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1 | .\" Copyright (C) Andreas Gruenbacher, February 2001 |
2 | .\" Copyright (C) Silicon Graphics Inc, September 2001 | |
fea681da | 3 | .\" |
1dd72f9c | 4 | .\" %%%LICENSE_START(GPLv2+_DOC_FULL) |
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5 | .\" This is free documentation; you can redistribute it and/or |
6 | .\" modify it under the terms of the GNU General Public License as | |
7 | .\" published by the Free Software Foundation; either version 2 of | |
8 | .\" the License, or (at your option) any later version. | |
9 | .\" | |
10 | .\" The GNU General Public License's references to "object code" | |
11 | .\" and "executables" are to be interpreted as the output of any | |
12 | .\" document formatting or typesetting system, including | |
13 | .\" intermediate and printed output. | |
14 | .\" | |
15 | .\" This manual is distributed in the hope that it will be useful, | |
16 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | .\" GNU General Public License for more details. | |
19 | .\" | |
20 | .\" You should have received a copy of the GNU General Public | |
c715f741 MK |
21 | .\" License along with this manual; if not, see |
22 | .\" <http://www.gnu.org/licenses/>. | |
6a8d8745 | 23 | .\" %%%LICENSE_END |
fea681da | 24 | .\" |
9ba01802 | 25 | .TH GETXATTR 2 2019-03-06 "Linux" "Linux Programmer's Manual" |
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26 | .SH NAME |
27 | getxattr, lgetxattr, fgetxattr \- retrieve an extended attribute value | |
28 | .SH SYNOPSIS | |
29 | .fam C | |
30 | .nf | |
31 | .B #include <sys/types.h> | |
4f72d935 | 32 | .B #include <sys/xattr.h> |
68e4db0a | 33 | .PP |
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34 | .BI "ssize_t getxattr(const char\ *" path ", const char\ *" name , |
35 | .BI " void\ *" value ", size_t " size ); | |
36 | .BI "ssize_t lgetxattr(const char\ *" path ", const char\ *" name , | |
37 | .BI " void\ *" value ", size_t " size ); | |
d3b03141 | 38 | .BI "ssize_t fgetxattr(int " fd ", const char\ *" name , |
c10859eb | 39 | .BI " void\ *" value ", size_t " size ); |
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40 | .fi |
41 | .fam T | |
42 | .SH DESCRIPTION | |
43 | Extended attributes are | |
44 | .IR name :\c | |
45 | .I value | |
0967c11f | 46 | pairs associated with inodes (files, directories, symbolic links, etc.). |
fea681da | 47 | They are extensions to the normal attributes which are associated |
75b94dc3 | 48 | with all inodes in the system (i.e., the |
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49 | .BR stat (2) |
50 | data). | |
51 | A complete overview of extended attributes concepts can be found in | |
89fabe2e | 52 | .BR xattr (7). |
fea681da | 53 | .PP |
e511ffb6 | 54 | .BR getxattr () |
fae9230b | 55 | retrieves the value of the extended attribute identified by |
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56 | .I name |
57 | and associated with the given | |
58 | .I path | |
9ee4a2b6 | 59 | in the filesystem. |
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60 | The attribute value is placed in the buffer pointed to by |
61 | .IR value ; | |
62 | .I size | |
63 | specifies the size of that buffer. | |
64 | The return value of the call is the number of bytes placed in | |
65 | .IR value . | |
fea681da | 66 | .PP |
e511ffb6 | 67 | .BR lgetxattr () |
c13182ef | 68 | is identical to |
e511ffb6 | 69 | .BR getxattr (), |
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70 | except in the case of a symbolic link, where the link itself is |
71 | interrogated, not the file that it refers to. | |
72 | .PP | |
e511ffb6 | 73 | .BR fgetxattr () |
fea681da | 74 | is identical to |
e511ffb6 | 75 | .BR getxattr (), |
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76 | only the open file referred to by |
77 | .I fd | |
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78 | (as returned by |
79 | .BR open (2)) | |
80 | is interrogated in place of | |
81 | .IR path . | |
82 | .PP | |
83 | An extended attribute | |
84 | .I name | |
fae9230b | 85 | is a null-terminated string. |
df8a3cac | 86 | The name includes a namespace prefix; there may be several, disjoint |
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87 | namespaces associated with an individual inode. |
88 | The value of an extended attribute is a chunk of arbitrary textual or | |
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89 | binary data that was assigned using |
90 | .BR setxattr (2). | |
fea681da | 91 | .PP |
fae9230b | 92 | If |
fea681da | 93 | .I size |
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94 | is specified as zero, these calls return the current size of the |
95 | named extended attribute (and leave | |
96 | .I value | |
97 | unchanged). | |
98 | This can be used to determine the size of the buffer that | |
99 | should be supplied in a subsequent call. | |
100 | (But, bear in mind that there is a possibility that the | |
101 | attribute value may change between the two calls, | |
102 | so that it is still necessary to check the return status | |
103 | from the second call.) | |
fea681da | 104 | .SH RETURN VALUE |
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105 | On success, these calls return a nonnegative value which is |
106 | the size (in bytes) of the extended attribute value. | |
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107 | On failure, \-1 is returned and |
108 | .I errno | |
109 | is set appropriately. | |
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110 | .SH ERRORS |
111 | .TP | |
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112 | .B E2BIG |
113 | The size of the attribute value is larger than the maximum size allowed; the | |
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114 | attribute cannot be retrieved. |
115 | This can happen on filesystems that support | |
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116 | very large attribute values such as NFSv4, for example. |
117 | .TP | |
acac1139 | 118 | .B ENODATA |
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119 | The named attribute does not exist, or the process has no access to |
120 | this attribute. | |
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121 | .\" .RB ( ENOATTR |
122 | .\" is defined to be a synonym for | |
123 | .\" .BR ENODATA | |
124 | .\" in | |
125 | .\" .IR <attr/attributes.h> .) | |
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126 | .TP |
127 | .B ENOTSUP | |
9ee4a2b6 | 128 | Extended attributes are not supported by the filesystem, or are disabled. |
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129 | .TP |
130 | .B ERANGE | |
131 | The | |
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132 | .I size |
133 | of the | |
134 | .I value | |
92d67001 | 135 | buffer is too small to hold the result. |
fea681da | 136 | .PP |
92d67001 | 137 | In addition, the errors documented in |
fea681da | 138 | .BR stat (2) |
92d67001 | 139 | can also occur. |
570dd978 MK |
140 | .SH VERSIONS |
141 | These system calls have been available on Linux since kernel 2.4; | |
142 | glibc support is provided since version 2.3. | |
47297adb | 143 | .SH CONFORMING TO |
8382f16d | 144 | These system calls are Linux-specific. |
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145 | .\" .SH AUTHORS |
146 | .\" Andreas Gruenbacher, | |
147 | .\" .RI < a.gruenbacher@computer.org > | |
148 | .\" and the SGI XFS development team, | |
149 | .\" .RI < linux-xfs@oss.sgi.com >. | |
150 | .\" Please send any bug reports or comments to these addresses. | |
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151 | .SH EXAMPLE |
152 | See | |
153 | .BR listxattr (2). | |
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154 | .SH SEE ALSO |
155 | .BR getfattr (1), | |
156 | .BR setfattr (1), | |
157 | .BR listxattr (2), | |
158 | .BR open (2), | |
159 | .BR removexattr (2), | |
160 | .BR setxattr (2), | |
161 | .BR stat (2), | |
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162 | .BR symlink (7), |
163 | .BR xattr (7) |