lookup_dcookie(2) — Linux manual page


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

NAME         top

       lookup_dcookie - return a directory entry's path

SYNOPSIS         top

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

DESCRIPTION         top

       Look up the full path of the directory entry specified by the value
       cookie.  The cookie is an opaque identifier uniquely identifying a
       particular 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         top

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

ERRORS         top

       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
              directory entry.

              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         top

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

CONFORMING TO         top

       lookup_dcookie() is Linux-specific.

NOTES         top

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

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

SEE ALSO         top


COLOPHON         top

       This page is part of release 5.08 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

Linux                            2017-09-15                LOOKUP_DCOOKIE(2)

Pages that refer to this page: syscalls(2)capabilities(7)