@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 isfdtype

@node isfdtype, io
@findex isfdtype

@subheading Syntax

@example
#include <sys/socket.h>

int isfdtype (int fd, int fd_type);
@end example

@subheading Description

The @code{isfdtype()} function determines whether the file descriptor @var{fd}
has the properties specified by @var{fd_type}.

Valid values of @var{fd_type} include:

@table @samp
@item S_IFSOCK
Tests whether @var{fd} is a socket
@end table

@subheading Return Value

1 if the type matches, 0 otherwise.  If an error occurs, -1 is returned and
@var{errno} is set to:

@table @samp
@item EBADF
@var{fd} is not a valid file descriptor.
@end table

@subheading Portability

@portability posix, !unix98

@code{isfdtype()} is usually declared in @samp{sys/stat.h} rather than
@samp{sys/socket.h}.

@subheading Example

@example
@end example