kern_environment.c

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    1 /*-
    2  * Copyright (c) 1998 Michael Smith
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD$
   27  */
   28 
   29 /*
   30  * The unified bootloader passes us a pointer to a preserved copy of
   31  * bootstrap/kernel environment variables.
   32  * We make these available using sysctl for both in-kernel and
   33  * out-of-kernel consumers.
   34  *
   35  * Note that the current sysctl infrastructure doesn't allow 
   36  * dynamic insertion or traversal through handled spaces.  Grr.
   37  */
   38 
   39 #include <sys/param.h>
   40 #include <sys/kernel.h>
   41 #include <sys/systm.h>
   42 #include <sys/sysctl.h>
   43 #include <sys/libkern.h>
   44 #include <machine/bootinfo.h>
   45 
   46 char    *kern_envp;
   47 
   48 static char     *kernenv_next(char *cp);
   49 
   50 char *
   51 getenv(char *name)
   52 {
   53     char        *cp, *ep;
   54     int         len;
   55     
   56     for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
   57         for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
   58             ;
   59         len = ep - cp;
   60         if (*ep == '=')
   61             ep++;
   62         if (!strncmp(name, cp, len))
   63             return(ep);
   64     }
   65     return(NULL);
   66 }
   67 
   68 /*
   69  * Return an integer value from an environment variable.
   70  */
   71 int
   72 getenv_int(char *name, int *data)
   73 {
   74     quad_t tmp;
   75     int rval;
   76 
   77     rval = getenv_quad(name, &tmp);
   78     if (rval) {
   79         *data = (int) tmp;
   80     }
   81     return (rval);
   82 }
   83 
   84 /*
   85  * Return a quad_t value from an environment variable.
   86  */
   87 quad_t
   88 getenv_quad(char *name, quad_t *data)
   89 {
   90     const char  *value;
   91     char        *vtp;
   92     quad_t      iv;
   93     
   94     if ((value = getenv(name)) == NULL)
   95         return(0);
   96     
   97     iv = strtoq(value, &vtp, 0);
   98     if ((vtp == value) || (*vtp != 0))
   99         return(0);
  100     
  101     *data = iv;
  102     return(1);
  103 }
  104 
  105 static int
  106 sysctl_kernenv SYSCTL_HANDLER_ARGS
  107 {
  108     int         *name = (int *)arg1;
  109     u_int       namelen = arg2;
  110     char        *cp;
  111     int         i, error;
  112 
  113     if (kern_envp == NULL)
  114         return(ENOENT);
  115     
  116     name++;
  117     namelen--;
  118     
  119     if (namelen != 1)
  120         return(EINVAL);
  121 
  122     cp = kern_envp;
  123     for (i = 0; i < name[0]; i++) {
  124         cp = kernenv_next(cp);
  125         if (cp == NULL)
  126             break;
  127     }
  128     
  129     if (cp == NULL)
  130         return(ENOENT);
  131     
  132     error = SYSCTL_OUT(req, cp, strlen(cp) + 1);
  133     return (error);
  134 }
  135 
  136 SYSCTL_NODE(_kern, OID_AUTO, environment, CTLFLAG_RD, sysctl_kernenv, "kernel environment space");
  137 
  138 /*
  139  * Find the next entry after the one which (cp) falls within, return a
  140  * pointer to its start or NULL if there are no more.
  141  */
  142 static char *
  143 kernenv_next(char *cp)
  144 {
  145     if (cp != NULL) {
  146         while (*cp != 0)
  147             cp++;
  148         cp++;
  149         if (*cp == 0)
  150             cp = NULL;
  151     }
  152     return(cp);
  153 }
  154

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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_environment.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_environment.c