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by brian
clean slate |
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/* Copyright (C) 2000-2003 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#include "mysys_priv.h" |
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#include "mysys_err.h" |
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#include <errno.h> |
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#undef MY_HOW_OFTEN_TO_ALARM
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#define MY_HOW_OFTEN_TO_ALARM ((int) my_time_to_wait_for_lock)
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#ifdef NO_ALARM_LOOP
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#undef NO_ALARM_LOOP
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#endif
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#include <my_alarm.h> |
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/*
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Lock a part of a file
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RETURN VALUE
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0 Success
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-1 An error has occured and 'my_errno' is set
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to indicate the actual error code.
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*/
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int my_lock(File fd, int locktype, my_off_t start, my_off_t length, |
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myf MyFlags) |
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{
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#ifdef HAVE_FCNTL
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int value; |
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ALARM_VARIABLES; |
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#endif
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DBUG_ENTER("my_lock"); |
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DBUG_PRINT("my",("Fd: %d Op: %d start: %ld Length: %ld MyFlags: %d", |
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fd,locktype,(long) start,(long) length,MyFlags)); |
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if (my_disable_locking) |
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DBUG_RETURN(0); |
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#if defined(HAVE_FCNTL)
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{
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struct flock lock; |
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lock.l_type= (short) locktype; |
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lock.l_whence= SEEK_SET; |
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lock.l_start= (off_t) start; |
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lock.l_len= (off_t) length; |
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if (MyFlags & MY_DONT_WAIT) |
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{
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if (fcntl(fd,F_SETLK,&lock) != -1) /* Check if we can lock */ |
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DBUG_RETURN(0); /* Ok, file locked */ |
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DBUG_PRINT("info",("Was locked, trying with alarm")); |
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ALARM_INIT; |
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while ((value=fcntl(fd,F_SETLKW,&lock)) && ! ALARM_TEST && |
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errno == EINTR) |
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{ /* Setup again so we don`t miss it */ |
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ALARM_REINIT; |
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}
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ALARM_END; |
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if (value != -1) |
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DBUG_RETURN(0); |
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if (errno == EINTR) |
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errno=EAGAIN; |
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}
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else if (fcntl(fd,F_SETLKW,&lock) != -1) /* Wait until a lock */ |
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DBUG_RETURN(0); |
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}
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#else
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if (MyFlags & MY_SEEK_NOT_DONE) |
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{
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if (my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE)) |
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== MY_FILEPOS_ERROR) |
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{
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/*
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If an error has occured in my_seek then we will already
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have an error code in my_errno; Just return error code.
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*/
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DBUG_RETURN(-1); |
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}
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}
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if (lockf(fd,locktype,length) != -1) |
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DBUG_RETURN(0); |
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#endif /* HAVE_FCNTL */ |
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/* We got an error. We don't want EACCES errors */
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my_errno=(errno == EACCES) ? EAGAIN : errno ? errno : -1; |
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if (MyFlags & MY_WME) |
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{
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if (locktype == F_UNLCK) |
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my_error(EE_CANTUNLOCK,MYF(ME_BELL+ME_WAITTANG),my_errno); |
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else
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my_error(EE_CANTLOCK,MYF(ME_BELL+ME_WAITTANG),my_errno); |
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}
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DBUG_PRINT("error",("my_errno: %d (%d)",my_errno,errno)); |
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DBUG_RETURN(-1); |
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} /* my_lock */ |