1.Dd December 19, 2018 2.Dt SQLITE_SHM_UNLOCK 3 3.Os 4.Sh NAME 5.Nm SQLITE_SHM_UNLOCK , 6.Nm SQLITE_SHM_LOCK , 7.Nm SQLITE_SHM_SHARED , 8.Nm SQLITE_SHM_EXCLUSIVE 9.Nd Flags for the xShmLock VFS method 10.Sh SYNOPSIS 11.Fd #define SQLITE_SHM_UNLOCK 12.Fd #define SQLITE_SHM_LOCK 13.Fd #define SQLITE_SHM_SHARED 14.Fd #define SQLITE_SHM_EXCLUSIVE 15.Sh DESCRIPTION 16These integer constants define the various locking operations allowed 17by the xShmLock method of sqlite3_io_methods. 18The following are the only legal combinations of flags to the xShmLock 19method: 20.Bl -bullet 21.It 22SQLITE_SHM_LOCK | SQLITE_SHM_SHARED 23.It 24SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE 25.It 26SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED 27.It 28SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE 29.El 30.Pp 31When unlocking, the same SHARED or EXCLUSIVE flag must be supplied 32as was given on the corresponding lock. 33.Pp 34The xShmLock method can transition between unlocked and SHARED or between 35unlocked and EXCLUSIVE. 36It cannot transition between SHARED and EXCLUSIVE. 37.Sh SEE ALSO 38.Xr sqlite3_io_methods 3 39