DISGEN(1)

NAME
disgen - DIS protocol compiler

SYNOPSIS
disgen infile
disgen [ -Dname[=value] ] [ -I [ -K seconds ] ] [ -L ] [ -T ] infile
disgen -c | -h | -l | -m | -t [ -o outfile ] [ infile ]
disgen -s transport [ -o outfile ] [ infile ]

DESCRIPTION

disgen generates C code to implement the Distributed Interactive Simulation protocol. The input to disgen is a language similar to C known as the RPC Language (Remote Procedure Call Language). Information about the syntax of RPC Language is available in the `rpcgen' Programming Guide in the manual.

disgen is normally used as in the first synopsis where it takes an input file and generates four output files. If the infile is named proto.x, then disgen generates a header file in proto.h, XDR routines in proto_xdr.c, server side stubs in proto_svc.c, and client side stubs in proto_clnt.c. With the -T option, it also generates the RPC dispatch table in proto_tbl.i.

The second synposis provides special features which allow for the creation of more sophisticated RPC servers. These features include support for RPC dispatch tables, and user provided #defines. The entries in the RPC dispatch table contain:

    •   pointers to the service routine corresponding to that procedure
    •   a pointer to the input and output arguments
    •   the size of these routines

A server can use the dispatch table to check authorization and then to execute the service routine; a client library may use it to deal with the details of storage management and XDR data conversion.

The other two synopses shown above are used when one does not want to generate all the output files, but only a particular one. Their usage is described in the EXAMPLES section below.

The C-preprocessor, cpp(1), is run on the input file before it is actually interpreted by disgen, so all the cpp directives are legal within an disgen input file. For each type of output file, disgen defines a special cpp symbol for use by the disgen programmer:

    RPC_HDR
        defined when compiling into header files
    RPC_XDR
        defined when compiling into XDR routines
    RPC_SVC
        defined when compiling into server side stubs
    RPC_CLNT
        defined when compiling into client side stubs
    RPC_TBL
        defined when compiling into RPC dispatch tables

In addition, disgen does a little preprocessing of its own. Any line beginning with `%' is passed directly into the output file, uninterpreted by disgen. For every data type referred to in infile, disgen assumes that there exists a routine with the string `xdr_' prepended to the data type. If this routine does not exist in the RPC/XDR library, it must be provided. Providing an undefined data type allows customization of XDR routines.

OPTIONS

-c  Compile into XDR routines.

-Dname[=value]
    Define a symbol name. Equivalent to the #define directive in the source. If no value is given, name is defined as 1. This option may be called more than once.

-h  Compile into C data-definitions (a header file). The -T option can be used in conjunction to produce a header file which supports RPC dispatch tables.

-I  Compile support for inetd(8C) in the server side stubs. Such servers can be self started or can be started by inetd. When the server is self-started, it backgrounds itself by default. A special define symbol RPC_SVC_FG can be used to run the server process in foreground, or alternately the user may just compile it without the -I option. If there are no pending client requests, the inetd servers exit after 120 seconds (default). The default can be changed with the -K option. All the error messages for inetd servers are always logged in with syslog(3).

-K seconds
    If the server was started by inetd, specify the time in seconds after which the server should exit if there is no further activity. This option is useful for customization. If seconds is 0, the server exits after serving that given request. If seconds is -1, the server hangs around for ever after being started by inetd. This option is valid only with the -I option.

-l  Compile into client side stubs.

-L  When the servers are started in foreground, use syslog() to log the server errors instead of printing them on the standard error.

-m  Compile into server side stubs, but do not generate a “main” routine. This option is useful for doing callback-routines and for people who need to write their own “main” routine to do initialization. For inetd support, they should be compiled with the -I option. In such cases, it defines 2 global variables: _rpcpmstart and _rpcfdtype. The value of _rpcpmstart should be 1 or 0 depending upon whether it was started by inetd or not. The value of _rpcfdtype should be SOCK_STREAM or SOCK_DGRAM depending upon the type of the connection.

-o outfile
    Specify the name of the output file. If none is specified, the standard output is used (-c, -h, -l, -m, -s and -t modes only).

-s transport
    Compile into server side stubs for the given transport. The supported transports are udp and tcp. This option may be called more than once so as to compile a server that serves multiple transports. For inetd support, they should be compiled with the -I option.

-t  Compile into RPC dispatch table.

-T  Generate the code to support RPC dispatch tables.

The options -c, -h, -l, -m, -s and -t are used exclusively to generate a particular type of file, while the options -D, -I, -L and -T are global and can be used with the other options.

EXAMPLES

The following example generates all the five files: prot.h, prot_clnt.c, prot_svc.c, prot_xdr.c and prot_tbl.i. The server error messages are logged, instead of being sent to the standard error.

    example% disgen -LT prot.x

The following example generates prot.h, prot_clnt.c, prot_xdr.c and prot_svc.c. prot_svc.c supports server invocation by inetd. If the server is started by inetd, the server exits after 20 seconds of inactivity.

    example% disgen -I -K 20 prot.x

The following example sends the header file (with support for dispatch tables) on the standard output.

    example% disgen -hT prot.x

The following example sends the server side stubs file for the transport tcp on the standard output.

    example% disgen -s tcp prot.x

SEE ALSO
cpp(1), rpc(3N), inetd(8C)

`disgen' Programming Guide in

BUGS

The RPC Language does not support nesting of structures. As a work-around, structures can be declared at the top-level, and their name used inside other structures in order to achieve the same effect.

Name clashes can occur when using program definitions, since the apparent scoping does not really apply. Most of these can be avoided by giving unique names for programs, versions, procedures and types.