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28 .\" @(#)fts.3 8.5 (Berkeley) 4/16/94
36 .Nd traverse a file hierarchy
42 .Fn fts_open "char * const *path_argv" "int options" "int (*compar)(const FTSENT * const *, const FTSENT * const *)"
44 .Fn fts_read "FTS *ftsp"
46 .Fn fts_children "FTS *ftsp" "int options"
48 .Fn fts_set "FTS *ftsp" "FTSENT *f" "int options"
50 .Fn fts_set_clientptr "FTS *ftsp" "void *clientdata"
52 .Fn fts_get_clientptr "FTS *ftsp"
54 .Fn fts_get_stream "FTSENT *f"
56 .Fn fts_close "FTS *ftsp"
60 functions are provided for traversing
63 A simple overview is that the
67 on a file hierarchy, which is then supplied to
73 returns a pointer to a structure describing one of the files in the file
77 returns a pointer to a linked list of structures, each of which describes
78 one of the files contained in a directory in the hierarchy.
79 In general, directories are visited two distinguishable times; in pre-order
80 (before any of their descendants are visited) and in post-order (after all
81 of their descendants have been visited).
82 Files are visited once.
83 It is possible to walk the hierarchy
85 (ignoring symbolic links)
86 or physically (visiting symbolic links), order the walk of the hierarchy or
87 prune and/or re-visit portions of the hierarchy.
89 Two structures are defined (and typedef'd) in the include file
93 the structure that represents the file hierarchy itself.
96 the structure that represents a file in the file
100 structure is returned for every file in the file
105 .Dq Vt FTSENT No structure
111 structure contains space for a single pointer, which may be used to
112 store application data or per-hierarchy state.
114 .Fn fts_set_clientptr
116 .Fn fts_get_clientptr
117 functions may be used to set and retrieve this pointer.
118 This is likely to be useful only when accessed from the sort
119 comparison function, which can determine the original
121 stream of its arguments using the
126 functions are also available as macros of the same name.
130 structure contains at least the following fields, which are
131 described in greater detail below:
133 typedef struct _ftsent {
134 int fts_info; /* status for FTSENT structure */
135 char *fts_accpath; /* access path */
136 char *fts_path; /* root path */
137 size_t fts_pathlen; /* strlen(fts_path) */
138 char *fts_name; /* file name */
139 size_t fts_namelen; /* strlen(fts_name) */
140 long fts_level; /* depth (\-1 to N) */
141 int fts_errno; /* file errno */
142 long long fts_number; /* local numeric value */
143 void *fts_pointer; /* local address value */
144 struct ftsent *fts_parent; /* parent directory */
145 struct ftsent *fts_link; /* next file structure */
146 struct ftsent *fts_cycle; /* cycle structure */
147 struct stat *fts_statp; /* stat(2) information */
151 These fields are defined as follows:
152 .Bl -tag -width "fts_namelen"
154 One of the following values describing the returned
157 the file it represents.
158 With the exception of directories without errors
161 entries are terminal, that is, they will not be revisited, nor will any
162 of their descendants be visited.
163 .Bl -tag -width FTS_DEFAULT
165 A directory being visited in pre-order.
167 A directory that causes a cycle in the tree.
172 structure will be filled in as well.)
176 structure that represents a file type not explicitly described
181 A directory which cannot be read.
182 This is an error return, and the
184 field will be set to indicate what caused the error.
190 which was not specified as a file name to
195 A directory being visited in post-order.
198 structure will be unchanged from when
199 the directory was visited in pre-order, except for the
203 This is an error return, and the
205 field will be set to indicate what caused the error.
211 information was available.
215 This is an error return, and the
217 field will be set to indicate what caused the error.
221 information was requested.
228 A symbolic link with a non-existent target.
231 field reference the file characteristic information for the symbolic link
235 A path for accessing the file from the current directory.
237 The path for the file relative to the root of the traversal.
238 This path contains the path specified to
242 The length of the string referenced by
245 The name of the file.
247 The length of the string referenced by
250 The depth of the traversal, numbered from \-1 to N, where this file
254 structure representing the parent of the starting point (or root)
255 of the traversal is numbered
256 .Dv FTS_ROOTPARENTLEVEL
259 structure for the root
279 field contains the value of the external variable
281 specifying the cause of the error.
282 Otherwise, the contents of the
286 This field is provided for the use of the application program and is
290 It is initialized to 0.
292 This field is provided for the use of the application program and is
301 structure referencing the file in the hierarchy
302 immediately above the current file, i.e., the directory of which this
304 A parent structure for the initial entry point is provided as well,
311 fields are guaranteed to be initialized.
317 field points to the next structure in the NULL-terminated linked list of
319 Otherwise, the contents of the
323 If a directory causes a cycle in the hierarchy (see
326 of a hard link between two directories, or a symbolic link pointing to a
329 field of the structure will point to the
331 structure in the hierarchy that references the same file as the current
334 Otherwise, the contents of the
340 information for the file.
343 A single buffer is used for all of the paths of all of the files in the
349 fields are guaranteed to be
350 .Dv NUL Ns -terminated
352 for the file most recently returned by
354 To use these fields to reference any files represented by other
356 structures will require that the path buffer be modified using the
357 information contained in that
362 Any such modifications should be undone before further calls to
368 .Dv NUL Ns -terminated .
372 is mutually exclusive with the use of
379 function takes a pointer to an array of character pointers naming one
380 or more paths which make up a logical file hierarchy to be traversed.
381 The array must be terminated by a
386 a number of options, at least one of which (either
391 The options are selected by
393 the following values:
394 .Bl -tag -width "FTS_PHYSICAL"
396 This option causes any symbolic link specified as a root path to be
397 followed immediately whether or not
401 This option causes the
405 structures for the targets of symbolic links
406 instead of the symbolic links themselves.
407 If this option is set, the only symbolic links for which
410 are returned to the application are those referencing non-existent files.
420 To allow descending to arbitrary depths
423 and improve performance, the
425 functions change directories as they walk the file hierarchy.
426 This has the side-effect that an application cannot rely on being
427 in any particular directory during the traversal.
430 option turns off this feature, and the
432 functions will not change the current directory.
433 Note that applications should not themselves change their current directory
434 and try to access files unless
436 is specified and absolute
437 pathnames were provided as arguments to
442 structures reference file characteristic information (the
444 field) for each file visited.
445 This option relaxes that requirement as a performance optimization,
452 and leave the contents of the
456 This option causes the
460 structures for symbolic links themselves instead
461 of the target files they point to.
462 If this option is set,
464 structures for all symbolic links in the
465 hierarchy are returned to the application.
475 By default, unless they are specified as path arguments to
481 encountered in the file hierarchy are ignored.
482 This option causes the
490 from descending into directories that have a different device number
491 than the file from which the descent began.
496 specifies a user-defined function which may be used to order the traversal
499 takes two pointers to pointers to
501 structures as arguments and
502 should return a negative value, zero, or a positive value to indicate
503 if the file referenced by its first argument comes before, in any order
504 with respect to, or after, the file referenced by its second argument.
514 be used in this comparison.
523 field may not either.
528 the directory traversal order is in the order listed in
530 for the root paths, and in the order listed in the directory for
535 function returns a pointer to an
537 structure describing a file in
539 Directories (that are readable and do not cause cycles) are visited at
540 least twice, once in pre-order and once in post-order.
541 All other files are visited at least once.
542 (Hard links between directories that do not cause cycles or symbolic
543 links to symbolic links may cause files to be visited more than once,
544 or directories more than twice.)
546 If all the members of the hierarchy have been returned,
550 and sets the external variable
553 If an error unrelated to a file in the hierarchy occurs,
560 If an error related to a returned file occurs, a pointer to an
562 structure is returned, and
564 may or may not have been set (see
569 structures returned by
571 may be overwritten after a call to
573 on the same file hierarchy stream, or, after a call to
575 on the same file hierarchy stream unless they represent a file of type
576 directory, in which case they will not be overwritten until after a call to
580 structure has been returned by the function
586 function returns a pointer to an
588 structure describing the first entry in a NULL-terminated linked list of
589 the files in the directory represented by the
591 structure most recently returned by
593 The list is linked through the
597 structure, and is ordered by the user-specified comparison function, if any.
600 will recreate this linked list.
602 As a special case, if
604 has not yet been called for a hierarchy,
606 will return a pointer to the files in the logical directory specified to
608 i.e., the arguments specified to
612 structure most recently returned by
614 is not a directory being visited in pre-order,
615 or the directory does not contain any files,
632 structures returned by
634 may be overwritten after a call to
639 on the same file hierarchy stream.
642 may be set to the following value:
643 .Bl -tag -width FTS_NAMEONLY
645 Only the names of the files are needed.
646 The contents of all the fields in the returned linked list of structures
647 are undefined with the exception of the
656 allows the user application to determine further processing for the
664 returns 0 on success, and \-1 if an error occurs.
666 must be set to one of the following values:
667 .Bl -tag -width FTS_PHYSICAL
669 Re-visit the file; any file type may be re-visited.
672 will return the referenced file.
677 fields of the structure will be reinitialized at that time,
678 but no other fields will have been changed.
679 This option is meaningful only for the most recently returned
682 Normal use is for post-order directory visits, where it causes the
683 directory to be re-visited (in both pre and post-order) as well as all
686 The referenced file must be a symbolic link.
687 If the referenced file is the one most recently returned by
691 returns the file with the
695 fields reinitialized to reflect the target of the symbolic link instead
696 of the symbolic link itself.
697 If the file is one of those most recently returned by
703 fields of the structure, when returned by
705 will reflect the target of the symbolic link instead of the symbolic link
707 In either case, if the target of the symbolic link does not exist the
708 fields of the returned structure will be unchanged and the
713 If the target of the link is a directory, the pre-order return, followed
714 by the return of all of its descendants, followed by a post-order return,
717 No descendants of this file are visited.
718 The file may be one of those most recently returned by either
726 function closes a file hierarchy stream
728 and restores the current directory to the directory from which
735 returns 0 on success, and \-1 if an error occurs.
741 for any of the errors specified for the library functions
750 for any of the errors specified for the library functions
761 for any of the errors specified for the library functions
779 The options were invalid, or the list were empty.
790 interface was first introduced in
793 .Fn fts_get_clientptr ,
796 .Fn fts_set_clientptr
797 functions were introduced in
799 principally to provide for alternative interfaces to the
801 functionality using different data structures.
805 function will automatically set the
809 option is provided, or if it cannot
811 the current directory.