Fix for bug #21205: Different number of digits for float/double/real in --ps-protocol

Various parts of code used different 'precision' arguments for sprintf("%g") when converting
floating point numbers to a string. This led to differences in results in some cases 
depending on whether the text-based or prepared statements protocol is used for a query.

Fixed by changing arguments to sprintf("%g") to always be 15 (DBL_DIG) so that results are
consistent regardless of the protocol.

This patch will be null-merged to 6.0 as the problem does not exists there (fixed by the
patch for WL#2934).

client/sql_string.cc:
  Use 15 (DBL_DIG) as a precision argument for sprintf(), as Field_double::val_str() does.
libmysql/libmysql.c:
  Use 15 (DBL_DIG) as a precision argument for sprintf(), as Field_double::val_str() does.
mysql-test/r/archive_gis.result:
  Fixed test results to take additional precision into account.
mysql-test/r/func_group.result:
  Fixed test results to take additional precision into account.
mysql-test/r/func_math.result:
  Fixed test results to take additional precision into account.
mysql-test/r/func_str.result:
  Fixed test results to take additional precision into account.
mysql-test/r/gis.result:
  Fixed test results to take additional precision into account.
mysql-test/r/innodb_gis.result:
  Fixed test results to take additional precision into account.
mysql-test/r/select.result:
  Fixed test results to take additional precision into account.
mysql-test/r/sp.result:
  Fixed test results to take additional precision into account.
mysql-test/r/type_float.result:
  Fixed test results to take additional precision into account.
mysql-test/t/type_float.test:
  Fixed test results to take additional precision into account.
sql/sql_string.cc:
  Use 15 (DBL_DIG) as a precision argument for sprintf(), as Field_double::val_str() does.

1 files changed, 2 insertions, 2 deletions

diff --git a/libmysql/libmysql.c b/libmysql/libmysql.c
index dd66a325169..2a5e1cc657b 100644
--- a/libmysql/libmysql.c
+++ b/libmysql/libmysql.c
@@ -3786,13 +3786,13 @@ static void fetch_float_with_conversion(MYSQL_BIND *param, MYSQL_FIELD *field,
 #undef NOT_FIXED_DEC
     {
       /*
-        The 14 below is to ensure that the server and client has the same
+        DBL_DIG below is to ensure that the server and client has the same
         precisions. This will ensure that on the same machine you get the
         same value as a string independent of the protocol you use.
       */
       sprintf(buff, "%-*.*g", (int) min(sizeof(buff)-1,
                                         param->buffer_length),
-	      min(14,width), value);
+              min(DBL_DIG, width), value);
       end= strcend(buff, ' ');
       *end= 0;
     }