Add script to test configs with single key exchanges

tests/scripts/curves.pl

@@ -32,7 +32,7 @@ for my $curve (@curves) {
     system( "scripts/config.pl unset $curve" )
         and abort "Failed to disable $curve\n";
 
-    system( "make mbedtls" ) and abort "Failed to build lib: $curve\n";
+    system( "make lib" ) and abort "Failed to build lib: $curve\n";
     system( "cd tests && make" ) and abort "Failed to build tests: $curve\n";
     system( "make test" ) and abort "Failed test suite: $curve\n";
 

tests/scripts/key-exchanges.pl

@@ -0,0 +1,43 @@
+#!/usr/bin/perl
+
+# test that all configs with only a single key exchange enabled build
+#
+# Usage: tests/scripts/key-exchanges.pl
+
+use warnings;
+use strict;
+
+-d 'library' && -d 'include' && -d 'tests' or die "Must be run from root\n";
+
+my $sed_cmd = 's/^#define \(MBEDTLS_KEY_EXCHANGE_.*_ENABLED\)/\1/p';
+my $config_h = 'include/mbedtls/config.h';
+my @kexes = split( /\s+/, `sed -n -e '$sed_cmd' $config_h` );
+
+system( "cp $config_h $config_h.bak" ) and die;
+sub abort {
+    system( "mv $config_h.bak $config_h" ) and warn "$config_h not restored\n";
+    die $_[0];
+}
+
+for my $kex (@kexes) {
+    system( "cp $config_h.bak $config_h" ) and die "$config_h not restored\n";
+    system( "make clean" ) and die;
+
+    print "\n******************************************\n";
+    print "* Testing with key exchange: $kex\n";
+    print "******************************************\n";
+
+    # full config with all key exchanges disabled except one
+    system( "scripts/config.pl full" ) and abort "Failed config full\n";
+    for my $k (@kexes) {
+        next if $k eq $kex;
+        system( "scripts/config.pl unset $k" )
+            and abort "Failed to disable $k\n";
+    }
+
+    system( "make lib" ) and abort "Failed to build lib: $kex\n";
+}
+
+system( "mv $config_h.bak $config_h" ) and die "$config_h not restored\n";
+system( "make clean" ) and die;
+exit 0;