172 lines
4.6 KiB
Groff
172 lines
4.6 KiB
Groff
.\" $OpenBSD: scandir.3,v 1.17 2024/04/15 15:47:58 florian Exp $
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.\"
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.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd $Mdocdate: April 15 2024 $
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.Dt SCANDIR 3
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.Os
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.Sh NAME
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.Nm scandir ,
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.Nm scandirat ,
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.Nm alphasort
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.Nd scan a directory
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.Sh SYNOPSIS
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.In sys/types.h
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.In dirent.h
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.Ft int
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.Fo scandir
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.Fa "const char *dirname"
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.Fa "struct dirent ***namelist"
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.Fa "int (*select)(const struct dirent *)"
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.Fa "int (*compar)(const struct dirent **, const struct dirent **)"
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.Fc
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.Ft int
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.Fo scandirat
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.Fa "int dirfd"
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.Fa "const char *dirname"
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.Fa "struct dirent ***namelist"
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.Fa "int (*select)(const struct dirent *)"
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.Fa "int (*compar)(const struct dirent **, const struct dirent **)"
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.Fc
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.Ft int
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.Fn alphasort "const struct dirent **d1" "const struct dirent **d2"
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.Sh DESCRIPTION
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The
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.Fn scandir
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function reads the directory
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.Fa dirname
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and builds an array of pointers to directory
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entries using
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.Xr malloc 3 .
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It returns the number of entries in the array.
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A pointer to the array of directory entries is stored in the location
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referenced by
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.Fa namelist .
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.Pp
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The
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.Fa select
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parameter is a pointer to a user-supplied subroutine which is called by
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.Fn scandir
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to select which entries are to be included in the array.
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The select routine is passed a
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pointer to a directory entry and should return a non-zero
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value if the directory entry is to be included in the array.
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If
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.Fa select
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is
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.Dv NULL ,
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then all directory entries will be included.
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.Pp
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The
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.Fa compar
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parameter is a pointer to a user-supplied subroutine which is passed to
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.Xr qsort 3
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to sort the completed array.
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If this pointer is
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.Dv NULL ,
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the array is not sorted.
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.Pp
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The
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.Fn alphasort
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function is a routine which can be used for the
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.Fa compar
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parameter to sort the array alphabetically.
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.Pp
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The memory allocated for the array can be deallocated with
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.Xr free 3 ,
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by freeing each pointer in the array and then the array itself.
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.Pp
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The
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.Fn scandirat
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function is similar to
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.Fn scandir ,
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but takes an additional
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.Fa dirfd
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argument.
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If
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.Fa dirname
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is relative,
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.Fa dirfd
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must be a valid file descriptor referencing a directory, in which case the
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.Fa dirname
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lookup is performed relative to the directory referenced by
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.Fa dirfd .
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If
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.Fa dirfd
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has the special value
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.Va AT_FDCWD ,
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then the current process directory is used as the base for relative lookups.
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See
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.Xr openat 2
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for additional details.
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.Sh DIAGNOSTICS
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Returns \-1 if the directory cannot be opened for reading or if
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.Xr malloc 3
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cannot allocate enough memory to hold all the data structures.
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.Sh SEE ALSO
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.Xr malloc 3 ,
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.Xr opendir 3 ,
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.Xr qsort 3 ,
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.Xr dir 5
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.Sh STANDARDS
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The
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.Fn scandir
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and
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.Fn alphasort
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functions conform to
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.St -p1003.1-2008 .
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.Sh HISTORY
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The
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.Fn scandir
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and
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.Fn alphasort
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functions appeared in
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.Bx 4.2 .
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.Pp
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The argument types for
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.Fn alphasort
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and for the
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.Fa compar
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argument to
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.Fn scandir
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were originally
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.Vt "void *" ,
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then changed to
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.Vt "const void *" ,
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and then finally changed by
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.St -p1003.1-2008
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to their current form of
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.Vt "const struct dirent **" .
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Similarly, the
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.Fn select
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argument to
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.Fn scandir
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was originally
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.Vt "struct dirent *"
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until it was changed to its current form of
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.Vt "const struct dirent *" .
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