The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 2010 Jaakko Heinonen <jh@FreeBSD.org>
    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: releng/9.0/sys/fs/devfs/devfs_dir.c 213215 2010-09-27 17:47:09Z jh $
   27  */
   28 
   29 #include <sys/param.h>
   30 #include <sys/conf.h>
   31 #include <sys/types.h>
   32 #include <sys/kernel.h>
   33 #include <sys/libkern.h>
   34 #include <sys/lock.h>
   35 #include <sys/malloc.h>
   36 #include <sys/mutex.h>
   37 #include <sys/queue.h>
   38 #include <sys/systm.h>
   39 #include <sys/sx.h>
   40 
   41 #include <fs/devfs/devfs.h>
   42 #include <fs/devfs/devfs_int.h>
   43 
   44 struct dirlistent {
   45         char                    *dir;
   46         int                     refcnt;
   47         LIST_ENTRY(dirlistent)  link;
   48 };
   49 
   50 static LIST_HEAD(, dirlistent) devfs_dirlist =
   51     LIST_HEAD_INITIALIZER(devfs_dirlist);
   52 
   53 static MALLOC_DEFINE(M_DEVFS4, "DEVFS4", "DEVFS directory list");
   54 
   55 static struct mtx dirlist_mtx;
   56 MTX_SYSINIT(dirlist_mtx, &dirlist_mtx, "devfs dirlist lock", MTX_DEF);
   57 
   58 /* Returns 1 if the path is in the directory list. */
   59 int
   60 devfs_dir_find(const char *path)
   61 {
   62         struct dirlistent *dle;
   63 
   64         mtx_lock(&dirlist_mtx);
   65         LIST_FOREACH(dle, &devfs_dirlist, link) {
   66                 if (devfs_pathpath(dle->dir, path) != 0) {
   67                         mtx_unlock(&dirlist_mtx);
   68                         return (1);
   69                 }
   70         }
   71         mtx_unlock(&dirlist_mtx);
   72 
   73         return (0);
   74 }
   75 
   76 static struct dirlistent *
   77 devfs_dir_findent_locked(const char *dir)
   78 {
   79         struct dirlistent *dle;
   80 
   81         mtx_assert(&dirlist_mtx, MA_OWNED);
   82 
   83         LIST_FOREACH(dle, &devfs_dirlist, link) {
   84                 if (strcmp(dir, dle->dir) == 0)
   85                         return (dle);
   86         }
   87 
   88         return (NULL);
   89 }
   90 
   91 static void
   92 devfs_dir_ref(const char *dir)
   93 {
   94         struct dirlistent *dle, *dle_new;
   95 
   96         if (*dir == '\0')
   97                 return;
   98 
   99         dle_new = malloc(sizeof(*dle), M_DEVFS4, M_WAITOK);
  100         dle_new->dir = strdup(dir, M_DEVFS4);
  101         dle_new->refcnt = 1;
  102 
  103         mtx_lock(&dirlist_mtx);
  104         dle = devfs_dir_findent_locked(dir);
  105         if (dle != NULL) {
  106                 dle->refcnt++;
  107                 mtx_unlock(&dirlist_mtx);
  108                 free(dle_new->dir, M_DEVFS4);
  109                 free(dle_new, M_DEVFS4);
  110                 return;
  111         }
  112         LIST_INSERT_HEAD(&devfs_dirlist, dle_new, link);
  113         mtx_unlock(&dirlist_mtx);
  114 }
  115 
  116 void
  117 devfs_dir_ref_de(struct devfs_mount *dm, struct devfs_dirent *de)
  118 {
  119         char dirname[SPECNAMELEN + 1], *namep;
  120 
  121         namep = devfs_fqpn(dirname, dm, de, NULL);
  122         KASSERT(namep != NULL, ("devfs_ref_dir_de: NULL namep"));
  123 
  124         devfs_dir_ref(namep);
  125 }
  126 
  127 static void
  128 devfs_dir_unref(const char *dir)
  129 {
  130         struct dirlistent *dle;
  131 
  132         if (*dir == '\0')
  133                 return;
  134 
  135         mtx_lock(&dirlist_mtx);
  136         dle = devfs_dir_findent_locked(dir);
  137         KASSERT(dle != NULL, ("devfs_dir_unref: dir %s not referenced", dir));
  138         dle->refcnt--;
  139         KASSERT(dle->refcnt >= 0, ("devfs_dir_unref: negative refcnt"));
  140         if (dle->refcnt == 0) {
  141                 LIST_REMOVE(dle, link);
  142                 mtx_unlock(&dirlist_mtx);
  143                 free(dle->dir, M_DEVFS4);
  144                 free(dle, M_DEVFS4);
  145         } else
  146                 mtx_unlock(&dirlist_mtx);
  147 }
  148 
  149 void
  150 devfs_dir_unref_de(struct devfs_mount *dm, struct devfs_dirent *de)
  151 {
  152         char dirname[SPECNAMELEN + 1], *namep;
  153 
  154         namep = devfs_fqpn(dirname, dm, de, NULL);
  155         KASSERT(namep != NULL, ("devfs_unref_dir_de: NULL namep"));
  156 
  157         devfs_dir_unref(namep);
  158 }
  159 
  160 /* Returns 1 if the path p1 contains the path p2. */
  161 int
  162 devfs_pathpath(const char *p1, const char *p2)
  163 {
  164 
  165         for (;;p1++, p2++) {
  166                 if (*p1 != *p2) {
  167                         if (*p1 == '/' && *p2 == '\0')
  168                                 return (1);
  169                         else
  170                                 return (0);
  171                 } else if (*p1 == '\0')
  172                         return (1);
  173         }
  174         /* NOTREACHED */
  175 }

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