bsd/man/man2/getdirentries.2

   1 .\"     $NetBSD: getdirentries.2,v 1.7 1995/10/12 15:40:50 jtc Exp $
   2 .\"
   3 .\" Copyright (c) 1989, 1991, 1993
   4 .\"     The Regents of the University of California.  All rights reserved.
   5 .\"
   6 .\" Redistribution and use in source and binary forms, with or without
   7 .\" modification, are permitted provided that the following conditions
   8 .\" are met:
   9 .\" 1. Redistributions of source code must retain the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer.
  11 .\" 2. Redistributions in binary form must reproduce the above copyright
  12 .\"    notice, this list of conditions and the following disclaimer in the
  13 .\"    documentation and/or other materials provided with the distribution.
  14 .\" 3. All advertising materials mentioning features or use of this software
  15 .\"    must display the following acknowledgement:
  16 .\"     This product includes software developed by the University of
  17 .\"     California, Berkeley and its contributors.
  18 .\" 4. Neither the name of the University nor the names of its contributors
  19 .\"    may be used to endorse or promote products derived from this software
  20 .\"    without specific prior written permission.
  21 .\"
  22 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32 .\" SUCH DAMAGE.
  33 .\"
  34 .\"     @(#)getdirentries.2     8.1 (Berkeley) 6/9/93
  35 .\"
  36 .Dd June 9, 1993
  37 .Dt GETDIRENTRIES 2
  38 .Os
  39 .Sh NAME
  40 .Nm getdirentries
  41 .Nd "get directory entries in a filesystem independent format"
  42 .Sh SYNOPSIS
  43 .Fd #include <dirent.h>
  44 .Fd #include <sys/types.h>
  45 .Fd #include <sys/dirent.h>
  46 .Ft int
  47 .Fn getdirentries "int fd" "char *buf" "int nbytes" "long *basep"
  48 .Sh DESCRIPTION
  49 .Fn getdirentries
  50 reads directory entries from the directory
  51 referenced by the file descriptor
  52 .Fa fd
  53 into the buffer pointed to by
  54 .Fa buf ,
  55 in a filesystem independent format.
  56 Up to
  57 .Fa nbytes
  58 of data will be transferred.
  59 .Fa Nbytes
  60 must be greater than or equal to the
  61 block size associated with the file,
  62 see
  63 .Xr stat 2 .
  64 Some filesystems may not support
  65 .Fn getdirentries
  66 with buffers smaller than this size.
  67 .Pp
  68 The data in the buffer is a series of
  69 .Em dirent
  70 structures (see
  71 .Xr dir 5)
  72 The order of the directory entries vended out via
  73 .Fn getdirentries
  74 is not specified. Some filesystems may return entries in lexicographic sort order
  75 and others may not.
  76 .Pp
  77 The
  78 .Fa d_fileno
  79 entry is a number which is unique for each
  80 distinct file in the filesystem.
  81 Files that are linked by hard links (see
  82 .Xr link 2 )
  83 have the same
  84 .Fa d_fileno .
  85 Users of
  86 .Fn getdirentries
  87 should skip
  88 entries with
  89 .Fa d_fileno
  90 = 0, as such entries represent files which have been deleted but not yet removed from the directory entry.
  91 The
  92 .Fa d_reclen
  93 entry is the length, in bytes, of the directory record.
  94 The
  95 .Fa d_name
  96 entry contains a null terminated file name.
  97 The
  98 .Fa d_namlen
  99 entry specifies the length of the file name excluding the null byte.
 100 Thus the actual size of
 101 .Fa d_name
 102 may vary from 1 to
 103 .Dv MAXNAMELEN
 104 \&+ 1.
 105 .Fa d_type
 106 is a integer representing the type of the directory entry.  The following types are defined in
 107 .Aq sys/dirent.h :
 108 .Bd -literal -offset indent
 109 #define DT_UNKNOWN       0
 110 #define DT_FIFO          1
 111 #define DT_CHR           2
 112 #define DT_DIR           4
 113 #define DT_BLK           6
 114 #define DT_REG           8
 115 #define DT_LNK          10
 116 #define DT_SOCK         12
 117 #define DT_WHT          14
 118 .Ed
 119 .Pp
 120 Entries may be separated by extra space.
 121 The
 122 .Fa d_reclen
 123 entry may be used as an offset from the start of a
 124 .Fa dirent
 125 structure to the next structure, if any.
 126 .Pp
 127 The actual number of bytes transferred is returned.
 128 The current position pointer associated with
 129 .Fa fd
 130 is set to point to the next block of entries.
 131 The pointer may not advance by the number of bytes returned by
 132 .Fn getdirentries .
 133 A value of zero is returned when
 134 the end of the directory has been reached.
 135 .Pp
 136 .Fn getdirentries
 137 writes the position of the block read into the location pointed to by
 138 .Fa basep .
 139 Alternatively, the current position pointer may be set and retrieved by
 140 .Xr lseek 2 .
 141 The current position pointer should only be set to a value returned by
 142 .Xr lseek 2 ,
 143 a value returned in the location pointed to by
 144 .Fa basep ,
 145 or zero.
 146 .Sh NOTES
 147 .Fn getdirentries
 148 should rarely be used directly; instead,
 149 .Xr opendir 3
 150 and
 151 .Xr readdir 3
 152 should be used.
 153 .Pp
 154 As of Mac OS X 10.6,
 155 .Fn getdirentries
 156 is deprecated, and it is recommended that applications
 157 use
 158 .Xr readdir 3
 159 rather than using
 160 .Fn getdirentries
 161 directly.  Due to limitations with the system call,
 162 .Fn getdirentries
 163 will not work
 164 with 64-bit inodes; in order to use
 165 .Fn getdirentries ,
 166 .Dv _DARWIN_NO_64_BIT_INODE
 167 must be defined.  See
 168 .Xr stat 2
 169 for more information on
 170 .Dv _DARWIN_NO_64_BIT_INODE
 171 and its other effects.
 172 .Sh RETURN VALUES
 173 If successful, the number of bytes actually transferred is returned.
 174 Otherwise, -1 is returned and the global variable
 175 .Va errno
 176 is set to indicate the error.
 177 .Sh ERRORS
 178 .Fn getdirentries
 179 will fail if:
 180 .Bl -tag -width Er
 181 .It Bq Er EBADF
 182 .Fa fd
 183 is not a valid file descriptor open for reading.
 184 .It Bq Er EFAULT
 185 Either
 186 .Fa buf
 187 or
 188 .Fa basep
 189 point outside the allocated address space.
 190 .It Bq Er EIO
 191 An
 192 .Tn I/O
 193 error occurred while reading from or writing to the file system.
 194 .El
 195 .Sh SEE ALSO
 196 .Xr lseek 2 ,
 197 .Xr open 2 ,
 198 .Xr stat 2 ,
 199 .Xr opendir 3 ,
 200 .Xr readdir 3 ,
 201 .Xr dir 5
 202 .Sh HISTORY
 203 The
 204 .Fn getdirentries
 205 function first appeared in 4.4BSD.