[OE-core] [PATCH][V2 1/2] openssl: sanity check that the bignum module is present

[Ross Burton]

The crypto_use_bigint_in_x86-64_perl patch uses the "bigint" module to
transparently support 64-bit integers on 32-bit hosts.  Whilst bigint (part of
bignum) is a core Perl module not all distributions install it (notable Fedora
23).

As the error message when bignum isn't installed is obscure, add a task to check
that it is available and alert the user if it isn't.

[ YOCTO #8562 ]

Signed-off-by: Ross Burton <ross.burton at intel.com>
---
 meta/recipes-connectivity/openssl/openssl_1.0.2d.bb | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/meta/recipes-connectivity/openssl/openssl_1.0.2d.bb b/meta/recipes-connectivity/openssl/openssl_1.0.2d.bb
index fd56841..659e0bd 100644
--- a/meta/recipes-connectivity/openssl/openssl_1.0.2d.bb
+++ b/meta/recipes-connectivity/openssl/openssl_1.0.2d.bb
@@ -56,3 +56,13 @@ PARALLEL_MAKEINST = ""
 do_configure_prepend() {
   cp ${WORKDIR}/find.pl ${S}/util/find.pl
 }
+
+# The crypto_use_bigint patch means that perl's bignum module needs to be
+# installed, but some distributions (for example Fedora 23) don't ship it by
+# default.  As the resulting error is very misleading check for bignum before
+# building.
+do_configure_prepend() {
+	if ! perl -Mbigint -e true; then
+		bbfatal "The perl module 'bignum' was not found but this is required to build openssl.  Please install this module (often packaged as perl-bignum) and re-run bitbake."
+	fi
+}
-- 
2.1.4