repair/dir_stack.c

   1 /*
   2  * Copyright (c) 2000 Silicon Graphics, Inc.  All Rights Reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it would be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11  *
  12  * Further, this software is distributed without any warranty that it is
  13  * free of the rightful claim of any third person regarding infringement
  14  * or the like.  Any license provided herein, whether implied or
  15  * otherwise, applies only to this software file.  Patent licenses, if
  16  * any, provided herein do not apply to combinations of this program with
  17  * other software, or any other product whatsoever.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write the Free Software Foundation, Inc., 59
  21  * Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22  *
  23  * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
  24  * Mountain View, CA  94043, or:
  25  *
  26  * http://www.sgi.com
  27  *
  28  * For further information regarding this notice, see:
  29  *
  30  * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
  31  */
  32
  33 #include <libxfs.h>
  34 #include "dir_stack.h"
  35 #include "err_protos.h"
  36
  37 /*
  38  * a directory stack for holding directories while
  39  * we traverse filesystem hierarchy subtrees.
  40  * names are kind of misleading as this is really
  41  * implemented as an inode stack.  so sue me...
  42  */
  43
  44 static dir_stack_t      dirstack_freelist;
  45 static int              dirstack_init = 0;
  46
  47 void
  48 dir_stack_init(dir_stack_t *stack)
  49 {
  50         stack->cnt = 0;
  51         stack->head = NULL;
  52
  53         if (dirstack_init == 0)  {
  54                 dirstack_init = 1;
  55                 dir_stack_init(&dirstack_freelist);
  56         }
  57
  58         stack->cnt = 0;
  59         stack->head = NULL;
  60
  61         return;
  62 }
  63
  64 static void
  65 dir_stack_push(dir_stack_t *stack, dir_stack_elem_t *elem)
  66 {
  67         ASSERT(stack->cnt > 0 || (stack->cnt == 0 && stack->head == NULL));
  68
  69         elem->next = stack->head;
  70         stack->head = elem;
  71         stack->cnt++;
  72
  73         return;
  74 }
  75
  76 static dir_stack_elem_t *
  77 dir_stack_pop(dir_stack_t *stack)
  78 {
  79         dir_stack_elem_t *elem;
  80
  81         if (stack->cnt == 0)  {
  82                 ASSERT(stack->head == NULL);
  83                 return(NULL);
  84         }
  85
  86         elem = stack->head;
  87
  88         ASSERT(elem != NULL);
  89
  90         stack->head = elem->next;
  91         elem->next = NULL;
  92         stack->cnt--;
  93
  94         return(elem);
  95 }
  96
  97 void
  98 push_dir(dir_stack_t *stack, xfs_ino_t ino)
  99 {
 100         dir_stack_elem_t *elem;
 101
 102         if (dirstack_freelist.cnt == 0)  {
 103                 if ((elem = malloc(sizeof(dir_stack_elem_t))) == NULL)  {
 104                         do_error(
 105                         "couldn't malloc dir stack element, try more swap\n");
 106                         exit(1);
 107                 }
 108         } else  {
 109                 elem = dir_stack_pop(&dirstack_freelist);
 110         }
 111
 112         elem->ino = ino;
 113
 114         dir_stack_push(stack, elem);
 115
 116         return;
 117 }
 118
 119 xfs_ino_t
 120 pop_dir(dir_stack_t *stack)
 121 {
 122         dir_stack_elem_t *elem;
 123         xfs_ino_t ino;
 124
 125         elem = dir_stack_pop(stack);
 126
 127         if (elem == NULL)
 128                 return(NULLFSINO);
 129
 130         ino = elem->ino;
 131         elem->ino = NULLFSINO;
 132
 133         dir_stack_push(&dirstack_freelist, elem);
 134
 135         return(ino);
 136 }