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28 .\" @(#)fts.3 8.5 (Berkeley) 4/16/94
36 .Nd traverse a file hierarchy
44 .Fn fts_open "char * const *path_argv" "int options" "int (*compar)(const FTSENT * const *, const FTSENT * const *)"
46 .Fn fts_read "FTS *ftsp"
48 .Fn fts_children "FTS *ftsp" "int options"
50 .Fn fts_set "FTS *ftsp" "FTSENT *f" "int options"
52 .Fn fts_set_clientptr "FTS *ftsp" "void *clientdata"
54 .Fn fts_get_clientptr "FTS *ftsp"
56 .Fn fts_get_stream "FTSENT *f"
58 .Fn fts_close "FTS *ftsp"
62 functions are provided for traversing
65 A simple overview is that the
69 on a file hierarchy, which is then supplied to
75 returns a pointer to a structure describing one of the files in the file
79 returns a pointer to a linked list of structures, each of which describes
80 one of the files contained in a directory in the hierarchy.
81 In general, directories are visited two distinguishable times; in pre-order
82 (before any of their descendants are visited) and in post-order (after all
83 of their descendants have been visited).
84 Files are visited once.
85 It is possible to walk the hierarchy
87 (ignoring symbolic links)
88 or physically (visiting symbolic links), order the walk of the hierarchy or
89 prune and/or re-visit portions of the hierarchy.
91 Two structures are defined (and typedef'd) in the include file
95 the structure that represents the file hierarchy itself.
98 the structure that represents a file in the file
102 structure is returned for every file in the file
107 .Dq Vt FTSENT No structure
113 structure contains space for a single pointer, which may be used to
114 store application data or per-hierarchy state.
116 .Fn fts_set_clientptr
118 .Fn fts_get_clientptr
119 functions may be used to set and retrieve this pointer.
120 This is likely to be useful only when accessed from the sort
121 comparison function, which can determine the original
123 stream of its arguments using the
128 functions are also available as macros of the same name.
132 structure contains at least the following fields, which are
133 described in greater detail below:
135 typedef struct _ftsent {
136 int fts_info; /* status for FTSENT structure */
137 char *fts_accpath; /* access path */
138 char *fts_path; /* root path */
139 size_t fts_pathlen; /* strlen(fts_path) */
140 char *fts_name; /* file name */
141 size_t fts_namelen; /* strlen(fts_name) */
142 long fts_level; /* depth (\-1 to N) */
143 int fts_errno; /* file errno */
144 long long fts_number; /* local numeric value */
145 void *fts_pointer; /* local address value */
146 struct ftsent *fts_parent; /* parent directory */
147 struct ftsent *fts_link; /* next file structure */
148 struct ftsent *fts_cycle; /* cycle structure */
149 struct stat *fts_statp; /* stat(2) information */
153 These fields are defined as follows:
154 .Bl -tag -width "fts_namelen"
156 One of the following values describing the returned
159 the file it represents.
160 With the exception of directories without errors
163 entries are terminal, that is, they will not be revisited, nor will any
164 of their descendants be visited.
165 .Bl -tag -width FTS_DEFAULT
167 A directory being visited in pre-order.
169 A directory that causes a cycle in the tree.
174 structure will be filled in as well.)
178 structure that represents a file type not explicitly described
183 A directory which cannot be read.
184 This is an error return, and the
186 field will be set to indicate what caused the error.
192 which was not specified as a file name to
197 A directory being visited in post-order.
200 structure will be unchanged from when
201 the directory was visited in pre-order, except for the
205 This is an error return, and the
207 field will be set to indicate what caused the error.
213 information was available.
217 This is an error return, and the
219 field will be set to indicate what caused the error.
223 information was requested.
230 A symbolic link with a non-existent target.
233 field reference the file characteristic information for the symbolic link
237 A path for accessing the file from the current directory.
239 The path for the file relative to the root of the traversal.
240 This path contains the path specified to
244 The length of the string referenced by
247 The name of the file.
249 The length of the string referenced by
252 The depth of the traversal, numbered from \-1 to N, where this file
256 structure representing the parent of the starting point (or root)
257 of the traversal is numbered
258 .Dv FTS_ROOTPARENTLEVEL
261 structure for the root
281 field contains the value of the external variable
283 specifying the cause of the error.
284 Otherwise, the contents of the
288 This field is provided for the use of the application program and is
292 It is initialized to 0.
294 This field is provided for the use of the application program and is
303 structure referencing the file in the hierarchy
304 immediately above the current file, i.e., the directory of which this
306 A parent structure for the initial entry point is provided as well,
313 fields are guaranteed to be initialized.
319 field points to the next structure in the NULL-terminated linked list of
321 Otherwise, the contents of the
325 If a directory causes a cycle in the hierarchy (see
328 of a hard link between two directories, or a symbolic link pointing to a
331 field of the structure will point to the
333 structure in the hierarchy that references the same file as the current
336 Otherwise, the contents of the
342 information for the file.
345 A single buffer is used for all of the paths of all of the files in the
351 fields are guaranteed to be
352 .Dv NUL Ns -terminated
354 for the file most recently returned by
356 To use these fields to reference any files represented by other
358 structures will require that the path buffer be modified using the
359 information contained in that
364 Any such modifications should be undone before further calls to
370 .Dv NUL Ns -terminated .
374 is mutually exclusive with the use of
381 function takes a pointer to an array of character pointers naming one
382 or more paths which make up a logical file hierarchy to be traversed.
383 The array must be terminated by a
388 a number of options, at least one of which (either
393 The options are selected by
395 the following values:
396 .Bl -tag -width "FTS_PHYSICAL"
398 This option causes any symbolic link specified as a root path to be
399 followed immediately whether or not
403 This option causes the
407 structures for the targets of symbolic links
408 instead of the symbolic links themselves.
409 If this option is set, the only symbolic links for which
412 are returned to the application are those referencing non-existent files.
422 To allow descending to arbitrary depths
425 and improve performance, the
427 functions change directories as they walk the file hierarchy.
428 This has the side-effect that an application cannot rely on being
429 in any particular directory during the traversal.
432 option turns off this feature, and the
434 functions will not change the current directory.
435 Note that applications should not themselves change their current directory
436 and try to access files unless
438 is specified and absolute
439 pathnames were provided as arguments to
444 structures reference file characteristic information (the
446 field) for each file visited.
447 This option relaxes that requirement as a performance optimization,
454 and leave the contents of the
458 This option causes the
462 structures for symbolic links themselves instead
463 of the target files they point to.
464 If this option is set,
466 structures for all symbolic links in the
467 hierarchy are returned to the application.
477 By default, unless they are specified as path arguments to
483 encountered in the file hierarchy are ignored.
484 This option causes the
492 from descending into directories that have a different device number
493 than the file from which the descent began.
498 specifies a user-defined function which may be used to order the traversal
501 takes two pointers to pointers to
503 structures as arguments and
504 should return a negative value, zero, or a positive value to indicate
505 if the file referenced by its first argument comes before, in any order
506 with respect to, or after, the file referenced by its second argument.
516 be used in this comparison.
525 field may not either.
530 the directory traversal order is in the order listed in
532 for the root paths, and in the order listed in the directory for
537 function returns a pointer to an
539 structure describing a file in
541 Directories (that are readable and do not cause cycles) are visited at
542 least twice, once in pre-order and once in post-order.
543 All other files are visited at least once.
544 (Hard links between directories that do not cause cycles or symbolic
545 links to symbolic links may cause files to be visited more than once,
546 or directories more than twice.)
548 If all the members of the hierarchy have been returned,
552 and sets the external variable
555 If an error unrelated to a file in the hierarchy occurs,
562 If an error related to a returned file occurs, a pointer to an
564 structure is returned, and
566 may or may not have been set (see
571 structures returned by
573 may be overwritten after a call to
575 on the same file hierarchy stream, or, after a call to
577 on the same file hierarchy stream unless they represent a file of type
578 directory, in which case they will not be overwritten until after a call to
582 structure has been returned by the function
588 function returns a pointer to an
590 structure describing the first entry in a NULL-terminated linked list of
591 the files in the directory represented by the
593 structure most recently returned by
595 The list is linked through the
599 structure, and is ordered by the user-specified comparison function, if any.
602 will recreate this linked list.
604 As a special case, if
606 has not yet been called for a hierarchy,
608 will return a pointer to the files in the logical directory specified to
610 i.e., the arguments specified to
614 structure most recently returned by
616 is not a directory being visited in pre-order,
617 or the directory does not contain any files,
634 structures returned by
636 may be overwritten after a call to
641 on the same file hierarchy stream.
644 may be set to the following value:
645 .Bl -tag -width FTS_NAMEONLY
647 Only the names of the files are needed.
648 The contents of all the fields in the returned linked list of structures
649 are undefined with the exception of the
658 allows the user application to determine further processing for the
666 returns 0 on success, and \-1 if an error occurs.
668 must be set to one of the following values:
669 .Bl -tag -width FTS_PHYSICAL
671 Re-visit the file; any file type may be re-visited.
674 will return the referenced file.
679 fields of the structure will be reinitialized at that time,
680 but no other fields will have been changed.
681 This option is meaningful only for the most recently returned
684 Normal use is for post-order directory visits, where it causes the
685 directory to be re-visited (in both pre and post-order) as well as all
688 The referenced file must be a symbolic link.
689 If the referenced file is the one most recently returned by
693 returns the file with the
697 fields reinitialized to reflect the target of the symbolic link instead
698 of the symbolic link itself.
699 If the file is one of those most recently returned by
705 fields of the structure, when returned by
707 will reflect the target of the symbolic link instead of the symbolic link
709 In either case, if the target of the symbolic link does not exist the
710 fields of the returned structure will be unchanged and the
715 If the target of the link is a directory, the pre-order return, followed
716 by the return of all of its descendants, followed by a post-order return,
719 No descendants of this file are visited.
720 The file may be one of those most recently returned by either
728 function closes a file hierarchy stream
730 and restores the current directory to the directory from which
737 returns 0 on success, and \-1 if an error occurs.
743 for any of the errors specified for the library functions
752 for any of the errors specified for the library functions
763 for any of the errors specified for the library functions
781 The options were invalid, or the list were empty.
792 interface was first introduced in
795 .Fn fts_get_clientptr ,
798 .Fn fts_set_clientptr
799 functions were introduced in
801 principally to provide for alternative interfaces to the
803 functionality using different data structures.
807 function will automatically set the
811 option is provided, or if it cannot
813 the current directory.