From 626abc5205745ff002be2c4910460999df294439 Mon Sep 17 00:00:00 2001 From: unknown Date: Wed, 30 Aug 2006 17:28:34 -0400 Subject: 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 . --- mysys/my_read.c | 47 +++++++++++++++++++++++++---------------------- 1 file changed, 25 insertions(+), 22 deletions(-) diff --git a/mysys/my_read.c b/mysys/my_read.c index b7621ac99eb..bca28694295 100644 --- a/mysys/my_read.c +++ b/mysys/my_read.c @@ -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); -- cgit v1.2.1