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32 .\" @(#)fts.3 8.5 (Berkeley) 4/16/94
33 .\" $FreeBSD: src/lib/libc/gen/fts.3,v 1.13 2001/09/20 12:32:45 ru Exp $
40 .Nd traverse a file hierarchy
48 .Fn fts_open "char * const *path_argv" "int options" "int (*compar)(const FTSENT **, const FTSENT **)"
50 .Fn fts_open_b "char * const *path_argv" "int options" "int (^compar)(const FTSENT **, const FTSENT **)"
52 .Fn fts_read "FTS *ftsp"
54 .Fn fts_children "FTS *ftsp" "int options"
56 .Fn fts_set "FTS *ftsp" "FTSENT *f" "int options"
58 .Fn fts_close "FTS *ftsp"
62 functions are provided for traversing
65 A simple overview is that the
71 on a file hierarchy, which is then supplied to
77 returns a pointer to a structure describing one of the files in the file
81 returns a pointer to a linked list of structures, each of which describes
82 one of the files contained in a directory in the hierarchy.
83 In general, directories are visited two distinguishable times; in pre-order
84 (before any of their descendants are visited) and in post-order (after all
85 of their descendants have been visited).
86 Files are visited once.
87 It is possible to walk the hierarchy
89 (ignoring symbolic links)
90 or physically (visiting symbolic links), order the walk of the hierarchy or
91 prune and/or re-visit portions of the hierarchy.
93 Two structures are defined (and typedef'd) in the include file
97 the structure that represents the file hierarchy itself.
100 the structure that represents a file in the file
104 structure is returned for every file in the file
109 .Dq Fa FTSENT No structure
114 structure contains at least the following fields, which are
115 described in greater detail below:
117 typedef struct _ftsent {
118 u_short fts_info; /* flags for FTSENT structure */
119 char *fts_accpath; /* access path */
120 char *fts_path; /* root path */
121 u_short fts_pathlen; /* strlen(fts_path) */
122 char *fts_name; /* file name */
123 u_short fts_namelen; /* strlen(fts_name) */
124 short fts_level; /* depth (\-1 to N) */
125 int fts_errno; /* file errno */
126 long fts_number; /* local numeric value */
127 void *fts_pointer; /* local address value */
128 struct ftsent *fts_parent; /* parent directory */
129 struct ftsent *fts_link; /* next file structure */
130 struct ftsent *fts_cycle; /* cycle structure */
131 struct stat *fts_statp; /* stat(2) information */
135 These fields are defined as follows:
136 .Bl -tag -width "fts_namelen"
138 One of the following values describing the returned
141 the file it represents.
142 With the exception of directories without errors
145 entries are terminal, that is, they will not be revisited, nor will any
146 of their descendants be visited.
147 .Bl -tag -width FTS_DEFAULT
149 A directory being visited in pre-order.
151 A directory that causes a cycle in the tree.
156 structure will be filled in as well.)
160 structure that represents a file type not explicitly described
165 A directory which cannot be read.
166 This is an error return, and the
168 field will be set to indicate what caused the error.
174 which was not specified as a file name to
181 A directory being visited in post-order.
184 structure will be unchanged from when
185 it was returned in pre-order, i.e. with the
190 This is an error return, and the
192 field will be set to indicate what caused the error.
198 information was available.
202 This is an error return, and the
204 field will be set to indicate what caused the error.
208 information was requested.
215 A symbolic link with a non-existent target.
218 field reference the file characteristic information for the symbolic link
222 A path for accessing the file from the current directory.
224 The path for the file relative to the root of the traversal.
225 This path contains the path specified to
231 The length of the string referenced by
234 The name of the file.
236 The length of the string referenced by
239 The depth of the traversal, numbered from \-1 to N, where this file
243 structure representing the parent of the starting point (or root)
244 of the traversal is numbered
245 .Dv FTS_ROOTPARENTLEVEL
248 structure for the root
268 field contains the value of the external variable
270 specifying the cause of the error.
271 Otherwise, the contents of the
275 This field is provided for the use of the application program and is
279 It is initialized to 0.
281 This field is provided for the use of the application program and is
290 structure referencing the file in the hierarchy
291 immediately above the current file, i.e. the directory of which this
293 A parent structure for the initial entry point is provided as well,
299 fields are guaranteed to be initialized.
305 field points to the next structure in the NULL-terminated linked list of
307 Otherwise, the contents of the
311 If a directory causes a cycle in the hierarchy (see
314 of a hard link between two directories, or a symbolic link pointing to a
317 field of the structure will point to the
319 structure in the hierarchy that references the same file as the current
322 Otherwise, the contents of the
328 information for the file.
331 A single buffer is used for all of the paths of all of the files in the
337 fields are guaranteed to be
338 .Dv NUL Ns -terminated
340 for the file most recently returned by
342 To use these fields to reference any files represented by other
344 structures will require that the path buffer be modified using the
345 information contained in that
350 Any such modifications should be undone before further calls to
356 .Dv NUL Ns -terminated .
360 function takes a pointer to an array of character pointers naming one
361 or more paths which make up a logical file hierarchy to be traversed.
362 The array must be terminated by a
367 a number of options, at least one of which (either
372 The options are selected by
374 the following values:
375 .Bl -tag -width "FTS_PHYSICAL"
377 This option causes any symbolic link specified as a root path to be
378 followed immediately whether or not
382 This option causes the
386 structures for the targets of symbolic links
387 instead of the symbolic links themselves.
388 If this option is set, the only symbolic links for which
391 are returned to the application are those referencing non-existent files.
401 As a performance optimization, the
403 functions change directories as they walk the file hierarchy.
404 This has the side-effect that an application cannot rely on being
405 in any particular directory during the traversal.
408 option turns off this optimization, and the
410 functions will not change the current directory.
411 Note that applications should not themselves change their current directory
412 and try to access files unless
414 is specified and absolute
415 pathnames were provided as arguments to
420 structures reference file characteristic information (the
422 field) for each file visited.
423 This option relaxes that requirement as a performance optimization,
430 and leave the contents of the
434 This option causes the
438 structures for symbolic links themselves instead
439 of the target files they point to.
440 If this option is set,
442 structures for all symbolic links in the
443 hierarchy are returned to the application.
453 By default, unless they are specified as path arguments to
459 encountered in the file hierarchy are ignored.
460 This option causes the
468 from descending into directories that have a different device number
469 than the file from which the descent began.
474 specifies a user-defined function which may be used to order the traversal
477 takes two pointers to pointers to
479 structures as arguments and
480 should return a negative value, zero, or a positive value to indicate
481 if the file referenced by its first argument comes before, in any order
482 with respect to, or after, the file referenced by its second argument.
492 be used in this comparison.
501 field may not either.
506 the directory traversal order is in the order listed in
508 for the root paths, and in the order listed in the directory for
517 is a block pointer instead of a function pointer.
518 This block is passed to
522 passes its function pointer to
524 .Bd -ragged -offset indent
531 to make a copy of the block, especially for the case when a stack-based
532 block might go out of scope when the subroutine returns.
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.
792 utility is expected to be included in a future
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