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

NAME

       lookup_dcookie - return a directory entry's path

SYNOPSIS

       int lookup_dcookie(u64 cookie, char *buffer, size_t len);

DESCRIPTION

       Look up the full path of the directory entry specified by the value cookie.  The cookie is an opaque identifier uniquely identifying a par-
       ticular directory entry.  The buffer given is filled in with the full path of the directory entry.

       For lookup_dcookie() to return successfully, the kernel must still hold a cookie reference to the directory entry.

RETURN VALUE

       On success, lookup_dcookie() returns the length of the path string copied into the buffer.  On error, -1 is  returned,  and  errno  is  set
       appropriately.

ERRORS

       EFAULT The buffer was not valid.

       EINVAL The  kernel  has no registered cookie/directory entry mappings at the time of lookup, or the cookie does not refer to a valid direc-
	      tory entry.

       ENAMETOOLONG
	      The name could not fit in the buffer.

       ENOMEM The kernel could not allocate memory for the temporary buffer holding the path.

       EPERM  The process does not have the capability CAP_SYS_ADMIN required to look up cookie values.

       ERANGE The buffer was not large enough to hold the path of the directory entry.

VERSIONS

       Available since Linux 2.5.43.  The ENAMETOOLONG error return was added in 2.5.70.

CONFORMING TO

       lookup_dcookie() is Linux-specific.

NOTES

       lookup_dcookie() is a special-purpose system call, currently used only by the oprofile(1) profiler.  It relies on a kernel driver to regis-
       ter cookies for directory entries.

       The path returned may be suffixed by the string " (deleted)" if the directory entry has been removed.

SEE ALSO

       oprofile(1)

COLOPHON

       This  page is part of release 4.15 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								    2017-09-15							 LOOKUP_DCOOKIE(2)