@comment Written by Alain Magloire, modified by Richard Dawe.

@comment The start of a comment is indicated by the following comment. This
@comment syntax is used by the script funcstxh.sh: @comment function <name>

@comment function sockatmark

@node sockatmark, socket
@findex sockatmark

@subheading Syntax

@example
#include <sys/socket.h>

int sockatmark (int s);
@end example

@subheading Description

The @code{sockatmark()} function determines whether the socket descriptor
@var{s} is at the out-of-band data mark.  If the libsocket interface supports
it, @code{sockatmark()} will return 1 when all data preceding the mark have
been read and the out-of-band data mark is the first element in the receive
queue.  @code{sockatmark()} does not remove the mark from the stream.

@subheading Return Values

On successful initialization the function returns 1, if the protocol
has marked the data stream and all data preceeding the mark have been read.
It returns 0, if there is no mark, or if data preceeds the mark in the receive
queue.  Otherwise, -1 is return and errno is set:

@table @samp
@item EBADF
The parameter is not a valid file descriptor.
@item ENOSYS
The inteface does not support the @code{sockatmark()} operation.
@end table

@subheading Portability

@portability !ansi, posix

@subheading Example

@example
@end example