DESCRIPTION
Process contracts allow processes to create a fault boundary around a set of subprocesses and observe events which occur within that boundary.
Process contracts are managed using the
contract(4) file system and the
libcontract(3LIB) library. The process contract type directory is
/system/contract/process.
CREATION
A process contract is created when an LWP that has an active process contract template calls fork(2). Initially, the child process created by fork() is the only resource managed by the contract. When an LWP that does not have an active process contract template calls fork(), the child process created by fork() is added as a resource to the process contract of which the parent was a member.
EVENT TYPES
The following events types are defined:
CT_PR_EV_EMPTY
The last member of the process contract exited.
CT_PR_EV_FORK
A new process has been added to the process contract.
CT_PR_EV_EXIT
A member of the process contract exited.
CT_PR_EV_CORE
A process failed and dumped core. This could also occur if the process would have dumped core had appropriate coreadm(1M) options been enabled and core file size was unlimited.
CT_PR_EV_SIGNAL
A process received a fatal signal from a process, other than the owner of the process contract, that is a member of a different process contract.
CT_PR_EV_HWERR
A process was killed because of an uncorrectable hardware error.
TERMS
The following common contract terms, defined in
contract(4), have process-contract specific attributes:
critical event set
The default value for the critical event set is
(CT_PR_EV_EMPTY | CT_PR_EV_HWERR).
An attempt by a user without the
{PRIV_CONTRACT_EVENT} privilege in its effective set to add an event, other than
CT_PR_EV_EMPTY, to the critical event set which is not present in the fatal set, or if the
CT_PR_PGONLY parameter is set and the same user attempts to add any event, other than
CT_PR_EV_EMPTY, to the critical event set, fails.
informative event set
The default value for the informative event set is (CT_PR_EV_CORE | CT_PR_EV_SIGNAL).
The following contract terms can be read from or written to a process contract template using the named
libcontract(3LIB) interfaces. These contract terms are in addition to those described in
contract(4).
creator's aux
Auxiliary contract description. The purpose of this field is to provide the contract creator with a way to differentiate process contracts it creates under the same service FMRI. Use ct_pr_tmpl_set_svc_aux(3CONTRACT) to set this term. The default value is an empty string. The contents of this field should be limited to 7-bit ASCII values.
fatal event set
Defines a set of events which, when generated, causes all members of the process contract to be killed with
SIGKILL, or the intersection of the contract and the containing process group if the
CT_PR_PGRPONLY parameter is set. Set this term with
ct_pr_tmpl_set_fatal(3CONTRACT). The fatal event set is restricted to
CT_PR_EV_CORE,
CT_PR_EV_SIGNAL, and
CT_PR_EV_HWERR. For
CT_PR_EV_CORE and
CT_PR_EV_SIGNAL events, the scope of
SIGKILL is limited to those processes which the contract author or the event source could have normally sent signals to.
The default value for the fatal event set is
CT_PR_EV_HWERR.
If a user without the
{PRIV_CONTRACT_EVENT} privilege in its effective set removes an event from the fatal event set which is present in the critical event set, the corresponding event is automatically removed from the critical event set and added to the informative event set.
parameter set
Defines miscellaneous other settings. Use
ct_pr_tmpl_set_param(3CONTRACT) to set this term.
The default parameter set is empty.
The value is a bit vector comprised of some or all of:
CT_PR_INHERIT
If set, indicates that the process contract is to be inherited by the process contract the contract owner is a member of if the contract owner exits before explicitly abandoning the process contract.
If not set, the process contract is automatically abandoned when the owner exits.
CT_PR_KEEP_EXEC
If set, the process contract template remains active across exec(2). This can be used to setup a contract for children of an application which is not contract-aware. If this is not set then the system clears the active template when the process execs. Because this option is intended for an application which is not contract-aware, new child process contracts will be automatically abandoned by the parent.
CT_PR_NOORPHAN
If set, all processes in a process contract are sent
SIGKILL if the process contract is abandoned, either explicitly or because the holder died and
CT_PR_INHERIT was not set. The scope of
SIGKILL is limited to those processes which the contract author or the event source could have normally sent signals to.
If this is not set and the process contract is abandoned, the process contract is orphaned, that is, continues to exist without owner.
CT_PR_PGRPONLY
If set, only those processes within the same process group and process contract as a fatal error-generating process are killed.
If not set, all processes within the process contract are killed if a member process encounters an error specified in the fatal set.
If a user without the
{PRIV_CONTRACT_EVENT} privilege in its effective set adds
CT_PR_PGRPONLY to a template's parameter set, any events other than
CT_PR_EV_EMPTY are automatically removed from the critical event set and added to the informative event set.
CT_PR_REGENT
If set, the process contract can inherit unabandoned contracts left by exiting member processes.
If not set, indicates that the process contract should not inherit contracts from member processes. If a process exits before abandoning a contract it owns and is a member of a process contract which does not have
CT_PR_REGENT set, the system automatically abandons the contract.
If a regent process contract has inherited contracts and is abandoned by its owner, its inherited contracts are abandoned.
service FMRI
Specifies the service FMRI associated with the process contract. Use ct_pr_tmpl_set_svc_fmri(3CONTRACT) to set this term. The default is to inherit the value from the creator's process contract. When this term is uninitialized, ct_pr_tmpl_get_svc_fmri(3CONTRACT) returns the token string inherited: to indicate the value has not been set and is inherited. Setting the service FMRI to inherited: clears the current ( B value and the term is inherited from the creator's process contract. To set this term a process must have {PRIV_CONTRACT_IDENTITY} in its effective set.
transfer contract
Specifies the ID of an empty process contract held by the caller whose inherited process contracts are to be transferred to the newly created contract. Use
ct_pr_tmpl_set_transfer(3CONTRACT) to set the tranfer contract. Attempts to specify a contract not held by the calling process, or a contract which still has processes in it, fail.
The default transfer term is
0, that is, no contract.
STATUS
In addition to the standard items, the status object read from a status file descriptor contains the following items to obtain this information respectively:
service contract ID
Specifies the process contract id which defined the service FMRI term. Use
ct_pr_status_get_svc_ctid(3CONTRACT) to read the term's value. It can be used to determine if the service FMRI was inherited as in the example below.
ctid_t ctid; /* our contract id */
int fd; /* fd of ctid's status file */
ct_stathdl_(Bt status;
ctid_t svc_ctid;
if (ct_status_read(fd, CTD_FIXED, &status) == 0) {
if (ct_pr_status_get_svc_ctid(status, &svc_ctid) == 0) {
if (svc_ctid == ctid)
/* not inherited */
else
/* inherited */
}
ct_status_free(status);
}
If
CTD_ALL is specified, the following items are also available:
Member list
The PIDs of processes which are members of the process contract. Use ct_pr_status_get_members(3CONTRACT) for this information.
Inherited contract list
The IDs of contracts which have been inherited by the process contract. Use ct_pr_status_get_contracts(3CONTRACT) to obtain this information.
Service FMRI (term)
Values equal to the terms used when the contract was written. The Service FMRI term of the process contract of a process en( Btering a zone has the value svc:/system/zone_enter:default when read from the non-global zone.
contract creator
Specifies the process that created the process contract. Use ct_pr_status_get_svc_creator(3CONTRACT) to read the term's value.
creator's aux (term)
Values equal to the terms used when the contract was written.
The following standard status items have different meanings in some situations:
Ownership state
If the process contract has a state of CTS_OWNED or CTS_INHERITED and is held by an entity in the global zone, but contains processes in a non-global zone, it appears to have the state CTS_OWNED when observed by processes in the non-global zone.
Contract holder
If the process contract has a state of CTS_OWNED or CTS_INHERITED and is held by an entity in the global zone, but contains processes in a non-global zone, it appears to be held by the non-global zone's zsched when observed by processes in the non-global zone.
EVENTS
In addition to the standard items, an event generated by a process contract contains the following information:
Generating PID
The process ID of the member process which experienced the event, or caused the contract event to be generated (in the case of CT_PR_EV_EMPTY). Use ct_pr_event_get_pid(3CONTRACT) to obtain this information.
If the event type is
CT_PR_EV_FORK, the event contains:
Parent PID
The process ID which forked [Generating PID]. Use ct_pr_event_get_ppid(3CONTRACT) to obtain this information.
If the event type is
CT_PR_EV_EXIT, the event contains:
Exit status
The exit status of the process. Use ct_pr_event_get_exitstatus(3CONTRACT) to obtain this information.
If the event type is
CT_PR_EV_CORE, the event can contain:
Process core name
The name of the per-process core file. Use ct_pr_event_get_pcorefile(3CONTRACT) to obtain this information.
Global core name
The name of the process's zone's global core file. Use ct_pr_event_get_gcorefile(3CONTRACT) to obtain this information.
Zone core name
The name of the system-wide core file in the global zone. Use ct_pr_event_get_zcorefile(3CONTRACT) to obtain this information.
See
coreadm(1M) for more information about per-process, global, and system-wide core files.
If the event type is
CT_PR_EV_SIGNAL, the event contains:
Signal
The number of the signal which killed the process. Use ct_pr_event_get_signal(3CONTRACT) to obtain this information.
It can contain:
sender
The PID of the process which sent the signal. Use ct_pr_event_get_sender(3CONTRACT) to obtain this information.