bsd/man/man2/getdirentries.2

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  34 .\"     @(#)getdirentries.2     8.1 (Berkeley) 6/9/93
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  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 .Pp
  73 The
  74 .Fa d_fileno
  75 entry is a number which is unique for each
  76 distinct file in the filesystem.
  77 Files that are linked by hard links (see
  78 .Xr link 2 )
  79 have the same
  80 .Fa d_fileno .
  81 Users of
  82 .Fn getdirentries
  83 should skip
  84 entries with
  85 .Fa d_fileno
  86 = 0, as such entries represent files which have been deleted but not yet removed from the directory entry.
  87 The
  88 .Fa d_reclen
  89 entry is the length, in bytes, of the directory record.
  90 The
  91 .Fa d_name
  92 entry contains a null terminated file name.
  93 The
  94 .Fa d_namlen
  95 entry specifies the length of the file name excluding the null byte.
  96 Thus the actual size of
  97 .Fa d_name
  98 may vary from 1 to
  99 .Dv MAXNAMELEN
 100 \&+ 1.
 101 .Fa d_type
 102 is a integer representing the type of the directory entry.  The following types are defined in
 103 .Aq sys/dirent.h :
 104 .Bd -literal -offset indent
 105 #define DT_UNKNOWN       0
 106 #define DT_FIFO          1
 107 #define DT_CHR           2
 108 #define DT_DIR           4
 109 #define DT_BLK           6
 110 #define DT_REG           8
 111 #define DT_LNK          10
 112 #define DT_SOCK         12
 113 #define DT_WHT          14
 114 .Ed
 115 .Pp
 116 Entries may be separated by extra space.
 117 The
 118 .Fa d_reclen
 119 entry may be used as an offset from the start of a
 120 .Fa dirent
 121 structure to the next structure, if any.
 122 .Pp
 123 The actual number of bytes transferred is returned.
 124 The current position pointer associated with
 125 .Fa fd
 126 is set to point to the next block of entries.
 127 The pointer may not advance by the number of bytes returned by
 128 .Fn getdirentries .
 129 A value of zero is returned when
 130 the end of the directory has been reached.
 131 .Pp
 132 .Fn Getdirentries
 133 writes the position of the block read into the location pointed to by
 134 .Fa basep .
 135 Alternatively, the current position pointer may be set and retrieved by
 136 .Xr lseek 2 .
 137 The current position pointer should only be set to a value returned by
 138 .Xr lseek 2 ,
 139 a value returned in the location pointed to by
 140 .Fa basep ,
 141 or zero.
 142 .Sh NOTES
 143 .Fn getdirentries
 144 should rarely be used directly; instead,
 145 .Xr opendir 3
 146 and
 147 .Xr readdir 3
 148 should be used.
 149 .Pp
 150 As of Mac OS X 10.6,
 151 .Fn getdirentries
 152 is deprecated, and it is recommended that applications
 153 use
 154 .Xr readdir 3
 155 rather than using
 156 .Fn getdirentries
 157 directly.  Due to limitations with the system call,
 158 .Fn getdirentries
 159 will not work
 160 with 64-bit inodes; in order to use
 161 .Fn getdirentries ,
 162 .Dv _DARWIN_NO_64_BIT_INODE
 163 must be defined.  See
 164 .Xr stat 2
 165 for more information on
 166 .Dv _DARWIN_NO_64_BIT_INODE
 167 and its other effects.
 168 .Sh RETURN VALUES
 169 If successful, the number of bytes actually transferred is returned.
 170 Otherwise, -1 is returned and the global variable
 171 .Va errno
 172 is set to indicate the error.
 173 .Sh ERRORS
 174 .Fn Getdirentries
 175 will fail if:
 176 .Bl -tag -width Er
 177 .It Bq Er EBADF
 178 .Fa fd
 179 is not a valid file descriptor open for reading.
 180 .It Bq Er EFAULT
 181 Either
 182 .Fa buf
 183 or
 184 .Fa basep
 185 point outside the allocated address space.
 186 .It Bq Er EIO
 187 An
 188 .Tn I/O
 189 error occurred while reading from or writing to the file system.
 190 .El
 191 .Sh SEE ALSO
 192 .Xr lseek 2 ,
 193 .Xr open 2 ,
 194 .Xr stat 2 ,
 195 .Xr opendir 3 ,
 196 .Xr readdir 3 ,
 197 .Xr dir 5
 198 .Sh HISTORY
 199 The
 200 .Fn getdirentries
 201 function first appeared in 4.4BSD.