Fix for bugs #68114 (Build fails on OS X due to undefined symbols)

and #68657 (Reading 4 byte floats with Mysqli and libmysqlclient
has rounding errors).

The patch removes support for Decimal floating point numbers and
now defaults to using similar logic as what libmysqlclient does:
convert a 4 byte floating point number into a string, and then the
string into a double. The quirks of MySQL are maintained as seen in
Field_Float::val_str()

2 files changed, 5 insertions, 79 deletions

diff --git a/ext/mysqlnd/config9.m4 b/ext/mysqlnd/config9.m4
index 8f749cf273..0e08b977af 100644
--- a/ext/mysqlnd/config9.m4
+++ b/ext/mysqlnd/config9.m4
@@ -49,34 +49,3 @@ fi
 if test "$PHP_MYSQLND" != "no" || test "$PHP_MYSQLND_ENABLED" = "yes" || test "$PHP_MYSQLI" != "no"; then
   PHP_ADD_BUILD_DIR([ext/mysqlnd], 1)
 fi
-
-dnl
-dnl Check if the compiler supports Decimal32/64/128 types from the IEEE-754 2008 version
-dnl References: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1657.pdf
-dnl http://speleotrove.com/decimal/
-dnl
-AC_CACHE_CHECK([whether whether compiler supports Decimal32/64/128 types], ac_cv_decimal_fp_supported,[
-AC_TRY_RUN( [
-#include <stdio.h>
-#include <string.h>
-
-int main(int argc, char **argv) {
-	typedef float dec32 __attribute__((mode(SD)));
-	dec32 k = 99.49f;
-	double d2 = (double)k;
-	const char *check_str = "99.49";
-	char print_str[32];
-
-	snprintf(print_str, 32, "%f", d2);
-	return memcmp(print_str, check_str, 5);
-}
-],[
-  ac_cv_decimal_fp_supported=yes
-],[
-  ac_cv_decimal_fp_supported=no
-],[
-  ac_cv_decimal_fp_supported=no
-])])
-if test "$ac_cv_decimal_fp_supported" = "yes"; then
-  AC_DEFINE(HAVE_DECIMAL_FP_SUPPORT, 1, [Define if the compiler supports Decimal32/64/128 types.])
-fi
diff --git a/ext/mysqlnd/mysqlnd_ps_codec.c b/ext/mysqlnd/mysqlnd_ps_codec.c
index b2dd22ba8a..d2e5763210 100644
--- a/ext/mysqlnd/mysqlnd_ps_codec.c
+++ b/ext/mysqlnd/mysqlnd_ps_codec.c
@@ -24,6 +24,7 @@
 #include "mysqlnd_wireprotocol.h"
 #include "mysqlnd_priv.h"
 #include "mysqlnd_debug.h"
+#include "ext/standard/float_to_double.h"
 
 #define MYSQLND_SILENT
 
@@ -181,56 +182,12 @@ ps_fetch_float(zval * zv, const MYSQLND_FIELD * const field, unsigned int pack_l
 	(*row)+= 4;
 	DBG_INF_FMT("value=%f", fval);
 
-	/*
-	 * The following is needed to correctly support 4-byte floats.
-	 * Otherwise, a value of 9.99 in a FLOAT column comes out of mysqli
-	 * as 9.9998998641968.
-	 *
-	 * For GCC, we use the built-in decimal support to "up-convert" a
-	 * 4-byte float to a 8-byte double.
-	 * When that is not available, we fall back to converting the float
-	 * to a string and then converting the string to a double. This mimics
-	 * what MySQL does.
-	 */
-#ifdef HAVE_DECIMAL_FP_SUPPORT
-	{
-		typedef float dec32 __attribute__((mode(SD)));
-		/* volatile so the compiler will not optimize away the conversion */
-		volatile dec32 d32val = fval;
-
-		/* The following cast is guaranteed to do the right thing */
-		dval = (double) d32val;
-	}
-#elif defined(PHP_WIN32)
-	{
-		/* float datatype on Winows is already 4 byte but has a precision of 7 digits */
-		char num_buf[2048];
-		(void)_gcvt_s(num_buf, 2048, fval, field->decimals >= 31 ? 7 : field->decimals);
-		dval = zend_strtod(num_buf, NULL);
-	}
-#else
-	{
-		char num_buf[2048]; /* Over allocated */
-		char *s;
-
-#ifndef FLT_DIG
-# define FLT_DIG 6
-#endif
-		/* Convert to string. Ignoring localization, etc.
-		 * Following MySQL's rules. If precision is undefined (NOT_FIXED_DEC i.e. 31)
-		 * or larger than 31, the value is limited to 6 (FLT_DIG).
-		 */
-		s = php_gcvt(fval,
-			     field->decimals >= 31 ? FLT_DIG : field->decimals,
-			     '.',
-			     'e',
-			     num_buf);
-
-		/* And now convert back to double */
-		dval = zend_strtod(s, NULL);
-	}
+#ifndef NOT_FIXED_DEC
+# define NOT_FIXED_DEC 31
 #endif
 
+	dval = float_to_double(fval, (field->decimals >= NOT_FIXED_DEC) ? -1 : field->decimals);
+
 	ZVAL_DOUBLE(zv, dval);
 	DBG_VOID_RETURN;
 }