Bug#11762667: MYSQLBINLOG IGNORES ERRORS WHILE WRITING OUTPUT

Problem: mysqlbinlog exits without any error code in case of
file write error. It is because of the fact that the calls
to Log_event::print() method does not return a value and the
thus any error were being ignored.

Resolution: We resolve this problem by checking for the 
IO_CACHE::error == -1 after every call to Log_event:: print()
and terminating the further execution.

client/mysqlbinlog.cc:
  - handled error conditions during event->print() calls
  - added check for error in end_io_cache()
mysys/my_write.c:
  Added debug code to simulate file write error.
  error returned will be ENOSPC=> error no space on the disk
sql/log_event.cc:
  Added debug code to simulate file write error, by reducing the size of io cache.

1 files changed, 11 insertions, 1 deletions

diff --git a/mysys/my_write.c b/mysys/my_write.c
index f261c768dcb..b545ab776b0 100644
--- a/mysys/my_write.c
+++ b/mysys/my_write.c
@@ -38,7 +38,17 @@ size_t my_write(int Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
   
   for (;;)
   {
-    if ((writenbytes= write(Filedes, Buffer, Count)) == Count)
+    writenbytes= write(Filedes, Buffer, Count);
+    /**
+       To simulate the write error set the errno = error code
+       and the number pf written bytes to -1.
+     */
+    DBUG_EXECUTE_IF ("simulate_file_write_error",
+                     {
+                       errno= ENOSPC;
+                       writenbytes= (size_t) -1;
+                     });
+    if (writenbytes == Count)
       break;
     if (writenbytes != (size_t) -1)
     {						/* Safeguard */