lookup_dcookie

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
       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
       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
              directory 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 register
       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 5.03 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)