Port fix for mysqlbinlog reading big records from stdin

Summary:
Fixed mysqlbinlog error when reading big records from stdin.

When mysqlbinlog tries to read a big record (over 128KB) from stdin, the
glibc read in my_read will return 128KB instead of the full size. This
causes _my_b_read to fail.

Ported the folowing change
In mysqlbinlog.cc, enable MY_FULL_IO, and in my_read.c, fix the
MY_FULL_IO logic.

Test Plan:
ported the test case which generates an event of size greater
than greater than 128kb and runs mysqlbinlog.

Reviewers: steaphan

Reviewed By: steaphan

client/mysqlbinlog.cc

@@ -2811,7 +2811,7 @@ static Exit_status dump_local_log_entries(PRINT_EVENT_INFO *print_event_info,
     }
 #endif 
     if (init_io_cache(file, my_fileno(stdin), 0, READ_CACHE, (my_off_t) 0,
-		      0, MYF(MY_WME | MY_NABP | MY_DONT_CHECK_FILESIZE)))
+		      0, MYF(MY_WME | MY_NABP | MY_DONT_CHECK_FILESIZE | MY_FULL_IO)))
     {
       error("Failed to init IO cache.");
       return ERROR_STOP;

mysql-test/t/mysqlbinlog_big_event-master.opt

@@ -0,0 +1 @@
+--force-restart

mysql-test/t/mysqlbinlog_big_event.test

@@ -0,0 +1,39 @@
+# ==== Purpose ====
+# Test mysqlbinlog with a binlog event larger than 128kb.
+# using have_binlog_format_statement to create a statement
+# based binlog event greater than 128kb. The idea is to insert
+# a big string in a table having a BLOB column.
+#
+# === Implementaion ===
+
+-- source include/have_binlog_format_statement.inc
+
+# Reset master to cleanup binlog
+reset master;
+
+# we need this for getting fixed timestamps inside of this test
+set timestamp=1000000000;
+
+--disable_warnings
+drop table if exists t2;
+--enable_warnings
+
+let $MYSQLD_DATADIR=`select @@datadir`;
+create table t2 (word LONGBLOB);
+let $i = 33000;
+--disable_query_log
+set @string = 'testing ';
+while($i > 0)
+{
+  set @string = concat(@string, 'testing ');
+  dec $i;
+}
+
+insert into t2 values(@string);
+--enable_query_log
+let $binlog_file= query_get_value(SHOW MASTER STATUS, File, 1);
+flush logs;
+--replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
+--replace_regex /SQL_LOAD_MB-[0-9]-[0-9]/SQL_LOAD_MB-#-#/
+--exec cat $MYSQLD_DATADIR/$binlog_file | $MYSQL_BINLOG --short-form --local-load=$MYSQLTEST_VARDIR/tmp/ -
+drop table t2;

mysys/my_read.c

@@ -35,11 +35,11 @@
 
 size_t my_read(File Filedes, uchar *Buffer, size_t Count, myf MyFlags)
 {
-  size_t readbytes, save_count;
+  size_t readbytes, savedbytes;
   DBUG_ENTER("my_read");
   DBUG_PRINT("my",("fd: %d  Buffer: %p  Count: %lu  MyFlags: %d",
                    Filedes, Buffer, (ulong) Count, MyFlags));
-  save_count= Count;
+  savedbytes= 0;
 
   for (;;)
   {
@@ -87,18 +87,20 @@ size_t my_read(File Filedes, uchar *Buffer, size_t Count, myf MyFlags)
       if (readbytes == (size_t) -1 ||
           ((MyFlags & (MY_FNABP | MY_NABP)) && !(MyFlags & MY_FULL_IO)))
         DBUG_RETURN(MY_FILE_ERROR);	/* Return with error */
-      if (readbytes != (size_t) -1 && (MyFlags & MY_FULL_IO))
+      /* readbytes == 0 when EOF. No need to continue in case of EOF */
+      if (readbytes != 0 && (MyFlags & MY_FULL_IO))
       {
         Buffer+= readbytes;
         Count-= readbytes;
+        savedbytes+= readbytes;
         continue;
       }
     }
 
     if (MyFlags & (MY_NABP | MY_FNABP))
       readbytes= 0;			/* Ok on read */
     else if (MyFlags & MY_FULL_IO)
-      readbytes= save_count;
+      readbytes+= savedbytes;
     break;
   }
   DBUG_RETURN(readbytes);