src/unlink.c

   1 /* This file is part of GNU tar.
   2    Copyright (C) 2009 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify it
   5    under the terms of the GNU General Public License as published by the
   6    Free Software Foundation; either version 3, or (at your option) any later
   7    version.
   8
   9    This program is distributed in the hope that it will be useful, but
  10    WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  12    Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License along
  15    with this program; if not, write to the Free Software Foundation, Inc.,
  16    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 #include <system.h>
  19 #include "common.h"
  20 #include <quotearg.h>
  21
  22 struct deferred_unlink
  23   {
  24     struct deferred_unlink *next;   /* Next unlink in the queue */
  25     char *file_name;                /* Absolute name of the file to unlink */
  26     bool is_dir;                    /* True if file_name is a directory */
  27     off_t records_written;          /* Number of records written when this
  28                                        entry got added to the queue */
  29   };
  30
  31 /* The unlink queue */
  32 static struct deferred_unlink *dunlink_head, *dunlink_tail;
  33
  34 /* Number of entries in the queue */
  35 static size_t dunlink_count;
  36
  37 /* List of entries available for allocation */
  38 static struct deferred_unlink *dunlink_avail;
  39
  40 /* Delay (number of records written) between adding entry to the
  41    list and its actual removal. */
  42 size_t deferred_unlink_delay = 0;
  43
  44 static struct deferred_unlink *
  45 dunlink_alloc (void)
  46 {
  47   struct deferred_unlink *p;
  48   if (dunlink_avail)
  49     {
  50       p = dunlink_avail;
  51       dunlink_avail = p->next;
  52       p->next  = NULL;
  53     }
  54   else
  55     p = xmalloc (sizeof (*p));
  56   return p;
  57 }
  58
  59 static void
  60 dunlink_reclaim (struct deferred_unlink *p)
  61 {
  62   free (p->file_name);
  63   p->next = dunlink_avail;
  64   dunlink_avail = p;
  65 }
  66
  67 static void
  68 flush_deferred_unlinks (bool force)
  69 {
  70   struct deferred_unlink *p, *prev = NULL;
  71
  72   for (p = dunlink_head; p; )
  73     {
  74       struct deferred_unlink *next = p->next;
  75       if (force
  76           || records_written > p->records_written + deferred_unlink_delay)
  77         {
  78           if (p->is_dir)
  79             {
  80               if (unlinkat (chdir_fd, p->file_name, AT_REMOVEDIR) != 0)
  81                 {
  82                   switch (errno)
  83                     {
  84                     case ENOENT:
  85                       /* nothing to worry about */
  86                       break;
  87                     case ENOTEMPTY:
  88                       if (!force)
  89                         {
  90                           /* Keep the record in list, in the hope we'll
  91                              be able to remove it later */
  92                           prev = p;
  93                           p = next;
  94                           continue;
  95                         }
  96                       /* fall through */
  97                     default:
  98                       rmdir_error (p->file_name);
  99                     }
 100                 }
 101             }
 102           else
 103             {
 104               if (unlinkat (chdir_fd, p->file_name, 0) != 0 && errno != ENOENT)
 105                 unlink_error (p->file_name);
 106             }
 107           dunlink_reclaim (p);
 108           dunlink_count--;
 109           p = next;
 110           if (prev)
 111             prev->next = p;
 112           else
 113             dunlink_head = p;
 114         }
 115       else
 116         {
 117           prev = p;
 118           p = next;
 119         }
 120     }
 121   if (!dunlink_head)
 122     dunlink_tail = NULL;
 123 }
 124
 125 void
 126 finish_deferred_unlinks (void)
 127 {
 128   flush_deferred_unlinks (true);
 129   while (dunlink_avail)
 130     {
 131       struct deferred_unlink *next = dunlink_avail->next;
 132       free (dunlink_avail);
 133       dunlink_avail = next;
 134     }
 135 }
 136
 137 void
 138 queue_deferred_unlink (const char *name, bool is_dir)
 139 {
 140   struct deferred_unlink *p;
 141
 142   if (dunlink_head
 143       && records_written > dunlink_head->records_written + deferred_unlink_delay)
 144     flush_deferred_unlinks (false);
 145
 146   p = dunlink_alloc ();
 147   p->next = NULL;
 148   p->file_name = normalize_filename (name);
 149   p->is_dir = is_dir;
 150   p->records_written = records_written;
 151
 152   if (dunlink_tail)
 153     dunlink_tail->next = p;
 154   else
 155     dunlink_head = p;
 156   dunlink_tail = p;
 157   dunlink_count++;
 158 }