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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 | |
4 | .\" The Regents of the University of California. All rights reserved. | |
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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 | |
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20 | .\" without specific prior written permission. | |
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22 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
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25 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
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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 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. |