X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=hv.h;h=81044c9097c9a753bcb32155e5e4fa2b299da137;hb=e1aef32ff2ada03d3013c36fb3b878f3c9d9d5c1;hp=3746b6090566162871506411fbc71439491f0929;hpb=ddac11c4801daf29180327d37faf88031955526c;p=p5sagit%2Fp5-mst-13.2.git diff --git a/hv.h b/hv.h index 3746b60..81044c9 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 whether 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); \ @@ -65,6 +89,25 @@ struct xpvhv { (hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \ } STMT_END +/* Only hv.c and mod_perl should be doing this. */ +#ifdef PERL_HASH_INTERNAL_ACCESS +#define PERL_HASH_INTERNAL(hash,str,len) \ + STMT_START { \ + 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 = PL_rehash_seed; \ + while (i_PeRlHaSh--) { \ + hash_PeRlHaSh += *s_PeRlHaSh++; \ + hash_PeRlHaSh += (hash_PeRlHaSh << 10); \ + hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \ + } \ + hash_PeRlHaSh += (hash_PeRlHaSh << 3); \ + hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \ + (hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \ + } STMT_END +#endif + /* =head1 Hash Manipulation Functions @@ -170,6 +213,7 @@ C. * is utf8 (including 8 bit keys that were entered as utf8, and need upgrading * when retrieved during iteration. It may still be set when there are no longer * any utf8 keys. + * See HVhek_ENABLEHVKFLAGS for the trigger. */ #define HvHASKFLAGS(hv) (SvFLAGS(hv) & SVphv_HASKFLAGS) #define HvHASKFLAGS_on(hv) (SvFLAGS(hv) |= SVphv_HASKFLAGS) @@ -179,6 +223,10 @@ C. #define HvLAZYDEL_on(hv) (SvFLAGS(hv) |= SVphv_LAZYDEL) #define HvLAZYDEL_off(hv) (SvFLAGS(hv) &= ~SVphv_LAZYDEL) +#define HvREHASH(hv) (SvFLAGS(hv) & SVphv_REHASH) +#define HvREHASH_on(hv) (SvFLAGS(hv) |= SVphv_REHASH) +#define HvREHASH_off(hv) (SvFLAGS(hv) &= ~SVphv_REHASH) + /* Maybe amagical: */ /* #define HV_AMAGICmb(hv) (SvFLAGS(hv) & (SVpgv_badAM | SVpgv_AM)) */ @@ -200,6 +248,7 @@ C. #define HeKLEN(he) HEK_LEN(HeKEY_hek(he)) #define HeKUTF8(he) HEK_UTF8(HeKEY_hek(he)) #define HeKWASUTF8(he) HEK_WASUTF8(HeKEY_hek(he)) +#define HeKREHASH(he) HEK_REHASH(HeKEY_hek(he)) #define HeKLEN_UTF8(he) (HeKUTF8(he) ? -HeKLEN(he) : HeKLEN(he)) #define HeKFLAGS(he) HEK_FLAGS(HeKEY_hek(he)) #define HeVAL(he) (he)->hent_val @@ -230,15 +279,30 @@ C. #define HVhek_UTF8 0x01 /* Key is utf8 encoded. */ #define HVhek_WASUTF8 0x02 /* Key is bytes here, but was supplied as utf8. */ +#define HVhek_REHASH 0x04 /* This key is in an hv using a custom HASH . */ #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 +/* Which flags enable HvHASKFLAGS? Somewhat a hack on a hack, as + HVhek_REHASH is only needed because the rehash flag has to be duplicated + into all keys as hv_iternext has no access to the hash flags. At this + point Storable's tests get upset, because sometimes hashes are "keyed" + and sometimes not, depending on the order of data insertion, and whether + it triggered rehashing. So currently HVhek_REHAS is exempt. +*/ + +#define HVhek_ENABLEHVKFLAGS (HVhek_MASK - HVhek_REHASH) + #define HEK_UTF8(hek) (HEK_FLAGS(hek) & HVhek_UTF8) #define HEK_UTF8_on(hek) (HEK_FLAGS(hek) |= HVhek_UTF8) #define HEK_UTF8_off(hek) (HEK_FLAGS(hek) &= ~HVhek_UTF8) #define HEK_WASUTF8(hek) (HEK_FLAGS(hek) & HVhek_WASUTF8) #define HEK_WASUTF8_on(hek) (HEK_FLAGS(hek) |= HVhek_WASUTF8) #define HEK_WASUTF8_off(hek) (HEK_FLAGS(hek) &= ~HVhek_WASUTF8) +#define HEK_REHASH(hek) (HEK_FLAGS(hek) & HVhek_REHASH) +#define HEK_REHASH_on(hek) (HEK_FLAGS(hek) |= HVhek_REHASH) /* calculate HV array allocation */ #if defined(STRANGE_MALLOC) || defined(MYMALLOC) @@ -251,6 +315,9 @@ C. : (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)