FreeBSD/Linux Kernel Cross Reference
sys/fs/devfs/devfs_dir.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2010 Jaakko Heinonen <jh@FreeBSD.org>
      * 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.
     *
     * $FreeBSD$
     */
    
    #include <sys/param.h>
    #include <sys/conf.h>
    #include <sys/types.h>
    #include <sys/kernel.h>
    #include <sys/libkern.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/queue.h>
    #include <sys/systm.h>
    #include <sys/sx.h>
    
    #include <fs/devfs/devfs.h>
    #include <fs/devfs/devfs_int.h>
    
    struct dirlistent {
            char                    *dir;
            int                     refcnt;
            LIST_ENTRY(dirlistent)  link;
    };
    
    static LIST_HEAD(, dirlistent) devfs_dirlist =
        LIST_HEAD_INITIALIZER(devfs_dirlist);
    
    static MALLOC_DEFINE(M_DEVFS4, "DEVFS4", "DEVFS directory list");
    
    static struct mtx dirlist_mtx;
    MTX_SYSINIT(dirlist_mtx, &dirlist_mtx, "devfs dirlist lock", MTX_DEF);
    
    /* Returns 1 if the path is in the directory list. */
    int
    devfs_dir_find(const char *path)
    {
            struct dirlistent *dle;
    
            mtx_lock(&dirlist_mtx);
            LIST_FOREACH(dle, &devfs_dirlist, link) {
                    if (devfs_pathpath(dle->dir, path) != 0) {
                            mtx_unlock(&dirlist_mtx);
                            return (1);
                    }
            }
            mtx_unlock(&dirlist_mtx);
    
            return (0);
    }
    
    static struct dirlistent *
    devfs_dir_findent_locked(const char *dir)
    {
            struct dirlistent *dle;
    
            mtx_assert(&dirlist_mtx, MA_OWNED);
    
            LIST_FOREACH(dle, &devfs_dirlist, link) {
                    if (strcmp(dir, dle->dir) == 0)
                            return (dle);
            }
    
            return (NULL);
    }
    
    static void
    devfs_dir_ref(const char *dir)
    {
            struct dirlistent *dle, *dle_new;
    
            if (*dir == '\0')
                    return;
   
           dle_new = malloc(sizeof(*dle), M_DEVFS4, M_WAITOK);
           dle_new->dir = strdup(dir, M_DEVFS4);
           dle_new->refcnt = 1;
   
           mtx_lock(&dirlist_mtx);
           dle = devfs_dir_findent_locked(dir);
           if (dle != NULL) {
                   dle->refcnt++;
                   mtx_unlock(&dirlist_mtx);
                   free(dle_new->dir, M_DEVFS4);
                   free(dle_new, M_DEVFS4);
                   return;
           }
           LIST_INSERT_HEAD(&devfs_dirlist, dle_new, link);
           mtx_unlock(&dirlist_mtx);
   }
   
   void
   devfs_dir_ref_de(struct devfs_mount *dm, struct devfs_dirent *de)
   {
           char dirname[SPECNAMELEN + 1], *namep;
   
           namep = devfs_fqpn(dirname, dm, de, NULL);
           KASSERT(namep != NULL, ("devfs_ref_dir_de: NULL namep"));
   
           devfs_dir_ref(namep);
   }
   
   static void
   devfs_dir_unref(const char *dir)
   {
           struct dirlistent *dle;
   
           if (*dir == '\0')
                   return;
   
           mtx_lock(&dirlist_mtx);
           dle = devfs_dir_findent_locked(dir);
           KASSERT(dle != NULL, ("devfs_dir_unref: dir %s not referenced", dir));
           dle->refcnt--;
           KASSERT(dle->refcnt >= 0, ("devfs_dir_unref: negative refcnt"));
           if (dle->refcnt == 0) {
                   LIST_REMOVE(dle, link);
                   mtx_unlock(&dirlist_mtx);
                   free(dle->dir, M_DEVFS4);
                   free(dle, M_DEVFS4);
           } else
                   mtx_unlock(&dirlist_mtx);
   }
   
   void
   devfs_dir_unref_de(struct devfs_mount *dm, struct devfs_dirent *de)
   {
           char dirname[SPECNAMELEN + 1], *namep;
   
           namep = devfs_fqpn(dirname, dm, de, NULL);
           KASSERT(namep != NULL, ("devfs_unref_dir_de: NULL namep"));
   
           devfs_dir_unref(namep);
   }
   
   /* Returns 1 if the path p1 contains the path p2. */
   int
   devfs_pathpath(const char *p1, const char *p2)
   {
   
           for (;;p1++, p2++) {
                   if (*p1 != *p2) {
                           if (*p1 == '/' && *p2 == '\0')
                                   return (1);
                           else
                                   return (0);
                   } else if (*p1 == '\0')
                           return (1);
           }
           /* NOTREACHED */
   }

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