[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.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 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 1.8 2002/12/19 09:40:21 ru 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.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)scandir.3 8.1 (Berkeley) 6/4/93
	33	.\" $FreeBSD: src/lib/libc/gen/scandir.3,v 1.8 2002/12/19 09:40:21 ru Exp $
	34	.\"
	35	.Dd May 20, 2008
	36	.Dt SCANDIR 3
	37	.Os
	38	.Sh NAME
	39	.Nm scandir ,
	40	#ifdef UNIFDEF_BLOCKS
	41	.Nm scandir_b ,
	42	#endif
	43	.Nm alphasort
	44	.Nd scan a directory
	45	.Sh SYNOPSIS
	46	.In sys/types.h
	47	.In dirent.h
	48	.Ft int
	49	.Fn scandir "const char dirname" "struct dirent *namelist" "int \\(lpselect\\(rp\\(lpstruct dirent \\(rp" "int \\(lpcompar\\(rp\\(lpconst void , const void \\(rp"
	50	.Ft int
	51	.Fn alphasort "const void d1" "const void d2"
	52	#ifdef UNIFDEF_BLOCKS
	53	.Ft int
	54	.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"
	55	#endif
	56	.Sh DESCRIPTION
	57	The
	58	.Fn scandir
	59	function
	60	reads the directory
	61	.Fa dirname
	62	and builds an array of pointers to directory
	63	entries using
	64	.Xr malloc 3 .
65	It returns the number of entries in the array.
66	A pointer to the array of directory entries is stored in the location
67	referenced by
68	.Fa namelist .
69	.Pp
70	The
71	.Fa select
72	argument is a pointer to a user supplied subroutine which is called by
73	.Fn scandir
74	to select which entries are to be included in the array.
75	The select routine is passed a
76	pointer to a directory entry and should return a non-zero
77	value if the directory entry is to be included in the array.
78	If
79	.Fa select
80	is null, then all the directory entries will be included.
81	.Pp
82	The
83	.Fa compar
84	argument is a pointer to a user supplied subroutine which is passed to
85	.Xr qsort 3
86	to sort the completed array.
87	If this pointer is null, the array is not sorted.
88	Note that from within the
89	.Fa compar
90	subroutine, the two arguments are of type
91	.Ft const struct dirent ** ,
92	so that a double-dereference is needed to access the fields in the
93	.Ft dirent
94	structure.
95	.Pp
96	The
97	.Fn alphasort
98	function
99	is a routine which can be used for the
100	.Fa compar
101	argument to sort the array alphabetically.
102	.Pp
103	The memory allocated for the array can be deallocated with
104	.Xr free 3 ,
105	by freeing each pointer in the array and then the array itself.
106	#ifdef UNIFDEF_BLOCKS
107	.Pp
108	The
109	.Fn scandir_b
110	function works the same way as the
111	.Fn scandir
112	function, except that
113	.Fa select
114	and
115	.Fa compar
116	are blocks instead of subroutines.
117	#endif
118	.Sh DIAGNOSTICS
119	Returns \-1 if the directory cannot be opened for reading or if
120	.Xr malloc 3
121	cannot allocate enough memory to hold all the data structures.
122	.Sh SEE ALSO
123	.Xr directory 3 ,
124	.Xr malloc 3 ,
125	.Xr qsort 3 ,
126	.Xr dir 5
127	.Sh HISTORY
128	The
129	.Fn scandir
130	and
131	.Fn alphasort
132	functions appeared in
133	.Bx 4.2 .
134	#ifdef UNIFDEF_BLOCKS
135	The
136	.Fn scandir_b
137	function appeared in Mac OS X 10.6.
138	#endif