1.\" $OpenBSD: scandir.3,v 1.16 2021/06/17 18:18:15 jmc Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 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. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd $Mdocdate: June 17 2021 $ 31.Dt SCANDIR 3 32.Os 33.Sh NAME 34.Nm scandir , 35.Nm alphasort 36.Nd scan a directory 37.Sh SYNOPSIS 38.In sys/types.h 39.In dirent.h 40.Ft int 41.Fo scandir 42.Fa "const char *dirname" 43.Fa "struct dirent ***namelist" 44.Fa "int (*select)(const struct dirent *)" 45.Fa "int (*compar)(const struct dirent **, const struct dirent **)" 46.Fc 47.Ft int 48.Fn alphasort "const struct dirent **d1" "const struct dirent **d2" 49.Sh DESCRIPTION 50The 51.Fn scandir 52function reads the directory 53.Fa dirname 54and builds an array of pointers to directory 55entries using 56.Xr malloc 3 . 57It returns the number of entries in the array. 58A pointer to the array of directory entries is stored in the location 59referenced by 60.Fa namelist . 61.Pp 62The 63.Fa select 64parameter is a pointer to a user-supplied subroutine which is called by 65.Fn scandir 66to select which entries are to be included in the array. 67The select routine is passed a 68pointer to a directory entry and should return a non-zero 69value if the directory entry is to be included in the array. 70If 71.Fa select 72is 73.Dv NULL , 74then all directory entries will be included. 75.Pp 76The 77.Fa compar 78parameter is a pointer to a user-supplied subroutine which is passed to 79.Xr qsort 3 80to sort the completed array. 81If this pointer is 82.Dv NULL , 83the array is not sorted. 84.Pp 85The 86.Fn alphasort 87function is a routine which can be used for the 88.Fa compar 89parameter to sort the array alphabetically. 90.Pp 91The memory allocated for the array can be deallocated with 92.Xr free 3 , 93by freeing each pointer in the array and then the array itself. 94.Sh DIAGNOSTICS 95Returns \-1 if the directory cannot be opened for reading or if 96.Xr malloc 3 97cannot allocate enough memory to hold all the data structures. 98.Sh SEE ALSO 99.Xr malloc 3 , 100.Xr opendir 3 , 101.Xr qsort 3 , 102.Xr dir 5 103.Sh STANDARDS 104The 105.Fn scandir 106and 107.Fn alphasort 108functions conform to 109.St -p1003.1-2008 . 110.Sh HISTORY 111The 112.Fn scandir 113and 114.Fn alphasort 115functions appeared in 116.Bx 4.2 . 117.Pp 118The argument types for 119.Fn alphasort 120and for the 121.Fa compar 122argument to 123.Fn scandir 124were originally 125.Vt "void *" , 126then changed to 127.Vt "const void *" , 128and then finally changed by 129.St -p1003.1-2008 130to their current form of 131.Vt "const struct dirent **" . 132Similarly, the 133.Fn select 134argument to 135.Fn scandir 136was originally 137.Vt "struct dirent *" 138until it was changed to its current form of 139.Vt "const struct dirent *" . 140