lookup_dcookie(2)

1LOOKUP_DCOOKIE(2)          Linux Programmer's Manual         LOOKUP_DCOOKIE(2)
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NAME

6       lookup_dcookie - return a directory entry's path
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SYNOPSIS

9       int lookup_dcookie(u64 cookie, char *buffer, size_t len);
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DESCRIPTION

12       Look  up  the  full  path of the directory entry specified by the value
13       cookie.  The cookie is an opaque identifier uniquely identifying a par‐
14       ticular  directory  entry.  The buffer given is filled in with the full
15       path of the directory entry.
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17       For lookup_dcookie() to return successfully, the kernel must still hold
18       a cookie reference to the directory entry.
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RETURN VALUE

21       On  success,  lookup_dcookie()  returns  the  length of the path string
22       copied into the buffer.  On error, -1 is returned,  and  errno  is  set
23       appropriately.
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ERRORS

26       EFAULT The buffer was not valid.
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28       EINVAL The  kernel has no registered cookie/directory entry mappings at
29              the time of lookup, or the cookie does  not  refer  to  a  valid
30              directory entry.
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32       ENAMETOOLONG
33              The name could not fit in the buffer.
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35       ENOMEM The  kernel  could  not allocate memory for the temporary buffer
36              holding the path.
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38       EPERM  The process does not have the capability CAP_SYS_ADMIN  required
39              to look up cookie values.
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41       ERANGE The  buffer  was not large enough to hold the path of the direc‐
42              tory entry.
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VERSIONS

45       Available since Linux 2.5.43.  The ENAMETOOLONG error return was  added
46       in 2.5.70.
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CONFORMING TO

49       lookup_dcookie() is Linux-specific.
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NOTES

52       lookup_dcookie()  is a special-purpose system call, currently used only
53       by the oprofile(1) profiler.  It relies on a kernel driver to  register
54       cookies for directory entries.
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56       The  path  returned  may  be suffixed by the string " (deleted)" if the
57       directory entry has been removed.
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COLOPHON

63       This page is part of release 5.07 of the Linux  man-pages  project.   A
64       description  of  the project, information about reporting bugs, and the
65       latest    version    of    this    page,    can     be     found     at
66       https://www.kernel.org/doc/man-pages/.
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70Linux                             2017-09-15                 LOOKUP_DCOOKIE(2)