1 /* Traverse a file hierarchy.
2
3 Copyright (C) 2004-2023 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 */