enable cross-compiling
diff --git a/configure.ac b/configure.ac
index 7f068c3..b10473e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -30,6 +30,11 @@
[include classes for streaming compressed data in and out @<:@default=check@:>@])],
[],[with_zlib=check])
+AC_ARG_WITH([protoc],
+ [AS_HELP_STRING([--with-protoc=COMMAND],
+ [use the given protoc command instead of building a new one when building tests (useful for cross-compiling)])],
+ [],[with_protoc=no])
+
# Checks for programs.
AC_PROG_CC
AC_PROG_CXX
@@ -90,6 +95,25 @@
fi])])
AM_CONDITIONAL([HAVE_ZLIB], [test $HAVE_ZLIB = 1])
+AS_IF([test "$with_protoc" != "no"], [
+ PROTOC=$with_protoc
+ AS_IF([test "$with_protoc" == "yes"], [
+ # No argument given. Use system protoc.
+ PROTOC=protoc
+ ])
+ AS_IF([echo "$PROTOC" | grep -q '^@<:@^/@:>@.*/'], [
+ # Does not start with a slash, but contains a slash. So, it's a relative
+ # path (as opposed to an absolute path or an executable in $PATH).
+ # Since it will actually be executed from the src directory, prefix with
+ # the current directory. We also insert $ac_top_build_prefix in case this
+ # is a nested package and --with-protoc was actually given on the outer
+ # package's configure script.
+ PROTOC=`pwd`/${ac_top_build_prefix}$PROTOC
+ ])
+ AC_SUBST([PROTOC])
+])
+AM_CONDITIONAL([USE_EXTERNAL_PROTOC], [test "$with_protoc" != "no"])
+
ACX_PTHREAD
AC_CXX_STL_HASH