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[dragonfly.git] / lib / libc / gen / scandir.3
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1.\" Copyright (c) 1983, 1991, 1993
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32.\" @(#)scandir.3 8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: src/lib/libc/gen/scandir.3,v 1.3.2.5 2003/03/15 15:11:05 trhodes Exp $
1de703da 34.\" $DragonFly: src/lib/libc/gen/scandir.3,v 1.2 2003/06/17 04:26:42 dillon Exp $
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35.\"
36.Dd June 4, 1993
37.Dt SCANDIR 3
38.Os
39.Sh NAME
40.Nm scandir ,
41.Nm alphasort
42.Nd scan a directory
43.Sh LIBRARY
44.Lb libc
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 \\*(lp*select\\*(rp\\*(lpstruct dirent *\\*(rp" "int \\*(lp*compar\\*(rp\\*(lpconst void *, const void *\\*(rp"
50.Ft int
51.Fn alphasort "const void *d1" "const void *d2"
52.Sh DESCRIPTION
53The
54.Fn scandir
55function
56reads the directory
57.Fa dirname
58and builds an array of pointers to directory
59entries using
60.Xr malloc 3 .
61It returns the number of entries in the array.
62A pointer to the array of directory entries is stored in the location
63referenced by
64.Fa namelist .
65.Pp
66The
67.Fa select
68argument is a pointer to a user supplied subroutine which is called by
69.Fn scandir
70to select which entries are to be included in the array.
71The select routine is passed a
72pointer to a directory entry and should return a non-zero
73value if the directory entry is to be included in the array.
74If
75.Fa select
76is null, then all the directory entries will be included.
77.Pp
78The
79.Fa compar
80argument is a pointer to a user supplied subroutine which is passed to
81.Xr qsort 3
82to sort the completed array.
83If this pointer is null, the array is not sorted.
84.Pp
85The
86.Fn alphasort
87function
88is a routine which can be used for the
89.Fa compar
90argument to sort the array alphabetically.
91.Pp
92The memory allocated for the array can be deallocated with
93.Xr free 3 ,
94by freeing each pointer in the array and then the array itself.
95.Sh DIAGNOSTICS
96Returns \-1 if the directory cannot be opened for reading or if
97.Xr malloc 3
98cannot allocate enough memory to hold all the data structures.
99.Sh SEE ALSO
100.Xr directory 3 ,
101.Xr malloc 3 ,
102.Xr qsort 3 ,
103.Xr dir 5
104.Sh HISTORY
105The
106.Fn scandir
107and
108.Fn alphasort
109functions appeared in
110.Bx 4.2 .