Fix Cwd::getcwd() not being tainted, as noticed

by Schwern.

p4raw-id: //depot/perl@11873

3 files changed, 27 insertions, 8 deletions

diff --git a/ext/Cwd/Cwd.xs b/ext/Cwd/Cwd.xs
index 303ef70a02..a82404f156 100644
--- a/ext/Cwd/Cwd.xs
+++ b/ext/Cwd/Cwd.xs
@@ -226,22 +226,20 @@ PPCODE:
 {
     dXSTARG;
     char *path;
-    STRLEN len;
     char buf[MAXPATHLEN];
 
-    if (pathsv)
-      path = SvPV(pathsv, len);
-    else {
-        path = ".";
-        len  = 1;
-    }
+    path = pathsv ? SvPV_nolen(pathsv) : ".";
 
     if (bsd_realpath(path, buf)) {
         sv_setpvn(TARG, buf, strlen(buf));
         SvPOK_only(TARG);
+	SvTAINTED_on(TARG);
     }
     else
-      sv_setsv(TARG, &PL_sv_undef);
+        sv_setsv(TARG, &PL_sv_undef);
 
     XSprePUSH; PUSHTARG;
+#ifndef INCOMPLETE_TAINTS
+    SvTAINTED_on(TARG);
+#endif
 }
diff --git a/ext/Cwd/Cwd.t b/ext/Cwd/t/cwd.t
index 09b45d6004..09b45d6004 100644
--- a/ext/Cwd/Cwd.t
+++ b/ext/Cwd/t/cwd.t
diff --git a/ext/Cwd/t/taint.t b/ext/Cwd/t/taint.t
new file mode 100644
index 0000000000..036b2b1b8e
--- /dev/null
+++ b/ext/Cwd/t/taint.t
@@ -0,0 +1,21 @@
+#!./perl -Tw
+# Testing Cwd under taint mode.
+
+BEGIN {
+    chdir 't' if -d 't';
+    @INC = '../lib';
+}
+
+use Cwd;
+use Test::More tests => 2;
+
+# The normal kill() trick is not portable.
+sub is_tainted { 
+    return ! eval { eval("#" . substr(join("", @_), 0, 0)); 1 };
+}
+
+my $cwd;
+eval { $cwd = getcwd; };
+is( $@, '',                 'getcwd() does not explode under taint mode' );
+ok( is_tainted($cwd),       "it's return value is tainted" );
+