Tests for processing zero-length content in SMIME format

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/13087)

test/recipes/80-test_cms.t

@@ -45,6 +45,7 @@ my $provname = 'default';
 my $datadir = srctop_dir("test", "recipes", "80-test_cms_data");
 my $smdir    = srctop_dir("test", "smime-certs");
 my $smcont   = srctop_file("test", "smcont.txt");
+my $smcont_zero = srctop_file("test", "smcont_zero.txt");
 my ($no_des, $no_dh, $no_dsa, $no_ec, $no_ec2m, $no_rc2, $no_zlib)
     = disabled qw/des dh dsa ec ec2m rc2 zlib/;
 
@@ -169,6 +170,15 @@ my @smime_pkcs7_tests = (
       \&final_compare
     ],
 
+    [ "signed zero-length content S/MIME format, RSA key SHA1",
+      [ "{cmd1}", @defaultprov, "-sign", "-in", $smcont_zero, "-md", "sha1",
+        "-certfile", catfile($smdir, "smroot.pem"),
+        "-signer", catfile($smdir, "smrsa1.pem"), "-out", "{output}.cms" ],
+      [ "{cmd2}", @prov, "-verify", "-in", "{output}.cms",
+        "-CAfile", catfile($smdir, "smroot.pem"), "-out", "{output}.txt" ],
+      \&zero_compare
+    ],
+
     [ "signed content test streaming S/MIME format, 2 DSA and 2 RSA keys",
       [ "{cmd1}", @prov, "-sign", "-in", $smcont, "-nodetach",
         "-signer", catfile($smdir, "smrsa1.pem"),
@@ -679,6 +689,13 @@ sub final_compare {
     return compare_text($smcont, "$opts{output}.txt") == 0;
 }
 
+sub zero_compare {
+    my %opts = @_;
+
+    diag "Checking for zero-length file";
+    return (-e "$opts{output}.txt" && -z "$opts{output}.txt");
+}
+
 subtest "CMS => PKCS#7 compatibility tests\n" => sub {
     plan tests => scalar @smime_pkcs7_tests;