Commit 6f6951d2 authored by unknown's avatar unknown
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Fix for BUG#25628: "mysqlbinlog crashes while processing binary logs". 

mysqlbinlog prints all row-based events of a single statement as a
single "BINLOG" statement containing the concatenation of those events.
Big (i.e. >64k) concatenations of row-based events
(e.g. Write_rows_log_event) caused mysqlbinlog's IO_CACHE to overflow
to a temporary file but the IO_CACHE had not been inited with
open_cached_file(), so it tried to create a temporary file in
an uninitialized directory (thus failing to create, then to write;
some OS errors were printed, and it finally segfaulted).
After fixing this, it appeared that mysqlbinlog was printing only
a piece of big concatenations of row-based events (it printed
at most the size of the IO_CACHE's buffer i.e. 64k); that caused data
loss at restore. We fix and test that.
Last, mysqlbinlog's printouts looked a bit strange with the informative
header (#-prefixed) of groupped Rows_log_event all on one line,
so we insert \n. After that, a small bug in the --hexdump code appeared
(only if the string to hex-print had its length a multiple of 16),
we fix it.



client/mysqlbinlog.cc:
  if we write to IO_CACHE more than can fit into its memory buffer,
  it will try to overflow into a file; for that to work, IO_CACHE
  must be inited via open_cached_file().
mysql-test/r/mysqlbinlog_base64.result:
  result update
mysql-test/t/mysqlbinlog_base64.test:
  test for BUG#25628: test that mysqlbinlog does not have OS errors
  with big concatenations of row-based events
  (e.g. Write_rows_log_event), and prints those concatenations entirely
  (testing by piping the output back into the server and comparing data).
mysys/mf_iocache2.c:
  my_b_copy_to_file() had a problem: it assumed that bytes_in_cache
  are all the bytes to copy to the file, while it only tells how many
  bytes are in the buffer; so the code forgot to copy what had already
  overflown into a temporary file. Thus any big event was printed only
  partially by mysqlbinlog (loss of data at restore). The fix is
  inspired by MYSQL_BIN_LOG::write_cache().
sql/log_event.cc:
  Several Table_map/Write_rows events generated by one single statement
  get groupped together in mysqlbinlog's output; it printed things like
  #718 7:30:51 server id 12 end_log_pos 988      Write_rows: table id 17#718 7:30:51 server id 12 #718 7:30:51 server id 12  end_log_pos 988      Write_rows: table id 17#718 7:30:51 server id 12 end_log_pos 1413 <cut>
  It didn't look nice to have printouts glued like this without line
  breaks. Adding a line break.
  Doing this, when using --hexdump the result was:
  #718 7:30:51 server id 12 end_log_pos 988
  # <hexdump output>
  # Write_rows: table id 17
  which is correct; unfortunately if the hex dump had only full lines
  (i.e the string to print in hex had its length a multiple of 16),
  then the # in front of Write_rows was not printed. Fixed.
sql/log_event.h:
  removing strcpy() (one less function call).
  If we write to IO_CACHE more than can fit into its memory buffer,
  it will try to overflow into a file; for that to work, IO_CACHE
  must be inited via open_cached_file().
  open_cached_file(), like init_io_cache(), can fail; we make sure to
  catch this constructor's problem via the init_ok() method.
parent 8777e35a

client/mysqlbinlog.cc

+5 −5
Original line number Diff line number Diff line
@@ -487,18 +487,15 @@ write_event_header_and_base64(Log_event *ev, FILE *result_file, 
  DBUG_ENTER("write_event_header_and_base64");

  /* Write header and base64 output to cache */

  IO_CACHE result_cache;

  if (init_io_cache(&result_cache, -1, 0, WRITE_CACHE, 0L, FALSE,

                    MYF(MY_WME | MY_NABP)))

  {

  if (open_cached_file(&result_cache, NULL, NULL, 0, MYF(MY_WME | MY_NABP)))

    return 1;

  }



  ev->print_header(&result_cache, print_event_info, FALSE);

  ev->print_base64(&result_cache, print_event_info, FALSE);



  /* Read data from cache and write to result file */

  my_b_copy_to_file(&result_cache, result_file);

  end_io_cache(&result_cache);

  close_cached_file(&result_cache);

  DBUG_RETURN(0);

}
@@ -1016,6 +1013,9 @@ static int dump_log_entries(const char* logname) 
{

  int rc;

  PRINT_EVENT_INFO print_event_info;



  if (!print_event_info.init_ok())

    return 1;

  /*

     Set safe delimiter, to dump things

     like CREATE PROCEDURE safely

mysql-test/r/mysqlbinlog_base64.result

+20 −0
Original line number Diff line number Diff line
@@ -86,5 +86,25 @@ Aberdeen 
Abernathy

aberrant

aberration

flush logs;

drop table t2;

create table t2 (word varchar(20));

load data infile '../std_data_ln/words.dat' into table t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

select count(*) from t2;

count(*)

35840

flush logs;

select count(*) from t2;

count(*)

35840

drop table t1;

drop table t2;

mysql-test/t/mysqlbinlog_base64.test

+28 −0
Original line number Diff line number Diff line
@@ -31,6 +31,34 @@ drop table t2; 
select * from t1;

select * from t2;



#

#  Verify that events larger than the default IO_CACHE buffer

#  are handled correctly (BUG#25628).

#

flush logs;

drop table t2;

create table t2 (word varchar(20));

load data infile '../std_data_ln/words.dat' into table t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

insert into t2 select * from t2;

select count(*) from t2;



flush logs;

--exec $MYSQL_BINLOG --hexdump $MYSQLTEST_VARDIR/log/master-bin.000003 > $MYSQLTEST_VARDIR/tmp/mysqlbinlog_base64.sql

--exec $MYSQL test < $MYSQLTEST_VARDIR/tmp/mysqlbinlog_base64.sql



#

#  Verify that all binlog events have been executed

#

select count(*) from t2;



#

#  Test cleanup

#

mysys/mf_iocache2.c

+7 −10
Original line number Diff line number Diff line
@@ -50,7 +50,6 @@ 
int

my_b_copy_to_file(IO_CACHE *cache, FILE *file)

{

  byte buf[IO_SIZE];

  uint bytes_in_cache;

  DBUG_ENTER("my_b_copy_to_file");
@@ -58,19 +57,17 @@ my_b_copy_to_file(IO_CACHE *cache, FILE *file) 
  if (reinit_io_cache(cache, READ_CACHE, 0L, FALSE, FALSE))

    DBUG_RETURN(1);

  bytes_in_cache= my_b_bytes_in_cache(cache);

  while (bytes_in_cache > 0) {

    uint const read_bytes= min(bytes_in_cache, sizeof(buf));

    DBUG_PRINT("debug", ("Remaining %u bytes - Reading %u bytes",

                         bytes_in_cache, read_bytes));

    if (my_b_read(cache, buf, read_bytes))

      DBUG_RETURN(1);

    if (my_fwrite(file, buf, read_bytes, MYF(MY_WME | MY_NABP)) == (uint) -1)

  do

  {

    if (my_fwrite(file, cache->read_pos, bytes_in_cache,

                  MYF(MY_WME | MY_NABP)) == (uint) -1)

      DBUG_RETURN(1);

    bytes_in_cache -= read_bytes;

  }

    cache->read_pos= cache->read_end;

  } while ((bytes_in_cache= my_b_fill(cache)));

  DBUG_RETURN(0);

}





my_off_t my_b_append_tell(IO_CACHE* info)

{

  /*

sql/log_event.cc

+7 −2
Original line number Diff line number Diff line
@@ -1144,13 +1144,18 @@ void Log_event::print_header(IO_CACHE* file, 
      char emit_buf[256];

      int const bytes_written=

        my_snprintf(emit_buf, sizeof(emit_buf),

                    "# %8.8lx %-48.48s |%s|\n# ",

                    "# %8.8lx %-48.48s |%s|\n",

                    (unsigned long) (hexdump_from + (i & 0xfffffff0)),

                    hex_string, char_string);

      DBUG_ASSERT(bytes_written >= 0);

      DBUG_ASSERT(static_cast<my_size_t>(bytes_written) < sizeof(emit_buf));

      my_b_write(file, (byte*) emit_buf, bytes_written);

    }

    /*

      need a # to prefix the rest of printouts for example those of

      Rows_log_event::print_helper().

    */

    my_b_write(file, "# ", 2);

  }

  DBUG_VOID_RETURN;

}
@@ -6106,7 +6111,7 @@ void Rows_log_event::print_helper(FILE *file, 
  {

    bool const last_stmt_event= get_flags(STMT_END_F);

    print_header(head, print_event_info, !last_stmt_event);

    my_b_printf(head, "\t%s: table id %lu", name, m_table_id);

    my_b_printf(head, "\t%s: table id %lu\n", name, m_table_id);

    print_base64(body, print_event_info, !last_stmt_event);

  }