lib/fts_.h

   1 /* Traverse a file hierarchy.
   2
   3    Copyright (C) 2004-2024 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation, either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /*
  19  * Copyright (c) 1989, 1993
  20  *      The Regents of the University of California.  All rights reserved.
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  * 4. Neither the name of the University nor the names of its contributors
  31  *    may be used to endorse or promote products derived from this software
  32  *    without specific prior written permission.
  33  *
  34  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
  35  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  36  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  37  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  38  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  39  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  40  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  41  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  42  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  43  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  44  * SUCH DAMAGE.
  45  *
  46  *      @(#)fts.h       8.3 (Berkeley) 8/14/94
  47  */
  48
  49 #ifndef _FTS_H
  50 # define _FTS_H 1
  51
  52 /* This file uses _GL_ATTRIBUTE_DEALLOC, _GL_ATTRIBUTE_NODISCARD.  */
  53 # if !_LIBC && !_GL_CONFIG_H_INCLUDED
  54 #  error "Please include config.h first."
  55 # endif
  56
  57 # ifdef _LIBC
  58 #  include <features.h>
  59 #  if __STDC_VERSION__ < 199901L
  60 #   define __FLEXIBLE_ARRAY_MEMBER 1
  61 #  else
  62 #   define __FLEXIBLE_ARRAY_MEMBER
  63 #  endif
  64 # else
  65 #  define __FLEXIBLE_ARRAY_MEMBER FLEXIBLE_ARRAY_MEMBER
  66 #  undef __THROW
  67 #  define __THROW
  68 #  undef __BEGIN_DECLS
  69 #  undef __END_DECLS
  70 #  ifdef __cplusplus
  71 #   define __BEGIN_DECLS extern "C" {
  72 #   define __END_DECLS }
  73 #  else
  74 #   define __BEGIN_DECLS
  75 #   define __END_DECLS
  76 #  endif
  77 # endif
  78
  79 # include <stddef.h>
  80 # include <sys/types.h>
  81 # include <dirent.h>
  82 # include <sys/stat.h>
  83 # include "i-ring.h"
  84
  85 typedef struct {
  86         struct _ftsent *fts_cur;        /* current node */
  87         struct _ftsent *fts_child;      /* linked list of children */
  88         struct _ftsent **fts_array;     /* sort array */
  89         dev_t fts_dev;                  /* starting device # */
  90         char *fts_path;                 /* file name for this descent */
  91         int fts_rfd;                    /* fd for root */
  92         int fts_cwd_fd;                 /* the file descriptor on which the
  93                                            virtual cwd is open, or AT_FDCWD */
  94         size_t fts_pathlen;             /* sizeof(path) */
  95         size_t fts_nitems;              /* elements in the sort array */
  96         int (*fts_compar) (struct _ftsent const **, struct _ftsent const **);
  97                                         /* compare fn */
  98
  99 # define FTS_COMFOLLOW  0x0001          /* follow command line symlinks */
 100 # define FTS_LOGICAL    0x0002          /* logical walk */
 101 # define FTS_NOCHDIR    0x0004          /* don't change directories */
 102 # define FTS_NOSTAT     0x0008          /* don't get stat info */
 103 # define FTS_PHYSICAL   0x0010          /* physical walk */
 104 # define FTS_SEEDOT     0x0020          /* return dot and dot-dot */
 105 # define FTS_XDEV       0x0040          /* don't cross devices */
 106 # define FTS_WHITEOUT   0x0080          /* return whiteout information */
 107
 108   /* There are two ways to detect cycles.
 109      The lazy way (which works only with FTS_PHYSICAL),
 110      with which one may process a directory that is a
 111      part of the cycle several times before detecting the cycle.
 112      The "tight" way, whereby fts uses more memory (proportional
 113      to number of "active" directories, aka distance from root
 114      of current tree to current directory -- see active_dir_ht)
 115      to detect any cycle right away.  For example, du must use
 116      this option to avoid counting disk space in a cycle multiple
 117      times, but chown -R need not.
 118      The default is to use the constant-memory lazy way, when possible
 119      (see below).
 120
 121      However, with FTS_LOGICAL (when following symlinks, e.g., chown -L)
 122      using lazy cycle detection is inadequate.  For example, traversing
 123      a directory containing a symbolic link to a peer directory, it is
 124      possible to encounter the same directory twice even though there
 125      is no cycle:
 126      dir
 127      ...
 128      slink -> dir
 129      So, when FTS_LOGICAL is selected, we have to use a different
 130      mode of cycle detection: FTS_TIGHT_CYCLE_CHECK.  */
 131 # define FTS_TIGHT_CYCLE_CHECK  0x0100
 132
 133   /* Use this flag to enable semantics with which the parent
 134      application may be made both more efficient and more robust.
 135      Whereas the default is to visit each directory in a recursive
 136      traversal (via chdir), using this flag makes it so the initial
 137      working directory is never changed.  Instead, these functions
 138      perform the traversal via a virtual working directory, maintained
 139      through the file descriptor member, fts_cwd_fd.  */
 140 # define FTS_CWDFD              0x0200
 141
 142   /* Historically, for each directory that fts initially encounters, it would
 143      open it, read all entries, and stat each entry, storing the results, and
 144      then it would process the first entry.  But that behavior is bad for
 145      locality of reference, and also causes trouble with inode-simulating
 146      file systems like FAT, CIFS, FUSE-based ones, etc., when entries from
 147      their name/inode cache are flushed too early.
 148      Use this flag to make fts_open and fts_read defer the stat/lstat/fststat
 149      of each entry until it is actually processed.  However, note that if you
 150      use this option and also specify a comparison function, that function may
 151      not examine any data via fts_statp.  However, when fts_statp->st_mode is
 152      nonzero, the S_IFMT type bits are valid, with mapped dirent.d_type data.
 153      Of course, that happens only on file systems that provide useful
 154      dirent.d_type data.  */
 155 # define FTS_DEFER_STAT         0x0400
 156
 157   /* Use this flag to disable stripping of trailing slashes
 158      from input path names during fts_open initialization.  */
 159 # define FTS_VERBATIM   0x0800
 160
 161 # define FTS_OPTIONMASK 0x0fff          /* valid user option mask */
 162
 163 # define FTS_NAMEONLY   0x1000          /* (private) child names only */
 164 # define FTS_STOP       0x2000          /* (private) unrecoverable error */
 165         int fts_options;                /* fts_open options, global flags */
 166
 167         /* Map a directory's device number to a boolean.  The boolean is
 168            true if for that file system (type determined by a single fstatfs
 169            call per FS) st_nlink can be used to calculate the number of
 170            sub-directory entries in a directory.
 171            Using this table is an optimization that permits us to look up
 172            file system type on a per-inode basis at the minimal cost of
 173            calling fstatfs only once per traversed device.  */
 174         struct hash_table *fts_leaf_optimization_works_ht;
 175
 176         union {
 177                 /* This data structure is used if FTS_TIGHT_CYCLE_CHECK is
 178                    specified.  It records the directories between a starting
 179                    point and the current directory.  I.e., a directory is
 180                    recorded here IFF we have visited it once, but we have not
 181                    yet completed processing of all its entries.  Every time we
 182                    visit a new directory, we add that directory to this set.
 183                    When we finish with a directory (usually by visiting it a
 184                    second time), we remove it from this set.  Each entry in
 185                    this data structure is a device/inode pair.  This data
 186                    structure is used to detect directory cycles efficiently and
 187                    promptly even when the depth of a hierarchy is in the tens
 188                    of thousands.  */
 189                 struct hash_table *ht;
 190
 191                 /* FIXME: rename these two members to have the fts_ prefix */
 192                 /* This data structure uses a lazy cycle-detection algorithm,
 193                    as done by rm via cycle-check.c.  It's the default,
 194                    but it's not appropriate for programs like du.  */
 195                 struct cycle_check_state *state;
 196         } fts_cycle;
 197
 198         /* A stack of the file descriptors corresponding to the
 199            most-recently traversed parent directories.
 200            Currently used only in FTS_CWDFD mode.  */
 201         I_ring fts_fd_ring;
 202 } FTS;
 203
 204 typedef struct _ftsent {
 205         struct _ftsent *fts_cycle;      /* cycle node */
 206         struct _ftsent *fts_parent;     /* parent directory */
 207         struct _ftsent *fts_link;       /* next file in directory */
 208         DIR *fts_dirp;                  /* Dir pointer for any directory
 209                                            containing more entries than we
 210                                            read at one time.  */
 211         long fts_number;                /* local numeric value */
 212         void *fts_pointer;              /* local address value */
 213         char *fts_accpath;              /* access file name */
 214         char *fts_path;                 /* root name; == fts_fts->fts_path */
 215         int fts_errno;                  /* errno for this node */
 216         int fts_symfd;                  /* fd for symlink */
 217         size_t fts_pathlen;             /* strlen(fts_path) */
 218
 219         FTS *fts_fts;                   /* the file hierarchy itself */
 220
 221 # define FTS_ROOTPARENTLEVEL    (-1)
 222 # define FTS_ROOTLEVEL           0
 223         ptrdiff_t fts_level;            /* depth (-1 to N) */
 224
 225         size_t fts_namelen;             /* strlen(fts_name) */
 226
 227 # define FTS_D           1              /* preorder directory */
 228 # define FTS_DC          2              /* directory that causes cycles */
 229 # define FTS_DEFAULT     3              /* none of the above */
 230 # define FTS_DNR         4              /* unreadable directory */
 231 # define FTS_DOT         5              /* dot or dot-dot */
 232 # define FTS_DP          6              /* postorder directory */
 233 # define FTS_ERR         7              /* error; errno is set */
 234 # define FTS_F           8              /* regular file */
 235 # define FTS_INIT        9              /* initialized only */
 236 # define FTS_NS         10              /* stat(2) failed */
 237 # define FTS_NSOK       11              /* no stat(2) requested */
 238 # define FTS_SL         12              /* symbolic link */
 239 # define FTS_SLNONE     13              /* symbolic link without target */
 240 # define FTS_W          14              /* whiteout object */
 241         unsigned short int fts_info;    /* user flags for FTSENT structure */
 242
 243 # define FTS_DONTCHDIR   0x01           /* don't chdir .. to the parent */
 244 # define FTS_SYMFOLLOW   0x02           /* followed a symlink to get here */
 245         unsigned short int fts_flags;   /* private flags for FTSENT structure */
 246
 247 # define FTS_AGAIN       1              /* read node again */
 248 # define FTS_FOLLOW      2              /* follow symbolic link */
 249 # define FTS_NOINSTR     3              /* no instructions */
 250 # define FTS_SKIP        4              /* discard node */
 251         unsigned short int fts_instr;   /* fts_set() instructions */
 252
 253         struct stat fts_statp[1];       /* stat(2) information */
 254         char fts_name[__FLEXIBLE_ARRAY_MEMBER]; /* file name */
 255 } FTSENT;
 256
 257 __BEGIN_DECLS
 258
 259  _GL_ATTRIBUTE_NODISCARD
 260 FTSENT  *fts_children (FTS *, int) __THROW;
 261
 262 _GL_ATTRIBUTE_NODISCARD
 263 int      fts_close (FTS *) __THROW;
 264
 265 _GL_ATTRIBUTE_NODISCARD
 266 FTS     *fts_open (char * const *, int,
 267                    int (*)(const FTSENT **, const FTSENT **))
 268   _GL_ATTRIBUTE_DEALLOC (fts_close, 1) __THROW;
 269
 270 _GL_ATTRIBUTE_NODISCARD
 271 FTSENT  *fts_read (FTS *) __THROW;
 272
 273 int      fts_set (FTS *, FTSENT *, int) __THROW;
 274
 275 #if GNULIB_FTS_DEBUG
 276 void     fts_cross_check (FTS const *);
 277 #endif
 278 __END_DECLS
 279
 280 #endif /* fts.h */