| 1 | /* $NetBSD: vfs_cwd.c,v 1.4 2011/02/15 15:54:28 pooka Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2008 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 17 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 18 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 19 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 20 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 26 | * POSSIBILITY OF SUCH DAMAGE. |
| 27 | */ |
| 28 | |
| 29 | /* |
| 30 | * Current working directory. |
| 31 | */ |
| 32 | |
| 33 | #include <sys/cdefs.h> |
| 34 | __KERNEL_RCSID(0, "$NetBSD: vfs_cwd.c,v 1.4 2011/02/15 15:54:28 pooka Exp $" ); |
| 35 | |
| 36 | #include <sys/param.h> |
| 37 | #include <sys/atomic.h> |
| 38 | #include <sys/filedesc.h> |
| 39 | #include <sys/proc.h> |
| 40 | #include <sys/vnode.h> |
| 41 | |
| 42 | static int cwdi_ctor(void *, void *, int); |
| 43 | static void cwdi_dtor(void *, void *); |
| 44 | |
| 45 | static pool_cache_t cwdi_cache; |
| 46 | |
| 47 | void |
| 48 | cwd_sys_init(void) |
| 49 | { |
| 50 | |
| 51 | cwdi_cache = pool_cache_init(sizeof(struct cwdinfo), coherency_unit, |
| 52 | 0, 0, "cwdi" , NULL, IPL_NONE, cwdi_ctor, cwdi_dtor, NULL); |
| 53 | KASSERT(cwdi_cache != NULL); |
| 54 | } |
| 55 | |
| 56 | /* |
| 57 | * Create an initial cwdinfo structure, using the same current and root |
| 58 | * directories as curproc. |
| 59 | */ |
| 60 | struct cwdinfo * |
| 61 | cwdinit(void) |
| 62 | { |
| 63 | struct cwdinfo *cwdi; |
| 64 | struct cwdinfo *copy; |
| 65 | |
| 66 | cwdi = pool_cache_get(cwdi_cache, PR_WAITOK); |
| 67 | copy = curproc->p_cwdi; |
| 68 | |
| 69 | rw_enter(©->cwdi_lock, RW_READER); |
| 70 | cwdi->cwdi_cdir = copy->cwdi_cdir; |
| 71 | if (cwdi->cwdi_cdir) |
| 72 | vref(cwdi->cwdi_cdir); |
| 73 | cwdi->cwdi_rdir = copy->cwdi_rdir; |
| 74 | if (cwdi->cwdi_rdir) |
| 75 | vref(cwdi->cwdi_rdir); |
| 76 | cwdi->cwdi_edir = copy->cwdi_edir; |
| 77 | if (cwdi->cwdi_edir) |
| 78 | vref(cwdi->cwdi_edir); |
| 79 | cwdi->cwdi_cmask = copy->cwdi_cmask; |
| 80 | cwdi->cwdi_refcnt = 1; |
| 81 | rw_exit(©->cwdi_lock); |
| 82 | |
| 83 | return (cwdi); |
| 84 | } |
| 85 | |
| 86 | static int |
| 87 | cwdi_ctor(void *arg, void *obj, int flags) |
| 88 | { |
| 89 | struct cwdinfo *cwdi = obj; |
| 90 | |
| 91 | rw_init(&cwdi->cwdi_lock); |
| 92 | |
| 93 | return 0; |
| 94 | } |
| 95 | |
| 96 | static void |
| 97 | cwdi_dtor(void *arg, void *obj) |
| 98 | { |
| 99 | struct cwdinfo *cwdi = obj; |
| 100 | |
| 101 | rw_destroy(&cwdi->cwdi_lock); |
| 102 | } |
| 103 | |
| 104 | /* |
| 105 | * Make p2 share p1's cwdinfo. |
| 106 | */ |
| 107 | void |
| 108 | cwdshare(struct proc *p2) |
| 109 | { |
| 110 | struct cwdinfo *cwdi; |
| 111 | |
| 112 | cwdi = curproc->p_cwdi; |
| 113 | |
| 114 | atomic_inc_uint(&cwdi->cwdi_refcnt); |
| 115 | p2->p_cwdi = cwdi; |
| 116 | } |
| 117 | |
| 118 | /* |
| 119 | * Make sure proc has only one reference to its cwdi, creating |
| 120 | * a new one if necessary. |
| 121 | */ |
| 122 | void |
| 123 | cwdunshare(struct proc *p) |
| 124 | { |
| 125 | struct cwdinfo *cwdi = p->p_cwdi; |
| 126 | |
| 127 | if (cwdi->cwdi_refcnt > 1) { |
| 128 | cwdi = cwdinit(); |
| 129 | cwdfree(p->p_cwdi); |
| 130 | p->p_cwdi = cwdi; |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | /* |
| 135 | * Release a cwdinfo structure. |
| 136 | */ |
| 137 | void |
| 138 | cwdfree(struct cwdinfo *cwdi) |
| 139 | { |
| 140 | |
| 141 | if (atomic_dec_uint_nv(&cwdi->cwdi_refcnt) > 0) |
| 142 | return; |
| 143 | |
| 144 | vrele(cwdi->cwdi_cdir); |
| 145 | if (cwdi->cwdi_rdir) |
| 146 | vrele(cwdi->cwdi_rdir); |
| 147 | if (cwdi->cwdi_edir) |
| 148 | vrele(cwdi->cwdi_edir); |
| 149 | pool_cache_put(cwdi_cache, cwdi); |
| 150 | } |
| 151 | |
| 152 | void |
| 153 | cwdexec(struct proc *p) |
| 154 | { |
| 155 | |
| 156 | cwdunshare(p); |
| 157 | |
| 158 | if (p->p_cwdi->cwdi_edir) { |
| 159 | vrele(p->p_cwdi->cwdi_edir); |
| 160 | } |
| 161 | } |
| 162 | |