lookup_dcookie (2) Linux Manual Page
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.