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

     /*-
      * Copyright (c) 1998 Michael Smith
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    /*
     * The unified bootloader passes us a pointer to a preserved copy of
     * bootstrap/kernel environment variables.
     * We make these available using sysctl for both in-kernel and
     * out-of-kernel consumers.
     *
     * Note that the current sysctl infrastructure doesn't allow 
     * dynamic insertion or traversal through handled spaces.  Grr.
     */
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/systm.h>
    #include <sys/sysctl.h>
    #include <sys/libkern.h>
    
    char    *kern_envp;
    
    static char     *kernenv_next(char *cp);
    
    /*
     * Look up an environment variable by name.
     */
    char *
    getenv(const char *name)
    {
        char        *cp, *ep;
        int         len;
        
        for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
            for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
                ;
            if (*ep != '=')
                continue;
            len = ep - cp;
            ep++;
            if (!strncmp(name, cp, len) && name[len] == 0)
                return(ep);
        }
        return(NULL);
    }
    
    /*
     * Return a string value from an environment variable.
     */
    int
    getenv_string(const char *name, char *data, int size)
    {
        char *tmp;
    
        tmp = getenv(name);
        if (tmp != NULL) {
            strncpy(data, tmp, size);
            data[size - 1] = 0;
            return (1);
        } else
            return (0);
    }
    
    /*
     * Return an integer value from an environment variable.
     */
    int
    getenv_int(const char *name, int *data)
    {
        quad_t tmp;
        int rval;
    
        rval = getenv_quad(name, &tmp);
        if (rval) {
            *data = (int) tmp;
       }
       return (rval);
   }
   
   /*
    * Return a quad_t value from an environment variable.
    */
   int
   getenv_quad(const char *name, quad_t *data)
   {
       const char  *value;
       char        *vtp;
       quad_t      iv;
       
       if ((value = getenv(name)) == NULL)
           return(0);
       
       iv = strtoq(value, &vtp, 0);
       if ((vtp == value) || (*vtp != '\0'))
           return(0);
       
       *data = iv;
       return(1);
   }
   
   static int
   sysctl_kernenv(SYSCTL_HANDLER_ARGS)
   {
       int         *name = (int *)arg1;
       u_int       namelen = arg2;
       char        *cp;
       int         i, error;
   
       if (kern_envp == NULL)
           return(ENOENT);
       
       name++;
       namelen--;
       
       if (namelen != 1)
           return(EINVAL);
   
       cp = kern_envp;
       for (i = 0; i < name[0]; i++) {
           cp = kernenv_next(cp);
           if (cp == NULL)
               break;
       }
       
       if (cp == NULL)
           return(ENOENT);
       
       error = SYSCTL_OUT(req, cp, strlen(cp) + 1);
       return (error);
   }
   
   SYSCTL_NODE(_kern, OID_AUTO, environment, CTLFLAG_RD, sysctl_kernenv, "kernel environment space");
   
   /*
    * Find the next entry after the one which (cp) falls within, return a
    * pointer to its start or NULL if there are no more.
    */
   static char *
   kernenv_next(char *cp)
   {
       if (cp != NULL) {
           while (*cp != 0)
               cp++;
           cp++;
           if (*cp == 0)
               cp = NULL;
       }
       return(cp);
   }
   
   void
   tunable_int_init(void *data)
   { 
           struct tunable_int *d = (struct tunable_int *)data;
   
           TUNABLE_INT_FETCH(d->path, d->var);
   }
   
   void
   tunable_quad_init(void *data)
   {
           struct tunable_quad *d = (struct tunable_quad *)data;
   
           TUNABLE_QUAD_FETCH(d->path, d->var);
   }
   
   void
   tunable_str_init(void *data)
   {
           struct tunable_str *d = (struct tunable_str *)data;
   
           TUNABLE_STR_FETCH(d->path, d->var, d->size);
   }
   

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