table of contents
LOOKUP_DCOOKIE(2) | Linux Programmer's Manual | LOOKUP_DCOOKIE(2) |
NAME¶
lookup_dcookie - return a directory entry's path
SYNOPSIS¶
#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).
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 to indicate the error.
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.
SEE ALSO¶
oprofile(1)
COLOPHON¶
This page is part of release 5.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
2021-03-22 | Linux |