source/lib/repdir.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (C) Andrew Tridgell 2005
   5    Updated for Samba3 64-bit cleanliness (C) Jeremy Allison 2006
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21 /*
  22   a replacement for opendir/readdir/telldir/seekdir/closedir for BSD systems
  23
  24   This is needed because the existing directory handling in FreeBSD
  25   and OpenBSD (and possibly NetBSD) doesn't correctly handle unlink()
  26   on files in a directory where telldir() has been used. On a block
  27   boundary it will occasionally miss a file when seekdir() is used to
  28   return to a position previously recorded with telldir().
  29
  30   This also fixes a severe performance and memory usage problem with
  31   telldir() on BSD systems. Each call to telldir() in BSD adds an
  32   entry to a linked list, and those entries are cleaned up on
  33   closedir(). This means with a large directory closedir() can take an
  34   arbitrary amount of time, causing network timeouts as millions of
  35   telldir() entries are freed
  36
  37   Note! This replacement code is not portable. It relies on getdents()
  38   always leaving the file descriptor at a seek offset that is a
  39   multiple of DIR_BUF_SIZE. If the code detects that this doesn't
  40   happen then it will abort(). It also does not handle directories
  41   with offsets larger than can be stored in a long,
  42
  43   This code is available under other free software licenses as
  44   well. Contact the author.
  45 */
  46
  47 #include <include/includes.h>
  48
  49  void replace_readdir_dummy(void);
  50  void replace_readdir_dummy(void) {}
  51
  52 #if defined(REPLACE_READDIR)
  53
  54 #if defined(PARANOID_MALLOC_CHECKER)
  55 #ifdef malloc
  56 #undef malloc
  57 #endif
  58 #endif
  59
  60 #define DIR_BUF_BITS 9
  61 #define DIR_BUF_SIZE (1<<DIR_BUF_BITS)
  62
  63 struct dir_buf {
  64         int fd;
  65         int nbytes, ofs;
  66         SMB_OFF_T seekpos;
  67         char buf[DIR_BUF_SIZE];
  68 };
  69
  70 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_OPENDIR64)
  71  SMB_STRUCT_DIR *opendir64(const char *dname)
  72 #else
  73  SMB_STRUCT_DIR *opendir(const char *dname)
  74 #endif
  75 {
  76         struct dir_buf *d;
  77         d = malloc(sizeof(*d));
  78         if (d == NULL) {
  79                 errno = ENOMEM;
  80                 return NULL;
  81         }
  82 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_OPEN64)
  83         d->fd = open64(dname, O_RDONLY);
  84 #else
  85         d->fd = open(dname, O_RDONLY);
  86 #endif
  87
  88         if (d->fd == -1) {
  89                 free(d);
  90                 return NULL;
  91         }
  92         d->ofs = 0;
  93         d->seekpos = 0;
  94         d->nbytes = 0;
  95         return (SMB_STRUCT_DIR *)d;
  96 }
  97
  98 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_READDIR64)
  99  SMB_STRUCT_DIRENT *readdir64(SMB_STRUCT_DIR *dir)
 100 #else
 101  SMB_STRUCT_DIRENT *readdir(SMB_STRUCT_DIR *dir)
 102 #endif
 103 {
 104         struct dir_buf *d = (struct dir_buf *)dir;
 105         SMB_STRUCT_DIRENT *de;
 106
 107         if (d->ofs >= d->nbytes) {
 108 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_LSEEK64)
 109                 d->seekpos = lseek64(d->fd, 0, SEEK_CUR);
 110 #else
 111                 d->seekpos = lseek(d->fd, 0, SEEK_CUR);
 112 #endif
 113
 114 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_GETDENTS64)
 115                 d->nbytes = getdents64(d->fd, d->buf, DIR_BUF_SIZE);
 116 #else
 117                 d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
 118 #endif
 119                 d->ofs = 0;
 120         }
 121         if (d->ofs >= d->nbytes) {
 122                 return NULL;
 123         }
 124         de = (SMB_STRUCT_DIRENT *)&d->buf[d->ofs];
 125         d->ofs += de->d_reclen;
 126         return de;
 127 }
 128
 129 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_TELLDIR64)
 130  long telldir64(SMB_STRUCT_DIR *dir)
 131 #else
 132  long telldir(SMB_STRUCT_DIR *dir)
 133 #endif
 134 {
 135         struct dir_buf *d = (struct dir_buf *)dir;
 136         if (d->ofs >= d->nbytes) {
 137 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_LSEEK64)
 138                 d->seekpos = lseek64(d->fd, 0, SEEK_CUR);
 139 #else
 140                 d->seekpos = lseek(d->fd, 0, SEEK_CUR);
 141 #endif
 142                 d->ofs = 0;
 143                 d->nbytes = 0;
 144         }
 145         /* this relies on seekpos always being a multiple of
 146            DIR_BUF_SIZE. Is that always true on BSD systems? */
 147         if (d->seekpos & (DIR_BUF_SIZE-1)) {
 148                 abort();
 149         }
 150         return d->seekpos + d->ofs;
 151 }
 152
 153 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_SEEKDIR64)
 154  void seekdir64(SMB_STRUCT_DIR *dir, long ofs)
 155 #else
 156  void seekdir(SMB_STRUCT_DIR *dir, long ofs)
 157 #endif
 158 {
 159         struct dir_buf *d = (struct dir_buf *)dir;
 160 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_LSEEK64)
 161         d->seekpos = lseek64(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET);
 162 #else
 163         d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET);
 164 #endif
 165
 166 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_GETDENTS64)
 167         d->nbytes = getdents64(d->fd, d->buf, DIR_BUF_SIZE);
 168 #else
 169         d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
 170 #endif
 171
 172         d->ofs = 0;
 173         while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) {
 174 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_READDIR64)
 175                 if (readdir64(dir) == NULL) break;
 176 #else
 177                 if (readdir(dir) == NULL) break;
 178 #endif
 179         }
 180 }
 181
 182 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_REWINDDIR64)
 183  void rewinddir64(SMB_STRUCT_DIR *dir)
 184 #else
 185  void rewinddir(SMB_STRUCT_DIR *dir)
 186 #endif
 187 {
 188 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_SEEKDIR64)
 189         seekdir64(dir, 0);
 190 #else
 191         seekdir(dir, 0);
 192 #endif
 193 }
 194
 195 #if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_CLOSEDIR64)
 196  int closedir64(SMB_STRUCT_DIR *dir)
 197 #else
 198  int closedir(SMB_STRUCT_DIR *dir)
 199 #endif
 200 {
 201         struct dir_buf *d = (struct dir_buf *)dir;
 202         int r = close(d->fd);
 203         if (r != 0) {
 204                 return r;
 205         }
 206         free(d);
 207         return 0;
 208 }
 209
 210 #ifndef dirfd
 211 /* darn, this is a macro on some systems. */
 212  int dirfd(SMB_STRUCT_DIR *dir)
 213 {
 214         struct dir_buf *d = (struct dir_buf *)dir;
 215         return d->fd;
 216 }
 217 #endif
 218 #endif /* REPLACE_READDIR */