From 1043e25b6f3f5f804374e97bd87e1c003d7b92c2 Mon Sep 17 00:00:00 2001
From: Michael Kerrisk <mtk.manpages@gmail.com>
Date: Mon, 13 Dec 2004 12:42:20 +0000
Subject: [PATCH] New page from Andries Brouwer

---
 man3/lseek64.3 | 160 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 man3/lseek64.3

diff --git a/man3/lseek64.3 b/man3/lseek64.3
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+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date.  The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein.  The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\"
+.TH LSEEK64 3 2004-12-11 "Linux" "Linux Programmer's Manual"
+.SH NAME
+lseek64 \- reposition 64-bit read/write file offset
+.SH SYNOPSIS
+.B #define _LARGEFILE64_SOURCE
+.br
+.B #include <sys/types.h>
+.br
+.B #include <unistd.h>
+.sp
+.BI "off64_t lseek64(int " fd ", off64_t " offset ", int " whence );
+.SH DESCRIPTION
+The
+.BR lseek (2)
+family functions reposition the offset of the file descriptor
+.I fd
+to
+.I offset
+bytes relative to start, current position, or end-of-file of the file,
+when
+.I whence
+has the value
+.BR SEEK_SET ,
+.BR SEEK_CUR ,
+or
+.BR SEEK_END ,
+respectively.
+.LP
+For more details, return value, and errors, see
+.BR lseek (2).
+.PP
+Four interfaces are available:
+.IR lseek() ,
+.IR lseek64() ,
+.IR llseek() ,
+and the raw system call
+.IR _llseek() .
+.SS lseek
+Prototype:
+.nf
+.sp
+.in +5n
+.BI "off_t lseek(int " fd ", off_t " offset ", int " whence );
+.in -5n
+.fi
+.sp
+The library routine
+.I lseek()
+uses the type
+.B off_t
+which is a 32-bit signed type on 32-bit architectures, unless one
+compiles with
+.nf
+.sp
+.in +5n
+#define _FILE_OFFSET_BITS 64
+.in -5n
+.sp
+.fi
+in which case it is a 64-bit signed type.
+
+.SS lseek64
+Prototype:
+.nf
+.sp
+.in +5n
+.BI "off64_t lseek64(int " fd ", off64_t " offset ", int " whence );
+.in -5n
+.fi
+.sp
+The library routine
+.I lseek64()
+uses a 64-bit type even when
+.B off_t
+is a 32-bit type. Its prototype (and the type
+.BR off64_t )
+is available only when one compiles with
+.nf
+.sp
+.in +5n
+#define _LARGEFILE64_SOURCE
+.in -5n
+.sp
+.fi
+The function
+.I lseek64()
+.\" in glibc 2.0.94, not in 2.0.6
+is available since glibc 2.1, and is defined to be an alias of
+.IR llseek() .
+
+.SS llseek
+Prototype:
+.nf
+.sp
+.in +5n
+.BI "loff_t llseek(int " fd ", loff_t " offset ", int " whence );
+.in -5n
+.fi
+.sp
+The type
+.B loff_t
+is a 64-bit signed type.
+The library routine
+.I llseek()
+.\" in libc 5.0.9, not in 4.7.6
+is available in libc5 and glibc and works without special defines.
+Its prototype was given in
+.I <unistd.h>
+with libc5, but glibc does not provide a prototype.
+This is bad, since a prototype is needed. Users should add
+the above prototype, or something equivalent, to their own source.
+When users complained about data loss caused by a miscompilation of
+.BR e2fsck (8),
+glibc 2.1.3 added the link-time warning
+.sp
+.in +5n
+"the `llseek' function may be dangerous; use `lseek64' instead."
+.in -5b
+.sp
+This makes this function unusable if one desires a warning-free
+compilation.
+
+.SS _llseek
+All the above functions are implemented in terms of the system call.
+The prototype is:
+.nf
+.sp
+.in +5n
+.BI "int _llseek (int " fd ", off_t " offset_hi ", off_t " offset_lo ,
+.BI "loff_t *" result ", int " whence );
+.in -5n
+.fi
+.sp
+For more details, see
+.BR llseek (2).
+.SH "SEE ALSO"
+.BR llseek (2),
+.BR lseek (2)