undef sprintf
 
-#if (NEED_PRINTF_DIRECTIVE_A || NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_DOUBLE || NEED_PRINTF_INFINITE_DOUBLE) && !defined IN_LIBINTL
+/* GCC >= 4.0 with -Wall emits unjustified "... may be used uninitialized"
+   warnings in this file.  Use -Dlint to suppress them.  */
+#ifdef lint
+# define IF_LINT(Code) Code
+#else
+# define IF_LINT(Code) /* empty */
+#endif
+
+/* Avoid some warnings from "gcc -Wshadow".
+   This file doesn't use the exp() and remainder() functions.  */
+#undef exp
+#define exp expo
+#undef remainder
+#define remainder rem
+
+#if (NEED_PRINTF_DIRECTIVE_A || NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_INFINITE_LONG_DOUBLE || NEED_PRINTF_DOUBLE || NEED_PRINTF_INFINITE_DOUBLE) && !defined IN_LIBINTL
 /* Determine the decimal-point character according to the current locale.  */
 # ifndef decimal_point_char_defined
 #  define decimal_point_char_defined 1
@@ -236,18 +248,18 @@ decimal_point_char ()
 static int
 is_infinite_or_zero (double x)
 {
-  return isnan (x) || x + x == x;
+  return isnand (x) || x + x == x;
 }
 
 #endif
 
 #if NEED_PRINTF_INFINITE_LONG_DOUBLE && !NEED_PRINTF_LONG_DOUBLE && !defined IN_LIBINTL
 
-/* Equivalent to !isfinite(x), but does not require libm.  */
+/* Equivalent to !isfinite(x) || x == 0, but does not require libm.  */
 static int
-is_infinitel (long double x)
+is_infinite_or_zerol (long double x)
 {
-  return isnanl (x) || (x + x == x && x != 0.0L);
+  return isnanl (x) || x + x == x;
 }
 
 #endif
@@ -871,8 +883,11 @@ decode_long_double (long double x, int *ep, mpn_t *mp)
        abort ();
       m.limbs[--i] = (hi << (GMP_LIMB_BITS / 2)) | lo;
     }
+#if 0 /* On FreeBSD 6.1/x86, 'long double' numbers sometimes have excess
+         precision.  */
   if (!(y == 0.0L))
     abort ();
+#endif
   /* Normalise.  */
   while (m.nlimbs > 0 && m.limbs[m.nlimbs - 1] == 0)
     m.nlimbs--;
@@ -1198,7 +1213,7 @@ scale10_round_decimal_decoded (int e, mpn_t m, void *memory, int n)
 static char *
 scale10_round_decimal_long_double (long double x, int n)
 {
-  int e;
+  int e IF_LINT(= 0);
   mpn_t m;
   void *memory = decode_long_double (x, &e, &m);
   return scale10_round_decimal_decoded (e, m, memory, n);
@@ -1216,7 +1231,7 @@ scale10_round_decimal_long_double (long double x, int n)
 static char *
 scale10_round_decimal_double (double x, int n)
 {
-  int e;
+  int e IF_LINT(= 0);
   mpn_t m;
   void *memory = decode_double (x, &e, &m);
   return scale10_round_decimal_decoded (e, m, memory, n);
@@ -1303,9 +1318,9 @@ floorlog10l (long double x)
     }
   /* Now 0.95 <= z <= 1.01.  */
   z = 1 - z;
-  /* log(1-z) = - z - z^2/2 - z^3/3 - z^4/4 - ...
+  /* log2(1-z) = 1/log(2) * (- z - z^2/2 - z^3/3 - z^4/4 - ...)
      Four terms are enough to get an approximation with error < 10^-7.  */
-  l -= z * (1.0 + z * (0.5 + z * ((1.0 / 3) + z * 0.25)));
+  l -= 1.4426950408889634074 * z * (1.0 + z * (0.5 + z * ((1.0 / 3) + z * 0.25)));
   /* Finally multiply with log(2)/log(10), yields an approximation for
      log10(x).  */
   l *= 0.30102999566398119523;
@@ -1394,9 +1409,9 @@ floorlog10 (double x)
     }
   /* Now 0.95 <= z <= 1.01.  */
   z = 1 - z;
-  /* log(1-z) = - z - z^2/2 - z^3/3 - z^4/4 - ...
+  /* log2(1-z) = 1/log(2) * (- z - z^2/2 - z^3/3 - z^4/4 - ...)
      Four terms are enough to get an approximation with error < 10^-7.  */
-  l -= z * (1.0 + z * (0.5 + z * ((1.0 / 3) + z * 0.25)));
+  l -= 1.4426950408889634074 * z * (1.0 + z * (0.5 + z * ((1.0 / 3) + z * 0.25)));
   /* Finally multiply with log(2)/log(10), yields an approximation for
      log10(x).  */
   l *= 0.30102999566398119523;
@@ -1406,6 +1421,20 @@ floorlog10 (double x)
 
 # endif
 
+/* Tests whether a string of digits consists of exactly PRECISION zeroes and
+   a single '1' digit.  */
+static int
+is_borderline (const char *digits, size_t precision)
+{
+  for (; precision > 0; precision--, digits++)
+    if (*digits != '0')
+      return 0;
+  if (*digits != '1')
+    return 0;
+  digits++;
+  return *digits == '\0';
+}
+
 #endif
 
 DCHAR_T *
@@ -2324,7 +2353,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
 # if NEED_PRINTF_DIRECTIVE_A || NEED_PRINTF_DOUBLE
                    double arg = a.arg[dp->arg_index].a.a_double;
 
-                   if (isnan (arg))
+                   if (isnand (arg))
                      {
                        if (dp->conversion == 'A')
                          {
@@ -2549,8 +2578,10 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
 # elif NEED_PRINTF_INFINITE_LONG_DOUBLE
                         || (a.arg[dp->arg_index].type == TYPE_LONGDOUBLE
                             /* Some systems produce wrong output for Inf,
-                               -Inf, and NaN.  */
-                            && is_infinitel (a.arg[dp->arg_index].a.a_longdouble))
+                               -Inf, and NaN.  Some systems in this category
+                               (IRIX 5.3) also do so for -0.0.  Therefore we
+                               treat this case here as well.  */
+                            && is_infinite_or_zerol (a.arg[dp->arg_index].a.a_longdouble))
 # endif
                        ))
              {
@@ -2632,9 +2663,11 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
 
                /* POSIX specifies the default precision to be 6 for %f, %F,
                   %e, %E, but not for %g, %G.  Implementations appear to use
-                  the same default precision also for %g, %G.  */
+                  the same default precision also for %g, %G.  But for %a, %A,
+                  the default precision is 0.  */
                if (!has_precision)
-                 precision = 6;
+                 if (!(dp->conversion == 'a' || dp->conversion == 'A'))
+                   precision = 6;
 
                /* Allocate a temporary buffer of sufficient size.  */
 # if NEED_PRINTF_DOUBLE && NEED_PRINTF_LONG_DOUBLE
@@ -2673,7 +2706,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                  if (dp->conversion == 'f' || dp->conversion == 'F')
                    {
                      double arg = a.arg[dp->arg_index].a.a_double;
-                     if (!(isnan (arg) || arg + arg == arg))
+                     if (!(isnand (arg) || arg + arg == arg))
                        {
                          /* arg is finite and nonzero.  */
                          int exponent = floorlog10 (arg < 0 ? -arg : arg);
@@ -2855,8 +2888,32 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                          exponent += 1;
                                        adjusted = 1;
                                      }
-
                                    /* Here ndigits = precision+1.  */
+                                   if (is_borderline (digits, precision))
+                                     {
+                                       /* Maybe the exponent guess was too high
+                                          and a smaller exponent can be reached
+                                          by turning a 10...0 into 9...9x.  */
+                                       char *digits2 =
+                                         scale10_round_decimal_long_double (arg,
+                                                                            (int)precision - exponent + 1);
+                                       if (digits2 == NULL)
+                                         {
+                                           free (digits);
+                                           END_LONG_DOUBLE_ROUNDING ();
+                                           goto out_of_memory;
+                                         }
+                                       if (strlen (digits2) == precision + 1)
+                                         {
+                                           free (digits);
+                                           digits = digits2;
+                                           exponent -= 1;
+                                         }
+                                       else
+                                         free (digits2);
+                                     }
+                                   /* Here ndigits = precision+1.  */
+
                                    *p++ = digits[--ndigits];
                                    if ((flags & FLAG_ALT) || precision > 0)
                                      {
@@ -2968,6 +3025,30 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                        adjusted = 1;
                                      }
                                    /* Here ndigits = precision.  */
+                                   if (is_borderline (digits, precision - 1))
+                                     {
+                                       /* Maybe the exponent guess was too high
+                                          and a smaller exponent can be reached
+                                          by turning a 10...0 into 9...9x.  */
+                                       char *digits2 =
+                                         scale10_round_decimal_long_double (arg,
+                                                                            (int)(precision - 1) - exponent + 1);
+                                       if (digits2 == NULL)
+                                         {
+                                           free (digits);
+                                           END_LONG_DOUBLE_ROUNDING ();
+                                           goto out_of_memory;
+                                         }
+                                       if (strlen (digits2) == precision)
+                                         {
+                                           free (digits);
+                                           digits = digits2;
+                                           exponent -= 1;
+                                         }
+                                       else
+                                         free (digits2);
+                                     }
+                                   /* Here ndigits = precision.  */
 
                                    /* Determine the number of trailing zeroes
                                       that have to be dropped.  */
@@ -3062,7 +3143,65 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                              abort ();
 #  else
                            /* arg is finite.  */
-                           abort ();
+                           if (!(arg == 0.0L))
+                             abort ();
+
+                           pad_ptr = p;
+
+                           if (dp->conversion == 'f' || dp->conversion == 'F')
+                             {
+                               *p++ = '0';
+                               if ((flags & FLAG_ALT) || precision > 0)
+                                 {
+                                   *p++ = decimal_point_char ();
+                                   for (; precision > 0; precision--)
+                                     *p++ = '0';
+                                 }
+                             }
+                           else if (dp->conversion == 'e' || dp->conversion == 'E')
+                             {
+                               *p++ = '0';
+                               if ((flags & FLAG_ALT) || precision > 0)
+                                 {
+                                   *p++ = decimal_point_char ();
+                                   for (; precision > 0; precision--)
+                                     *p++ = '0';
+                                 }
+                               *p++ = dp->conversion; /* 'e' or 'E' */
+                               *p++ = '+';
+                               *p++ = '0';
+                               *p++ = '0';
+                             }
+                           else if (dp->conversion == 'g' || dp->conversion == 'G')
+                             {
+                               *p++ = '0';
+                               if (flags & FLAG_ALT)
+                                 {
+                                   size_t ndigits =
+                                     (precision > 0 ? precision - 1 : 0);
+                                   *p++ = decimal_point_char ();
+                                   for (; ndigits > 0; --ndigits)
+                                     *p++ = '0';
+                                 }
+                             }
+                           else if (dp->conversion == 'a' || dp->conversion == 'A')
+                             {
+                               *p++ = '0';
+                               *p++ = dp->conversion - 'A' + 'X';
+                               pad_ptr = p;
+                               *p++ = '0';
+                               if ((flags & FLAG_ALT) || precision > 0)
+                                 {
+                                   *p++ = decimal_point_char ();
+                                   for (; precision > 0; precision--)
+                                     *p++ = '0';
+                                 }
+                               *p++ = dp->conversion - 'A' + 'P';
+                               *p++ = '+';
+                               *p++ = '0';
+                             }
+                           else
+                             abort ();
 #  endif
                          }
 
@@ -3077,7 +3216,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                  {
                    double arg = a.arg[dp->arg_index].a.a_double;
 
-                   if (isnan (arg))
+                   if (isnand (arg))
                      {
                        if (dp->conversion >= 'A' && dp->conversion <= 'Z')
                          {
@@ -3208,8 +3347,31 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                          exponent += 1;
                                        adjusted = 1;
                                      }
-
                                    /* Here ndigits = precision+1.  */
+                                   if (is_borderline (digits, precision))
+                                     {
+                                       /* Maybe the exponent guess was too high
+                                          and a smaller exponent can be reached
+                                          by turning a 10...0 into 9...9x.  */
+                                       char *digits2 =
+                                         scale10_round_decimal_double (arg,
+                                                                       (int)precision - exponent + 1);
+                                       if (digits2 == NULL)
+                                         {
+                                           free (digits);
+                                           goto out_of_memory;
+                                         }
+                                       if (strlen (digits2) == precision + 1)
+                                         {
+                                           free (digits);
+                                           digits = digits2;
+                                           exponent -= 1;
+                                         }
+                                       else
+                                         free (digits2);
+                                     }
+                                   /* Here ndigits = precision+1.  */
+
                                    *p++ = digits[--ndigits];
                                    if ((flags & FLAG_ALT) || precision > 0)
                                      {
@@ -3334,6 +3496,29 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                        adjusted = 1;
                                      }
                                    /* Here ndigits = precision.  */
+                                   if (is_borderline (digits, precision - 1))
+                                     {
+                                       /* Maybe the exponent guess was too high
+                                          and a smaller exponent can be reached
+                                          by turning a 10...0 into 9...9x.  */
+                                       char *digits2 =
+                                         scale10_round_decimal_double (arg,
+                                                                       (int)(precision - 1) - exponent + 1);
+                                       if (digits2 == NULL)
+                                         {
+                                           free (digits);
+                                           goto out_of_memory;
+                                         }
+                                       if (strlen (digits2) == precision)
+                                         {
+                                           free (digits);
+                                           digits = digits2;
+                                           exponent -= 1;
+                                         }
+                                       else
+                                         free (digits2);
+                                     }
+                                   /* Here ndigits = precision.  */
 
                                    /* Determine the number of trailing zeroes
                                       that have to be dropped.  */
@@ -3563,7 +3748,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
              {
                arg_type type = a.arg[dp->arg_index].type;
                int flags = dp->flags;
-#if !USE_SNPRINTF || !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
+#if !USE_SNPRINTF || !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_LEFTADJUST || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
                int has_width;
                size_t width;
 #endif
@@ -3576,21 +3761,23 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
 #else
 #              define prec_ourselves 0
 #endif
-#if !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
+#if NEED_PRINTF_FLAG_LEFTADJUST
+#              define pad_ourselves 1
+#elif !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
                int pad_ourselves;
 #else
 #              define pad_ourselves 0
 #endif
                TCHAR_T *fbp;
                unsigned int prefix_count;
-               int prefixes[2];
+               int prefixes[2] IF_LINT (= { 0 });
 #if !USE_SNPRINTF
                size_t tmp_length;
                TCHAR_T tmpbuf[700];
                TCHAR_T *tmp;
 #endif
 
-#if !USE_SNPRINTF || !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
+#if !USE_SNPRINTF || !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_LEFTADJUST || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
                has_width = 0;
                width = 0;
                if (dp->width_start != dp->width_end)
@@ -3656,6 +3843,44 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                  }
 #endif
 
+               /* Decide whether to handle the precision ourselves.  */
+#if NEED_PRINTF_UNBOUNDED_PRECISION
+               switch (dp->conversion)
+                 {
+                 case 'd': case 'i': case 'u':
+                 case 'o':
+                 case 'x': case 'X': case 'p':
+                   prec_ourselves = has_precision && (precision > 0);
+                   break;
+                 default:
+                   prec_ourselves = 0;
+                   break;
+                 }
+#endif
+
+               /* Decide whether to perform the padding ourselves.  */
+#if !NEED_PRINTF_FLAG_LEFTADJUST && (!DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION)
+               switch (dp->conversion)
+                 {
+# if !DCHAR_IS_TCHAR || ENABLE_UNISTDIO
+                 /* If we need conversion from TCHAR_T[] to DCHAR_T[], we need
+                    to perform the padding after this conversion.  Functions
+                    with unistdio extensions perform the padding based on
+                    character count rather than element count.  */
+                 case 'c': case 's':
+# endif
+# if NEED_PRINTF_FLAG_ZERO
+                 case 'f': case 'F': case 'e': case 'E': case 'g': case 'G':
+                 case 'a': case 'A':
+# endif
+                   pad_ourselves = 1;
+                   break;
+                 default:
+                   pad_ourselves = prec_ourselves;
+                   break;
+                 }
+#endif
+
 #if !USE_SNPRINTF
                /* Allocate a temporary buffer of sufficient size for calling
                   sprintf.  */
@@ -3832,18 +4057,22 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                      abort ();
                    }
 
+                 if (!pad_ourselves)
+                   {
 # if ENABLE_UNISTDIO
-                 /* Padding considers the number of characters, therefore the
-                    number of elements after padding may be
-                      > max (tmp_length, width)
-                    but is certainly
-                      <= tmp_length + width.  */
-                 tmp_length = xsum (tmp_length, width);
+                     /* Padding considers the number of characters, therefore
+                        the number of elements after padding may be
+                          > max (tmp_length, width)
+                        but is certainly
+                          <= tmp_length + width.  */
+                     tmp_length = xsum (tmp_length, width);
 # else
-                 /* Padding considers the number of elements, says POSIX.  */
-                 if (tmp_length < width)
-                   tmp_length = width;
+                     /* Padding considers the number of elements,
+                        says POSIX.  */
+                     if (tmp_length < width)
+                       tmp_length = width;
 # endif
+                   }
 
                  tmp_length = xsum (tmp_length, 1); /* account for trailing NUL */
                }
@@ -3864,44 +4093,6 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                  }
 #endif
 
-               /* Decide whether to handle the precision ourselves.  */
-#if NEED_PRINTF_UNBOUNDED_PRECISION
-               switch (dp->conversion)
-                 {
-                 case 'd': case 'i': case 'u':
-                 case 'o':
-                 case 'x': case 'X': case 'p':
-                   prec_ourselves = has_precision && (precision > 0);
-                   break;
-                 default:
-                   prec_ourselves = 0;
-                   break;
-                 }
-#endif
-
-               /* Decide whether to perform the padding ourselves.  */
-#if !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
-               switch (dp->conversion)
-                 {
-# if !DCHAR_IS_TCHAR || ENABLE_UNISTDIO
-                 /* If we need conversion from TCHAR_T[] to DCHAR_T[], we need
-                    to perform the padding after this conversion.  Functions
-                    with unistdio extensions perform the padding based on
-                    character count rather than element count.  */
-                 case 'c': case 's':
-# endif
-# if NEED_PRINTF_FLAG_ZERO
-                 case 'f': case 'F': case 'e': case 'E': case 'g': case 'G':
-                 case 'a': case 'A':
-# endif
-                   pad_ourselves = 1;
-                   break;
-                 default:
-                   pad_ourselves = prec_ourselves;
-                   break;
-                 }
-#endif
-
                /* Construct the format string for calling snprintf or
                   sprintf.  */
                fbp = buf;
@@ -4005,7 +4196,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
 #endif
                  *fbp = dp->conversion;
 #if USE_SNPRINTF
-# if !(__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 3))
+# if !(__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 3) || ((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__))
                fbp[1] = '%';
                fbp[2] = 'n';
                fbp[3] = '\0';
@@ -4018,6 +4209,21 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                   in format strings in writable memory may crash the program
                   (if compiled with _FORTIFY_SOURCE=2), so we should avoid it
                   in this situation.  */
+               /* On native Win32 systems (such as mingw), we can avoid using
+                  %n because:
+                    - Although the gl_SNPRINTF_TRUNCATION_C99 test fails,
+                      snprintf does not write more than the specified number
+                      of bytes. (snprintf (buf, 3, "%d %d", 4567, 89) writes
+                      '4', '5', '6' into buf, not '4', '5', '\0'.)
+                    - Although the gl_SNPRINTF_RETVAL_C99 test fails, snprintf
+                      allows us to recognize the case of an insufficient
+                      buffer size: it returns -1 in this case.
+                  On native Win32 systems (such as mingw) where the OS is
+                  Windows Vista, the use of %n in format strings by default
+                  crashes the program. See
+                    <http://gcc.gnu.org/ml/gcc/2007-06/msg00122.html> and
+                    <http://msdn2.microsoft.com/en-us/library/ms175782(VS.80).aspx>
+                  So we should avoid %n in this situation.  */
                fbp[1] = '\0';
 # endif
 #else
@@ -4032,7 +4238,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                      abort ();
                    prefixes[prefix_count++] = a.arg[dp->width_arg_index].a.a_int;
                  }
-               if (dp->precision_arg_index != ARG_NONE)
+               if (!prec_ourselves && dp->precision_arg_index != ARG_NONE)
                  {
                    if (!(a.arg[dp->precision_arg_index].type == TYPE_INT))
                      abort ();
@@ -4324,7 +4530,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                    if (prec_ourselves)
                      {
                        /* Handle the precision.  */
-                       TCHAR_T *prec_ptr = 
+                       TCHAR_T *prec_ptr =
 # if USE_SNPRINTF
                          (TCHAR_T *) (result + length);
 # else
@@ -4383,14 +4589,14 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                      }
 #endif
 
-#if !DCHAR_IS_TCHAR
-# if !USE_SNPRINTF
+#if !USE_SNPRINTF
                    if (count >= tmp_length)
                      /* tmp_length was incorrectly calculated - fix the
                         code above!  */
                      abort ();
-# endif
+#endif
 
+#if !DCHAR_IS_TCHAR
                    /* Convert from TCHAR_T[] to DCHAR_T[].  */
                    if (dp->conversion == 'c' || dp->conversion == 's')
                      {
@@ -4491,7 +4697,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                    /* Here count <= allocated - length.  */
 
                    /* Perform padding.  */
-#if !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
+#if !DCHAR_IS_TCHAR || ENABLE_UNISTDIO || NEED_PRINTF_FLAG_LEFTADJUST || NEED_PRINTF_FLAG_ZERO || NEED_PRINTF_UNBOUNDED_PRECISION
                    if (pad_ourselves && has_width)
                      {
                        size_t w;
@@ -4508,7 +4714,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                        if (w < width)
                          {
                            size_t pad = width - w;
-# if USE_SNPRINTF
+
                            /* Make room for the result.  */
                            if (xsum (count, pad) > allocated - length)
                              {
@@ -4518,12 +4724,16 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                  xmax (xsum3 (length, count, pad),
                                        xtimes (allocated, 2));
 
+# if USE_SNPRINTF
                                length += count;
                                ENSURE_ALLOCATION (n);
                                length -= count;
+# else
+                               ENSURE_ALLOCATION (n);
+# endif
                              }
                            /* Here count + pad <= allocated - length.  */
-# endif
+
                            {
 # if !DCHAR_IS_TCHAR || USE_SNPRINTF
                              DCHAR_T * const rp = result + length;
@@ -4532,15 +4742,14 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
 # endif
                              DCHAR_T *p = rp + count;
                              DCHAR_T *end = p + pad;
-# if NEED_PRINTF_FLAG_ZERO
                              DCHAR_T *pad_ptr;
-#  if !DCHAR_IS_TCHAR
+# if !DCHAR_IS_TCHAR || ENABLE_UNISTDIO
                              if (dp->conversion == 'c'
                                  || dp->conversion == 's')
                                /* No zero-padding for string directives.  */
                                pad_ptr = NULL;
                              else
-#  endif
+# endif
                                {
                                  pad_ptr = (*rp == '-' ? rp + 1 : rp);
                                  /* No zero-padding of "inf" and "nan".  */
@@ -4548,7 +4757,6 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                      || (*pad_ptr >= 'a' && *pad_ptr <= 'z'))
                                    pad_ptr = NULL;
                                }
-# endif
                              /* The generated string now extends from rp to p,
                                 with the zero padding insertion point being at
                                 pad_ptr.  */
@@ -4561,7 +4769,6 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                  for (; pad > 0; pad--)
                                    *p++ = ' ';
                                }
-# if NEED_PRINTF_FLAG_ZERO
                              else if ((flags & FLAG_ZERO) && pad_ptr != NULL)
                                {
                                  /* Pad with zeroes.  */
@@ -4572,7 +4779,6 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                                  for (; pad > 0; pad--)
                                    *p++ = '0';
                                }
-# endif
                              else
                                {
                                  /* Pad with spaces on the left.  */
@@ -4588,13 +4794,6 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
                      }
 #endif
 
-#if DCHAR_IS_TCHAR && !USE_SNPRINTF
-                   if (count >= tmp_length)
-                     /* tmp_length was incorrectly calculated - fix the
-                        code above!  */
-                     abort ();
-#endif
-
                    /* Here still count <= allocated - length.  */
 
 #if !DCHAR_IS_TCHAR || USE_SNPRINTF
@@ -4651,6 +4850,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
        not have this limitation.  */
     return result;
 
+#if USE_SNPRINTF
   overflow:
     if (!(result == resultbuf || result == NULL))
       free (result);
@@ -4659,6 +4859,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
     CLEANUP ();
     errno = EOVERFLOW;
     return NULL;
+#endif
 
   out_of_memory:
     if (!(result == resultbuf || result == NULL))