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1 /* Traverse a file hierarchy.
2
3 Copyright (C) 2004-2021 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 # ifdef _LIBC
53 # include <features.h>
54 # if __STDC_VERSION__ < 199901L
55 # define __FLEXIBLE_ARRAY_MEMBER 1
56 # else
57 # define __FLEXIBLE_ARRAY_MEMBER
58 # endif
59 # else
60 # define __FLEXIBLE_ARRAY_MEMBER FLEXIBLE_ARRAY_MEMBER
61 # undef __THROW
62 # define __THROW
63 # undef __BEGIN_DECLS
64 # undef __END_DECLS
65 # ifdef __cplusplus
66 # define __BEGIN_DECLS extern "C" {
67 # define __END_DECLS }
68 # else
69 # define __BEGIN_DECLS
70 # define __END_DECLS
71 # endif
72 # endif
73
74 # include <stddef.h>
75 # include <sys/types.h>
76 # include <dirent.h>
77 # include <sys/stat.h>
78 # include "i-ring.h"
79
80 typedef struct {
81 struct _ftsent *fts_cur; /* current node */
82 struct _ftsent *fts_child; /* linked list of children */
83 struct _ftsent **fts_array; /* sort array */
84 dev_t fts_dev; /* starting device # */
85 char *fts_path; /* file name for this descent */
86 int fts_rfd; /* fd for root */
87 int fts_cwd_fd; /* the file descriptor on which the
88 virtual cwd is open, or AT_FDCWD */
89 size_t fts_pathlen; /* sizeof(path) */
90 size_t fts_nitems; /* elements in the sort array */
91 int (*fts_compar) (struct _ftsent const **, struct _ftsent const **);
92 /* compare fn */
93
94 # define FTS_COMFOLLOW 0x0001 /* follow command line symlinks */
95 # define FTS_LOGICAL 0x0002 /* logical walk */
96 # define FTS_NOCHDIR 0x0004 /* don't change directories */
97 # define FTS_NOSTAT 0x0008 /* don't get stat info */
98 # define FTS_PHYSICAL 0x0010 /* physical walk */
99 # define FTS_SEEDOT 0x0020 /* return dot and dot-dot */
100 # define FTS_XDEV 0x0040 /* don't cross devices */
101 # define FTS_WHITEOUT 0x0080 /* return whiteout information */
102
103 /* There are two ways to detect cycles.
104 The lazy way (which works only with FTS_PHYSICAL),
105 with which one may process a directory that is a
106 part of the cycle several times before detecting the cycle.
107 The "tight" way, whereby fts uses more memory (proportional
108 to number of "active" directories, aka distance from root
109 of current tree to current directory -- see active_dir_ht)
110 to detect any cycle right away. For example, du must use
111 this option to avoid counting disk space in a cycle multiple
112 times, but chown -R need not.
113 The default is to use the constant-memory lazy way, when possible
114 (see below).
115
116 However, with FTS_LOGICAL (when following symlinks, e.g., chown -L)
117 using lazy cycle detection is inadequate. For example, traversing
118 a directory containing a symbolic link to a peer directory, it is
119 possible to encounter the same directory twice even though there
120 is no cycle:
121 dir
122 ...
123 slink -> dir
124 So, when FTS_LOGICAL is selected, we have to use a different
125 mode of cycle detection: FTS_TIGHT_CYCLE_CHECK. */
126 # define FTS_TIGHT_CYCLE_CHECK 0x0100
127
128 /* Use this flag to enable semantics with which the parent
129 application may be made both more efficient and more robust.
130 Whereas the default is to visit each directory in a recursive
131 traversal (via chdir), using this flag makes it so the initial
132 working directory is never changed. Instead, these functions
133 perform the traversal via a virtual working directory, maintained
134 through the file descriptor member, fts_cwd_fd. */
135 # define FTS_CWDFD 0x0200
136
137 /* Historically, for each directory that fts initially encounters, it would
138 open it, read all entries, and stat each entry, storing the results, and
139 then it would process the first entry. But that behavior is bad for
140 locality of reference, and also causes trouble with inode-simulating
141 file systems like FAT, CIFS, FUSE-based ones, etc., when entries from
142 their name/inode cache are flushed too early.
143 Use this flag to make fts_open and fts_read defer the stat/lstat/fststat
144 of each entry until it is actually processed. However, note that if you
145 use this option and also specify a comparison function, that function may
146 not examine any data via fts_statp. However, when fts_statp->st_mode is
147 nonzero, the S_IFMT type bits are valid, with mapped dirent.d_type data.
148 Of course, that happens only on file systems that provide useful
149 dirent.d_type data. */
150 # define FTS_DEFER_STAT 0x0400
151
152 /* Use this flag to disable stripping of trailing slashes
153 from input path names during fts_open initialization. */
154 # define FTS_VERBATIM 0x0800
155
156 # define FTS_OPTIONMASK 0x0fff /* valid user option mask */
157
158 # define FTS_NAMEONLY 0x1000 /* (private) child names only */
159 # define FTS_STOP 0x2000 /* (private) unrecoverable error */
160 int fts_options; /* fts_open options, global flags */
161
162 /* Map a directory's device number to a boolean. The boolean is
163 true if for that file system (type determined by a single fstatfs
164 call per FS) st_nlink can be used to calculate the number of
165 sub-directory entries in a directory.
166 Using this table is an optimization that permits us to look up
167 file system type on a per-inode basis at the minimal cost of
168 calling fstatfs only once per traversed device. */
169 struct hash_table *fts_leaf_optimization_works_ht;
170
171 union {
172 /* This data structure is used if FTS_TIGHT_CYCLE_CHECK is
173 specified. It records the directories between a starting
174 point and the current directory. I.e., a directory is
175 recorded here IFF we have visited it once, but we have not
176 yet completed processing of all its entries. Every time we
177 visit a new directory, we add that directory to this set.
178 When we finish with a directory (usually by visiting it a
179 second time), we remove it from this set. Each entry in
180 this data structure is a device/inode pair. This data
181 structure is used to detect directory cycles efficiently and
182 promptly even when the depth of a hierarchy is in the tens
183 of thousands. */
184 struct hash_table *ht;
185
186 /* FIXME: rename these two members to have the fts_ prefix */
187 /* This data structure uses a lazy cycle-detection algorithm,
188 as done by rm via cycle-check.c. It's the default,
189 but it's not appropriate for programs like du. */
190 struct cycle_check_state *state;
191 } fts_cycle;
192
193 /* A stack of the file descriptors corresponding to the
194 most-recently traversed parent directories.
195 Currently used only in FTS_CWDFD mode. */
196 I_ring fts_fd_ring;
197 } FTS;
198
199 typedef struct _ftsent {
200 struct _ftsent *fts_cycle; /* cycle node */
201 struct _ftsent *fts_parent; /* parent directory */
202 struct _ftsent *fts_link; /* next file in directory */
203 DIR *fts_dirp; /* Dir pointer for any directory
204 containing more entries than we
205 read at one time. */
206 long fts_number; /* local numeric value */
207 void *fts_pointer; /* local address value */
208 char *fts_accpath; /* access file name */
209 char *fts_path; /* root name; == fts_fts->fts_path */
210 int fts_errno; /* errno for this node */
211 int fts_symfd; /* fd for symlink */
212 size_t fts_pathlen; /* strlen(fts_path) */
213
214 FTS *fts_fts; /* the file hierarchy itself */
215
216 # define FTS_ROOTPARENTLEVEL (-1)
217 # define FTS_ROOTLEVEL 0
218 ptrdiff_t fts_level; /* depth (-1 to N) */
219
220 size_t fts_namelen; /* strlen(fts_name) */
221
222 # define FTS_D 1 /* preorder directory */
223 # define FTS_DC 2 /* directory that causes cycles */
224 # define FTS_DEFAULT 3 /* none of the above */
225 # define FTS_DNR 4 /* unreadable directory */
226 # define FTS_DOT 5 /* dot or dot-dot */
227 # define FTS_DP 6 /* postorder directory */
228 # define FTS_ERR 7 /* error; errno is set */
229 # define FTS_F 8 /* regular file */
230 # define FTS_INIT 9 /* initialized only */
231 # define FTS_NS 10 /* stat(2) failed */
232 # define FTS_NSOK 11 /* no stat(2) requested */
233 # define FTS_SL 12 /* symbolic link */
234 # define FTS_SLNONE 13 /* symbolic link without target */
235 # define FTS_W 14 /* whiteout object */
236 unsigned short int fts_info; /* user flags for FTSENT structure */
237
238 # define FTS_DONTCHDIR 0x01 /* don't chdir .. to the parent */
239 # define FTS_SYMFOLLOW 0x02 /* followed a symlink to get here */
240 unsigned short int fts_flags; /* private flags for FTSENT structure */
241
242 # define FTS_AGAIN 1 /* read node again */
243 # define FTS_FOLLOW 2 /* follow symbolic link */
244 # define FTS_NOINSTR 3 /* no instructions */
245 # define FTS_SKIP 4 /* discard node */
246 unsigned short int fts_instr; /* fts_set() instructions */
247
248 struct stat fts_statp[1]; /* stat(2) information */
249 char fts_name[__FLEXIBLE_ARRAY_MEMBER]; /* file name */
250 } FTSENT;
251
252 __BEGIN_DECLS
253
254 _GL_ATTRIBUTE_NODISCARD
255 FTSENT *fts_children (FTS *, int) __THROW;
256
257 _GL_ATTRIBUTE_NODISCARD
258 int fts_close (FTS *) __THROW;
259
260 _GL_ATTRIBUTE_NODISCARD
261 FTS *fts_open (char * const *, int,
262 int (*)(const FTSENT **, const FTSENT **))
263 _GL_ATTRIBUTE_DEALLOC (fts_close, 1) __THROW;
264
265 _GL_ATTRIBUTE_NODISCARD
266 FTSENT *fts_read (FTS *) __THROW;
267
268 int fts_set (FTS *, FTSENT *, int) __THROW;
269 __END_DECLS
270
271 #endif /* fts.h */
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