extattrctl(2) - NetBSD Manual Pages

Command:
Section:
Arch:
Collection:
>>>
EXTATTRCTL(2)             NetBSD System Calls Manual             EXTATTRCTL(2)


NAME

     extattrctl -- control extended attributes on a UFS1 file system


SYNOPSIS

     #include <sys/extattr.h>
     #include <ufs/ufs/extattr.h>

     int
     extattrctl(const char *path, int cmd, const char *filename,
         int attrnamespace, const char *attrname);


DESCRIPTION

     The extattrctl() system call provides low-level control over extended
     attributes on a UFS1 file system.  It allows enabling, disabling, and
     managing extended attributes.

     Since there was no provision in the UFS1 file system for attributes, they
     are stored as regular files and directories in the file system under the
     /.attribute directory.  By convention, there are usually two directories
     directly under it, separating two namespaces: ``user'' and ``system''.
     Under these, there are named attributes that can be created and managed
     using extattrctl(8).

     This programming interface is currently only used by extattrctl(8), and
     is not intended for general use.


PARAMETERS

     path    The path to the mount point of the file system.

     cmd     The command to execute.  Valid commands are:

             UFS_EXTATTR_CMD_ENABLE
                     Enable a specific extended attribute.

             UFS_EXTATTR_CMD_DISABLE
                     Disable a specific extended attribute.

             UFS_EXTATTR_CMD_START
                     Start extended attribute support on the file system.

             UFS_EXTATTR_CMD_STOP
                     Stop extended attribute support on the file system.

     attrname
             The name of the extended attribute (for relevant commands).

     attrnamespace
             The attribute namespace, such as EXTATTR_NAMESPACE_USER or
             EXTATTR_NAMESPACE_SYSTEM.

     filename
             The path to a backing file for extended attribute storage (if
             required by the command).


RETURN VALUES

     The extattrctl() function returns the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.


EXAMPLES

     Enable an attribute on a file system:

           #include <sys/extattr.h>
           #include <ufs/ufs/extattr.h>

           if (extattrctl("/home", UFS_EXTATTR_CMD_ENABLE,
               "/.attribute/user/comment",
               EXTATTR_NAMESPACE_USER, "comment") == -1)
                   err(EXIT_FAILURE, "extattrctl");


ERRORS

     The extattrctl() system call may fail with the following errors:

           [EACCES]      The calling user does not have permission to access
                         the file specified.

           [EINVAL]      Invalid arguments were provided.

           [ENOENT]      The specified path, attribute, or file does not
                         exist.

           [EOPNOTSUPP]  The file system does not support extended attributes.

           [EPERM]       The calling user is not permitted to change extended
                         attributes.


SEE ALSO

     extattr_delete_file(2), extattr_get_file(2), extattr_list_file(2),
     extattr_set_file(2), extattrctl(8)


HISTORY

     The extattrctl() system call was imported from FreeBSD 5.0 in NetBSD 3.0.

NetBSD 10.99                     March 9, 2025                    NetBSD 10.99