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()

1 files changed, 5 insertions, 48 deletions

diff --git a/ext/mysqlnd/mysqlnd_ps_codec.c b/ext/mysqlnd/mysqlnd_ps_codec.c
index a57ff5d6a4..58b18b2ec9 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;
 }