1 /* Detect cycles in file tree walks.
3 Copyright (C) 2003-2006, 2009-2020 Free Software Foundation, Inc.
5 Written by Jim Meyering.
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 3 of the License, or
10 (at your option) any later version.
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.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <https://www.gnu.org/licenses/>. */
20 #include "cycle-check.h"
23 /* Use each of these to map a device/inode pair to an FTSENT. */
32 AD_compare (void const *x
, void const *y
)
34 struct Active_dir
const *ax
= x
;
35 struct Active_dir
const *ay
= y
;
36 return ax
->ino
== ay
->ino
37 && ax
->dev
== ay
->dev
;
41 AD_hash (void const *x
, size_t table_size
)
43 struct Active_dir
const *ax
= x
;
44 return (uintmax_t) ax
->ino
% table_size
;
47 /* Set up the cycle-detection machinery. */
52 if (fts
->fts_options
& (FTS_TIGHT_CYCLE_CHECK
| FTS_LOGICAL
))
54 enum { HT_INITIAL_SIZE
= 31 };
55 fts
->fts_cycle
.ht
= hash_initialize (HT_INITIAL_SIZE
, NULL
, AD_hash
,
57 if (! fts
->fts_cycle
.ht
)
62 fts
->fts_cycle
.state
= malloc (sizeof *fts
->fts_cycle
.state
);
63 if (! fts
->fts_cycle
.state
)
65 cycle_check_init (fts
->fts_cycle
.state
);
71 /* Enter a directory during a file tree walk. */
74 enter_dir (FTS
*fts
, FTSENT
*ent
)
76 if (fts
->fts_options
& (FTS_TIGHT_CYCLE_CHECK
| FTS_LOGICAL
))
78 struct stat
const *st
= ent
->fts_statp
;
79 struct Active_dir
*ad
= malloc (sizeof *ad
);
80 struct Active_dir
*ad_from_table
;
89 /* See if we've already encountered this directory.
90 This can happen when following symlinks as well as
91 with a corrupted directory hierarchy. */
92 ad_from_table
= hash_insert (fts
->fts_cycle
.ht
, ad
);
94 if (ad_from_table
!= ad
)
100 /* There was an entry with matching dev/inode already in the table.
101 Record the fact that we've found a cycle. */
102 ent
->fts_cycle
= ad_from_table
->fts_ent
;
103 ent
->fts_info
= FTS_DC
;
108 if (cycle_check (fts
->fts_cycle
.state
, ent
->fts_statp
))
110 /* FIXME: setting fts_cycle like this isn't proper.
111 To do what the documentation requires, we'd have to
112 go around the cycle again and find the right entry.
113 But no callers in coreutils use the fts_cycle member. */
114 ent
->fts_cycle
= ent
;
115 ent
->fts_info
= FTS_DC
;
122 /* Leave a directory during a file tree walk. */
125 leave_dir (FTS
*fts
, FTSENT
*ent
)
127 struct stat
const *st
= ent
->fts_statp
;
128 if (fts
->fts_options
& (FTS_TIGHT_CYCLE_CHECK
| FTS_LOGICAL
))
130 struct Active_dir obj
;
132 obj
.dev
= st
->st_dev
;
133 obj
.ino
= st
->st_ino
;
134 found
= hash_remove (fts
->fts_cycle
.ht
, &obj
);
141 FTSENT
*parent
= ent
->fts_parent
;
142 if (parent
!= NULL
&& 0 <= parent
->fts_level
)
143 CYCLE_CHECK_REFLECT_CHDIR_UP (fts
->fts_cycle
.state
,
144 *(parent
->fts_statp
), *st
);
148 /* Free any memory used for cycle detection. */
153 if (sp
->fts_options
& (FTS_TIGHT_CYCLE_CHECK
| FTS_LOGICAL
))
155 if (sp
->fts_cycle
.ht
)
156 hash_free (sp
->fts_cycle
.ht
);
159 free (sp
->fts_cycle
.state
);