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