snprintf.c bugs

snprintf.c is horrible.  The floating-point formatting is an utter
kludge, and a large number of bugs are lurking there.  Still, it's
better than nothing, and its bare-bones floating-point support seems
to be sufficient to satisfy Wget's needs.  Furthermore, snprintf is
still not as ubiquitous as one would like.

This patch imports some fixes from Samba and INN source trees, and
fixes several important bugs.  It also makes snprintf.c compilable
under ansi2knr and K&R in general.  (That last change is easy to
revert once we decide to drop K&R.)

This patch should not affect platforms with snprintf.


2005-04-16  Hrvoje Niksic  <[email protected]>

	* snprintf.c: Use the PARAMS macro to handle prototypes.  Write
	function definitions in the ansi2knr-friendly way.
	(fmtstr): If string precision is specified, don't read VALUE past
	it.
	(dopr): Actually print %g and %e formats.
	(fmtfp): Fix a bug that caused 0.01 to be printed as 0.1.
	(fmtfp): Use LLONG in floating point conversions to be able to
	convert more digits.
	(fmtfp): Interpret precision as number of significant digits with
	%g.
	(fmtfp): Omit trailing decimal zeros with %g.

	* snprintf.c: Don't include <ctype.h> because none of it is used.
	Include strings.h/string.h, as per Autoconf.

Index: src/snprintf.c
===================================================================
RCS file: /pack/anoncvs/wget/src/snprintf.c,v
retrieving revision 1.8
diff -u -r1.8 snprintf.c
--- src/snprintf.c	2003/10/11 12:41:11	1.8
+++ src/snprintf.c	2005/04/16 00:02:34
@@ -70,18 +70,48 @@
  *    don't declare argument types to (v)snprintf if stdarg is not used.
  *    use int instead of short int as 2nd arg to va_arg.
  *
+ *  alexk (INN) 2002-08-21
+ *    use LLONG in fmtfp to handle more characters during floating
+ *    point conversion.
+ *
+ *  herb (Samba) 2002-12-19
+ *    actually print args for %g and %e
+ *
+ *  Hrvoje Niksic <[email protected]> 2005-04-15
+ *    use the PARAMS macro to handle prototypes.
+ *    write function definitions in the ansi2knr-friendly way.
+ *    if string precision is specified, don't read VALUE past it.
+ *    fix bug in fmtfp that caused 0.01 to be printed as 0.1.
+ *    don't include <ctype.h> because none of it is used.
+ *    interpret precision as number of significant digits with %g
+ *    omit trailing decimal zeros with %g
+ *
  **************************************************************/
 
 #ifdef HAVE_CONFIG_H
 # include <config.h>
 #endif
 
+/* For testing purposes, always compile in the code. */
+#ifdef TEST_SNPRINTF
+# undef HAVE_SNPRINTF
+# undef HAVE_VSNPRINTF
+# ifndef SIZEOF_LONG_LONG
+#  ifdef __GNUC__
+#   define SIZEOF_LONG_LONG 8
+#  endif
+# endif
+#endif
+
 #if !defined(HAVE_SNPRINTF) || !defined(HAVE_VSNPRINTF)
 
-#include <string.h>
+#ifdef HAVE_STRING_H
+# include <string.h>
+#else
+# include <strings.h>
+#endif
 #include <sys/types.h>
 #include <stdio.h>		/* for NULL */
-#include <safe-ctype.h>
 
 /* varargs declarations: */
 
@@ -113,6 +143,13 @@
 # define LLONG long
 #endif
 
+/* If we're running the test suite, rename snprintf and vsnprintf to
+   avoid conflicts with the system version.  */
+#ifdef TEST_SNPRINTF
+# define snprintf test_snprintf
+# define vsnprintf test_vsnprintf
+#endif
+
 #ifdef HAVE_STDARGS
 int snprintf (char *str, size_t count, const char *fmt, ...);
 int vsnprintf (char *str, size_t count, const char *fmt, va_list arg);
@@ -120,16 +157,21 @@
 int snprintf ();
 int vsnprintf ();
 #endif
+
+#ifndef PARAMS
+# define PARAMS(x) x
+#endif
 
-static int dopr (char *buffer, size_t maxlen, const char *format, 
-                 va_list args);
-static int fmtstr (char *buffer, size_t *currlen, size_t maxlen,
-		   char *value, int flags, int min, int max);
-static int fmtint (char *buffer, size_t *currlen, size_t maxlen,
-		   LLONG value, int base, int min, int max, int flags);
-static int fmtfp (char *buffer, size_t *currlen, size_t maxlen,
-		  LDOUBLE fvalue, int min, int max, int flags);
-static int dopr_outch (char *buffer, size_t *currlen, size_t maxlen, char c );
+static int dopr PARAMS ((char *buffer, size_t maxlen, const char *format, 
+			 va_list args));
+static int fmtstr PARAMS ((char *buffer, size_t *currlen, size_t maxlen,
+			   char *value, int flags, int min, int max));
+static int fmtint PARAMS ((char *buffer, size_t *currlen, size_t maxlen,
+			   LLONG value, int base, int min, int max, int flags));
+static int fmtfp PARAMS ((char *buffer, size_t *currlen, size_t maxlen,
+			  LDOUBLE fvalue, int min, int max, int flags));
+static int dopr_outch PARAMS ((char *buffer, size_t *currlen, size_t maxlen,
+			       char c));
 
 /*
  * dopr(): poor man's version of doprintf
@@ -154,6 +196,7 @@
 #define DP_F_ZERO  	(1 << 4)
 #define DP_F_UP    	(1 << 5)
 #define DP_F_UNSIGNED 	(1 << 6)
+#define DP_F_FP_G 	(1 << 7)
 
 /* Conversion Flags */
 #define DP_C_SHORT   1
@@ -165,7 +208,8 @@
 #define MAX(p,q) ((p >= q) ? p : q)
 #define MIN(p,q) ((p <= q) ? p : q)
 
-static int dopr (char *buffer, size_t maxlen, const char *format, va_list args)
+static int
+dopr (char *buffer, size_t maxlen, const char *format, va_list args)
 {
   char ch;
   LLONG value;
@@ -309,7 +353,7 @@
       case 'd':
       case 'i':
 	if (cflags == DP_C_SHORT) 
-	  value = (short int)va_arg (args, int);
+	  value = (short int) va_arg (args, int);
 	else if (cflags == DP_C_LONG)
 	  value = va_arg (args, long int);
 	else if (cflags == DP_C_LLONG)
@@ -321,7 +365,7 @@
       case 'o':
 	flags |= DP_F_UNSIGNED;
 	if (cflags == DP_C_SHORT)
-	  value = (unsigned short int)va_arg (args, unsigned int);
+	  value = (unsigned short int) va_arg (args, unsigned int);
 	else if (cflags == DP_C_LONG)
 	  value = va_arg (args, unsigned long int);
 	else if (cflags == DP_C_LLONG)
@@ -333,7 +377,7 @@
       case 'u':
 	flags |= DP_F_UNSIGNED;
 	if (cflags == DP_C_SHORT)
-	  value = (unsigned short int)va_arg (args, unsigned int);
+	  value = (unsigned short int) va_arg (args, unsigned int);
 	else if (cflags == DP_C_LONG)
 	  value = va_arg (args, unsigned long int);
 	else if (cflags == DP_C_LLONG)
@@ -347,7 +391,7 @@
       case 'x':
 	flags |= DP_F_UNSIGNED;
 	if (cflags == DP_C_SHORT)
-	  value = (unsigned short int)va_arg (args, unsigned int);
+	  value = (unsigned short int) va_arg (args, unsigned int);
 	else if (cflags == DP_C_LONG)
 	  value = va_arg (args, unsigned long int);
 	else if (cflags == DP_C_LLONG)
@@ -361,7 +405,6 @@
 	  fvalue = va_arg (args, LDOUBLE);
 	else
 	  fvalue = va_arg (args, double);
-	/* um, floating point? */
 	total += fmtfp (buffer, &currlen, maxlen, fvalue, min, max, flags);
 	break;
       case 'E':
@@ -371,14 +414,20 @@
 	  fvalue = va_arg (args, LDOUBLE);
 	else
 	  fvalue = va_arg (args, double);
+	total += fmtfp (buffer, &currlen, maxlen, fvalue, min, max, flags);
 	break;
       case 'G':
 	flags |= DP_F_UP;
       case 'g':
+	flags |= DP_F_FP_G;
 	if (cflags == DP_C_LDOUBLE)
 	  fvalue = va_arg (args, LDOUBLE);
 	else
 	  fvalue = va_arg (args, double);
+	if (max == 0)
+	  /* C99 says: if precision [for %g] is zero, it is taken as one */
+	  max = 1;
+	total += fmtfp (buffer, &currlen, maxlen, fvalue, min, max, flags);
 	break;
       case 'c':
 	total += dopr_outch (buffer, &currlen, maxlen, va_arg (args, int));
@@ -451,8 +500,9 @@
   return total;
 }
 
-static int fmtstr (char *buffer, size_t *currlen, size_t maxlen,
-                   char *value, int flags, int min, int max)
+static int
+fmtstr (char *buffer, size_t *currlen, size_t maxlen,
+	char *value, int flags, int min, int max)
 {
   int padlen, strln;     /* amount to pad */
   int cnt = 0;
@@ -460,12 +510,15 @@
   
   if (value == 0)
   {
-    value = "<NULL>";
+    value = "(null)";
   }
 
-  for (strln = 0; value[strln]; ++strln); /* strlen */
-  if (max >= 0 && max < strln)
-    strln = max;
+  if (max < 0)
+    strln = strlen (value);
+  else
+    /* When precision is specified, don't read VALUE past precision. */
+    /*strln = strnlen (value, max);*/
+    for (strln = 0; strln < max && value[strln]; ++strln);
   padlen = min - strln;
   if (padlen < 0) 
     padlen = 0;
@@ -492,8 +545,9 @@
 
 /* Have to handle DP_F_NUM (ie 0x and 0 alternates) */
 
-static int fmtint (char *buffer, size_t *currlen, size_t maxlen,
-		   LLONG value, int base, int min, int max, int flags)
+static int
+fmtint (char *buffer, size_t *currlen, size_t maxlen,
+	LLONG value, int base, int min, int max, int flags)
 {
   int signvalue = 0;
   unsigned LLONG uvalue;
@@ -587,7 +641,8 @@
   return total;
 }
 
-static LDOUBLE abs_val (LDOUBLE value)
+static LDOUBLE
+abs_val (LDOUBLE value)
 {
   LDOUBLE result = value;
 
@@ -597,7 +652,8 @@
   return result;
 }
 
-static LDOUBLE pow10 (int exp)
+static LDOUBLE
+pow10 (int exp)
 {
   LDOUBLE result = 1;
 
@@ -610,9 +666,10 @@
   return result;
 }
 
-static long round (LDOUBLE value)
+static LLONG
+round (LDOUBLE value)
 {
-  long intpart;
+  LLONG intpart;
 
   intpart = value;
   value = value - intpart;
@@ -622,21 +679,25 @@
   return intpart;
 }
 
-static int fmtfp (char *buffer, size_t *currlen, size_t maxlen,
-		  LDOUBLE fvalue, int min, int max, int flags)
+static int
+fmtfp (char *buffer, size_t *currlen, size_t maxlen,
+       LDOUBLE fvalue, int min, int max, int flags)
 {
   int signvalue = 0;
   LDOUBLE ufvalue;
-  char iconvert[20];
-  char fconvert[20];
+  char iconvert[24];
+  char fconvert[24];
   int iplace = 0;
   int fplace = 0;
   int padlen = 0; /* amount to pad */
   int zpadlen = 0; 
-  int caps = 0;
   int total = 0;
-  long intpart;
-  long fracpart;
+  LLONG intpart;
+  LLONG fracpart;
+  LLONG mask10;
+  int leadingfrac0s = 0; /* zeros at the start of fractional part */
+  int omitzeros = 0;
+  int omitcount = 0;
   
   /* 
    * AIX manpage says the default is 0, but Solaris says the default
@@ -662,23 +723,57 @@
 
   intpart = ufvalue;
 
+  /* With %g precision is the number of significant digits, which
+     includes the digits in intpart. */
+  if (flags & DP_F_FP_G)
+    {
+      LLONG temp = intpart;
+      for (temp = intpart; temp != 0; temp /= 10)
+	--max;
+      if (max < 0)
+	max = 0;
+    }
+
+  /* C99: trailing zeros are removed from the fractional portion of the
+     result unless the # flag is specified */
+  if ((flags & DP_F_FP_G) && !(flags & DP_F_NUM))
+    omitzeros = 1;
+
+#if SIZEOF_LONG_LONG > 0
+# define MAX_DIGITS 18		/* grok more digits with long long */
+#else
+# define MAX_DIGITS 9		/* just long */
+#endif
+
   /* 
-   * Sorry, we only support 9 digits past the decimal because of our 
-   * conversion method
+   * Sorry, we only support several digits past the decimal because of
+   * our conversion method
    */
-  if (max > 9)
-    max = 9;
+  if (max > MAX_DIGITS)
+    max = MAX_DIGITS;
 
+  /* Factor of 10 with the needed number of digits, e.g. 1000 for max==3 */
+  mask10 = pow10 (max);
+
   /* We "cheat" by converting the fractional part to integer by
    * multiplying by a factor of 10
    */
-  fracpart = round ((pow10 (max)) * (ufvalue - intpart));
+  fracpart = round (mask10 * (ufvalue - intpart));
 
-  if (fracpart >= pow10 (max))
+  if (fracpart >= mask10)
   {
     intpart++;
-    fracpart -= pow10 (max);
+    fracpart -= mask10;
   }
+  else if (fracpart != 0)
+    /* If fracpart has less digits than the 10* mask, we need to
+       manually insert leading 0s.  For example 2.01's fractional part
+       requires one leading zero to distinguish it from 2.1. */
+    while (fracpart < mask10 / 10)
+      {
+	++leadingfrac0s;
+	mask10 /= 10;
+      }
 
 #ifdef DEBUG_SNPRINTF
   dprint (1, (debugfile, "fmtfp: %f =? %d.%d\n", fvalue, intpart, fracpart));
@@ -686,25 +781,29 @@
 
   /* Convert integer part */
   do {
-    iconvert[iplace++] =
-      (caps? "0123456789ABCDEF":"0123456789abcdef")[intpart % 10];
+    iconvert[iplace++] = '0' + intpart % 10;
     intpart = (intpart / 10);
-  } while(intpart && (iplace < 20));
-  if (iplace == 20) iplace--;
+  } while(intpart && (iplace < sizeof(iconvert)));
+  if (iplace == sizeof(iconvert)) iplace--;
   iconvert[iplace] = 0;
 
   /* Convert fractional part */
   do {
-    fconvert[fplace++] =
-      (caps? "0123456789ABCDEF":"0123456789abcdef")[fracpart % 10];
+    fconvert[fplace++] = '0' + fracpart % 10;
     fracpart = (fracpart / 10);
-  } while(fracpart && (fplace < 20));
-  if (fplace == 20) fplace--;
+  } while(fracpart && (fplace < sizeof(fconvert)));
+  while (leadingfrac0s-- > 0 && fplace < sizeof(fconvert))
+    fconvert[fplace++] = '0';
+  if (fplace == sizeof(fconvert)) fplace--;
   fconvert[fplace] = 0;
+  if (omitzeros)
+    while (omitcount < fplace && fconvert[omitcount] == '0')
+      ++omitcount;
 
   /* -1 for decimal point, another -1 if we are printing a sign */
-  padlen = min - iplace - max - 1 - ((signvalue) ? 1 : 0); 
-  zpadlen = max - fplace;
+  padlen = min - iplace - (max - omitcount) - 1 - ((signvalue) ? 1 : 0);
+  if (!omitzeros)
+    zpadlen = max - fplace;
   if (zpadlen < 0)
     zpadlen = 0;
   if (padlen < 0) 
@@ -741,11 +840,11 @@
    * Decimal point.  This should probably use locale to find the correct
    * char to print out.
    */
-  if (max > 0)
+  if (max > 0 && (fplace > omitcount || zpadlen > 0))
   {
     total += dopr_outch (buffer, currlen, maxlen, '.');
 
-    while (fplace > 0) 
+    while (fplace > omitcount) 
       total += dopr_outch (buffer, currlen, maxlen, fconvert[--fplace]);
   }
 
@@ -764,7 +863,8 @@
   return total;
 }
 
-static int dopr_outch (char *buffer, size_t *currlen, size_t maxlen, char c)
+static int
+dopr_outch (char *buffer, size_t *currlen, size_t maxlen, char c)
 {
   if (*currlen + 1 < maxlen)
     buffer[(*currlen)++] = c;
@@ -772,7 +872,8 @@
 }
 
 #ifndef HAVE_VSNPRINTF
-int vsnprintf (char *str, size_t count, const char *fmt, va_list args)
+int
+vsnprintf (char *str, size_t count, const char *fmt, va_list args)
 {
   if (str != NULL)
     str[0] = 0;
@@ -781,12 +882,8 @@
 #endif /* !HAVE_VSNPRINTF */
 
 #ifndef HAVE_SNPRINTF
-/* VARARGS3 */
-#ifdef HAVE_STDARGS
-int snprintf (char *str,size_t count,const char *fmt,...)
-#else
-int snprintf (va_alist) va_dcl
-#endif
+int
+snprintf (char *str, size_t count,const char *fmt,...)
 {
 #ifndef HAVE_STDARGS
   char *str;
@@ -809,12 +906,12 @@
 
 #ifdef TEST_SNPRINTF
 
-#include <stdio.h>
+# ifndef LONG_STRING
+#  define LONG_STRING 1024
+# endif
 
-#ifndef LONG_STRING
-#define LONG_STRING 1024
-#endif
-int main (void)
+int
+main (void)
 {
   char buf1[LONG_STRING];
   char buf2[LONG_STRING];
@@ -832,10 +929,13 @@
     "%3.2f",
     "%.0f",
     "%.1f",
+    "%-1.5g",
+    "%1.5g",
+    "%123.9g",
     NULL
   };
   double fp_nums[] = { -1.5, 134.21, 91340.2, 341.1234, 0203.9, 0.96, 0.996, 
-    0.9996, 1.996, 4.136, 0};
+    0.9996, 1.996, 4.136, 0.00205, 0};
   char *int_fmt[] = {
     "%-1.5d",
     "%1.5d",
@@ -922,5 +1022,6 @@
 #endif
 
   printf ("%d tests failed out of %d.\n", fail, num);
+  return 0;
 }
-#endif /* SNPRINTF_TEST */
+#endif /* TEST_SNPRINTF */