[apple/libc.git] / gen / scandir.3

.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)scandir.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/gen/scandir.3,v 1.9 2007/01/09 00:27:55 imp Exp $
.\"
.Dd May 20, 2008
.Dt SCANDIR 3
.Os
.Sh NAME
.Nm scandir ,
#ifdef UNIFDEF_BLOCKS
.Nm scandir_b ,
#endif
.Nm alphasort
.Nd scan a directory
.Sh SYNOPSIS
.In sys/types.h
.In dirent.h
.Ft int
.Fn scandir "const char *dirname" "struct dirent ***namelist" "int \\*(lp*select\\*(rp\\*(lpstruct dirent *\\*(rp" "int \\*(lp*compar\\*(rp\\*(lpconst void *, const void *\\*(rp"
.Ft int
.Fn alphasort "const void *d1" "const void *d2"
#ifdef UNIFDEF_BLOCKS
.Ft int
.Fn scandir_b "const char *dirname" "struct dirent ***namelist" "int \\*(lp^select\\*(rp\\*(lpstruct dirent *\\*(rp" "int \\*(lp^compar\\*(rp\\*(lpconst void *, const void *\\*(rp"
#endif
.Sh DESCRIPTION
The
.Fn scandir
function
reads the directory
.Fa dirname
and builds an array of pointers to directory
entries using
.Xr malloc 3 .
It returns the number of entries in the array.
A pointer to the array of directory entries is stored in the location
referenced by
.Fa namelist .
.Pp
The
.Fa select
argument is a pointer to a user supplied subroutine which is called by
.Fn scandir
to select which entries are to be included in the array.
The select routine is passed a
pointer to a directory entry and should return a non-zero
value if the directory entry is to be included in the array.
If
.Fa select
is null, then all the directory entries will be included.
.Pp
The
.Fa compar
argument is a pointer to a user supplied subroutine which is passed to
.Xr qsort 3
to sort the completed array.
If this pointer is null, the array is not sorted.
Note that from within the
.Fa compar
subroutine, the two arguments are of type
.Ft const struct dirent ** ,
so that a double-dereference is needed to access the fields in the
.Ft dirent
structure.
.Pp
The
.Fn alphasort
function
is a routine which can be used for the
.Fa compar
argument to sort the array alphabetically.
.Pp
The memory allocated for the array can be deallocated with
.Xr free 3 ,
by freeing each pointer in the array and then the array itself.
#ifdef UNIFDEF_BLOCKS
.Pp
The
.Fn scandir_b
function works the same way as the
.Fn scandir
function, except that
.Fa select
and
.Fa compar
are blocks instead of subroutines.
#endif
.Sh DIAGNOSTICS
Returns \-1 if the directory cannot be opened for reading or if
.Xr malloc 3
cannot allocate enough memory to hold all the data structures.
.Sh SEE ALSO
.Xr directory 3 ,
.Xr malloc 3 ,
.Xr qsort 3 ,
.Xr dir 5
.Sh HISTORY
The
.Fn scandir
and
.Fn alphasort
functions appeared in
.Bx 4.2 .
#ifdef UNIFDEF_BLOCKS
The
.Fn scandir_b
function appeared in Mac OS X 10.6.
#endif
Commit	Line	Data
34e8f829 A	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.
34e8f829 A	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
1f2f436a	29	.\" $FreeBSD: src/lib/libc/gen/scandir.3,v 1.9 2007/01/09 00:27:55 imp Exp $
34e8f829 A	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\\(lpstruct dirent \\(rp" "int \\(lpcompar\\(rp\\(lpconst void , const void \\(rp"
	46	.Ft int
	47	.Fn alphasort "const void d1" "const void d2"
	48	#ifdef UNIFDEF_BLOCKS
	49	.Ft int
	50	.Fn scandir_b "const char dirname" "struct dirent *namelist" "int \\(lp^select\\(rp\\(lpstruct dirent \\(rp" "int \\(lp^compar\\(rp\\(lpconst void , const void \\(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	.Pp
	66	The
	67	.Fa select
	68	argument is a pointer to a user supplied subroutine which is called by
	69	.Fn scandir
	70	to select which entries are to be included in the array.
	71	The select routine is passed a
	72	pointer to a directory entry and should return a non-zero
	73	value if the directory entry is to be included in the array.
	74	If
	75	.Fa select
	76	is null, then all the directory entries will be included.
	77	.Pp
	78	The
	79	.Fa compar
	80	argument is a pointer to a user supplied subroutine which is passed to
	81	.Xr qsort 3
	82	to sort the completed array.
	83	If this pointer is null, the array is not sorted.
	84	Note that from within the
	85	.Fa compar
	86	subroutine, the two arguments are of type
	87	.Ft const struct dirent ** ,
	88	so that a double-dereference is needed to access the fields in the
	89	.Ft dirent
	90	structure.
	91	.Pp
	92	The
	93	.Fn alphasort
94	function
95	is a routine which can be used for the
96	.Fa compar
97	argument to sort the array alphabetically.
98	.Pp
99	The memory allocated for the array can be deallocated with
100	.Xr free 3 ,
101	by freeing each pointer in the array and then the array itself.
102	#ifdef UNIFDEF_BLOCKS
103	.Pp
104	The
105	.Fn scandir_b
106	function works the same way as the
107	.Fn scandir
108	function, except that
109	.Fa select
110	and
111	.Fa compar
112	are blocks instead of subroutines.
113	#endif
114	.Sh DIAGNOSTICS
115	Returns \-1 if the directory cannot be opened for reading or if
116	.Xr malloc 3
117	cannot allocate enough memory to hold all the data structures.
118	.Sh SEE ALSO
119	.Xr directory 3 ,
120	.Xr malloc 3 ,
121	.Xr qsort 3 ,
122	.Xr dir 5
123	.Sh HISTORY
124	The
125	.Fn scandir
126	and
127	.Fn alphasort
128	functions appeared in
129	.Bx 4.2 .
130	#ifdef UNIFDEF_BLOCKS
131	The
132	.Fn scandir_b
133	function appeared in Mac OS X 10.6.
134	#endif