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man pages section 3: Basic Library Functions

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Updated: Wednesday, July 27, 2022



rctlblk_set_value, rctlblk_get_firing_time, rctlblk_get_global_action, rctlblk_get_global_flags, rctlblk_get_local_action, rctlblk_get_local_flags, rctlblk_get_privilege, rctlblk_get_recipient_pid, rctlblk_get_value, rctlblk_get_enforced_value, rctlblk_set_local_action, rctlblk_set_local_flags, rctlblk_set_privilege, rctlblk_set_recipient_pid, rctlblk_size - manipulate resource control blocks


#include <rctl.h>

hrtime_t  rctlblk_get_firing_time(rctlblk_t *rblk);
uint_t rctlblk_get_global_action(rctlblk_t *rblk);
uint_t rctlblk_get_global_flags(rctlblk_t *rblk);
uint_t rctlblk_get_local_action(rctlblk_t *rblk, int *signalp);
uint_t rctlblk_get_local_flags(rctlblk_t *rblk);
rctl_priv_t  rctlblk_get_privilege(rctlblk_t *rblk);
pid_t rctlblk_get_recipient_pid(rctlblk_t *rblk);
rctl_qty_t  rctlblk_get_value(rctlblk_t *rblk);
rctl_qty_t  rctlblk_get_enforced_value(rctlblk_t *rblk);
void rctlblk_set_local_action(rctlblk_t *rblk, uint_t action,
     int signal);
void rctlblk_set_local_flags(rctlblk_t *rblk, uint_t flags);
void rctlblk_set_privilege(rctlblk_t *rblk, rctl_priv_t privilege);
void rctlblk_set_value(rctlblk_t *rblk, rctl_qty_t value);
void  rctlblk_set_recipient_pid(pid_t pid);
size_t rctlblk_size(void);


The resource control block routines allow the establishment or retrieval of values from a resource control block used to transfer information using the getrctl(2) and setrctl(2) functions. Each of the routines accesses or sets the resource control block member corresponding to its name. Certain of these members are read-only and do not possess set routines.

The firing time of a resource control block is 0 if the resource control action-value has not been exceeded for its lifetime on the process. Otherwise the firing time is the value of gethrtime(3C) at the moment the action on the resource control value was taken.

The global actions and flags are the action and flags set by rctladm(8). These values cannot be set with setrctl(2). Valid global actions are listed in the table below. Global flags are generally a published property of the control and are not modifiable.


The action taken when a control value is exceeded on this control will always include denial of the resource.


The action taken when a control value is exceeded on this control will always exclude denial of the resource; the resource will always be granted, although other actions can also be taken.


No signal actions are permitted on this control.


The valid signals available as local actions include the SIGXCPU signal.


The valid signals available as local actions include the SIGXFSZ signal.


This resource control supports the concept of an unlimited value; generally true only of accumulation-oriented resources, such as CPU time.


Non-privileged callers are able to lower the value of privileged resource control values on this control.


No global action will be taken when a resource control value is exceeded on this control.


No values with the RCPRIV_BASIC privilege are permitted on this control.


A standard message will be logged by the syslog(3C) facility when any resource control value on a sequence associated with this control is exceeded.


The resource control does not support the syslog() global action. Exceeding a resource control value on this control will not result in a message logged by the syslog() facility.


The resource control (generally on a task- or project-related control) does not support observational control values. An RCPRIV_BASIC privileged control value placed by a process on the task or process will generate an action only if the value is exceeded by that process.


This resource control represents a number of bytes.


This resource control represents a quantity of time in seconds.


This resource control represents an integer count.

The local action and flags are those on the current resource control value represented by this resource control block. Valid actions and flags are listed in the table below. In the case of RCTL_LOCAL_SIGNAL, the second argument to rctlblk_set_local_action () contains the signal to be sent. Similarly, the signal to be sent is copied into the integer location specified by the second argument to rctlblk_get_local_action(). A restricted set of signals is made available for normal use by the resource control facility: SIGBART, SIGXRES, SIGHUP, SIGSTOP, SIGTERM, and SIGKILL. Other signals are permitted due to global properties of a specific control. Calls to setrctl() with illegal signals will fail.


When this resource control value is encountered, the request for the resource will be denied. Set on all values if RCTL_GLOBAL_DENY_ALWAYS is set for this control; cleared on all values if RCTL_GLOBAL_DENY_NEVER is set for this control.


This resource control value represents a request for the maximum amount of resource for this control. If RCTL_GLOBAL_INFINITE is set for this resource control, RCTL_LOCAL_MAXIMAL indicates an unlimited resource control value, one that will never be exceeded.


No local action will be taken when this resource control value is exceeded.


The specified signal, sent by rctlblk_set_local_action(), will be sent to the process that placed this resource control value in the value sequence. This behavior is also true for signal actions on project and task resource controls. The specified signal is sent only to the recipient process, not all processes within the project or task.

The rctlblk_get_privilege() function returns the privilege of the resource control block. Valid privileges are RCPRIV_BASIC, RCPRIV_PRIVILEGED, and RCPRIV_SYSTEM. System resource controls are read-only. Privileged resource controls require the {PRIV_SYS_RESOURCE} privilege to write, unless the RCTL_GLOBAL_LOWERABLE global flag is set, in which case unprivileged applications can lower the value of a privileged control.

An rctl value with privilege RCPRIV_BASIC and RCTL_LOCAL_SIGNAL flag set has a recipient process ID (pid), the pid which will receive the signal when this rctl value has been exceeded. This recipient pid can be retrieved by rctlblk_get_recipient_pid() function. For rctl values that does not have recipient pid, rctlblk_get_recipient_pid() function returns -1.

The rctlblk_set_recipient_pid() function sets the recipient pid for a basic rctl with a signal action. When setrctl() function is called with the flag RCTL_USE_RECIPIENT_PID, this pid is used.

The rctlblk_get_value() and rctlblk_set_value() functions return or establish the enforced value associated with the resource control. In cases where the process, task, or project associated with the control possesses fewer capabilities than allowable by the current value, the value returned by rctlblk_get_enforced_value() will differ from that returned by rctlblk_get_value(). This capability difference arises with processes using an address space model smaller than the maximum address space model supported by the system.

The rctlblk_size() function returns the size of a resource control block for use in memory allocation. The rctlblk_t * type is an opaque pointer whose size is not connected with that of the resource control block itself. Use of rctlblk_size() is illustrated in the example below.

Return Values

The various set routines have no return values. Incorrectly composed resource control blocks will generate errors when used with setrctl(2) or getrctl(2).


No error values are returned. Incorrectly constructed resource control blocks will be rejected by the system calls.


Example 1 Display the contents of a fetched resource control block.

The following example displays the contents of a fetched resource control block.

#include <rctl.h>
#include <stdio.h>
#include <stdlib.h>

rctlblk_t *rblk;
int rsignal;
uint_t raction;

if ((rblk = malloc(rctlblk_size())) == NULL) {
       (void) perror("rblk malloc");

if (getrctl("process.max-cpu-time", NULL, rblk, RCTL_FIRST) == -1) {
       (void) perror("getrctl");
    raction = rctlblk_get_local_action(rblk, &rsignal),
    (void) printf("Resource control for %s\n",
    (void) printf("Process ID:     %d\n",
    (void) printf("Privilege:      %x\n"
    (void) printf("Global flags:   %x\n"
    (void) printf("Global actions: %x\n"
    (void) printf("Local flags:    %x\n"
    (void) printf("Local action:   %x (%d)\n"
        raction, raction == RCTL_LOCAL_SIGNAL ? rsignal : 0);
    (void) printf("Value:          %llu\n",
    (void) printf("\tEnforced value: %llu\n",


See attributes(7) for descriptions of the following attributes:

Interface Stability

See Also

getrctl(2), setrctl(2), gethrtime(3C), attributes(7), rctladm(8)