Commit 626abc52 authored by unknown's avatar unknown

Bug#4053: too many of "error 1236: 'binlog truncated in the middle of \

	event' from master"

Since there is no repeatable test case, and this is obviously wrong, this is
the most conservative change that might possibly work.  

The syscall  read()  wasn't checked for a negative return value for an
interrupted read.  The kernel  sys_read()  returns -EINTR, and the "library" 
layer maps that to return value of -1 and sets  errno  to EINTR.  It's 
impossible (on Linux) for  read()  to set errno EINTR without the return 
value being -1 .

So, if we're checking for EINTR behavior, we should not require that the
return value be zero.


mysys/my_read.c:
  The read() syscall should check for negative one, since that (usually) signals
  errors (like being interrupted) and zero (usually) signals end-of-file .
parent d8e9dd61
......@@ -36,48 +36,51 @@
uint my_read(File Filedes, byte *Buffer, uint Count, myf MyFlags)
{
uint readbytes,save_count;
uint readbytes, save_count;
DBUG_ENTER("my_read");
DBUG_PRINT("my",("Fd: %d Buffer: %lx Count: %u MyFlags: %d",
Filedes, Buffer, Count, MyFlags));
save_count=Count;
Filedes, Buffer, Count, MyFlags));
save_count= Count;
for (;;)
{
errno=0; /* Linux doesn't reset this */
if ((readbytes = (uint) read(Filedes, Buffer, Count)) != Count)
errno= 0; /* Linux doesn't reset this */
if ((readbytes= (uint) read(Filedes, Buffer, Count)) != Count)
{
my_errno=errno ? errno : -1;
my_errno= errno ? errno : -1;
DBUG_PRINT("warning",("Read only %ld bytes off %ld from %d, errno: %d",
readbytes,Count,Filedes,my_errno));
readbytes, Count, Filedes, my_errno));
#ifdef THREAD
if (readbytes == 0 && errno == EINTR)
continue; /* Interrupted */
if ((int) readbytes <= 0 && errno == EINTR)
{
DBUG_PRINT("debug", ("my_read() was interrupted and returned %d", (int) readbytes));
continue; /* Interrupted */
}
#endif
if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
{
if ((int) readbytes == -1)
my_error(EE_READ, MYF(ME_BELL+ME_WAITTANG),
my_filename(Filedes),my_errno);
else if (MyFlags & (MY_NABP | MY_FNABP))
my_error(EE_EOFERR, MYF(ME_BELL+ME_WAITTANG),
my_filename(Filedes),my_errno);
if ((int) readbytes == -1)
my_error(EE_READ, MYF(ME_BELL+ME_WAITTANG),
my_filename(Filedes),my_errno);
else if (MyFlags & (MY_NABP | MY_FNABP))
my_error(EE_EOFERR, MYF(ME_BELL+ME_WAITTANG),
my_filename(Filedes),my_errno);
}
if ((int) readbytes == -1 ||
((MyFlags & (MY_FNABP | MY_NABP)) && !(MyFlags & MY_FULL_IO)))
DBUG_RETURN(MY_FILE_ERROR); /* Return with error */
((MyFlags & (MY_FNABP | MY_NABP)) && !(MyFlags & MY_FULL_IO)))
DBUG_RETURN(MY_FILE_ERROR); /* Return with error */
if (readbytes > 0 && (MyFlags & MY_FULL_IO))
{
Buffer+=readbytes;
Count-=readbytes;
continue;
Buffer+= readbytes;
Count-= readbytes;
continue;
}
}
if (MyFlags & (MY_NABP | MY_FNABP))
readbytes=0; /* Ok on read */
readbytes= 0; /* Ok on read */
else if (MyFlags & MY_FULL_IO)
readbytes=save_count;
readbytes= save_count;
break;
}
DBUG_RETURN(readbytes);
......
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