diff options
Diffstat (limited to 'mysys/my_lock.c')
| -rw-r--r-- | mysys/my_lock.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/mysys/my_lock.c b/mysys/my_lock.c new file mode 100644 index 00000000000..4f1506f20cf --- /dev/null +++ b/mysys/my_lock.c @@ -0,0 +1,161 @@ +/* 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 + +#ifdef HAVE_FCNTL +static struct flock lock; /* Must be static for sun-sparc */ +#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) + if (MyFlags & MY_SEEK_NOT_DONE) + VOID(my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE))); + if (!locking(fd,locktype,(ulong) length) || errno == EINVAL) + 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 */ |