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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 u_short fts_info; /* flags for FTSENT structure */
137 char *fts_accpath; /* access path */
138 char *fts_path; /* root path */
139 u_short fts_pathlen; /* strlen(fts_path) */
140 char *fts_name; /* file name */
141 u_short fts_namelen; /* strlen(fts_name) */
142 short fts_level; /* depth (\-1 to N) */
143 int fts_errno; /* file errno */
144 long fts_number; /* local numeric value */
145 void *fts_pointer; /* local address value */
146 int64_t fts_bignum; /* local 64-bit numeric value */
147 struct ftsent *fts_parent; /* parent directory */
148 struct ftsent *fts_link; /* next file structure */
149 struct ftsent *fts_cycle; /* cycle structure */
150 struct stat *fts_statp; /* stat(2) information */
154 These fields are defined as follows:
155 .Bl -tag -width "fts_namelen"
157 One of the following values describing the returned
160 the file it represents.
161 With the exception of directories without errors
164 entries are terminal, that is, they will not be revisited, nor will any
165 of their descendants be visited.
166 .Bl -tag -width FTS_DEFAULT
168 A directory being visited in pre-order.
170 A directory that causes a cycle in the tree.
175 structure will be filled in as well.)
179 structure that represents a file type not explicitly described
184 A directory which cannot be read.
185 This is an error return, and the
187 field will be set to indicate what caused the error.
193 which was not specified as a file name to
198 A directory being visited in post-order.
201 structure will be unchanged from when
202 it was returned in pre-order, i.e., with the
207 This is an error return, and the
209 field will be set to indicate what caused the error.
215 information was available.
219 This is an error return, and the
221 field will be set to indicate what caused the error.
225 information was requested.
232 A symbolic link with a non-existent target.
235 field reference the file characteristic information for the symbolic link
239 A path for accessing the file from the current directory.
241 The path for the file relative to the root of the traversal.
242 This path contains the path specified to
246 The length of the string referenced by
249 The name of the file.
251 The length of the string referenced by
254 The depth of the traversal, numbered from \-1 to N, where this file
258 structure representing the parent of the starting point (or root)
259 of the traversal is numbered
260 .Dv FTS_ROOTPARENTLEVEL
263 structure for the root
283 field contains the value of the external variable
285 specifying the cause of the error.
286 Otherwise, the contents of the
290 This field is provided for the use of the application program and is
294 It is initialized to 0.
295 Note that this field is overlaid by
298 This field is provided for the use of the application program and is
304 Note that this field is overlaid by
307 This field is provided for the use of the application program and is
311 It is initialized to 0.
312 Note that this field overlays
319 structure referencing the file in the hierarchy
320 immediately above the current file, i.e., the directory of which this
322 A parent structure for the initial entry point is provided as well,
329 fields are guaranteed to be initialized.
335 field points to the next structure in the NULL-terminated linked list of
337 Otherwise, the contents of the
341 If a directory causes a cycle in the hierarchy (see
344 of a hard link between two directories, or a symbolic link pointing to a
347 field of the structure will point to the
349 structure in the hierarchy that references the same file as the current
352 Otherwise, the contents of the
358 information for the file.
361 A single buffer is used for all of the paths of all of the files in the
367 fields are guaranteed to be
368 .Dv NUL Ns -terminated
370 for the file most recently returned by
372 To use these fields to reference any files represented by other
374 structures will require that the path buffer be modified using the
375 information contained in that
380 Any such modifications should be undone before further calls to
386 .Dv NUL Ns -terminated .
390 is mutually exclusive with the use of
397 function takes a pointer to an array of character pointers naming one
398 or more paths which make up a logical file hierarchy to be traversed.
399 The array must be terminated by a
404 a number of options, at least one of which (either
409 The options are selected by
411 the following values:
412 .Bl -tag -width "FTS_PHYSICAL"
414 This option causes any symbolic link specified as a root path to be
415 followed immediately whether or not
419 This option causes the
423 structures for the targets of symbolic links
424 instead of the symbolic links themselves.
425 If this option is set, the only symbolic links for which
428 are returned to the application are those referencing non-existent files.
438 As a performance optimization, the
440 functions change directories as they walk the file hierarchy.
441 This has the side-effect that an application cannot rely on being
442 in any particular directory during the traversal.
445 option turns off this optimization, and the
447 functions will not change the current directory.
448 Note that applications should not themselves change their current directory
449 and try to access files unless
451 is specified and absolute
452 pathnames were provided as arguments to
457 structures reference file characteristic information (the
459 field) for each file visited.
460 This option relaxes that requirement as a performance optimization,
467 and leave the contents of the
471 This option causes the
475 structures for symbolic links themselves instead
476 of the target files they point to.
477 If this option is set,
479 structures for all symbolic links in the
480 hierarchy are returned to the application.
490 By default, unless they are specified as path arguments to
496 encountered in the file hierarchy are ignored.
497 This option causes the
505 from descending into directories that have a different device number
506 than the file from which the descent began.
511 specifies a user-defined function which may be used to order the traversal
514 takes two pointers to pointers to
516 structures as arguments and
517 should return a negative value, zero, or a positive value to indicate
518 if the file referenced by its first argument comes before, in any order
519 with respect to, or after, the file referenced by its second argument.
529 be used in this comparison.
538 field may not either.
543 the directory traversal order is in the order listed in
545 for the root paths, and in the order listed in the directory for
550 function returns a pointer to an
552 structure describing a file in
554 Directories (that are readable and do not cause cycles) are visited at
555 least twice, once in pre-order and once in post-order.
556 All other files are visited at least once.
557 (Hard links between directories that do not cause cycles or symbolic
558 links to symbolic links may cause files to be visited more than once,
559 or directories more than twice.)
561 If all the members of the hierarchy have been returned,
565 and sets the external variable
568 If an error unrelated to a file in the hierarchy occurs,
575 If an error related to a returned file occurs, a pointer to an
577 structure is returned, and
579 may or may not have been set (see
584 structures returned by
586 may be overwritten after a call to
588 on the same file hierarchy stream, or, after a call to
590 on the same file hierarchy stream unless they represent a file of type
591 directory, in which case they will not be overwritten until after a call to
595 structure has been returned by the function
601 function returns a pointer to an
603 structure describing the first entry in a NULL-terminated linked list of
604 the files in the directory represented by the
606 structure most recently returned by
608 The list is linked through the
612 structure, and is ordered by the user-specified comparison function, if any.
615 will recreate this linked list.
617 As a special case, if
619 has not yet been called for a hierarchy,
621 will return a pointer to the files in the logical directory specified to
623 i.e., the arguments specified to
627 structure most recently returned by
629 is not a directory being visited in pre-order,
630 or the directory does not contain any files,
647 structures returned by
649 may be overwritten after a call to
654 on the same file hierarchy stream.
657 may be set to the following value:
658 .Bl -tag -width FTS_NAMEONLY
660 Only the names of the files are needed.
661 The contents of all the fields in the returned linked list of structures
662 are undefined with the exception of the
671 allows the user application to determine further processing for the
679 returns 0 on success, and \-1 if an error occurs.
681 must be set to one of the following values:
682 .Bl -tag -width FTS_PHYSICAL
684 Re-visit the file; any file type may be re-visited.
687 will return the referenced file.
692 fields of the structure will be reinitialized at that time,
693 but no other fields will have been changed.
694 This option is meaningful only for the most recently returned
697 Normal use is for post-order directory visits, where it causes the
698 directory to be re-visited (in both pre and post-order) as well as all
701 The referenced file must be a symbolic link.
702 If the referenced file is the one most recently returned by
706 returns the file with the
710 fields reinitialized to reflect the target of the symbolic link instead
711 of the symbolic link itself.
712 If the file is one of those most recently returned by
718 fields of the structure, when returned by
720 will reflect the target of the symbolic link instead of the symbolic link
722 In either case, if the target of the symbolic link does not exist the
723 fields of the returned structure will be unchanged and the
728 If the target of the link is a directory, the pre-order return, followed
729 by the return of all of its descendants, followed by a post-order return,
732 No descendants of this file are visited.
733 The file may be one of those most recently returned by either
741 function closes a file hierarchy stream
743 and restores the current directory to the directory from which
750 returns 0 on success, and \-1 if an error occurs.
756 for any of the errors specified for the library functions
765 for any of the errors specified for the library functions
776 for any of the errors specified for the library functions
794 The options were invalid.
805 interface was first introduced in
808 .Fn fts_get_clientptr ,
811 .Fn fts_set_clientptr
812 functions were introduced in
814 principally to provide for alternative interfaces to the
816 functionality using different data structures.