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| .\" Modified 2004-06-17 Michael Kerrisk <mtk.manpages@gmail.com> |
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| .TH LOOKUP_DCOOKIE 2 2021-03-22 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| lookup_dcookie \- return a directory entry's path |
| .SH SYNOPSIS |
| .nf |
| .BI "int lookup_dcookie(uint64_t " cookie ", char *" buffer ", size_t " len ); |
| .fi |
| .PP |
| .IR Note : |
| There is no glibc wrapper for this system call; see NOTES. |
| .SH DESCRIPTION |
| Look up the full path of the directory entry specified by the value |
| .IR 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. |
| .PP |
| For |
| .BR lookup_dcookie () |
| to return successfully, |
| the kernel must still hold a cookie reference to the directory entry. |
| .SH RETURN VALUE |
| On success, |
| .BR lookup_dcookie () |
| returns the length of the path string copied into the buffer. |
| On error, \-1 is returned, and |
| .I errno |
| is set to indicate the error. |
| .SH ERRORS |
| .TP |
| .B EFAULT |
| The buffer was not valid. |
| .TP |
| .B 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. |
| .TP |
| .B ENAMETOOLONG |
| The name could not fit in the buffer. |
| .TP |
| .B ENOMEM |
| The kernel could not allocate memory for the temporary buffer holding |
| the path. |
| .TP |
| .B EPERM |
| The process does not have the capability |
| .B CAP_SYS_ADMIN |
| required to look up cookie values. |
| .TP |
| .B ERANGE |
| The buffer was not large enough to hold the path of the directory entry. |
| .SH VERSIONS |
| Available since Linux 2.5.43. |
| The |
| .B ENAMETOOLONG |
| error return was added in 2.5.70. |
| .SH CONFORMING TO |
| .BR lookup_dcookie () |
| is Linux-specific. |
| .SH NOTES |
| .BR lookup_dcookie () |
| is a special-purpose system call, currently used only by the |
| .BR oprofile (1) |
| profiler. |
| It relies on a kernel driver to register cookies for directory entries. |
| .PP |
| The path returned may be suffixed by the string " (deleted)" if the directory |
| entry has been removed. |
| .PP |
| Glibc does not provide a wrapper for this system call; call it using |
| .BR syscall (2). |
| .SH SEE ALSO |
| .BR oprofile (1) |