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-rw-r--r--generic/tclHash.c144
1 files changed, 84 insertions, 60 deletions
diff --git a/generic/tclHash.c b/generic/tclHash.c
index 89fbb6f..90be511 100644
--- a/generic/tclHash.c
+++ b/generic/tclHash.c
@@ -9,8 +9,6 @@
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
- *
- * RCS: @(#) $Id: tclHash.c,v 1.37 2008/11/17 22:15:34 nijtmans Exp $
*/
#include "tclInt.h"
@@ -37,7 +35,7 @@
*/
#define RANDOM_INDEX(tablePtr, i) \
- (((((long) (i))*1103515245) >> (tablePtr)->downShift) & (tablePtr)->mask)
+ ((((i)*1103515245L) >> (tablePtr)->downShift) & (tablePtr)->mask)
/*
* Prototypes for the array hash key methods.
@@ -48,7 +46,9 @@ static int CompareArrayKeys(void *keyPtr, Tcl_HashEntry *hPtr);
static unsigned int HashArrayKey(Tcl_HashTable *tablePtr, void *keyPtr);
/*
- * Prototypes for the one word hash key methods.
+ * Prototypes for the one word hash key methods. Not actually declared because
+ * this is a critical path that is implemented in the core hash table access
+ * function.
*/
#if 0
@@ -74,6 +74,9 @@ static unsigned int HashStringKey(Tcl_HashTable *tablePtr, void *keyPtr);
static Tcl_HashEntry * BogusFind(Tcl_HashTable *tablePtr, const char *key);
static Tcl_HashEntry * BogusCreate(Tcl_HashTable *tablePtr, const char *key,
int *newPtr);
+static Tcl_HashEntry * CreateHashEntry(Tcl_HashTable *tablePtr, const char *key,
+ int *newPtr);
+static Tcl_HashEntry * FindHashEntry(Tcl_HashTable *tablePtr, const char *key);
static void RebuildTable(Tcl_HashTable *tablePtr);
const Tcl_HashKeyType tclArrayHashKeyType = {
@@ -121,7 +124,6 @@ const Tcl_HashKeyType tclStringHashKeyType = {
*----------------------------------------------------------------------
*/
-#undef Tcl_InitHashTable
void
Tcl_InitHashTable(
register Tcl_HashTable *tablePtr,
@@ -186,8 +188,8 @@ Tcl_InitCustomHashTable(
tablePtr->downShift = 28;
tablePtr->mask = 3;
tablePtr->keyType = keyType;
- tablePtr->findProc = Tcl_FindHashEntry;
- tablePtr->createProc = Tcl_CreateHashEntry;
+ tablePtr->findProc = FindHashEntry;
+ tablePtr->createProc = CreateHashEntry;
if (typePtr == NULL) {
/*
@@ -228,10 +230,17 @@ Tcl_InitCustomHashTable(
Tcl_HashEntry *
Tcl_FindHashEntry(
Tcl_HashTable *tablePtr, /* Table in which to lookup entry. */
- const char *key) /* Key to use to find matching entry. */
+ const void *key) /* Key to use to find matching entry. */
{
+ return (*((tablePtr)->findProc))(tablePtr, key);
+}
- return Tcl_CreateHashEntry(tablePtr, key, NULL);
+static Tcl_HashEntry *
+FindHashEntry(
+ Tcl_HashTable *tablePtr, /* Table in which to lookup entry. */
+ const char *key) /* Key to use to find matching entry. */
+{
+ return CreateHashEntry(tablePtr, key, NULL);
}
@@ -259,6 +268,17 @@ Tcl_FindHashEntry(
Tcl_HashEntry *
Tcl_CreateHashEntry(
Tcl_HashTable *tablePtr, /* Table in which to lookup entry. */
+ const void *key, /* Key to use to find or create matching
+ * entry. */
+ int *newPtr) /* Store info here telling whether a new entry
+ * was created. */
+{
+ return (*((tablePtr)->createProc))(tablePtr, key, newPtr);
+}
+
+static Tcl_HashEntry *
+CreateHashEntry(
+ Tcl_HashTable *tablePtr, /* Table in which to lookup entry. */
const char *key, /* Key to use to find or create matching
* entry. */
int *newPtr) /* Store info here telling whether a new entry
@@ -283,13 +303,13 @@ Tcl_CreateHashEntry(
if (typePtr->hashKeyProc) {
hash = typePtr->hashKeyProc(tablePtr, (void *) key);
if (typePtr->flags & TCL_HASH_KEY_RANDOMIZE_HASH) {
- index = RANDOM_INDEX (tablePtr, hash);
+ index = RANDOM_INDEX(tablePtr, hash);
} else {
index = hash & tablePtr->mask;
}
} else {
hash = PTR2UINT(key);
- index = RANDOM_INDEX (tablePtr, hash);
+ index = RANDOM_INDEX(tablePtr, hash);
}
/*
@@ -298,6 +318,7 @@ Tcl_CreateHashEntry(
if (typePtr->compareKeysProc) {
Tcl_CompareHashKeysProc *compareKeysProc = typePtr->compareKeysProc;
+
for (hPtr = tablePtr->buckets[index]; hPtr != NULL;
hPtr = hPtr->nextPtr) {
#if TCL_HASH_KEY_STORE_HASH
@@ -341,7 +362,7 @@ Tcl_CreateHashEntry(
if (typePtr->allocEntryProc) {
hPtr = typePtr->allocEntryProc(tablePtr, (void *) key);
} else {
- hPtr = (Tcl_HashEntry *) ckalloc((unsigned) sizeof(Tcl_HashEntry));
+ hPtr = ckalloc(sizeof(Tcl_HashEntry));
hPtr->key.oneWordValue = (char *) key;
hPtr->clientData = 0;
}
@@ -352,7 +373,7 @@ Tcl_CreateHashEntry(
hPtr->nextPtr = tablePtr->buckets[index];
tablePtr->buckets[index] = hPtr;
#else
- hPtr->bucketPtr = &(tablePtr->buckets[index]);
+ hPtr->bucketPtr = &tablePtr->buckets[index];
hPtr->nextPtr = *hPtr->bucketPtr;
*hPtr->bucketPtr = hPtr;
#endif
@@ -415,12 +436,12 @@ Tcl_DeleteHashEntry(
#if TCL_HASH_KEY_STORE_HASH
if (typePtr->hashKeyProc == NULL
|| typePtr->flags & TCL_HASH_KEY_RANDOMIZE_HASH) {
- index = RANDOM_INDEX (tablePtr, entryPtr->hash);
+ index = RANDOM_INDEX(tablePtr, PTR2INT(entryPtr->hash));
} else {
index = PTR2UINT(entryPtr->hash) & tablePtr->mask;
}
- bucketPtr = &(tablePtr->buckets[index]);
+ bucketPtr = &tablePtr->buckets[index];
#else
bucketPtr = entryPtr->bucketPtr;
#endif
@@ -441,9 +462,9 @@ Tcl_DeleteHashEntry(
tablePtr->numEntries--;
if (typePtr->freeEntryProc) {
- typePtr->freeEntryProc (entryPtr);
+ typePtr->freeEntryProc(entryPtr);
} else {
- ckfree((char *) entryPtr);
+ ckfree(entryPtr);
}
}
@@ -492,9 +513,9 @@ Tcl_DeleteHashTable(
while (hPtr != NULL) {
nextPtr = hPtr->nextPtr;
if (typePtr->freeEntryProc) {
- typePtr->freeEntryProc (hPtr);
+ typePtr->freeEntryProc(hPtr);
} else {
- ckfree((char *) hPtr);
+ ckfree(hPtr);
}
hPtr = nextPtr;
}
@@ -508,7 +529,7 @@ Tcl_DeleteHashTable(
if (typePtr->flags & TCL_HASH_KEY_SYSTEM_HASH) {
TclpSysFree((char *) tablePtr->buckets);
} else {
- ckfree((char *) tablePtr->buckets);
+ ckfree(tablePtr->buckets);
}
}
@@ -623,18 +644,6 @@ Tcl_HashStats(
double average, tmp;
register Tcl_HashEntry *hPtr;
char *result, *p;
- const Tcl_HashKeyType *typePtr;
-
- if (tablePtr->keyType == TCL_STRING_KEYS) {
- typePtr = &tclStringHashKeyType;
- } else if (tablePtr->keyType == TCL_ONE_WORD_KEYS) {
- typePtr = &tclOneWordHashKeyType;
- } else if (tablePtr->keyType == TCL_CUSTOM_TYPE_KEYS
- || tablePtr->keyType == TCL_CUSTOM_PTR_KEYS) {
- typePtr = tablePtr->typePtr;
- } else {
- typePtr = &tclArrayHashKeyType;
- }
/*
* Compute a histogram of bucket usage.
@@ -665,7 +674,7 @@ Tcl_HashStats(
* Print out the histogram and a few other pieces of information.
*/
- result = (char *) ckalloc((unsigned) (NUM_COUNTERS*60) + 300);
+ result = ckalloc((NUM_COUNTERS * 60) + 300);
sprintf(result, "%d entries in table, %d buckets\n",
tablePtr->numEntries, tablePtr->numBuckets);
p = result + strlen(result);
@@ -714,7 +723,7 @@ AllocArrayEntry(
if (size < sizeof(Tcl_HashEntry)) {
size = sizeof(Tcl_HashEntry);
}
- hPtr = (Tcl_HashEntry *) ckalloc(size);
+ hPtr = ckalloc(size);
for (iPtr1 = array, iPtr2 = hPtr->key.words;
count > 0; count--, iPtr1++, iPtr2++) {
@@ -820,14 +829,14 @@ AllocStringEntry(
{
const char *string = (const char *) keyPtr;
Tcl_HashEntry *hPtr;
- unsigned int size;
+ unsigned int size, allocsize;
- size = sizeof(Tcl_HashEntry) + strlen(string) + 1 - sizeof(hPtr->key);
- if (size < sizeof(Tcl_HashEntry)) {
- size = sizeof(Tcl_HashEntry);
+ allocsize = size = strlen(string) + 1;
+ if (size < sizeof(hPtr->key)) {
+ allocsize = sizeof(hPtr->key);
}
- hPtr = (Tcl_HashEntry *) ckalloc(size);
- strcpy(hPtr->key.string, string);
+ hPtr = ckalloc(TclOffset(Tcl_HashEntry, key) + allocsize);
+ memcpy(hPtr->key.string, string, size);
hPtr->clientData = 0;
return hPtr;
}
@@ -877,14 +886,14 @@ CompareStringKeys(
*----------------------------------------------------------------------
*/
-static unsigned int
+static unsigned
HashStringKey(
Tcl_HashTable *tablePtr, /* Hash table. */
void *keyPtr) /* Key from which to compute hash value. */
{
- register const char *string = (const char *) keyPtr;
+ register const char *string = keyPtr;
register unsigned int result;
- register int c;
+ register char c;
/*
* I tried a zillion different hash functions and asked many other people
@@ -894,19 +903,34 @@ HashStringKey(
* following reasons:
*
* 1. Multiplying by 10 is perfect for keys that are decimal strings, and
- * multiplying by 9 is just about as good.
+ * multiplying by 9 is just about as good.
* 2. Times-9 is (shift-left-3) plus (old). This means that each
- * character's bits hang around in the low-order bits of the hash value
- * for ever, plus they spread fairly rapidly up to the high-order bits
- * to fill out the hash value. This seems works well both for decimal
- * and non-decimal strings, but isn't strong against maliciously-chosen
- * keys.
+ * character's bits hang around in the low-order bits of the hash value
+ * for ever, plus they spread fairly rapidly up to the high-order bits
+ * to fill out the hash value. This seems works well both for decimal
+ * and non-decimal strings, but isn't strong against maliciously-chosen
+ * keys.
+ *
+ * Note that this function is very weak against malicious strings; it's
+ * very easy to generate multiple keys that have the same hashcode. On the
+ * other hand, that hardly ever actually occurs and this function *is*
+ * very cheap, even by comparison with industry-standard hashes like FNV.
+ * If real strength of hash is required though, use a custom hash based on
+ * Bob Jenkins's lookup3(), but be aware that it's significantly slower.
+ * Since Tcl command and namespace names are usually reasonably-named (the
+ * main use for string hashes in modern Tcl) speed is far more important
+ * than strength.
+ *
+ * See also HashString in tclLiteral.c.
+ * See also TclObjHashKey in tclObj.c.
+ *
+ * See [tcl-Feature Request #2958832]
*/
- result = 0;
-
- for (c=*string++ ; c ; c=*string++) {
- result += (result<<3) + c;
+ if ((result = UCHAR(*string)) != 0) {
+ while ((c = *++string) != 0) {
+ result += (result << 3) + UCHAR(c);
+ }
}
return result;
}
@@ -1020,8 +1044,8 @@ RebuildTable(
tablePtr->buckets = (Tcl_HashEntry **) TclpSysAlloc((unsigned)
(tablePtr->numBuckets * sizeof(Tcl_HashEntry *)), 0);
} else {
- tablePtr->buckets = (Tcl_HashEntry **) ckalloc((unsigned)
- (tablePtr->numBuckets * sizeof(Tcl_HashEntry *)));
+ tablePtr->buckets =
+ ckalloc(tablePtr->numBuckets * sizeof(Tcl_HashEntry *));
}
for (count = tablePtr->numBuckets, newChainPtr = tablePtr->buckets;
count > 0; count--, newChainPtr++) {
@@ -1041,7 +1065,7 @@ RebuildTable(
#if TCL_HASH_KEY_STORE_HASH
if (typePtr->hashKeyProc == NULL
|| typePtr->flags & TCL_HASH_KEY_RANDOMIZE_HASH) {
- index = RANDOM_INDEX (tablePtr, hPtr->hash);
+ index = RANDOM_INDEX(tablePtr, PTR2INT(hPtr->hash));
} else {
index = PTR2UINT(hPtr->hash) & tablePtr->mask;
}
@@ -1055,15 +1079,15 @@ RebuildTable(
hash = typePtr->hashKeyProc(tablePtr, key);
if (typePtr->flags & TCL_HASH_KEY_RANDOMIZE_HASH) {
- index = RANDOM_INDEX (tablePtr, hash);
+ index = RANDOM_INDEX(tablePtr, hash);
} else {
index = hash & tablePtr->mask;
}
} else {
- index = RANDOM_INDEX (tablePtr, key);
+ index = RANDOM_INDEX(tablePtr, key);
}
- hPtr->bucketPtr = &(tablePtr->buckets[index]);
+ hPtr->bucketPtr = &tablePtr->buckets[index];
hPtr->nextPtr = *hPtr->bucketPtr;
*hPtr->bucketPtr = hPtr;
#endif
@@ -1078,7 +1102,7 @@ RebuildTable(
if (typePtr->flags & TCL_HASH_KEY_SYSTEM_HASH) {
TclpSysFree((char *) oldBuckets);
} else {
- ckfree((char *) oldBuckets);
+ ckfree(oldBuckets);
}
}
}
generated by cgit v0.12 at 2025-10-21 21:13:36 (GMT)