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1.\" $NetBSD: getdirentries.2,v 1.7 1995/10/12 15:40:50 jtc Exp $
2.\"
3.\" Copyright (c) 1989, 1991, 1993
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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
50reads directory entries from the directory
51referenced by the file descriptor
52.Fa fd
53into the buffer pointed to by
54.Fa buf ,
55in a filesystem independent format.
56Up to
57.Fa nbytes
58of data will be transferred.
59.Fa Nbytes
60must be greater than or equal to the
61block size associated with the file,
62see
63.Xr stat 2 .
64Some filesystems may not support
65.Fn getdirentries
66with buffers smaller than this size.
67.Pp
68The data in the buffer is a series of
69.Em dirent
70structures each containing the following entries:
71.Bd -literal -offset indent
72u_int32_t d_fileno; /* file number of entry */
73u_int16_t d_reclen; /* length of this record */
74u_int8_t d_type; /* file type, see below */
75u_int8_t d_namlen; /* length of string in d_name */
76char d_name[MAXNAMELEN + 1]; /* see below */
77.Ed
78.Pp
79The
80.Fa d_fileno
81entry is a number which is unique for each
82distinct file in the filesystem.
83Files that are linked by hard links (see
84.Xr link 2 )
85have the same
86.Fa d_fileno .
87Users of
88.Fn getdirentries
89should skip
90entries with
91.Fa d_fileno
92= 0, as such entries represent files which have been deleted but not yet removed from the directory entry.
93The
94.Fa d_reclen
95entry is the length, in bytes, of the directory record.
96The
97.Fa d_name
98entry contains a null terminated file name.
99The
100.Fa d_namlen
101entry specifies the length of the file name excluding the null byte.
102Thus the actual size of
103.Fa d_name
104may vary from 1 to
105.Dv MAXNAMELEN
106\&+ 1.
107.Fa d_type
108is 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
122Entries may be separated by extra space.
123The
124.Fa d_reclen
125entry may be used as an offset from the start of a
126.Fa dirent
127structure to the next structure, if any.
128.Pp
129The actual number of bytes transferred is returned.
130The current position pointer associated with
131.Fa fd
132is set to point to the next block of entries.
133The pointer may not advance by the number of bytes returned by
134.Fn getdirentries .
135A value of zero is returned when
136the end of the directory has been reached.
137.Pp
138.Fn Getdirentries
139writes the position of the block read into the location pointed to by
140.Fa basep .
141Alternatively, the current position pointer may be set and retrieved by
142.Xr lseek 2 .
143The current position pointer should only be set to a value returned by
144.Xr lseek 2 ,
145a value returned in the location pointed to by
146.Fa basep ,
147or zero.
148.Sh NOTES
149.Fn getdirentries
150should rarely be used directly; instead,
151.Xr opendir 3
152and
153.Xr readdir 3
154should be used.
155.Pp
156As of Mac OS X 10.6,
157.Fn getdirentries
158is deprecated, and it is recommended that applications
159use
160.Xr readdir 3
161rather than using
162.Fn getdirentries
163directly. Due to limitations with the system call,
164.Fn getdirentries
165will not work
166with 64-bit inodes; in order to use
167.Fn getdirentries ,
168.Dv _DARWIN_NO_64_BIT_INODE
169must be defined.
170.Sh RETURN VALUES
171If successful, the number of bytes actually transferred is returned.
172Otherwise, -1 is returned and the global variable
173.Va errno
174is set to indicate the error.
175.Sh ERRORS
176.Fn Getdirentries
177will fail if:
178.Bl -tag -width Er
179.It Bq Er EBADF
180.Fa fd
181is not a valid file descriptor open for reading.
182.It Bq Er EFAULT
183Either
184.Fa buf
185or
186.Fa basep
187point outside the allocated address space.
188.It Bq Er EIO
189An
190.Tn I/O
191error 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
199The
200.Fn getdirentries
201function first appeared in 4.4BSD.