BUG#32580 (mysqlbinlog cannot read binlog event generated by user variable usage):

The client program 'mysqlbinlog' crashed when trying to print a User_var_log_event holding
a floating-point value since the format specifier for my_b_printf() does not support
floating-point format specifiers.

This patch prints the floating-point number to an internal buffer, and then writes
that buffer to the output instead.

mysql-test/r/mysqlbinlog.result

@@ -351,4 +351,29 @@ a	b
 1	root@localhost
 DROP DATABASE mysqltest1;
 DROP USER untrusted@localhost;
+BUG#32580: mysqlbinlog cannot read binlog event with user variables
+USE test;
+SET BINLOG_FORMAT = STATEMENT;
+FLUSH LOGS;
+CREATE TABLE t1 (a_real FLOAT, an_int INT, a_decimal DECIMAL(5,2), a_string CHAR(32));
+SET @a_real = rand(20) * 1000;
+SET @an_int = 1000;
+SET @a_decimal = CAST(rand(19) * 999 AS DECIMAL(5,2));
+SET @a_string = 'Just a test';
+INSERT INTO t1 VALUES (@a_real, @an_int, @a_decimal, @a_string);
+FLUSH LOGS;
+SELECT * FROM t1;
+a_real	158.883
+an_int	1000
+a_decimal	907.79
+a_string	Just a test
+DROP TABLE t1;
+>> mysqlbinlog var/log/master-bin.000019 > var/tmp/bug32580.sql
+>> mysql test < var/tmp/bug32580.sql
+SELECT * FROM t1;
+a_real	158.883
+an_int	1000
+a_decimal	907.79
+a_string	Just a test
+DROP TABLE t1;
 End of 5.1 tests

mysql-test/t/mysqlbinlog.test

@@ -278,4 +278,31 @@ connection default;
 DROP DATABASE mysqltest1;
 DROP USER untrusted@localhost;
 
+--echo BUG#32580: mysqlbinlog cannot read binlog event with user variables
+
+# Testing that various kinds of events can be read and restored properly.
+
+connection default;
+USE test;
+SET BINLOG_FORMAT = STATEMENT;
+FLUSH LOGS;
+CREATE TABLE t1 (a_real FLOAT, an_int INT, a_decimal DECIMAL(5,2), a_string CHAR(32));
+SET @a_real = rand(20) * 1000;
+SET @an_int = 1000;
+SET @a_decimal = CAST(rand(19) * 999 AS DECIMAL(5,2));
+SET @a_string = 'Just a test';
+INSERT INTO t1 VALUES (@a_real, @an_int, @a_decimal, @a_string);
+FLUSH LOGS;
+query_vertical SELECT * FROM t1;
+DROP TABLE t1;
+
+echo >> mysqlbinlog var/log/master-bin.000019 > var/tmp/bug32580.sql;
+exec $MYSQL_BINLOG $MYSQLTEST_VARDIR/log/master-bin.000019 > $MYSQLTEST_VARDIR/tmp/bug32580.sql;
+echo >> mysql test < var/tmp/bug32580.sql;
+exec $MYSQL test < $MYSQLTEST_VARDIR/tmp/bug32580.sql;
+remove_file $MYSQLTEST_VARDIR/tmp/bug32580.sql;
+
+query_vertical SELECT * FROM t1;
+DROP TABLE t1;
+
 --echo End of 5.1 tests

sql/log_event.cc

@@ -36,6 +36,16 @@
 
 #define FLAGSTR(V,F) ((V)&(F)?#F" ":"")
 
+
+/*
+  Size of buffer for printing a double in format %.<PREC>g
+
+  optional '-' + optional zero + '.'  + PREC digits + 'e' + sign +
+  exponent digits + '\0'
+*/
+#define FMT_G_BUFSIZE(PREC) (3 + (PREC) + 5 + 1)
+
+
 #if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION) && !defined(DBUG_OFF) && !defined(_lint)
 static const char *HA_ERR(int i)
 {
@@ -4404,8 +4414,10 @@ void User_var_log_event::print(FILE* file, PRINT_EVENT_INFO* print_event_info)
     switch (type) {
     case REAL_RESULT:
       double real_val;
+      char real_buf[FMT_G_BUFSIZE(14)];
       float8get(real_val, val);
-      my_b_printf(&cache, ":=%.14g%s\n", real_val, print_event_info->delimiter);
+      my_sprintf(real_buf, (real_buf, "%.14g", real_val));
+      my_b_printf(&cache, ":=%s%s\n", real_buf, print_event_info->delimiter);
       break;
     case INT_RESULT:
       char int_buf[22];