KERNEL OBJECTS - LOGICAL NAMES

An logical name is a named string that can be set, similar to an environmental variable. However, they are stored in shared memory so more than one process has access to any given name. They are organized into tables, and the tables themselves are logical names that are organized into special tables called directories.

Now each process has its own directory and table. Each job has its own directory and table. Each user has their own directory and table. Finally, there is a system-wide directory and table. But, if that's not enough, you can create your own tables and give them arbitrary scope by passing the handle around to whoever you want.

If you want to find the value of a particular logical name, you can explicitly specify which table to want the system to look the name up in. By default, it will search the process, job, user then system tables.

Each process, job and user has its own directory and table. They are called:

• OZ_PROCESS_DIRECTORY, OZ_PROCESS_TABLE
• OZ_JOB_DIRECTORY, OZ_JOB_TABLE
• OZ_USER_DIRECTORY, OZ_USER_TABLE

• OZ_SYSTEM_DIRECTORY, OZ_SYSTEM_TABLE

By default, when you create a logical, it goes in the OZ_PROCESS_TABLE for that process. When looking up logicals, the default is to look in the process table, then the job table, then the user table, then finally the system table. If you want to explicitly specify a table, prefix the logical name with the table name followed by a percent. So, for example, to specify logical 'abc' in the job table, you would put OZ_JOB_TABLE%abc.

Examples of process logicals are:

OZ_DEFAULT_DIR	this process' default device and directory (or working directory)
OZ_INPUT	this process' input file
OZ_THIS_PROCESS	this process' process object

Examples of job logicals are:

OZ_CONSOLE	this job's console device
OZ_THIS_JOB	this job's job object

Examples of user logicals are:

OZ_THIS_USER	this user's user object
OZ_USERNAME	this user's username

Examples of system logicals are:

OZ_LOAD_DIR	the directory the kernel was loaded from
GCC_INCLUDE_DIR	the directory where the GCC includes files are

Each logical name has the following properties:

• reference count
• the table that it is in
• its name
• processor mode that defined it (kernel, user)
• attribute flags (table, nosupersede, nooutermode)
• if table, list of logicals in the table
• if not table, the list of values for the logical

These methods are defined:

• oz_knl_logname_search - perform recursive search
• oz_knl_logname_creobj - create logical name that points to a single object
• oz_knl_logname_crestr - create logical name that points to a single string
• oz_knl_logname_create - create logical name, general list of values
• oz_knl_logname_lookup - non-recursive lookup
• oz_knl_logname_parse - parse composite name string into table pointer and name string
• oz_knl_logname_getobj - get the object pointed to by an logical name
• oz_knl_logname_getval - get the string pointed to by an logical name
• oz_knl_logname_gettblent - get first/next entry in a table
• oz_knl_logname_getname - get a logical's name (given a pointer to the logical's object)
• oz_knl_logname_increfc - increment/decrement logical's reference count
• oz_knl_logname_delete - mark logical for delete when refcount goes zero
• oz_knl_logname_incobjrefc - increment/decrement the refcount of object pointed to by logname