4003214ed8
Fixed #includes in synopsis to declare the prototype in the synopsis. Fixed stale types in description of struct dirent.
183 lines
5.2 KiB
Groff
183 lines
5.2 KiB
Groff
.\" Copyright (c) 1989, 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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. 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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.\" @(#)getdirentries.2 8.2 (Berkeley) 5/3/95
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.\"
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.Dd May 3, 1995
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.Dt GETDIRENTRIES 2
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.Os
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.Sh NAME
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.Nm getdirentries
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.Nd "get directory entries in a filesystem independent format"
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <dirent.h>
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.Ft int
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.Fn getdirentries "int fd" "char *buf" "int nbytes" "long *basep"
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.Sh DESCRIPTION
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.Fn Getdirentries
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reads directory entries from the directory
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referenced by the file descriptor
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.Fa fd
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into the buffer pointed to by
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.Fa buf ,
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in a filesystem independent format.
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Up to
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.Fa nbytes
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of data will be transferred.
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.Fa Nbytes
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must be greater than or equal to the
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block size associated with the file,
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see
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.Xr stat 2 .
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Some filesystems may not support
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.Fn getdirentries
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with buffers smaller than this size.
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.Pp
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The data in the buffer is a series of
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.Em dirent
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structures each containing the following entries:
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.Bd -literal -offset indent
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u_int32_t d_fileno;
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u_int16_t d_reclen;
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u_int8_t d_type;
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u_int8_t d_namelen;
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char d_name[MAXNAMELEN + 1]; /* see below */
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.Ed
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.Pp
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The
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.Fa d_fileno
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entry is a number which is unique for each
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distinct file in the filesystem.
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Files that are linked by hard links (see
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.Xr link 2 )
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have the same
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.Fa d_fileno .
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The
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.Fa d_reclen
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entry is the length, in bytes, of the directory record.
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The
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.Fa d_type
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entry is the type of the file pointed to by the directory record.
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The file type values are defined in
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.Fa <sys/dirent.h> .
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The
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.Fa d_name
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entry contains a null terminated file name.
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The
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.Fa d_namlen
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entry specifies the length of the file name excluding the null byte.
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Thus the actual size of
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.Fa d_name
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may vary from 1 to
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.Dv MAXNAMELEN
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\&+ 1.
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.Pp
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Entries may be separated by extra space.
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The
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.Fa d_reclen
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entry may be used as an offset from the start of a
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.Fa dirent
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structure to the next structure, if any.
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.Pp
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The actual number of bytes transferred is returned.
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The current position pointer associated with
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.Fa fd
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is set to point to the next block of entries.
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The pointer may not advance by the number of bytes returned by
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.Fn getdirentries .
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A value of zero is returned when
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the end of the directory has been reached.
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.Pp
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.Fn Getdirentries
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writes the position of the block read into the location pointed to by
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.Fa basep .
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Alternatively, the current position pointer may be set and retrieved by
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.Xr lseek 2 .
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The current position pointer should only be set to a value returned by
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.Xr lseek 2 ,
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a value returned in the location pointed to by
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.Fa basep ,
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or zero.
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.Sh IMPLEMENTATION NOTES
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.Pp
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In the non-threaded library
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.Fn getdirentries
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is implemented as the
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.Va getdirentries
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syscall.
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.Pp
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In the threaded library, the
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.Va getdirentries
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syscall is assembled to
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.Fn _thread_sys_getdirentries
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and
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.Fn getdirentries
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is implemented as a function which locks
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.Va fd
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for read and write, then calls
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.Fn _thread_sys_getdirentries .
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Before returning,
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.Fn getdirentries
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unlocks
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.Va fd .
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.Sh RETURN VALUES
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If successful, the number of bytes actually transferred is returned.
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Otherwise, -1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Fn Getdirentries
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will fail if:
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.Bl -tag -width [EFAULT]
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.It Bq Er EBADF
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.Fa fd
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is not a valid file descriptor open for reading.
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.It Bq Er EFAULT
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Either
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.Fa buf
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or
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.Fa basep
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point outside the allocated address space.
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.It Bq Er EIO
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An
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.Tn I/O
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error occurred while reading from or writing to the file system.
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.El
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.Sh SEE ALSO
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.Xr lseek 2 ,
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.Xr open 2
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.Sh HISTORY
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The
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.Fn getdirentries
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function first appeared in
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.Bx 4.4 .
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