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 each containing the following entries:
  71 .Bd -literal -offset indent
  72 u_int32_t       d_fileno;             /* file number of entry */
  73 u_int16_t       d_reclen;             /* length of this record */
  74 u_int8_t        d_type;               /* file type, see below */
  75 u_int8_t        d_namlen;             /* length of string in d_name */
  76 char            d_name[MAXNAMELEN + 1]; /* see below */
  77 .Ed
  78 .Pp
  79 The
  80 .Fa d_fileno
  81 entry is a number which is unique for each
  82 distinct file in the filesystem.
  83 Files that are linked by hard links (see
  84 .Xr link 2 )
  85 have the same
  86 .Fa d_fileno .
  87 Users of
  88 .Fn getdirentries
  89 should skip
  90 entries with
  91 .Fa d_fileno
  92 = 0, as such entries represent files which have been deleted but not yet removed from the directory entry.
  93 The
  94 .Fa d_reclen
  95 entry is the length, in bytes, of the directory record.
  96 The
  97 .Fa d_name
  98 entry contains a null terminated file name.
  99 The
 100 .Fa d_namlen
 101 entry specifies the length of the file name excluding the null byte.
 102 Thus the actual size of
 103 .Fa d_name
 104 may vary from 1 to
 105 .Dv MAXNAMELEN
 106 \&+ 1.
 107 .Fa d_type
 108 is a integer representing the type of the directory entry.  The following types are defined in
 109 .Aq sys/dirent.h :
 110 .Bd -literal -offset indent
 111 #define DT_UNKNOWN       0
 112 #define DT_FIFO          1
 113 #define DT_CHR           2
 114 #define DT_DIR           4
 115 #define DT_BLK           6
 116 #define DT_REG           8
 117 #define DT_LNK          10
 118 #define DT_SOCK         12
 119 #define DT_WHT          14
 120 .Ed
 121 .Pp
 122 Entries may be separated by extra space.
 123 The
 124 .Fa d_reclen
 125 entry may be used as an offset from the start of a
 126 .Fa dirent
 127 structure to the next structure, if any.
 128 .Pp
 129 The actual number of bytes transferred is returned.
 130 The current position pointer associated with
 131 .Fa fd
 132 is set to point to the next block of entries.
 133 The pointer may not advance by the number of bytes returned by
 134 .Fn getdirentries .
 135 A value of zero is returned when
 136 the end of the directory has been reached.
 137 .Pp
 138 .Fn Getdirentries
 139 writes the position of the block read into the location pointed to by
 140 .Fa basep .
 141 Alternatively, the current position pointer may be set and retrieved by
 142 .Xr lseek 2 .
 143 The current position pointer should only be set to a value returned by
 144 .Xr lseek 2 ,
 145 a value returned in the location pointed to by
 146 .Fa basep ,
 147 or zero.
 148 .Sh NOTES
 149 .Fn getdirentries
 150 should rarely be used directly; instead,
 151 .Xr opendir 3
 152 and
 153 .Xr readdir 3
 154 should be used.
 155 .Pp
 156 As of Mac OS X 10.6,
 157 .Fn getdirentries
 158 is deprecated, and it is recommended that applications
 159 use
 160 .Xr readdir 3
 161 rather than using
 162 .Fn getdirentries
 163 directly.  Due to limitations with the system call,
 164 .Fn getdirentries
 165 will not work
 166 with 64-bit inodes; in order to use
 167 .Fn getdirentries ,
 168 .Dv _DARWIN_NO_64_BIT_INODE
 169 must be defined.
 170 .Sh RETURN VALUES
 171 If successful, the number of bytes actually transferred is returned.
 172 Otherwise, -1 is returned and the global variable
 173 .Va errno
 174 is set to indicate the error.
 175 .Sh ERRORS
 176 .Fn Getdirentries
 177 will fail if:
 178 .Bl -tag -width Er
 179 .It Bq Er EBADF
 180 .Fa fd
 181 is not a valid file descriptor open for reading.
 182 .It Bq Er EFAULT
 183 Either
 184 .Fa buf
 185 or
 186 .Fa basep
 187 point outside the allocated address space.
 188 .It Bq Er EIO
 189 An
 190 .Tn I/O
 191 error occurred while reading from or writing to the file system.
 192 .El
 193 .Sh SEE ALSO
 194 .Xr lseek 2 ,
 195 .Xr open 2 ,
 196 .Xr opendir 3 ,
 197 .Xr readdir 3
 198 .Sh HISTORY
 199 The
 200 .Fn getdirentries
 201 function first appeared in 4.4BSD.