From: Nicholas Clark <nick@ccl4.org>
Date: Sun, 28 Dec 2008 09:36:16 +0000 (+0000)
Subject: Precomputing the hash value for a string representable in bytes, but passed in
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=527df579b2667fd0b8db4c07bcab268e0f401be9;p=p5sagit%2Fp5-mst-13.2.git

Precomputing the hash value for a string representable in bytes, but passed in
in UTF-8, would result in storing the wrong hash value in the hash, and hence
failing lookups. I guess not that much XS code precomputes hash values.
---

diff --git a/ext/XS/APItest/APItest.xs b/ext/XS/APItest/APItest.xs
index 78ee526..e63d804 100644
--- a/ext/XS/APItest/APItest.xs
+++ b/ext/XS/APItest/APItest.xs
@@ -448,10 +448,14 @@ common(params)
 	if ((svp = hv_fetchs(params, "action", 0)))
 	    action = SvIV(*svp);
 	if ((svp = hv_fetchs(params, "val", 0)))
-	    val = *svp;
+	    val = newSVsv(*svp);
 	if ((svp = hv_fetchs(params, "hash", 0)))
 	    hash = SvUV(*svp);
 
+	if ((svp = hv_fetchs(params, "hash_pv", 0))) {
+	    PERL_HASH(hash, key, klen);
+	}
+
 	result = (HE *)hv_common(hv, keysv, key, klen, flags, action, val, hash);
 	if (!result) {
 	    XSRETURN_EMPTY;
diff --git a/ext/XS/APItest/t/hash.t b/ext/XS/APItest/t/hash.t
index 1ef99ed..47d4437 100644
--- a/ext/XS/APItest/t/hash.t
+++ b/ext/XS/APItest/t/hash.t
@@ -150,6 +150,27 @@ if ($] > 5.009) {
     }
 }
 
+{
+    my $as_utf8 = "\241" . chr 256;
+    chop $as_utf8;
+    my $as_bytes = "\243";
+    foreach my $key ('N', $as_bytes, $as_utf8, "\x{2623}") {
+	my $ord = ord $key;
+	foreach my $hash_pv (0, 1) {
+	    my %hash;
+	    is (XS::APItest::Hash::common({hv => \%hash, keypv => $key,
+					   val => $ord, hash_pv => $hash_pv,
+					   action =>
+					   XS::APItest::HV_FETCH_ISSTORE}),
+		$ord, "store $ord \$hash_pv = $hash_pv");
+	    is_deeply ([each %hash], [$key, $ord], "First key read is good");
+	    is_deeply ([each %hash], [], "No second key good");
+
+	    is ($hash{$key}, $ord, "Direct hash read finds $ord");
+	}
+    }
+}
+
 exit;
 
 ################################   The End   ################################
diff --git a/hv.c b/hv.c
index 78a1097..b764c55 100644
--- a/hv.c
+++ b/hv.c
@@ -606,6 +606,11 @@ Perl_hv_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
 	    if (flags & HVhek_FREEKEY)
 		Safefree(keysave);
             flags |= HVhek_WASUTF8 | HVhek_FREEKEY;
+	    /* If the caller calculated a hash, it was on the sequence of
+	       octets that are the UTF-8 form. We've now changed the sequence
+	       of octets stored to that of the equivalent byte representation,
+	       so the hash we need is different.  */
+	    hash = 0;
 	}
     }