Let rpcgen(1) support an environment variable RPCGEN_CPP to find the C

preprocessor to run.  Previously, it always ran /usr/bin/cpp, unless you
used the -Y option, and even then you could not set the basename.  It
also attempted to run /usr/ccs/lib/cpp for SVR4 compatibility, but this
is obsolete, and has been removed.

Note that setting RPCGEN_CPP to a command with arguments is supported,
though the command line parsing is simplistic.  However, setting it to
e.g. "gcc46 -E" or "clang -E" will lead to problems, because both gcc
and clang in -E mode will consider files with unknown extensions (such
as .x) as object files, and attempt to link them.

This could be worked around by also adding "-x c", but it is much safer
to set RPCGEN_CPP to e.g. "cpp46" or "clang-cpp" instead.

MFC after:	1 week

1 files changed, 5 insertions, 0 deletions

diff --git a/usr.bin/rpcgen/rpcgen.1 b/usr.bin/rpcgen/rpcgen.1
index 2a4a25e..1389adf 100644
--- a/usr.bin/rpcgen/rpcgen.1
+++ b/usr.bin/rpcgen/rpcgen.1
@@ -490,6 +490,11 @@ Give the name of the directory where
 .Nm
 will start looking for the C-preprocessor.
 .El
+.Sh ENVIRONMENT
+If the
+.Ev RPCGEN_CPP
+environment variable is set, its value is used as the command line of the
+C preprocessor to be run on the input file.
 .Sh EXAMPLES
 The following example:
 .Dl example% rpcgen -T prot.x