| .\" Copyright (C) Andreas Gruenbacher, February 2001 |
| .\" Copyright (C) Silicon Graphics Inc, September 2001 |
| .\" |
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| .TH GETXATTR 2 2019-03-06 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| getxattr, lgetxattr, fgetxattr \- retrieve an extended attribute value |
| .SH SYNOPSIS |
| .fam C |
| .nf |
| .B #include <sys/types.h> |
| .B #include <sys/xattr.h> |
| .PP |
| .BI "ssize_t getxattr(const char\ *" path ", const char\ *" name , |
| .BI " void\ *" value ", size_t " size ); |
| .BI "ssize_t lgetxattr(const char\ *" path ", const char\ *" name , |
| .BI " void\ *" value ", size_t " size ); |
| .BI "ssize_t fgetxattr(int " fd ", const char\ *" name , |
| .BI " void\ *" value ", size_t " size ); |
| .fi |
| .fam T |
| .SH DESCRIPTION |
| Extended attributes are |
| .IR name :\c |
| .I value |
| pairs associated with inodes (files, directories, symbolic links, etc.). |
| They are extensions to the normal attributes which are associated |
| with all inodes in the system (i.e., the |
| .BR stat (2) |
| data). |
| A complete overview of extended attributes concepts can be found in |
| .BR xattr (7). |
| .PP |
| .BR getxattr () |
| retrieves the value of the extended attribute identified by |
| .I name |
| and associated with the given |
| .I path |
| in the filesystem. |
| The attribute value is placed in the buffer pointed to by |
| .IR value ; |
| .I size |
| specifies the size of that buffer. |
| The return value of the call is the number of bytes placed in |
| .IR value . |
| .PP |
| .BR lgetxattr () |
| is identical to |
| .BR getxattr (), |
| except in the case of a symbolic link, where the link itself is |
| interrogated, not the file that it refers to. |
| .PP |
| .BR fgetxattr () |
| is identical to |
| .BR getxattr (), |
| only the open file referred to by |
| .I fd |
| (as returned by |
| .BR open (2)) |
| is interrogated in place of |
| .IR path . |
| .PP |
| An extended attribute |
| .I name |
| is a null-terminated string. |
| The name includes a namespace prefix; there may be several, disjoint |
| namespaces associated with an individual inode. |
| The value of an extended attribute is a chunk of arbitrary textual or |
| binary data that was assigned using |
| .BR setxattr (2). |
| .PP |
| If |
| .I size |
| is specified as zero, these calls return the current size of the |
| named extended attribute (and leave |
| .I value |
| unchanged). |
| This can be used to determine the size of the buffer that |
| should be supplied in a subsequent call. |
| (But, bear in mind that there is a possibility that the |
| attribute value may change between the two calls, |
| so that it is still necessary to check the return status |
| from the second call.) |
| .SH RETURN VALUE |
| On success, these calls return a nonnegative value which is |
| the size (in bytes) of the extended attribute value. |
| On failure, \-1 is returned and |
| .I errno |
| is set appropriately. |
| .SH ERRORS |
| .TP |
| .B E2BIG |
| The size of the attribute value is larger than the maximum size allowed; the |
| attribute cannot be retrieved. |
| This can happen on filesystems that support |
| very large attribute values such as NFSv4, for example. |
| .TP |
| .B ENODATA |
| The named attribute does not exist, or the process has no access to |
| this attribute. |
| .\" .RB ( ENOATTR |
| .\" is defined to be a synonym for |
| .\" .BR ENODATA |
| .\" in |
| .\" .IR <attr/attributes.h> .) |
| .TP |
| .B ENOTSUP |
| Extended attributes are not supported by the filesystem, or are disabled. |
| .TP |
| .B ERANGE |
| The |
| .I size |
| of the |
| .I value |
| buffer is too small to hold the result. |
| .PP |
| In addition, the errors documented in |
| .BR stat (2) |
| can also occur. |
| .SH VERSIONS |
| These system calls have been available on Linux since kernel 2.4; |
| glibc support is provided since version 2.3. |
| .SH CONFORMING TO |
| These system calls are Linux-specific. |
| .\" .SH AUTHORS |
| .\" Andreas Gruenbacher, |
| .\" .RI < a.gruenbacher@computer.org > |
| .\" and the SGI XFS development team, |
| .\" .RI < linux-xfs@oss.sgi.com >. |
| .\" Please send any bug reports or comments to these addresses. |
| .SH EXAMPLE |
| See |
| .BR listxattr (2). |
| .SH SEE ALSO |
| .BR getfattr (1), |
| .BR setfattr (1), |
| .BR listxattr (2), |
| .BR open (2), |
| .BR removexattr (2), |
| .BR setxattr (2), |
| .BR stat (2), |
| .BR symlink (7), |
| .BR xattr (7) |