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/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; 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>
#ifdef __WIN__
#include <sys/locking.h>
#endif
#ifdef __EMX__
#define INCL_BASE
#define INCL_NOPMAPI
#include <os2emx.h>
#endif
#ifndef __EMX__
#ifdef HAVE_FCNTL
static struct flock lock; /* Must be static for sun-sparc */
#endif
#endif
/* Lock a part of a file */
int my_lock(File fd, int locktype, my_off_t start, my_off_t length,
myf MyFlags)
{
#ifdef __EMX__
FILELOCK LockArea = {0,0}, UnlockArea = {0,0};
APIRET rc = 0;
fpos_t oldpos;
int lockflags = 0;
#endif
#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));
#ifdef VMS
DBUG_RETURN(0);
#else
if (my_disable_locking)
DBUG_RETURN(0);
#if defined(__EMX__)
if (locktype == F_UNLCK) {
UnlockArea.lOffset = start;
if (length)
UnlockArea.lRange = length;
else
UnlockArea.lRange = 0x7FFFFFFFL;
} else
if (locktype == F_RDLCK || locktype == F_WRLCK) {
if (locktype == F_RDLCK) lockflags |= 1;
LockArea.lOffset = start;
if (length)
LockArea.lRange = length;
else
LockArea.lRange = 0x7FFFFFFFL;
} else {
my_errno = EINVAL;
DBUG_RETURN(-1);
}
if (!LockArea.lRange && !UnlockArea.lRange)
DBUG_RETURN(0);
if (MyFlags & MY_DONT_WAIT) {
if (!(rc = DosSetFileLocks(fd,&UnlockArea,&LockArea,0,lockflags)))
DBUG_RETURN(0); /* Lock was OK */
if (rc == 175 && locktype == F_RDLCK) {
lockflags &= ~1;
rc = DosSetFileLocks(fd,&UnlockArea,&LockArea,0,lockflags);
}
if (rc == 33) { /* Lock Violation */
DBUG_PRINT("info",("Was locked, trying with timeout"));
rc = DosSetFileLocks(fd,&UnlockArea,&LockArea,MY_HOW_OFTEN_TO_ALARM * 1000,lockflags);
}
if (!rc) DBUG_RETURN(0);
if (rc == 33) errno = EAGAIN;
else {
errno = EINVAL;
printf("Error: DosSetFileLocks() == %d\n",rc);
}
} else {
while (rc = DosSetFileLocks(fd,&UnlockArea,&LockArea,
MY_HOW_OFTEN_TO_ALARM * 1000,lockflags) && (rc == 33 || rc == 175)) {
printf(".");
if (rc == 175) lockflags &= ~1;
}
if (!rc) DBUG_RETURN(0);
errno = EINVAL;
printf("Error: DosSetFileLocks() == %d\n",rc);
}
#elif defined(HAVE_LOCKING)
/* Windows */
{
my_bool error;
pthread_mutex_lock(&my_file_info[fd].mutex);
if (MyFlags & MY_SEEK_NOT_DONE)
VOID(my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE)));
error= locking(fd,locktype,(ulong) length) && errno != EINVAL;
pthread_mutex_unlock(&my_file_info[fd].mutex);
if (!error)
DBUG_RETURN(0);
}
#else
#if defined(HAVE_FCNTL)
lock.l_type= (short) locktype;
lock.l_whence=0L;
lock.l_start=(long) start;
lock.l_len=(long) 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)
VOID(my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE)));
if (lockf(fd,locktype,length) != -1)
DBUG_RETURN(0);
#endif /* HAVE_FCNTL */
#endif /* HAVE_LOCKING */
/* 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);
#endif /* ! VMS */
} /* my_lock */
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