man2/llseek.2

   1 .\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
   2 .\" Written 10 June 1995 by Andries Brouwer <aeb@cwi.nl>
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  26 .\" Modified Thu Oct 31 15:16:23 1996 by Eric S. Raymond <esr@thyrsus.com>
  27 .\"
  28 .TH LLSEEK 2 2016-03-15 "Linux" "Linux Programmer's Manual"
  29 .SH NAME
  30 _llseek \- reposition read/write file offset
  31 .SH SYNOPSIS
  32 .nf
  33 .B #include <sys/types.h>
  34 .B #include <unistd.h>
  35 .PP
  36 .BI "int _llseek(unsigned int " fd ", unsigned long " offset_high ,
  37 .BI "            unsigned long " offset_low ", loff_t *" result ,
  38 .BI "            unsigned int " whence );
  39 .fi
  40 .PP
  41 .IR Note :
  42 There is no glibc wrapper for this system call; see NOTES.
  43 .SH DESCRIPTION
  44 The
  45 .BR _llseek ()
  46 function repositions the offset of the open file description associated
  47 with the file descriptor
  48 .I fd
  49 to
  50 .I (offset_high<<32) | offset_low
  51 bytes relative to the beginning of the file, the current file offset,
  52 or the end of the file, depending on whether
  53 .I whence
  54 is
  55 .BR SEEK_SET ,
  56 .BR SEEK_CUR ,
  57 or
  58 .BR SEEK_END ,
  59 respectively.
  60 It returns the resulting file position in the argument
  61 .IR result .
  62
  63 This system call exists on various 32-bit platforms to support
  64 seeking to large file offsets.
  65 .SH RETURN VALUE
  66 Upon successful completion,
  67 .BR _llseek ()
  68 returns 0.
  69 Otherwise, a value of \-1 is returned and
  70 .I errno
  71 is set to indicate the error.
  72 .SH ERRORS
  73 .TP
  74 .B EBADF
  75 .I fd
  76 is not an open file descriptor.
  77 .TP
  78 .B EFAULT
  79 Problem with copying results to user space.
  80 .TP
  81 .B EINVAL
  82 .I whence
  83 is invalid.
  84 .SH CONFORMING TO
  85 This function is Linux-specific, and should not be used in programs
  86 intended to be portable.
  87 .SH NOTES
  88 Glibc does not provide a wrapper for this system call.
  89 To invoke it directly, use
  90 .BR syscall (2).
  91 However, you probably want to use the
  92 .BR lseek (2)
  93 wrapper function instead.
  94 .SH SEE ALSO
  95 .BR lseek (2),
  96 .BR open (2),
  97 .BR lseek64 (3)