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.Dd September 14, 2016
.Dt RCTL_ADD_RULE 2
.Os
.Sh NAME
.Nm rctl_add_rule ,
.Nm rctl_get_limits ,
.Nm rctl_get_racct ,
.Nm rctl_get_rules ,
.Nm rctl_remove_rule
.Nd manipulate and query the resource limits database
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/rctl.h
.Ft int
.Fo rctl_add_rule
.Fa "const char *inbufp" "size_t inbuflen" "char *outbufp" "size_t outbuflen"
.Fc
.Ft int
.Fo rctl_get_limits
.Fa "const char *inbufp" "size_t inbuflen" "char *outbufp" "size_t outbuflen"
.Fc
.Ft int
.Fo rctl_get_racct
.Fa "const char *inbufp" "size_t inbuflen" "char *outbufp" "size_t outbuflen"
.Fc
.Ft int
.Fo rctl_get_rules
.Fa "const char *inbufp" "size_t inbuflen" "char *outbufp" "size_t outbuflen"
.Fc
.Ft int
.Fo rctl_remove_rule
.Fa "const char *inbufp" "size_t inbuflen" "char *outbufp" "size_t outbuflen"
.Fc
.Sh DESCRIPTION
These system calls are used to manipulate and query the resource limits
database.
For all functions,
.Fa inbuflen
refers to the length of the buffer pointed to by
.Fa inbufp
and
.Fa outbuflen
refers to the length of the buffer pointed to by
.Fa outbufp .
.Pp
The
.Fn rctl_add_rule
function adds the rule pointed to by
.Fa inbufp
to the resource limits database.
The
.Fa outbufp
and
.Fa outbuflen
arguments are unused.
Rule format is as described in
.Xr rctl 8 ,
with exceptions noted in the
.Sx RULES AND FILTERS
section.
.Pp
The
.Fn rctl_get_limits
function returns in
.Fa outbufp
a comma-separated list of rules that apply to the process that
matches the filter specified in
.Fa inbufp .
This includes rules with a subject of the process itself as well as rules
with a different subject (such as user or loginclass) that apply to the
process.
.Pp
The
.Fn rctl_get_racct
function returns resource usage information for a given subject.
The subject is specified by passing a filter in
.Fa inbufp .
Filter syntax is as described in
.Xr rctl 8 ,
with exceptions noted in the
.Sx RULES AND FILTERS
section.
A comma-separated list of resources and the amount used of each by the
specified subject is returned in
.Fa outbufp .
The resource and amount is formatted as
.Qq resource=amount .
.Pp
The
.Fn rctl_get_rules
function returns in
.Fa outbufp
a comma-separated list of rules from the resource limits database that
match the filter passed in
.Fa inbufp .
Filter syntax is as described in
.Xr rctl 8 ,
with exceptions noted in the
.Sx RULES AND FILTERS
section.
A filter of
.Va ::
may be passed to return all rules.
.Pp
The
.Fn rctl_remove_rule
function removes all rules matching the filter passed in
.Fa inbufp
from the resource limits database.
Filter syntax is as described in
.Xr rctl 8 ,
with exceptions noted in the
.Sx RULES AND FILTERS
section.
.Fa outbufp
and
.Fa outbuflen
are unused.
.Sh RULES AND FILTERS
This section explains how the rule and filter format described in
.Xr rctl 8
differs from the format passed to the system calls themselves.
The rctl tool provides several conveniences that the system calls do not.
When using the system call:
.Bl -dash -offset indent
.It
The subject must be fully specified.
For example, abbreviating
.Ql user
to
.Ql u
is not acceptable.
.It
User and group IDs must be numeric.
For example,
.Ql root
must be expressed as
.Ql 0 .
.It
Units are not permitted on resource amounts.
For example, a quantity of 1024 bytes must be expressed as
.Ql 1024
and not
.Ql 1k .
.El
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The rctl system calls may fail if:
.Bl -tag -width Er
.It Bq Er ENOSYS
RACCT/RCTL support is not present in the kernel or the
.Va kern.racct.enable
sysctl is 0.
.It Bq Er EINVAL
The rule or filter passed in
.Fa inbufp
is invalid.
.It Bq Er EPERM
User has insufficient privileges to carry out the requested operation.
.It Bq Er E2BIG
.Fa inbufp
or
.Fa outbufp
are too large.
.It Bq Er ESRCH
No process matched the provided rule or filter.
.It Bq Er ENAMETOOLONG
The loginclass or jail name specified is too long.
.It Bq Er ERANGE
The rule amount is outside of the allowable range or
.Fa outbufp
is too small.
.It Bq Er EOPNOTSUPP
The requested operation is not supported for the given rule or filter.
.It Bq Er EFAULT
.Fa inbufp
or
.Fa outbufp
refer to invalid addresses.
.El
.Sh SEE ALSO
.Xr rctl 8
.Sh HISTORY
The rctl family of system calls appeared in
.Fx 9.0 .
.Sh AUTHORS
.An -nosplit
The rctl system calls were developed by
.An Edward Tomasz Napierala Aq Mt trasz@FreeBSD.org
under sponsorship from the FreeBSD Foundation.
This manual page was written by
.An Eric Badger Aq Mt badger@FreeBSD.org .
