NAME
rpcgen —
Remote Procedure Call (RPC)
protocol compiler
SYNOPSIS
rpcgen |
[-AaBbILMNTv]
[-D name
[=value]]
[-i size]
[-K secs]
[-Y
pathname] infile |
rpcgen |
-c | -h | -l |
-m | -t | -Sc |
-Ss [-o
outfile]
[infile] |
rpcgen |
[-s
nettype]
[-o
outfile]
[infile] |
rpcgen |
[-n
netid] [-o
outfile]
[infile] |
DESCRIPTION
rpcgen is a tool that generates C code to implement an RPC
protocol. The input to
rpcgen is a language similar to C
known as RPC Language (Remote Procedure Call Language).
rpcgen is normally used as in the first synopsis where it
takes an input file and generates up to four output files. If the
infile is named
proto.x, then
rpcgen will generate 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 will
also generate the RPC dispatch table in
proto_tbl.i. With
the
-Sc option, it will also generate sample code which
would illustrate how to use the remote procedures on the client side. This
code would be created in
proto_client.c. With the
-Ss option, it will also generate a sample server code which
would illustrate how to write the remote procedures. This code would be
created in
proto_server.c.
The server created can be started both by the port monitors (for example,
inetd or
listen) or by itself. When it is
started by a port monitor, it creates servers only for the transport for which
the file descriptor 0 was passed. The name of the transport must be specified
by setting up the environmental variable
PM_TRANSPORT
.
When the server generated by
rpcgen is executed, it creates
server handles for all the transports specified in
NETPATH
environment variable, or if it is unset, it
creates server handles for all the visible transports from
/etc/netconfig file.
Note: the transports are chosen at run time and not at compile
time. 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.
The second synopsis provides special features which allow for the creation of
more sophisticated RPC servers. These features include support for user
provided
#defines
and RPC dispatch tables. 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 three synopses shown above are used when one does not want to generate
all the output files, but only a particular one. Some examples of their usage
is described in the
EXAMPLES section below.
When
rpcgen is executed with the
-s
option, it creates servers for that particular class of transports. When
executed with the
-n option, it creates a server for the
transport specified by
netid. If
infile is not specified,
rpcgen
accepts the standard input.
The C preprocessor,
cpp(1) is run on
the input file before it is actually interpreted by
rpcgen
For each type of output file,
rpcgen defines a special
preprocessor symbol for use by the
rpcgen 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
Any line beginning with ‘%’ is passed directly into the output file,
uninterpreted by
rpcgen.
For every data type referred to in
infile
rpcgen assumes that there exists a routine with the string
“xdr_” prepended to the name of 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
-
-
- -A
- Generate an svc_caller() function.
-
-
- -a
- Generate all the files including sample code for client and
server side.
-
-
- -B
- Generate BSD cplusplus macros (__BEGIN_DECLS,
__END_DECLS).
-
-
- -b
- Compile stubs in "backwards compatible" mode,
disabling support for transport-independent RPC. The -b
should always be specified when generating files for
NetBSD, since there is no transport-independent
RPC support in NetBSD.
-
-
- -c
- Compile into XDR routines.
-
-
- -D
name[=value]
- Define a symbol
name
. Equivalent to
the #define
directive in the source. If no
value
is given, value
is
defined as 1. This option may be specified 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
- Support
inetd(8) in the server side
stubs. Servers generated using this flag can either be standalone or
started from inetd(8). If a
server is started as standalone, then it places itself in the background,
unless
RCP_SVC_FG
is defined, or the server is
compiled without -I.
-
-
- -i
size
- Size to decide when to start generating inline code. The
default size is 3.
-
-
- -K
secs
- By default, services created using rpcgen
wait 120 seconds after servicing a request before exiting. That interval
can be changed using the -K flag. To create a server
that exits immediately upon servicing a request,
“-K 0” can be used.
To create a server that never exits, the appropriate argument is
“-K -1”.
When monitoring for a server, some port monitors, like the
AT&T System V Release 4 UNIX utility
listen, always spawn a new process in
response to a service request. If it is known that a server will be used
with such a monitor, the server should exit immediately on completion. For
such servers, rpcgen should be used with
“-K -1”.
-
-
- -L
- Server errors will be sent to syslog instead of
stderr.
-
-
- -l
- Compile into client-side stubs.
inetd(8).
-
-
- -M
- Generate thread-safe stubs. This alters the calling pattern
of client and server stubs so that storage for results is allocated by the
caller. Note that all components for a particular service (stubs, client
and service wrappers, etc.) must be built either with or without the
-M flag.
-
-
- -m
- Compile into server-side stubs, but do not generate a
main() routine. This option is useful for doing
callback-routines and for users who need to write their own
main() routine to do initialization.
-
-
- -N
- Use the newstyle of rpcgen. This allows
procedures to have multiple arguments. It also uses the style of parameter
passing that closely resembles C. So, when passing an argument to a remote
procedure you do not have to pass a pointer to the argument but the
argument itself. This behaviour is different from the oldstyle of
rpcgen generated code. The newstyle is not the default
case because of backward compatibility.
-
-
- -n
netid
- Compile into server-side stubs for the transport specified
by netid. There should be an entry for
netid in the netconfig database. This option may be
specified more than once, so as to compile a server that serves multiple
transports.
-
-
- -o
outfile
- Specify the name of the output file. If none is specified,
standard output is used (-c -h
-l -m -n
-s modes only)
-
-
- -s
nettype
- Compile into server-side stubs for all the transports
belonging to the class nettype. The supported
classes are netpath, visible,
circuit_n, circuit_v,
datagram_n, datagram_v,
tcp, and udp [see
rpc(3) for the meanings
associated with these classes. Note:
BSD currently supports only the
tcp and udp classes]. This option may
be specified more than once. Note: the transports are
chosen at run time and not at compile time.
-
-
- -Sc
- Generate sample code to show the use of remote procedure
and how to bind to the server before calling the client side stubs
generated by rpcgen.
-
-
- -Ss
- Generate skeleton code for the remote procedures on the
server side. You would need to fill in the actual code for the remote
procedures.
-
-
- -T
- Generate the code to support RPC dispatch tables.
-
-
- -t
- Compile into RPC dispatch table.
-
-
- -v
- Display the version number.
-
-
- -Y
pathname
- Specify the directory where rpcgen looks
for the C pre-processor.
The options
-c,
-h,
-l,
-m,
-s, and
-t are used
exclusively to generate a particular type of file, while the options
-D and
-T are global and can be used with
the other options.
ENVIRONMENT
If the
RPCGEN_CPP
environment variable is set, its value
is used as the pathname of the C preprocessor to be run on the input file.
NOTES
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.
The server code generated with
-n option refers to the
transport indicated by
netid and hence is very site
specific.
EXAMPLES
The command
generates the five files:
prot.h,
prot_clnt.c,
prot_svc.c,
prot_xdr.c and
prot_tbl.i.
The following example sends the C data-definitions (header file) to standard
output.
To send the test version of the
-DTEST
, server side
stubs for all the transport belonging to the class
datagram_n to standard output, use:
$ rpcgen -s datagram_n -DTEST prot.x
To create the server side stubs for the transport indicated by
netid tcp, use:
$ rpcgen -n tcp -o prot_svc.c prot.x
SEE ALSO
cpp(1),
inetd(8)
HISTORY
The
-M option was first implemented in RedHat Linux, and was
reimplemented by Charles M. Hannum in
NetBSD
1.6.