LOCK
NAME
lock - Lock or open and lock a file.
SYNOPSIS
lock([locktype:1,2,0x0010,0x000F] [permissions:integer, owner:"rwx", group:"rwx", other:"rwx",][read:bool,write:bool,append:true|false,create:true|false,error:variable]"src filename");
lock([locktype:1,2,0x0010,0x000F] [permissions:integer, owner:"rwx", group:"rwx", other:"rwx",][read:bool,write:bool,append:true|false,create:true|false,error:variable]filename:"src filename");
lock([locktype:1,2,0x0010,0x000F] [permissions:integer, owner:"rwx", group:"rwx", other:"rwx",][read:bool,write:bool,append:true|false,create:true|false,error:variable]filedes: pointer);
DESCRIPTION
This function is used to lock a file. The file is automatically unlock at the end of the request or by using the unction unlock
The type of lock are (defined as constant in extenso.sn):
APR_FLOCK_EXCLUSIVE 2
Exclusive lock. Only one process may hold an exclusive lock at any given time. This is analogous to a "write lock".
APR_FLOCK_NONBLOCK 0x0010
do not block while acquiring the file lock
APR_FLOCK_SHARED 1
Shared lock. More than one process or thread can hold a shared lock at any given time. Essentially, this is a "read lock", preventing writers from establishing an exclusive lock.
APR_FLOCK_TYPEMASK 0x000F
mask to extract lock type
If the file is correctly lock, a pointer to the file open (lock open the file for locking) is returned.
If the file is not correctly lock, an integer is return.
If the file is already open, you can use the pointer return by open to lock the file.
EXAMPLES
Note: In the followings examples, the _ between the { should be removed to make it work.
l = lock(create:true,write:true,locktype:LOCK_EXCLUSIVE|LOCK_NONBLOCK,"/tmp/lock");
if type(l) eq "int" then
"An error has occured.\n";
endif
SEE ALSO
{{ include("includes/files.sn") }}
AUTHOR
Written by Pierre Laplante, <laplante@sednove.com>
MODIFICATIONS
1.0 2016-07-22 21:24:14 laplante@sednove.com
VERSION
Implemented in version 5.66 of Sncode
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