man2/lookup_dcookie.2

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  25 .\" Modified 2004-06-17 Michael Kerrisk <mtk-manpages@gmx.net>
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  27 .TH LOOKUP_DCOOKIE 2 2004-06-17 "Linux 2.6.7" "Linux Programmer's Manual"
  28 .SH NAME
  29 lookup_dcookie \- return a directory entry's path
  30 .SH SYNOPSIS
  31 .sp
  32 .BI "int lookup_dcookie(u64 " cookie ", char *" buffer ", size_t " len );
  33 .SH DESCRIPTION
  34 Look up the full path of the directory entry specified by the value
  35 .I cookie
  36 .
  37 The cookie is an opaque identifier uniquely identifying a particular
  38 directory entry.
  39 The buffer given is filled in with the full path of the directory entry.
  40
  41 For
  42 .BR lookup_dcookie ()
  43 to return successfully,
  44 the kernel must still hold a cookie reference to the directory entry.
  45 .SH "RETURN VALUE"
  46 On success,
  47 .BR lookup_dcookie ()
  48 returns the length of the path string copied into the buffer.
  49 On error, \-1 is returned, and
  50 .I errno
  51 is set appropriately.
  52 .SH ERRORS
  53 .TP
  54 .B EFAULT
  55 The buffer was not valid.
  56 .TP
  57 .B EINVAL
  58 The kernel has no registered cookie/directory entry mappings at the
  59 time of lookup, or the cookie does not refer to a valid directory entry.
  60 .TP
  61 .B ENAMETOOLONG
  62 The name could not fit in the buffer.
  63 .TP
  64 .B ENOMEM
  65 The kernel could not allocate memory for the temporary buffer holding
  66 the path.
  67 .TP
  68 .B EPERM
  69 The process does not have the capability
  70 .B CAP_SYS_ADMIN
  71 required to look up cookie values.
  72 .TP
  73 .B ERANGE
  74 The buffer was not large enough to hold the path of the directory entry.
  75 .SH VERSIONS
  76 Available since Linux 2.5.43.
  77 The ENAMETOOLONG error return was added in 2.5.70.
  78 .SH "CONFORMING TO"
  79 .BR lookup_dcookie ()
  80 is Linux specific.
  81 .SH "NOTES"
  82 .BR lookup_dcookie ()
  83 is a special-purpose system call, currently used only by the oprofile profiler.
  84 It relies on a kernel driver to register cookies for directory entries.
  85
  86 The path returned may be suffixed by the string " (deleted)" if the directory
  87 entry has been removed.