FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/lib/libspl/os/linux/zone.c

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License (the "License").
      * You may not use this file except in compliance with the License.
      *
      * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      * or https://opensource.org/licenses/CDDL-1.0.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     */
    /*
     * Copyright 2006 Ricardo Correia.  All rights reserved.
     * Use is subject to license terms.
     */
    
    #include <unistd.h>
    #include <stdio.h>
    #include <errno.h>
    #include <stdlib.h>
    #include <limits.h>
    #include <string.h>
    
    #include <zone.h>
    
    zoneid_t
    getzoneid(void)
    {
            char path[PATH_MAX];
            char buf[128] = { '\0' };
            char *cp;
    
            int c = snprintf(path, sizeof (path), "/proc/self/ns/user");
            /* This API doesn't have any error checking... */
            if (c < 0 || c >= sizeof (path))
                    return (0);
    
            ssize_t r = readlink(path, buf, sizeof (buf) - 1);
            if (r < 0)
                    return (0);
    
            cp = strchr(buf, '[');
            if (cp == NULL)
                    return (0);
            cp++;
    
            unsigned long n = strtoul(cp, NULL, 10);
            if (n == ULONG_MAX && errno == ERANGE)
                    return (0);
            zoneid_t z = (zoneid_t)n;
    
            return (z);
    }

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