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man:lgetxattr

GETXATTR(2) Linux Programmer's Manual GETXATTR(2)

NAME

     getxattr, lgetxattr, fgetxattr - retrieve an extended attribute value

SYNOPSIS

     #include <sys/types.h>
     #include <sys/xattr.h>
     ssize_t getxattr(const char *path, const char *name,
                      void *value, size_t size);
     ssize_t lgetxattr(const char *path, const char *name,
                      void *value, size_t size);
     ssize_t fgetxattr(int fd, const char *name,
                      void *value, size_t size);

DESCRIPTION

     Extended attributes are name: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 stat(2) data).  A complete overview of extended attributes concepts
     can be found in xattr(7).
     getxattr()  retrieves the value of the extended attribute identified by
     name and associated  with  the  given  path  in  the  filesystem.   The
     attribute value is placed in the buffer pointed to by value; size spec-
     ifies the size of that buffer.  The return value of  the  call  is  the
     number of bytes placed in value.
     lgetxattr()  is  identical  to getxattr(), except in the case of a sym-
     bolic link, where the link itself is interrogated, not the file that it
     refers to.
     fgetxattr()  is identical to getxattr(), only the open file referred to
     by fd (as returned by open(2)) is interrogated in place of path.
     An extended attribute 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 setxattr(2).
     If size is specified as zero, these calls return the  current  size  of
     the  named extended attribute (and leave 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.)

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 errno is set appropriately.

ERRORS

     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.
     ENOATTR
            The named attribute does not exist, or the process has no access
            to this attribute.  (ENOATTR is defined to be a synonym for ENO-
            DATA in <attr/xattr.h>.)
     ENOTSUP
            Extended attributes are not supported by the filesystem, or  are
            disabled.
     ERANGE The size of the value buffer is too small to hold the result.
     In addition, the errors documented in stat(2) can also occur.

VERSIONS

     These system calls have been available on Linux since kernel 2.4; glibc
     support is provided since version 2.3.

CONFORMING TO

     These system calls are Linux-specific.

EXAMPLE

     See listxattr(2).

SEE ALSO

     getfattr(1), setfattr(1), listxattr(2), open(2), removexattr(2),  setx-
     attr(2), stat(2), symlink(7), xattr(7)

COLOPHON

     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at
     https://www.kernel.org/doc/man-pages/.

Linux 2017-03-13 GETXATTR(2)

/data/webs/external/dokuwiki/data/pages/man/lgetxattr.txt · Last modified: 2019/05/17 09:32 by 127.0.0.1

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