X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=hv.h;h=4fa4239be93b2d509d978c4fb5184f2eaa343e73;hb=17ad61e03fe30671fca57305b7cdb9cef95a1b94;hp=68fc9da651c5338dd3d6f25767a00784f097b4a5;hpb=19692e8d256164f96817d6df6ecee26c3cda4ae9;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/hv.h b/hv.h
index 68fc9da..4fa4239 100644
--- a/hv.h
+++ b/hv.h
@@ -1,6 +1,7 @@
 /*    hv.h
  *
- *    Copyright (c) 1991-2002, Larry Wall
+ *    Copyright (C) 1991, 1992, 1993, 1996, 1997, 1998, 1999,
+ *    2000, 2001, 2002, by Larry Wall and others
  *
  *    You may distribute under the terms of either the GNU General Public
  *    License or the Artistic License, as specified in the README file.
@@ -24,8 +25,8 @@ struct hek {
     I32		hek_len;	/* length of hash key */
     char	hek_key[1];	/* variable-length hash key */
     /* the hash-key is \0-terminated */
-    /* after the \0 there is a byte for flags, such as whehter the key is
-       UTF8 */
+    /* after the \0 there is a byte for flags, such as whether the key
+       is UTF-8 */
 };
 
 /* hash structure: */
@@ -47,14 +48,37 @@ struct xpvhv {
 };
 
 /* hash a key */
-/* FYI: This is the "One-at-a-Time" algorithm by Bob Jenkins */
-/* from requirements by Colin Plumb. */
-/* (http://burtleburtle.net/bob/hash/doobs.html) */
+/* FYI: This is the "One-at-a-Time" algorithm by Bob Jenkins
+ * from requirements by Colin Plumb.
+ * (http://burtleburtle.net/bob/hash/doobs.html) */
+/* The use of a temporary pointer and the casting games
+ * is needed to serve the dual purposes of
+ * (a) the hashed data being interpreted as "unsigned char" (new since 5.8,
+ *     a "char" can be either signed or signed, depending on the compiler)
+ * (b) catering for old code that uses a "char"
+ *
+ * The "hash seed" feature was added in Perl 5.8.1 to perturb the results
+ * to avoid "algorithmic complexity attacks".
+ *
+ * If USE_HASH_SEED is defined, hash randomisation is done by default
+ * If USE_HASH_SEED_EXPLICIT is defined, hash randomisation is done
+ * only if the environment variable PERL_HASH_SEED is set.
+ * For maximal control, one can define PERL_HASH_SEED.
+ * (see also erl.c:perl_parse()).
+ */
+#ifndef PERL_HASH_SEED
+#   if defined(USE_HASH_SEED) || defined(USE_HASH_SEED_EXPLICIT)
+#       define PERL_HASH_SEED	PL_hash_seed
+#   else
+#       define PERL_HASH_SEED	0
+#   endif
+#endif
 #define PERL_HASH(hash,str,len) \
      STMT_START	{ \
-	register const char *s_PeRlHaSh = str; \
+	register const char *s_PeRlHaSh_tmp = str; \
+	register const unsigned char *s_PeRlHaSh = (const unsigned char *)s_PeRlHaSh_tmp; \
 	register I32 i_PeRlHaSh = len; \
-	register U32 hash_PeRlHaSh = 0; \
+	register U32 hash_PeRlHaSh = PERL_HASH_SEED; \
 	while (i_PeRlHaSh--) { \
 	    hash_PeRlHaSh += *s_PeRlHaSh++; \
 	    hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
@@ -231,6 +255,8 @@ C<SV*>.
 #define HVhek_UTF8	0x01 /* Key is utf8 encoded. */
 #define HVhek_WASUTF8	0x02 /* Key is bytes here, but was supplied as utf8. */
 #define HVhek_FREEKEY	0x100 /* Internal flag to say key is malloc()ed.  */
+#define HVhek_PLACEHOLD	0x200 /* Internal flag to create placeholder.
+                               * (may change, but Storable is a core module) */
 #define HVhek_MASK	0xFF
 
 #define HEK_UTF8(hek)		(HEK_FLAGS(hek) & HVhek_UTF8)
@@ -251,6 +277,9 @@ C<SV*>.
 			 : (size) * sizeof(HE*) * 2 - MALLOC_OVERHEAD)
 #endif
 
+/* Flags for hv_iternext_flags.  */
+#define HV_ITERNEXT_WANTPLACEHOLDERS	0x01	/* Don't skip placeholders.  */
+
 /* available as a function in hv.c */
 #define Perl_sharepvn(sv, len, hash) HEK_KEY(share_hek(sv, len, hash))
 #define sharepvn(sv, len, hash)	     Perl_sharepvn(sv, len, hash)