SQL Scalar function to check access to an IFS file or folder

IFS_ACCESS - SQL Scalar function to check access to an IFS file or folder

It returns:

0=If the file or folder Exists and you have access

-1=No access or file does not exists

use case:

-- returns 0 for the home folder - it exists

values IFS_ACCESS (

ifs_path => '/home'

);

-- returns -1 for files that does not exists

values IFS_ACCESS (

ifs_path => '/home/does_not_exists'

);

-- returns 0 for the "cat" file exists

values IFS_ACCESS (

ifs_path => '/bin/cat'

);

-- Can i execute /bin/cat

values IFS_ACCESS (

ifs_path => '/bin/cat',

access_type => ifs_access_execute

);

-- Can i write to home folder

values IFS_ACCESS (

ifs_path => '/home',

access_type => ifs_access_write

);

It returns:

0=If the file or folder Exists and you have access

-1=No access or file does not exists

This is a wrapper for the access() unix API:

https://pubs.opengroup.org/onlinepubs/009695299/functions/access.html

Note second parameter is the access mode, that defaults to F_OK

Constants for access() are also declare as SQL global variables

The implementation can be found here:

https://gist.github.com/NielsLiisberg/dd45d94da1cd21a2f4eaa178023ab4f0

or paste from here:

_____________

ifs_access.sql

-- SQL Scalar function to check access to an IFS file or folder

-- It returns:

-- 0=If the file or folder Exists and you have access

-- -1=No access or file does not exists

--

-- This is a wrapper for the access() unix API:

-- https://pubs.opengroup.org/onlinepubs/009695299/functions/access.html

-- Note second parameter is the acces mode, that defaults to F_OK

-- Constants for access() are also declare as SQL global variables

-- Simply paste this gist into ACS SQL and run it to create the feature.

-- Note: I am using library QUSRSYS. I suggest you put it into your own tool library

-- It is a cool example how far you can go with SQL: Have fun -

-- (C) Niels Liisberg 2023

-- This gist is distributed on an "as is" basis, without warranties

-- or conditions of any kind, either express or implied.

----------------------------------------------------------------------------------------------

call qcmdexc ('addlible qsysinc');

--call qcmdexc ('dltf FILE(QTEMP/C) ');

call qcmdexc ('crtsrcpf FILE(QTEMP/C) MBR(C) rcdlen(256)');

truncate qtemp.c;

insert into qtemp.c (srcdta) values

('#include <unistd.h>'),

('IFS_ACCESS.IFS_PATH.DAT[IFS_ACCESS.IFS_PATH.LEN] = 0;'),

('MAIN.RC = access ( IFS_ACCESS.IFS_PATH.DAT , IFS_ACCESS.ACCESS_TYPE);')

;

create or replace function qusrsys.ifs_access (

ifs_path varchar(256) ,

access_type int default 0 -- Posix: 0 = F_OK = Test for existence of a file

)

returns int

specific IFS_ACCESS

no external action

set option output=*print, commit=*none, dbgview = *source

main:

begin

declare rc int default 0;

include qtemp/c(c);

return rc;

end;

-- Constants for access()

create or replace variable qusrsys.ifs_access_read int default 4; -- R_OK 4

create or replace variable qusrsys.ifs_access_write int default 2; -- W_OK 2

create or replace variable qusrsys.ifs_access_execute int default 1; -- X_OK 1

stop;

-- use case:

------------

-- returns 0 for the home folder - it exists

values qusrsys.IFS_ACCESS (

ifs_path => '/home'

);

-- returns -1 for files that does not exists

values qusrsys.IFS_ACCESS (

ifs_path => '/home/does_not_exists'

);

-- returns 0 for the "cat" file exists

values qusrsys.IFS_ACCESS (

ifs_path => '/bin/cat'

);

-- Can i execute /bin/cat

values qusrsys.IFS_ACCESS (

ifs_path => '/bin/cat',

access_type => qusrsys.ifs_access_execute

);

-- Can i write to home folder

values qusrsys.IFS_ACCESS (

ifs_path => '/home',

access_type => qusrsys.ifs_access_write

);