lookup_dcookie − return a directory entry’s path
Standard C library (libc, −lc)
#include
<sys/syscall.h> /* Definition of SYS_*
constants */
#include <unistd.h>
int
syscall(SYS_lookup_dcookie, uint64_t cookie,
char *buffer,
size_t len);
Note: glibc provides no wrapper for lookup_dcookie(), necessitating the use of syscall(2).
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.
On success, lookup_dcookie() returns the length of the path string copied into the buffer. On error, −1 is returned, and errno is set to indicate the error.
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. |
Linux.
Linux 2.5.43.
The ENAMETOOLONG error was added in Linux 2.5.70.
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.
oprofile(1)