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	1	.\" Copyright (c) 1983, 1991, 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 4. Neither the name of the University nor the names of its contributors
	13	.\" may be used to endorse or promote products derived from this software
	14	.\" without specific prior written permission.
	15	.\"
	16	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	17	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	18	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	19	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	20	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	21	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	22	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	23	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	24	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	25	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	26	.\" SUCH DAMAGE.
	27	.\"
	28	.\" @(#)scandir.3 8.1 (Berkeley) 6/4/93
	29	.\" $FreeBSD: src/lib/libc/gen/scandir.3,v 1.9 2007/01/09 00:27:55 imp Exp $
	30	.\"
	31	.Dd May 20, 2008
	32	.Dt SCANDIR 3
	33	.Os
	34	.Sh NAME
	35	.Nm scandir ,
	36	#ifdef UNIFDEF_BLOCKS
	37	.Nm scandir_b ,
	38	#endif
	39	.Nm alphasort
	40	.Nd scan a directory
	41	.Sh SYNOPSIS
	42	.In sys/types.h
	43	.In dirent.h
	44	.Ft int
	45	.Fn scandir "const char dirname" "struct dirent *namelist" "int \\(lpselect\\(rp\\(lpconst struct dirent \\(rp" "int \\(lpcompar\\(rp\\(lpconst struct dirent , const struct dirent \\(rp"
	46	.Ft int
	47	.Fn alphasort "const struct dirent d1" "const struct dirent d2"
	48	#ifdef UNIFDEF_BLOCKS
	49	.Ft int
	50	.Fn scandir_b "const char dirname" "struct dirent *namelist" "int \\(lp^select\\(rp\\(lpconst struct dirent \\(rp" "int \\(lp^compar\\(rp\\(lpconst struct dirent , const struct dirent \\(rp"
	51	#endif
	52	.Sh DESCRIPTION
	53	The
	54	.Fn scandir
	55	function
	56	reads the directory
	57	.Fa dirname
	58	and builds an array of pointers to directory
	59	entries using
	60	.Xr malloc 3 .
	61	It returns the number of entries in the array.
	62	A pointer to the array of directory entries is stored in the location
	63	referenced by
	64	.Fa namelist
	65	(even if the number of entries is 0).
	66	.Pp
	67	The
	68	.Fa select
	69	argument is a pointer to a user supplied subroutine which is called by
	70	.Fn scandir
	71	to select which entries are to be included in the array.
	72	The select routine is passed a
	73	pointer to a directory entry and should return a non-zero
	74	value if the directory entry is to be included in the array.
	75	If
	76	.Fa select
	77	is null, then all the directory entries will be included.
	78	.Pp
	79	The
	80	.Fa compar
	81	argument is a pointer to a user supplied subroutine which is passed to
	82	.Xr qsort 3
	83	to sort the completed array.
	84	If this pointer is null, the array is not sorted.
	85	.Pp
	86	The
	87	.Fn alphasort
	88	function
	89	is a routine which can be used for the
	90	.Fa compar
	91	argument to sort the array alphabetically.
	92	.Pp
	93	The memory allocated for the array can be deallocated with
	94	.Xr free 3 ,
	95	by freeing each pointer in the array and then the array itself.
	96	#ifdef UNIFDEF_BLOCKS
	97	.Pp
	98	The
	99	.Fn scandir_b
	100	function works the same way as the
	101	.Fn scandir
	102	function, except that
	103	.Fa select
	104	and
	105	.Fa compar
	106	are blocks instead of subroutines.
	107	#endif
	108	.Sh DIAGNOSTICS
	109	Returns \-1 if the directory cannot be opened for reading or if
	110	.Xr malloc 3
	111	cannot allocate enough memory to hold all the data structures.
	112	.Sh SEE ALSO
	113	.Xr directory 3 ,
	114	.Xr malloc 3 ,
	115	.Xr qsort 3 ,
	116	.Xr dir 5
	117	.Sh HISTORY
	118	The
	119	.Fn scandir
	120	and
	121	.Fn alphasort
	122	functions appeared in
	123	.Bx 4.2 .
	124	#ifdef UNIFDEF_BLOCKS
	125	The
	126	.Fn scandir_b
	127	function appeared in Mac OS X 10.6.
	128	#endif