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				.\" Copyright (c) 2018 Stefan Grundmann
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				.\" $FreeBSD$
				.\"
				.Dd May 11, 2018
				.Dt CAP_JAIL 3
				.Os
				.Sh NAME
				.Nm cap_jail
				.Nd "library for getting jail information in capability mode"
				.Sh LIBRARY
				.Lb libcap_jail
				.Sh SYNOPSIS
				.In sys/uio.h
				.In libcasper.h
				.In casper/cap_jail.h
				.Ft int
				.Fn cap_jail_get "cap_channel_t chan" " struct iovec iov" " u_int niov" " int flags"
				.Sh DESCRIPTION
				The function
				.Fn cap_jail_get
				is equivalent to
				.Xr jail_get 2
				except that the connection to the
				.Nm system.jail
				service needs to be provided.
				.Sh EXAMPLES
				The following example first opens a capability to casper and then uses this
				capability to create the
				.Nm system.jail
				casper service and uses it to get the
				.Dv jid
				and
				.Dv name
				of the first jail
				.Bd -literal
				cap_channel_t capcas, capjail;
				struct iovec iov[4];
				char name[256];
				int jid;

				capcas = cap_init();
				if (capcas == NULL)
				err(1, "Unable to contact Casper");

				/* Enter capability mode sandbox. */
				if (cap_enter() < 0 && errno != ENOSYS)
				err(1, "Unable to enter capability mode");

				/* Use Casper capability to create capability to the system.jail service. */
				capjail = cap_service_open(capcas, "system.jail");
				if (capjail == NULL)
				err(1, "Unable to open system.jail service");

				/* Close Casper capability, we don't need it anymore. */
				cap_close(capcas);

				/* prepare iovs */
				jid = 0;
				iov[0].iov_base = __DECONST(char *, "lastjid");
				iov[0].iov_len = strlen(iov[0].iov_base) + 1;
				iov[1].iov_base = &jid;
				iov[1].iov_len = sizeof(jid);
				iov[2].iov_base = __DECONST(char *, "name");
				iov[2].iov_len = strlen(iov[2].iov_base) + 1;
				iov[3].iov_base = name;
				iov[3].iov_len = sizeof(name);

				/* Fetch values */
				jid = cap_jail_get(capjail, iov, 4, 0);

				if (jid < 0 && errno != ENOENT)
				err(1, "Unable to get jail information");
				if (jid > 0)
				printf("jid = %d name = %s\\n", jid, name);
				else
				printf("no jails\\n");

				cap_close(capjail);
				.Ed
				.Sh SEE ALSO
				.Xr cap_enter 2 ,
				.Xr jail_get 2 ,
				.Xr capsicum 4 ,
				.Sh AUTHORS
				The
				.Nm cap_jail
				service and this manual page were written by
				.An Stefan Grundmann