.TH ftp_lseek 3 "January 2004" "Feep Networks" "C Library Calls"
.SH NAME
ftp_lseek \- reposition read/write FTP file offset
.SH SYNOPSIS
.B #include <libfget.h>

.BI "off_t ftp_lseek(FTPFILE *" ftpfile ", off_t " offset ","
.BI "int " whence ");"
.SH VERSION
This man page documents version 1.3 of \fBlibfget\fP.
.SH DESCRIPTION
The \fBftp_lseek\fP() function repositions the offset of \fIftpfile\fP
to the specified \fIoffset\fP.  The interpretation of \fIoffset\fP is
controlled by the directive \fIwhence\fP, which may be one of the
following values: 
.IP \fBSEEK_SET\fP
The offset is set to \fIoffset\fP bytes.
.IP \fBSEEK_CUR\fP
The offset is set to its current location plus \fIoffset\fP bytes.
.SH RETURN VALUE
The \fBftp_lseek\fP() function returns the resulting offset location
as measured in bytes from the beginning of the file on success, or -1 on
error (and sets \fIerrno\fP).
.SH ERRORS
The \fBftp_lseek\fP() function fails if:
.TP
.B ECONNRESET
The server shut down the connection.  The caller is then responsible
for calling \fBftp_quit\fP() with the \fBFTP_QUIT_FAST\fP flag set.
.TP
.B ETIMEDOUT
The operation timed out.  (The timeout interval can be set via the
\fBFTP_OPT_IO_TIMEOUT\fP option; see the \fBftp_set_options\fP(3) man
page for details.)
.TP
.B EINVAL
Unexpected response code received from server.
.TP
.B EINVAL
The \fIwhence\fP directive was set to an invalid value.
.TP
.B ENOSYS
The \fIwhence\fP directive was set to \fBSEEK_END\fP, which is not
currently supported.
.TP
.B ENOSYS
The file pointer \fIFTPFILE\fP was opened in \fBO_WRONLY\fP mode.  The
\fBftp_lseek\fP() function only supports \fBO_RDONLY\fP files.
.PP
It may also fail for any of the errors specified for the underlying
\fBpoll\fP(2), \fBread\fP(2), \fBwrite\fP(2), \fBsend\fP(2),
\fBsocket\fP(2), \fBconnect\fP(2), \fBfcntl\fP(2) (using \fBF_GETFL\fP
and \fBF_SETFL\fP), or \fBcalloc\fP(3) system and library calls.
.SH NOTES
The \fBftp_lseek\fP() function cannot be used if \fIftpfile\fP was created
with \fImode\fP set to \fBO_WRONLY\fP.  As a consequence of this, it does
not support the \fBSEEK_END\fP directive.

Unlike \fBlseek\fP(2), \fBftp_lseek\fP() does not allow seeking past
the end of a file.
.SH SEE ALSO
.BR libfget (3),
.BR lseek (2)