1.\" $NetBSD: fts.3,v 1.21 2002/02/07 07:00:12 ross Exp $ 2.\" 3.\" Copyright (c) 1989, 1991, 1993, 1994 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)fts.3 8.5 (Berkeley) 4/16/94 35.\" 36.Dd April 16, 1994 37.Dt FTS 3 38.Os 39.Sh NAME 40.Nm fts , 41.Nm fts_open , 42.Nm fts_read , 43.Nm fts_children , 44.Nm fts_set , 45.Nm fts_close 46.Nd traverse a file hierarchy 47.Sh LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.Fd #include \*[Lt]sys/types.h\*[Gt] 51.Fd #include \*[Lt]sys/stat.h\*[Gt] 52.Fd #include \*[Lt]fts.h\*[Gt] 53.Ft FTS * 54.Fn fts_open "char * const *path_argv" "int options" "int (*compar)(const FTSENT **, const FTSENT **)" 55.Ft FTSENT * 56.Fn fts_read "FTS *ftsp" 57.Ft FTSENT * 58.Fn fts_children "FTS *ftsp" "int options" 59.Ft int 60.Fn fts_set "FTS *ftsp" "FTSENT *f" "int options" 61.Ft int 62.Fn fts_close "FTS *ftsp" 63.Sh DESCRIPTION 64The 65.Nm fts 66functions are provided for traversing 67.Ux 68file hierarchies. 69A simple overview is that the 70.Fn fts_open 71function returns a ``handle'' on a file hierarchy, which is then supplied to 72the other 73.Nm fts 74functions. 75The function 76.Fn fts_read 77returns a pointer to a structure describing one of the files in the file 78hierarchy. 79The function 80.Fn fts_children 81returns a pointer to a linked list of structures, each of which describes 82one of the files contained in a directory in the hierarchy. 83In general, directories are visited two distinguishable times; in pre-order 84(before any of their descendants are visited) and in post-order (after all 85of their descendants have been visited). 86Files are visited once. 87It is possible to walk the hierarchy ``logically'' (ignoring symbolic links) 88or physically (visiting symbolic links), order the walk of the hierarchy or 89prune and/or re-visit portions of the hierarchy. 90.Pp 91Two structures are defined (and typedef'd) in the include file 92.Aq Pa fts.h . 93The first is 94.Fa FTS , 95the structure that represents the file hierarchy itself. 96The second is 97.Fa FTSENT , 98the structure that represents a file in the file 99hierarchy. 100Normally, an 101.Fa FTSENT 102structure is returned for every file in the file 103hierarchy. 104In this manual page, ``file'' and 105.Dq Fa FTSENT No structure 106are generally 107interchangeable. 108The 109.Fa FTSENT 110structure contains at least the following fields, which are 111described in greater detail below: 112.Bd -literal 113typedef struct _ftsent { 114 u_short fts_info; /* flags for FTSENT structure */ 115 char *fts_accpath; /* access path */ 116 char *fts_path; /* root path */ 117 short fts_pathlen; /* strlen(fts_path) */ 118 char *fts_name; /* file name */ 119 short fts_namelen; /* strlen(fts_name) */ 120 short fts_level; /* depth (\-1 to N) */ 121 int fts_errno; /* file errno */ 122 long fts_number; /* local numeric value */ 123 void *fts_pointer; /* local address value */ 124 struct ftsent *fts_parent; /* parent directory */ 125 struct ftsent *fts_link; /* next file structure */ 126 struct ftsent *fts_cycle; /* cycle structure */ 127 struct stat *fts_statp; /* stat(2) information */ 128} FTSENT; 129.Ed 130.Pp 131These fields are defined as follows: 132.Bl -tag -width "fts_namelen" 133.It Fa fts_info 134One of the following flags describing the returned 135.Fa FTSENT 136structure and 137the file it represents. 138With the exception of directories without errors 139.Pq Dv FTS_D , 140all of these 141entries are terminal, that is, they will not be revisited, nor will any 142of their descendants be visited. 143.Bl -tag -width FTS_DEFAULT 144.It Dv FTS_D 145A directory being visited in pre-order. 146.It Dv FTS_DC 147A directory that causes a cycle in the tree. 148(The 149.Fa fts_cycle 150field of the 151.Fa FTSENT 152structure will be filled in as well). 153.It Dv FTS_DEFAULT 154Any 155.Fa FTSENT 156structure that represents a file type not explicitly described 157by one of the other 158.Fa fts_info 159values. 160.It Dv FTS_DNR 161A directory which cannot be read. 162This is an error return, and the 163.Fa fts_errno 164field will be set to indicate what caused the error. 165.It Dv FTS_DOT 166A file named 167.Ql \&. 168or 169.Ql .. 170which was not specified as a file name to 171.Fn fts_open 172(see 173.Dv FTS_SEEDOT ) . 174.It Dv FTS_DP 175A directory being visited in post-order. 176The contents of the 177.Fa FTSENT 178structure will be unchanged from when 179it was returned in pre-order, i.e. with the 180.Fa fts_info 181field set to 182.Dv FTS_D . 183.It Dv FTS_ERR 184This is an error return, and the 185.Fa fts_errno 186field will be set to indicate what caused the error. 187.It Dv FTS_F 188A regular file. 189.It Dv FTS_NS 190A file for which no 191.Xr stat 2 192information was available. 193The contents of the 194.Fa fts_statp 195field are undefined. 196This is an error return, and the 197.Fa fts_errno 198field will be set to indicate what caused the error. 199.It Dv FTS_NSOK 200A file for which no 201.Xr stat 2 202information was requested. 203The contents of the 204.Fa fts_statp 205field are undefined. 206.It Dv FTS_SL 207A symbolic link. 208.It Dv FTS_SLNONE 209A symbolic link with a non-existent target. 210The contents of the 211.Fa fts_statp 212field reference the file characteristic information for the symbolic link 213itself. 214.El 215.It Fa fts_accpath 216A path for accessing the file from the current directory. 217.It Fa fts_path 218The path for the file relative to the root of the traversal. 219This path contains the path specified to 220.Fn fts_open 221as a prefix. 222.It Fa fts_pathlen 223The length of the string referenced by 224.Fa fts_path . 225.It Fa fts_name 226The name of the file. 227.It Fa fts_namelen 228The length of the string referenced by 229.Fa fts_name . 230.It Fa fts_level 231The depth of the traversal, numbered from \-1 to N, where this file 232was found. 233The 234.Fa FTSENT 235structure representing the parent of the starting point (or root) 236of the traversal is numbered \-1, and the 237.Fa FTSENT 238structure for the root 239itself is numbered 0. 240.It Fa fts_errno 241Upon return of a 242.Fa FTSENT 243structure from the 244.Fn fts_children 245or 246.Fn fts_read 247functions, with its 248.Fa fts_info 249field set to 250.Dv FTS_DNR , 251.Dv FTS_ERR 252or 253.Dv FTS_NS , 254the 255.Fa fts_errno 256field contains the value of the external variable 257.Va errno 258specifying the cause of the error. 259Otherwise, the contents of the 260.Fa fts_errno 261field are undefined. 262.It Fa fts_number 263This field is provided for the use of the application program and is 264not modified by the 265.Nm fts 266functions. 267It is initialized to 0. 268.It Fa fts_pointer 269This field is provided for the use of the application program and is 270not modified by the 271.Nm fts 272functions. 273It is initialized to 274.Dv NULL . 275.It Fa fts_parent 276A pointer to the 277.Fa FTSENT 278structure referencing the file in the hierarchy 279immediately above the current file, i.e. the directory of which this 280file is a member. 281A parent structure for the initial entry point is provided as well, 282however, only the 283.Fa fts_level , 284.Fa fts_number 285and 286.Fa fts_pointer 287fields are guaranteed to be initialized. 288.It Fa fts_link 289Upon return from the 290.Fn fts_children 291function, the 292.Fa fts_link 293field points to the next structure in the NULL-terminated linked list of 294directory members. 295Otherwise, the contents of the 296.Fa fts_link 297field are undefined. 298.It Fa fts_cycle 299If a directory causes a cycle in the hierarchy (see 300.Dv FTS_DC ) , 301either because 302of a hard link between two directories, or a symbolic link pointing to a 303directory, the 304.Fa fts_cycle 305field of the structure will point to the 306.Fa FTSENT 307structure in the hierarchy that references the same file as the current 308.Fa FTSENT 309structure. 310Otherwise, the contents of the 311.Fa fts_cycle 312field are undefined. 313.It Fa fts_statp 314A pointer to 315.Xr stat 2 316information for the file. 317.El 318.Pp 319A single buffer is used for all of the paths of all of the files in the 320file hierarchy. 321Therefore, the 322.Fa fts_path 323and 324.Fa fts_accpath 325fields are guaranteed to be 326.Dv NULL Ns -terminated 327.Em only 328for the file most recently returned by 329.Fn fts_read . 330To use these fields to reference any files represented by other 331.Fa FTSENT 332structures will require that the path buffer be modified using the 333information contained in that 334.Fa FTSENT 335structure's 336.Fa fts_pathlen 337field. 338Any such modifications should be undone before further calls to 339.Fn fts_read 340are attempted. 341The 342.Fa fts_name 343field is always 344.Dv NULL Ns -terminated . 345.Sh FTS_OPEN 346The 347.Fn fts_open 348function takes a pointer to an array of character pointers naming one 349or more paths which make up a logical file hierarchy to be traversed. 350The array must be terminated by a 351.Dv NULL 352pointer. 353.Pp 354There are 355a number of options, at least one of which (either 356.Dv FTS_LOGICAL 357or 358.Dv FTS_PHYSICAL ) 359must be specified. 360The options are selected by 361.Em or Ns 'ing 362the following values: 363.Bl -tag -width "FTS_PHYSICAL" 364.It Dv FTS_COMFOLLOW 365This option causes any symbolic link specified as a root path to be 366followed immediately whether or not 367.Dv FTS_LOGICAL 368is also specified. 369.It Dv FTS_LOGICAL 370This option causes the 371.Nm fts 372routines to return 373.Fa FTSENT 374structures for the targets of symbolic links 375instead of the symbolic links themselves. 376If this option is set, the only symbolic links for which 377.Fa FTSENT 378structures 379are returned to the application are those referencing non-existent files. 380Either 381.Dv FTS_LOGICAL 382or 383.Dv FTS_PHYSICAL 384.Em must 385be provided to the 386.Fn fts_open 387function. 388.It Dv FTS_NOCHDIR 389As a performance optimization, the 390.Nm fts 391functions change directories as they walk the file hierarchy. 392This has the side-effect that an application cannot rely on being 393in any particular directory during the traversal. 394The 395.Dv FTS_NOCHDIR 396option turns off this optimization, and the 397.Nm fts 398functions will not change the current directory. 399Note that applications should not themselves change their current directory 400and try to access files unless 401.Dv FTS_NOCHDIR 402is specified and absolute 403pathnames were provided as arguments to 404.Fn fts_open . 405.It Dv FTS_NOSTAT 406By default, returned 407.Fa FTSENT 408structures reference file characteristic information (the 409.Fa statp 410field) for each file visited. 411This option relaxes that requirement as a performance optimization, 412allowing the 413.Nm fts 414functions to set the 415.Fa fts_info 416field to 417.Dv FTS_NSOK 418and leave the contents of the 419.Fa statp 420field undefined. 421.It Dv FTS_PHYSICAL 422This option causes the 423.Nm fts 424routines to return 425.Fa FTSENT 426structures for symbolic links themselves instead 427of the target files they point to. 428If this option is set, 429.Fa FTSENT 430structures for all symbolic links in the 431hierarchy are returned to the application. 432Either 433.Dv FTS_LOGICAL 434or 435.Dv FTS_PHYSICAL 436.Em must 437be provided to the 438.Fn fts_open 439function. 440.It Dv FTS_SEEDOT 441By default, unless they are specified as path arguments to 442.Fn fts_open , 443any files named 444.Ql \&. 445or 446.Ql .. 447encountered in the file hierarchy are ignored. 448This option causes the 449.Nm fts 450routines to return 451.Fa FTSENT 452structures for them. 453.It Dv FTS_XDEV 454This option prevents 455.Nm fts 456from descending into directories that have a different device number 457than the file from which the descent began. 458.El 459.Pp 460The argument 461.Fn compar 462specifies a user-defined function which may be used to order the traversal 463of the hierarchy. 464It 465takes two pointers to pointers to 466.Fa FTSENT 467structures as arguments and 468should return a negative value, zero, or a positive value to indicate 469if the file referenced by its first argument comes before, in any order 470with respect to, or after, the file referenced by its second argument. 471The 472.Fa fts_accpath , 473.Fa fts_path 474and 475.Fa fts_pathlen 476fields of the 477.Fa FTSENT 478structures may 479.Em never 480be used in this comparison. 481If the 482.Fa fts_info 483field is set to 484.Dv FTS_NS 485or 486.Dv FTS_NSOK , 487the 488.Fa fts_statp 489field may not either. 490If the 491.Fn compar 492argument is 493.Dv NULL , 494the directory traversal order is in the order listed in 495.Fa path_argv 496for the root paths, and in the order listed in the directory for 497everything else. 498.Sh FTS_READ 499The 500.Fn fts_read 501function returns a pointer to an 502.Fa FTSENT 503structure describing a file in 504the hierarchy. 505Directories (that are readable and do not cause cycles) are visited at 506least twice, once in pre-order and once in post-order. 507All other files are visited at least once. 508(Hard links between directories that do not cause cycles or symbolic 509links to symbolic links may cause files to be visited more than once, 510or directories more than twice.) 511.Pp 512If all the members of the hierarchy have been returned, 513.Fn fts_read 514returns 515.Dv NULL 516and sets the external variable 517.Va errno 518to 0. 519If an error unrelated to a file in the hierarchy occurs, 520.Fn fts_read 521returns 522.Dv NULL 523and sets 524.Va errno 525appropriately. 526If an error related to a returned file occurs, a pointer to an 527.Fa FTSENT 528structure is returned, and 529.Va errno 530may or may not have been set (see 531.Fa fts_info ) . 532.Pp 533The 534.Fa FTSENT 535structures returned by 536.Fn fts_read 537may be overwritten after a call to 538.Fn fts_close 539on the same file hierarchy stream, or, after a call to 540.Fn fts_read 541on the same file hierarchy stream unless they represent a file of type 542directory, in which case they will not be overwritten until after a call to 543.Fn fts_read 544after the 545.Fa FTSENT 546structure has been returned by the function 547.Fn fts_read 548in post-order. 549.Sh FTS_CHILDREN 550The 551.Fn fts_children 552function returns a pointer to an 553.Fa FTSENT 554structure describing the first entry in a NULL-terminated linked list of 555the files in the directory represented by the 556.Fa FTSENT 557structure most recently returned by 558.Fn fts_read . 559The list is linked through the 560.Fa fts_link 561field of the 562.Fa FTSENT 563structure, and is ordered by the user-specified comparison function, if any. 564Repeated calls to 565.Fn fts_children 566will recreate this linked list. 567.Pp 568As a special case, if 569.Fn fts_read 570has not yet been called for a hierarchy, 571.Fn fts_children 572will return a pointer to the files in the logical directory specified to 573.Fn fts_open , 574i.e. the arguments specified to 575.Fn fts_open . 576Otherwise, if the 577.Fa FTSENT 578structure most recently returned by 579.Fn fts_read 580is not a directory being visited in pre-order, 581or the directory does not contain any files, 582.Fn fts_children 583returns 584.Dv NULL 585and sets 586.Va errno 587to zero. 588If an error occurs, 589.Fn fts_children 590returns 591.Dv NULL 592and sets 593.Va errno 594appropriately. 595.Pp 596The 597.Fa FTSENT 598structures returned by 599.Fn fts_children 600may be overwritten after a call to 601.Fn fts_children , 602.Fn fts_close 603or 604.Fn fts_read 605on the same file hierarchy stream. 606.Pp 607.Em Option 608may be set to the following value: 609.Bl -tag -width FTS_NAMEONLY 610.It Dv FTS_NAMEONLY 611Only the names of the files are needed. 612The contents of all the fields in the returned linked list of structures 613are undefined with the exception of the 614.Fa fts_name 615and 616.Fa fts_namelen 617fields. 618.El 619.Sh FTS_SET 620The function 621.Fn fts_set 622allows the user application to determine further processing for the 623file 624.Fa f 625of the stream 626.Fa ftsp . 627The 628.Fn fts_set 629function 630returns 0 on success, and \-1 if an error occurs. 631.Em Option 632must be set to one of the following values: 633.Bl -tag -width FTS_PHYSICAL 634.It Dv FTS_AGAIN 635Re-visit the file; any file type may be re-visited. 636The next call to 637.Fn fts_read 638will return the referenced file. 639The 640.Fa fts_stat 641and 642.Fa fts_info 643fields of the structure will be reinitialized at that time, 644but no other fields will have been changed. 645This option is meaningful only for the most recently returned 646file from 647.Fn fts_read . 648Normal use is for post-order directory visits, where it causes the 649directory to be re-visited (in both pre and post-order) as well as all 650of its descendants. 651.It Dv FTS_FOLLOW 652The referenced file must be a symbolic link. 653If the referenced file is the one most recently returned by 654.Fn fts_read , 655the next call to 656.Fn fts_read 657returns the file with the 658.Fa fts_info 659and 660.Fa fts_statp 661fields reinitialized to reflect the target of the symbolic link instead 662of the symbolic link itself. 663If the file is one of those most recently returned by 664.Fn fts_children , 665the 666.Fa fts_info 667and 668.Fa fts_statp 669fields of the structure, when returned by 670.Fn fts_read , 671will reflect the target of the symbolic link instead of the symbolic link 672itself. 673In either case, if the target of the symbolic link does not exist the 674fields of the returned structure will be unchanged and the 675.Fa fts_info 676field will be set to 677.Dv FTS_SLNONE . 678.Pp 679If the target of the link is a directory, the pre-order return, followed 680by the return of all of its descendants, followed by a post-order return, 681is done. 682.It Dv FTS_SKIP 683No descendants of this file are visited. 684The file may be one of those most recently returned by either 685.Fn fts_children 686or 687.Fn fts_read . 688.El 689.Sh FTS_CLOSE 690The 691.Fn fts_close 692function closes a file hierarchy stream 693.Fa ftsp 694and restores the current directory to the directory from which 695.Fn fts_open 696was called to open 697.Fa ftsp . 698The 699.Fn fts_close 700function 701returns 0 on success, and \-1 if an error occurs. 702.Sh ERRORS 703The function 704.Fn fts_open 705may fail and set 706.Va errno 707for any of the errors specified for the library functions 708.Xr open 2 709and 710.Xr malloc 3 . 711.Pp 712The function 713.Fn fts_close 714may fail and set 715.Va errno 716for any of the errors specified for the library functions 717.Xr chdir 2 718and 719.Xr close 2 . 720.Pp 721The functions 722.Fn fts_read 723and 724.Fn fts_children 725may fail and set 726.Va errno 727for any of the errors specified for the library functions 728.Xr chdir 2 , 729.Xr malloc 3 , 730.Xr opendir 3 , 731.Xr readdir 3 732and 733.Xr stat 2 . 734.Pp 735In addition, 736.Fn fts_children , 737.Fn fts_open 738and 739.Fn fts_set 740may fail and set 741.Va errno 742as follows: 743.Bl -tag -width Er 744.It Bq Er EINVAL 745The options were invalid. 746.El 747.Sh SEE ALSO 748.Xr find 1 , 749.Xr chdir 2 , 750.Xr stat 2 , 751.Xr qsort 3 , 752.Xr symlink 7 753.Sh STANDARDS 754The 755.Nm fts 756utility is expected to be included in a future 757.St -p1003.1-88 758revision. 759