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getxattr.2: Various rewordings plus one or two details clarified 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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Michael Kerrisk 2015-01-24 10:27:54 +01:00
parent f1ec5ad108
commit fae9230bda
1 changed files with 23 additions and 19 deletions
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man2/getxattr.2
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@ -52,16 +52,17 @@ A complete overview of extended attributes concepts can be found in
.BR attr (5).
.PP
.BR getxattr ()
retrieves the
.I value
of the extended attribute identified by
retrieves the value of the extended attribute identified by
.I name
and associated with the given
.I path
in the filesystem.
The length of the attribute
.I value
is returned.
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
@ -81,25 +82,28 @@ is interrogated in place of
.PP
An extended attribute
.I name
is a simple null-terminated string.
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 of specified length.
binary data that was assigned using
.BR setxattr (2).
.PP
An empty buffer of
If
.I size
zero can be passed into these calls to return the current size of the
named extended attribute, which can be used to estimate the size of a
buffer which is sufficiently large to hold the value associated with
the extended attribute.
.PP
The interface is designed to allow guessing of initial buffer
sizes, and to enlarge buffers when the return value indicates
that the buffer provided was too small.
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, a nonnegative number is returned indicating the size of the
extended attribute 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.