lookup_dcookie(2) -- Linux man page
NAMElookup_dcookie - return a directory entry's path
DESCRIPTIONLook 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.
NOTESlookup_dcookie is a special-purpose system call, currently used only by the oprofile 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.
RETURN VALUEOn success, lookup_dcookie returns the length of the path string copied into the buffer. On error, -1 is returned, and errno is set appropriately.
ERRORSEPERM The process does not have the capability to look up cookie values.
- 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 kernel could not allocate memory for the temporary buffer holding the path.
- The buffer was not large enough to hold the path of the directory entry.
- The name could not fit in the buffer.
The buffer was not valid.
CONFORMING TOlookup_dcookie is Linux-specific.
AVAILABILITYSince Linux 2.5.43. The ENAMETOOLONG error return was added in 2.5.70.