lib/libspl/os/linux/zone.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or https://opensource.org/licenses/CDDL-1.0.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2006 Ricardo Correia.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #include <unistd.h>
  27 #include <stdio.h>
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <limits.h>
  31 #include <string.h>
  32
  33 #include <zone.h>
  34
  35 zoneid_t
  36 getzoneid(void)
  37 {
  38         char path[PATH_MAX];
  39         char buf[128] = { '\0' };
  40         char *cp;
  41
  42         int c = snprintf(path, sizeof (path), "/proc/self/ns/user");
  43         /* This API doesn't have any error checking... */
  44         if (c < 0 || c >= sizeof (path))
  45                 return (GLOBAL_ZONEID);
  46
  47         ssize_t r = readlink(path, buf, sizeof (buf) - 1);
  48         if (r < 0)
  49                 return (GLOBAL_ZONEID);
  50
  51         cp = strchr(buf, '[');
  52         if (cp == NULL)
  53                 return (GLOBAL_ZONEID);
  54         cp++;
  55
  56         unsigned long n = strtoul(cp, NULL, 10);
  57         if (n == ULONG_MAX && errno == ERANGE)
  58                 return (GLOBAL_ZONEID);
  59         zoneid_t z = (zoneid_t)n;
  60
  61         return (z);
  62 }