man2/setxattr.2

   1 .\" Copyright (C) Andreas Gruenbacher, February 2001
   2 .\" Copyright (C) Silicon Graphics Inc, September 2001
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  25 .TH SETXATTR 2 2019-03-06 "Linux" "Linux Programmer's Manual"
  26 .SH NAME
  27 setxattr, lsetxattr, fsetxattr \- set an extended attribute value
  28 .SH SYNOPSIS
  29 .fam C
  30 .nf
  31 .B #include <sys/types.h>
  32 .B #include <sys/xattr.h>
  33 .PP
  34 .BI "int setxattr(const char\ *" path ", const char\ *" name ,
  35 .BI "              const void\ *" value ", size_t " size ", int " flags );
  36 .BI "int lsetxattr(const char\ *" path ", const char\ *" name ,
  37 .BI "              const void\ *" value ", size_t " size ", int " flags );
  38 .BI "int fsetxattr(int " fd ", const char\ *" name ,
  39 .BI "              const void\ *" value ", size_t " size ", int " flags );
  40 .fi
  41 .fam T
  42 .SH DESCRIPTION
  43 Extended attributes are
  44 .IR name :\c
  45 .I value
  46 pairs associated with inodes (files, directories, symbolic links, etc.).
  47 They are extensions to the normal attributes which are associated
  48 with all inodes in the system (i.e., the
  49 .BR stat (2)
  50 data).
  51 A complete overview of extended attributes concepts can be found in
  52 .BR xattr (7).
  53 .PP
  54 .BR setxattr ()
  55 sets the
  56 .I value
  57 of the extended attribute identified by
  58 .I name
  59 and associated with the given
  60 .I path
  61 in the filesystem.
  62 The
  63 .I size
  64 argument specifies the size (in bytes) of
  65 .IR value ;
  66 a zero-length value is permitted.
  67 .PP
  68 .BR lsetxattr ()
  69 is identical to
  70 .BR setxattr (),
  71 except in the case of a symbolic link, where the extended attribute is
  72 set on the link itself, not the file that it refers to.
  73 .PP
  74 .BR fsetxattr ()
  75 is identical to
  76 .BR setxattr (),
  77 only the extended attribute is set on the open file referred to by
  78 .I fd
  79 (as returned by
  80 .BR open (2))
  81 in place of
  82 .IR path .
  83 .PP
  84 An extended attribute name is a null-terminated string.
  85 The
  86 .I name
  87 includes a namespace prefix; there may be several, disjoint
  88 namespaces associated with an individual inode.
  89 The
  90 .I value
  91 of an extended attribute is a chunk of arbitrary textual or
  92 binary data of specified length.
  93 .PP
  94 By default
  95 (i.e.,
  96 .IR flags
  97 is zero),
  98 the extended attribute will be created if it does not exist,
  99 or the value will be replaced if the attribute already exists.
 100 To modify these semantics, one of the following values can be specified in
 101 .IR flags :
 102 .TP
 103 .B XATTR_CREATE
 104 Perform a pure create, which fails if the named attribute exists already.
 105 .TP
 106 .B XATTR_REPLACE
 107 Perform a pure replace operation,
 108 which fails if the named attribute does not already exist.
 109 .SH RETURN VALUE
 110 On success, zero is returned.
 111 On failure, \-1 is returned and
 112 .I errno
 113 is set appropriately.
 114 .SH ERRORS
 115 .TP
 116 .B EDQUOT
 117 Disk quota limits meant that
 118 there is insufficient space remaining to store the extended attribute.
 119 .TP
 120 .B EEXIST
 121 .B XATTR_CREATE
 122 was specified, and the attribute exists already.
 123 .TP
 124 .B ENODATA
 125 .B XATTR_REPLACE
 126 was specified, and the attribute does not exist.
 127 .\" .RB ( ENOATTR
 128 .\" is defined to be a synonym for
 129 .\" .BR ENODATA
 130 .\" in
 131 .\" .IR <attr/attributes.h> .)
 132 .TP
 133 .B ENOSPC
 134 There is insufficient space remaining to store the extended attribute.
 135 .TP
 136 .B ENOTSUP
 137 The namespace prefix of
 138 .I name
 139 is not valid.
 140 .TP
 141 .B ENOTSUP
 142 Extended attributes are not supported by the filesystem, or are disabled,
 143 .TP
 144 .B EPERM
 145 The file is marked immutable or append-only.
 146 (See
 147 .BR ioctl_iflags (2).)
 148 .PP
 149 In addition, the errors documented in
 150 .BR stat (2)
 151 can also occur.
 152 .TP
 153 .B ERANGE
 154 The size of
 155 .I name
 156 or
 157 .I value
 158 exceeds a filesystem-specific limit.
 159 .SH VERSIONS
 160 These system calls have been available on Linux since kernel 2.4;
 161 glibc support is provided since version 2.3.
 162 .SH CONFORMING TO
 163 These system calls are Linux-specific.
 164 .\" .SH AUTHORS
 165 .\" Andreas Gruenbacher,
 166 .\" .RI < a.gruenbacher@computer.org >
 167 .\" and the SGI XFS development team,
 168 .\" .RI < linux-xfs@oss.sgi.com >.
 169 .\" Please send any bug reports or comments to these addresses.
 170 .SH SEE ALSO
 171 .BR getfattr (1),
 172 .BR setfattr (1),
 173 .BR getxattr (2),
 174 .BR listxattr (2),
 175 .BR open (2),
 176 .BR removexattr (2),
 177 .BR stat (2),
 178 .BR symlink (7),
 179 .BR xattr (7)