lookup_dcookie (2) Linux Manual Page
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_ADMINrequired 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
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