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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
            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 direc-
            tory 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.