Copyright (c) 2002 William C. Fenner. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
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1. Redistributions of source code must retain the above copyright
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2. Redistributions in binary form must reproduce the above copyright
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THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
$FreeBSD$
.Dd October 13, 2002 .Dt SOCKATMARK 3 .Os .Sh NAME .Nm sockatmark .Nd determine whether the read pointer is at the OOB mark .Sh LIBRARY .Lb libc .Sh SYNOPSIS n sys/socket.h .Ft int .Fn sockatmark "int s" .Sh DESCRIPTION To find out if the read pointer is currently pointing at the mark in the data stream, the .Fn sockatmark function is provided. If .Fn sockatmark returns 1, the next read will return data after the mark. Otherwise (assuming out of band data has arrived), the next read will provide data sent by the client prior to transmission of the out of band signal. The routine used in the remote login process to flush output on receipt of an interrupt or quit signal is shown below. It reads the normal data up to the mark (to discard it), then reads the out-of-band byte. d -literal -offset indent #include <sys/socket.h> ... oob() { int out = FWRITE, mark; char waste[BUFSIZ]; /* flush local terminal output */ ioctl(1, TIOCFLUSH, (char *)&out); for (;;) { if ((mark = sockatmark(rem)) < 0) { perror("sockatmark"); break; } if (mark) break; (void) read(rem, waste, sizeof (waste)); } if (recv(rem, &mark, 1, MSG_OOB) < 0) { perror("recv"); ... } ... } .Ed .Sh RETURN VALUES Upon successful completion, the .Fn sockatmark function returns the value 1 if the read pointer is pointing at the OOB mark, 0 if it is not. Otherwise the value -1 is returned and the global variable .Va errno is set to indicate the error. .Sh ERRORS The .Fn sockatmark call fails if: l -tag -width Er t Bq Er EBADF The .Fa s argument is not a valid descriptor. t Bq Er ENOTTY The .Fa s argument is a descriptor for a file, not a socket. .El .Sh SEE ALSO .Xr recv 2 , .Xr send 2 .Sh HISTORY The .Fn sockatmark function was introduced by .St -p1003.1-2001 , to standardize the historical .Dv SIOCATMARK .Xr ioctl 2 . The .Er ENOTTY error instead of the usual .Er ENOTSOCK is to match the historical behavior of .Dv SIOCATMARK .
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
$FreeBSD$
.Dd October 13, 2002 .Dt SOCKATMARK 3 .Os .Sh NAME .Nm sockatmark .Nd determine whether the read pointer is at the OOB mark .Sh LIBRARY .Lb libc .Sh SYNOPSIS n sys/socket.h .Ft int .Fn sockatmark "int s" .Sh DESCRIPTION To find out if the read pointer is currently pointing at the mark in the data stream, the .Fn sockatmark function is provided. If .Fn sockatmark returns 1, the next read will return data after the mark. Otherwise (assuming out of band data has arrived), the next read will provide data sent by the client prior to transmission of the out of band signal. The routine used in the remote login process to flush output on receipt of an interrupt or quit signal is shown below. It reads the normal data up to the mark (to discard it), then reads the out-of-band byte. d -literal -offset indent #include <sys/socket.h> ... oob() { int out = FWRITE, mark; char waste[BUFSIZ]; /* flush local terminal output */ ioctl(1, TIOCFLUSH, (char *)&out); for (;;) { if ((mark = sockatmark(rem)) < 0) { perror("sockatmark"); break; } if (mark) break; (void) read(rem, waste, sizeof (waste)); } if (recv(rem, &mark, 1, MSG_OOB) < 0) { perror("recv"); ... } ... } .Ed .Sh RETURN VALUES Upon successful completion, the .Fn sockatmark function returns the value 1 if the read pointer is pointing at the OOB mark, 0 if it is not. Otherwise the value -1 is returned and the global variable .Va errno is set to indicate the error. .Sh ERRORS The .Fn sockatmark call fails if: l -tag -width Er t Bq Er EBADF The .Fa s argument is not a valid descriptor. t Bq Er ENOTTY The .Fa s argument is a descriptor for a file, not a socket. .El .Sh SEE ALSO .Xr recv 2 , .Xr send 2 .Sh HISTORY The .Fn sockatmark function was introduced by .St -p1003.1-2001 , to standardize the historical .Dv SIOCATMARK .Xr ioctl 2 . The .Er ENOTTY error instead of the usual .Er ENOTSOCK is to match the historical behavior of .Dv SIOCATMARK .