contract(4) (man pages section 4: File Formats)

man pages section 4: File Formats

contract(4)

Name | Synopsis | Description | Files | See Also

Name

contract– the contract file system

Synopsis

/system/contract

Description

The /system/contract file system acts as the primary interface to the contract subsystem. There is a subdirectory of /system/contract for each available contract type.

/system/contract can be mounted on any mount point, in addition to the standard /system/contract mount point, and can be mounted several places at once. Such additional mounts are allowed in order to facilitate the confinement of processes to subtrees of the file system using chroot(1M) and yet allow such processes to continue to use contract commands and interfaces.

A combination of standard system calls (for example, open(2), close(2), and poll(2)) and calls to libcontract(3LIB) access /system/contract files.

Consumers of the contract file system must be large file aware. See largefile(5) and lfcompile64(5).

DIRECTORY STRUCTURE

At the top level, the /system/contract directory contains subdirectories named with each available contract type, and one special directory, all. Each of these directories is world-readable and world-searchable.

STRUCTURE OF `/system/contract/type`

Each /system/contract/type directory contains a fixed number of files. It also contains a variable number of subdirectories corresponding to existing contracts of type type and named with the decimal representation of the contracts' IDs.

The following files are in a /system/contract/type directory:

template

Opening this file returns a file descriptor for a new type contract template.

You can use the following libcontract(3LIB) calls on a template file descriptor:

>

 ct_tmpl_activate(3contract)
 ct_tmpl_clear(3contract)
 ct_tmpl_create(3contract)

See TERMS for additional template functions.

latest

Opening this file returns a file descriptor for the status file of the last type contract written by the opening LWP. See STRUCTURE OF /system/contract/type/id. If the opening LWP has not created a type contract, opening latest fails with ESRCH.

bundle

Opening this file returns a file descriptor for an event endpoint which receives events from all type contracts on the system. No privileges are required to open a type bundle event endpoint. Events sent by contracts owned and written by users other than the reader's effective user id are invisible, that is, they are silently skipped, unless the reader has {PRIV_CONTRACT_OBSERVER} in its effective set. See EVENTS.

pbundle

Opening this file returns a file descriptor for an event endpoint which receives events from all type contracts held by the opening process. See EVENTS.

STRUCTURE OF /system/contract/all

The /system/contract/all directory contains a numerically named file for each contract in the system. Each file is a symbolic link to the type-specific directory for that contract, that is /system/contract/all/id points to /system/contract/type/id.

STRUCTURE OF /system/contract/`type`/`id`

Each /system/contract/type/id directory contains the following files:

ctl

Opening this file returns a file descriptor for contract id's control file. The open fails if the opening process does not hold contract id and the contract has not been inherited by the process contract of which the opening process is a member. See process(4).

The following libcontract(3LIB) calls can be made on a ctl file descriptor if the contract is owned by the caller:

ct_ctl_abandon(3contract)
ct_ctl_newct(3contract)
ct_ctl_ack(3contract)
ct_ctl_qack(3contract)

The following libcontract(3LIB) call can be made on a ctl file descriptor if the contract doesn't have an owner:

ct_ctl_adopt(3contract)

status

Opening this file returns a file descriptor for contract id's status file. The following libcontract(3LIB) calls can be made on a status file descriptor:

ct_status_read(3contract)

See STATUS.

events

Opening this file returns a file descriptor for an event endpoint which receives events from contract id. See EVENTS.

Only a process which has the same effective user ID as the process owning the contract, the same effective user ID as the contract's author, or has {PRIV_CONTRACT_OBSERVER} in its effective set can open the event endpoint for a contract.

TERMS

The following terms are defined for all contracts:

cookie: Specifies a 64-bit quantity that the contract author can use to identify the contract. Use ct_tmpl_set_cookie(3CONTRACT) to set this term.
informative event set: Selects which events are delivered as informative events. Use ct_tmpl_set_informative(3CONTRACT) to set this term.
critical event set: Selects which events are delivered as critical events. Use ct_tmpl_set_critical(3CONTRACT) to set this term.

STATUS

A status object returned by ct_status_read(3CONTRACT) contains the following pieces of information:

contract ID: The numeric ID of the contract. Use ct_status_get_id(3CONTRACT) to obtain this information.
contract type: The type of the contract, specifed as a string. Obtained using ct_status_get_type(3CONTRACT). The contract type is the same as its subdirectory name under /system/contract.
creator's zone ID: The zone ID of the process which created the contract. Obtained using ct_status_get_zoneid(3CONTRACT).
ownership state: The state of the contract, specified as CTS_OWNED, CTS_INHERITED, CTS_ORPHAN, or CTS_DEAD. Use ct_status_get_state(3CONTRACT) to obtain this information.
contract holder: If the contract's state is CTS_OWNED, the ID of the process which owns the contract. If the contract's state is CTS_INHERITED, the ID of the contract which is acting as regent. If the contract's state is CTS_ORPHAN or CTS_DEAD, this is undefined. Use ct_status_get_holder(3CONTRACT) to obtain this information.
number of critical events: The number of unacknowledged critical events pending on the contract's event queue. Use ct_status_get_nevents(3CONTRACT) to obtain this information.
negotiation time: The time remaining before the current synchronous negotiation times out. Use ct_status_get_ntime(3CONTRACT) to obtain this information.
negotiation quantum time: The time remaining before the current negotiation quantum runs out. Use ct_status_get_qtime(3CONTRACT) to obtain this information.
negotiation event ID: The ID of the event which initiated the negotiation timeout. Use ct_status_get_nevid(3CONTRACT) to obtain this information.
cookie (term): The contract's cookie term. Use ct_status_get_cookie(3CONTRACT) to obtain this information.
Informative event set (term): The contract's informative event set. Use ct_status_get_informative(3CONTRACT) to obtain this information.
Critical event set (term): The contract's critical event set. Use ct_status_get_critical(3CONTRACT) to obtain this information.

EVENTS

All three event endpoints, /system/contract/type/bundle, /system/contract/type/pbundle, and /system/contract/type/id/events, are accessed in the same manner.

The following libcontract(3LIB) interfaces are used with an event endpoint file descriptor:

ct_event_read(3contract)
ct_event_read_critical(3contract)
ct_event_reset(3contract) 
ct_event_next(3contract)

To facilitate processes watching multiple event endpoints, it is possible to poll(2) on event endpoints. When it is possible to receive on an endpoint file descriptor, POLLIN is set for that descriptor.

An event object returned by ct_event_read(3CONTRACT) contains the following information:

contract ID: The ID of the contract that generated the event. Use ct_event_read(3CONTRACT) to obtain this information.
event ID: The ID of the contract event.Use ct_event_get_evid(3CONTRACT).
flags: A bit vector possibly including CT_ACK and CTE_INFO. Use ct_event_get_flags(3CONTRACT) to obtain this information.
event type: The type of event, equal to one of the constants specified in the contract type's manual page or CT_EV_NEGEND. Use ct_event_get_type(3CONTRACT) to obtain this information.

EVENT TYPES

The following event types are defined:

CT_EV_NEGEND

Some time after an exit negotiation is initiated, the CT_EV_NEGEND event is sent. This indicates that the negotiation ended. This might be because the operation was cancelled, or because the operation was successful. If successful, and the owner requested that a new contract be written, this contains the ID of that contract.

CT_EV_NEGEND cannot be included in a contract's informative or critical event set. It is always delivered and always critical. If CT_EV_NEGEND indicates that the operation was successful, no further events are sent. The contract's owner should use ct_ctl_abandon(3CONTRACT) to abandon the contract.

A CT_EV_NEGEND event contains:

negotiation ID: The ID of the negotiation which ended. Use ct_event_get_nevid(3CONTRACT) to obain this information.
new contract ID: The ID of the newly created contract. This value is 0 if no contract was created, or the ID of the existing contract if the operation was not completed. Use ct_event_get_newct(3CONTRACT) to obtain this information.

Files

/system/contract: List of all contract types
/system/contract/all: Directory of all contract IDs
/system/contract/all/id: Symbolic link to the type-specific directory of contract id
/system/contract/type: Specific type directory
/system/contract/type/templete: Template for the contract type
/system/contract/type/bundle: Listening point for all contracts of that type
/system/contract/type/pbundle: Listening point for all contracts of that type for the opening process
/system/contract/type /latest: Status of most recent type contract created by the opening LWP
/system/contract/type/ID: Directory for contract id
/system/contract/type/ID/events: Listening point for contract id's events
/system/contract/type/ID/ctl: Control file for contract ID
/system/contract/type/ID/status: Status info for contract ID