=head1 NAME
-LHASH, DECLARE_LHASH_OF,
+LHASH, LHASH_OF, DEFINE_LHASH_OF_EX, DEFINE_LHASH_OF,
OPENSSL_LH_COMPFUNC, OPENSSL_LH_HASHFUNC, OPENSSL_LH_DOALL_FUNC,
LHASH_DOALL_ARG_FN_TYPE,
IMPLEMENT_LHASH_HASH_FN, IMPLEMENT_LHASH_COMP_FN,
lh_TYPE_new, lh_TYPE_free, lh_TYPE_flush,
lh_TYPE_insert, lh_TYPE_delete, lh_TYPE_retrieve,
-lh_TYPE_doall, lh_TYPE_doall_arg, lh_TYPE_error - dynamic hash table
+lh_TYPE_doall, lh_TYPE_doall_arg, lh_TYPE_num_items, lh_TYPE_get_down_load,
+lh_TYPE_set_down_load, lh_TYPE_error,
+OPENSSL_LH_new, OPENSSL_LH_free, OPENSSL_LH_flush,
+OPENSSL_LH_insert, OPENSSL_LH_delete, OPENSSL_LH_retrieve,
+OPENSSL_LH_doall, OPENSSL_LH_doall_arg, OPENSSL_LH_doall_arg_thunk,
+OPENSSL_LH_set_thunks, OPENSSL_LH_num_items,
+OPENSSL_LH_get_down_load, OPENSSL_LH_set_down_load, OPENSSL_LH_error
+- dynamic hash table
=head1 SYNOPSIS
#include <openssl/lhash.h>
- DECLARE_LHASH_OF(TYPE);
+ LHASH_OF(TYPE)
- LHASH *lh_TYPE_new(OPENSSL_LH_HASHFUNC hash, OPENSSL_LH_COMPFUNC compare);
+ DEFINE_LHASH_OF_EX(TYPE);
+
+ LHASH_OF(TYPE) *lh_TYPE_new(OPENSSL_LH_HASHFUNC hash, OPENSSL_LH_COMPFUNC compare);
void lh_TYPE_free(LHASH_OF(TYPE) *table);
void lh_TYPE_flush(LHASH_OF(TYPE) *table);
+ OPENSSL_LHASH *OPENSSL_LH_set_thunks(OPENSSL_LHASH *lh,
+ OPENSSL_LH_HASHFUNCTHUNK hw,
+ OPENSSL_LH_COMPFUNCTHUNK cw,
+ OPENSSL_LH_DOALL_FUNC_THUNK daw,
+ OPENSSL_LH_DOALL_FUNCARG_THUNK daaw)
TYPE *lh_TYPE_insert(LHASH_OF(TYPE) *table, TYPE *data);
TYPE *lh_TYPE_delete(LHASH_OF(TYPE) *table, TYPE *data);
- TYPE *lh_retrieve(LHASH_OF(TYPE) *table, TYPE *data);
+ TYPE *lh_TYPE_retrieve(LHASH_OF(TYPE) *table, TYPE *data);
void lh_TYPE_doall(LHASH_OF(TYPE) *table, OPENSSL_LH_DOALL_FUNC func);
void lh_TYPE_doall_arg(LHASH_OF(TYPE) *table, OPENSSL_LH_DOALL_FUNCARG func,
TYPE *arg);
+ void OPENSSL_LH_doall_arg_thunk(OPENSSL_LHASH *lh,
+ OPENSSL_LH_DOALL_FUNCARG_THUNK daaw,
+ OPENSSL_LH_DOALL_FUNCARG fn, void *arg)
+
+ unsigned long lh_TYPE_num_items(OPENSSL_LHASH *lh);
+ unsigned long lh_TYPE_get_down_load(OPENSSL_LHASH *lh);
+ void lh_TYPE_set_down_load(OPENSSL_LHASH *lh, unsigned long dl);
int lh_TYPE_error(LHASH_OF(TYPE) *table);
typedef void (*OPENSSL_LH_DOALL_FUNC)(const void *);
typedef void (*LHASH_DOALL_ARG_FN_TYPE)(const void *, const void *);
+ OPENSSL_LHASH *OPENSSL_LH_new(OPENSSL_LH_HASHFUNC h, OPENSSL_LH_COMPFUNC c);
+ void OPENSSL_LH_free(OPENSSL_LHASH *lh);
+ void OPENSSL_LH_flush(OPENSSL_LHASH *lh);
+
+ void *OPENSSL_LH_insert(OPENSSL_LHASH *lh, void *data);
+ void *OPENSSL_LH_delete(OPENSSL_LHASH *lh, const void *data);
+ void *OPENSSL_LH_retrieve(OPENSSL_LHASH *lh, const void *data);
+
+ void OPENSSL_LH_doall(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNC func);
+ void OPENSSL_LH_doall_arg(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNCARG func, void *arg);
+
+ unsigned long OPENSSL_LH_num_items(OPENSSL_LHASH *lh);
+ unsigned long OPENSSL_LH_get_down_load(OPENSSL_LHASH *lh);
+ void OPENSSL_LH_set_down_load(OPENSSL_LHASH *lh, unsigned long dl);
+
+ int OPENSSL_LH_error(OPENSSL_LHASH *lh);
+
+ #define LH_LOAD_MULT /* integer constant */
+
+The following macro is deprecated:
+
+ DEFINE_LHASH_OF(TYPE);
+
=head1 DESCRIPTION
This library implements type-checked dynamic hash tables. The hash
and value fields. In the description here, B<I<TYPE>> is used a placeholder
for any of the OpenSSL datatypes, such as I<SSL_SESSION>.
+To define a new type-checked dynamic hash table, use B<DEFINE_LHASH_OF_EX>().
+B<DEFINE_LHASH_OF>() was previously used for this purpose, but is now
+deprecated. The B<DEFINE_LHASH_OF_EX>() macro provides all functionality of
+B<DEFINE_LHASH_OF>() except for certain deprecated statistics functions (see
+OPENSSL_LH_stats(3)).
+
B<lh_I<TYPE>_new>() creates a new B<LHASH_OF>(B<I<TYPE>>) structure to store
arbitrary data entries, and specifies the 'hash' and 'compare'
callbacks to be used in organising the table's entries. The I<hash>
/* Then the hash table itself can be deallocated */
lh_TYPE_free(hashtable);
-When doing this, be careful if you delete entries from the hash table
-in your callbacks: the table may decrease in size, moving the item
-that you are currently on down lower in the hash table - this could
-cause some entries to be skipped during the iteration. The second
-best solution to this problem is to set hash-E<gt>down_load=0 before
-you start (which will stop the hash table ever decreasing in size).
-The best solution is probably to avoid deleting items from the hash
-table inside a "doall" callback!
-
B<lh_I<TYPE>_doall_arg>() is the same as B<lh_I<TYPE>_doall>() except that
I<func> will be called with I<arg> as the second argument and I<func>
should be of type B<LHASH_DOALL_ARG_FN>(B<I<TYPE>>) (a callback prototype
lh_TYPE_doall_arg(hashtable, LHASH_DOALL_ARG_FN(TYPE_print), BIO,
logging_bio);
+Note that it is by default B<not> safe to use B<lh_I<TYPE>_delete>() inside a
+callback passed to B<lh_I<TYPE>_doall>() or B<lh_I<TYPE>_doall_arg>(). The
+reason for this is that deleting an item from the hash table may result in the
+hash table being contracted to a smaller size and rehashed.
+B<lh_I<TYPE>_doall>() and B<lh_I<TYPE>_doall_arg>() are unsafe and will exhibit
+undefined behaviour under these conditions, as these functions assume the hash
+table size and bucket pointers do not change during the call.
+
+If it is desired to use B<lh_I<TYPE>_doall>() or B<lh_I<TYPE>_doall_arg>() with
+B<lh_I<TYPE>_delete>(), it is essential that you call
+B<lh_I<TYPE>_set_down_load>() with a I<down_load> argument of 0 first. This
+disables hash table contraction and guarantees that it will be safe to delete
+items from a hash table during a call to B<lh_I<TYPE>_doall>() or
+B<lh_I<TYPE>_doall_arg>().
+
+It is never safe to call B<lh_I<TYPE>_insert>() during a call to
+B<lh_I<TYPE>_doall>() or B<lh_I<TYPE>_doall_arg>().
B<lh_I<TYPE>_error>() can be used to determine if an error occurred in the last
operation.
+B<lh_I<TYPE>_num_items>() returns the number of items in the hash table.
+
+B<lh_I<TYPE>_get_down_load>() and B<lh_I<TYPE>_set_down_load>() get and set the
+factor used to determine when the hash table is contracted. The factor is the
+load factor at or below which hash table contraction will occur, multiplied by
+B<LH_LOAD_MULT>, where the load factor is the number of items divided by the
+number of nodes. Setting this value to 0 disables hash table contraction.
+
+OPENSSL_LH_new() is the same as the B<lh_I<TYPE>_new>() except that it is not
+type specific. So instead of returning an B<LHASH_OF(I<TYPE>)> value it returns
+a B<void *>. In the same way the functions OPENSSL_LH_free(),
+OPENSSL_LH_flush(), OPENSSL_LH_insert(), OPENSSL_LH_delete(),
+OPENSSL_LH_retrieve(), OPENSSL_LH_doall(), OPENSSL_LH_doall_arg(),
+OPENSSL_LH_num_items(), OPENSSL_LH_get_down_load(), OPENSSL_LH_set_down_load()
+and OPENSSL_LH_error() are equivalent to the similarly named B<lh_I<TYPE>>
+functions except that they return or use a B<void *> where the equivalent
+B<lh_I<TYPE>> function returns or uses a B<I<TYPE> *> or B<LHASH_OF(I<TYPE>) *>.
+B<lh_I<TYPE>> functions are implemented as type checked wrappers around the
+B<OPENSSL_LH> functions. Most applications should not call the B<OPENSSL_LH>
+functions directly.
+
+OPENSSL_LH_set_thunks() and OPENSSL_LH_doall_arg_thunk(), while public by
+necessity, are actually internal functions and should not be used.
+
=head1 RETURN VALUES
-B<lh_I<TYPE>_new>() returns NULL on error, otherwise a pointer to the new
-B<LHASH> structure.
+B<lh_I<TYPE>_new>() and OPENSSL_LH_new() return NULL on error, otherwise a
+pointer to the new B<LHASH> structure.
-When a hash table entry is replaced, B<lh_I<TYPE>_insert>() returns the value
-being replaced. NULL is returned on normal operation and on error.
+When a hash table entry is replaced, B<lh_I<TYPE>_insert>() or
+OPENSSL_LH_insert() return the value being replaced. NULL is returned on normal
+operation and on error.
-B<lh_I<TYPE>_delete>() returns the entry being deleted. NULL is returned if
-there is no such value in the hash table.
+B<lh_I<TYPE>_delete>() and OPENSSL_LH_delete() return the entry being deleted.
+NULL is returned if there is no such value in the hash table.
-B<lh_I<TYPE>_retrieve>() returns the hash table entry if it has been found,
-NULL otherwise.
+B<lh_I<TYPE>_retrieve>() and OPENSSL_LH_retrieve() return the hash table entry
+if it has been found, NULL otherwise.
-B<lh_I<TYPE>_error>() returns 1 if an error occurred in the last operation, 0
-otherwise. It's meaningful only after non-retrieve operations.
+B<lh_I<TYPE>_error>() and OPENSSL_LH_error() return 1 if an error occurred in
+the last operation, 0 otherwise. It's meaningful only after non-retrieve
+operations.
-B<lh_I<TYPE>_free>(), B<lh_I<TYPE>_flush>(), B<lh_I<TYPE>_doall>() and
-B<lh_I<TYPE>_doall_arg>() return no values.
+B<lh_I<TYPE>_free>(), OPENSSL_LH_free(), B<lh_I<TYPE>_flush>(),
+OPENSSL_LH_flush(), B<lh_I<TYPE>_doall>() OPENSSL_LH_doall(),
+B<lh_I<TYPE>_doall_arg>() and OPENSSL_LH_doall_arg() return no values.
=head1 NOTE
The LHASH code is not thread safe. All updating operations, as well as
-B<lh_I<TYPE>_error>() call must be performed under a write lock. All retrieve
-operations should be performed under a read lock, I<unless> accurate
-usage statistics are desired. In which case, a write lock should be used
-for retrieve operations as well. For output of the usage statistics,
-using the functions from L<OPENSSL_LH_stats(3)>, a read lock suffices.
+B<lh_I<TYPE>_error>() or OPENSSL_LH_error() calls must be performed under
+a write lock. All retrieve operations should be performed under a read lock,
+I<unless> accurate usage statistics are desired. In which case, a write lock
+should be used for retrieve operations as well. For output of the usage
+statistics, using the functions from L<OPENSSL_LH_stats(3)>, a read lock
+suffices.
The LHASH code regards table entries as constant data. As such, it
internally represents lh_insert()'d items with a "const void *"
As an example, a hash table may be maintained by code that, for
reasons of encapsulation, has only "const" access to the data being
-indexed in the hash table (ie. it is returned as "const" from
+indexed in the hash table (i.e. it is returned as "const" from
elsewhere in their code) - in this case the LHASH prototypes are
appropriate as-is. Conversely, if the caller is responsible for the
life-time of the data in question, then they may well wish to make
=head1 BUGS
-B<lh_I<TYPE>_insert>() returns NULL both for success and error.
+B<lh_I<TYPE>_insert>() and OPENSSL_LH_insert() return NULL both for success
+and error.
=head1 SEE ALSO
In OpenSSL 1.0.0, the lhash interface was revamped for better
type checking.
+In OpenSSL 3.1, B<DEFINE_LHASH_OF_EX>() was introduced and B<DEFINE_LHASH_OF>()
+was deprecated.
+
=head1 COPYRIGHT
-Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
projects / openssl.git / blobdiff