1=pod
2
3=head1 NAME
4
5DEFINE_STACK_OF, DEFINE_STACK_OF_CONST, DEFINE_SPECIAL_STACK_OF,
6DEFINE_SPECIAL_STACK_OF_CONST,
7sk_TYPE_num, sk_TYPE_value, sk_TYPE_new, sk_TYPE_new_null,
8sk_TYPE_reserve, sk_TYPE_free, sk_TYPE_zero, sk_TYPE_delete,
9sk_TYPE_delete_ptr, sk_TYPE_push, sk_TYPE_unshift, sk_TYPE_pop,
10sk_TYPE_shift, sk_TYPE_pop_free, sk_TYPE_insert, sk_TYPE_set,
11sk_TYPE_find, sk_TYPE_find_ex, sk_TYPE_sort, sk_TYPE_is_sorted,
12sk_TYPE_dup, sk_TYPE_deep_copy, sk_TYPE_set_cmp_func, sk_TYPE_new_reserve
13- stack container
14
15=head1 SYNOPSIS
16
17=for comment generic
18
19 #include <openssl/safestack.h>
20
21 STACK_OF(TYPE)
22 DEFINE_STACK_OF(TYPE)
23 DEFINE_STACK_OF_CONST(TYPE)
24 DEFINE_SPECIAL_STACK_OF(FUNCTYPE, TYPE)
25 DEFINE_SPECIAL_STACK_OF_CONST(FUNCTYPE, TYPE)
26
27 typedef int (*sk_TYPE_compfunc)(const TYPE *const *a, const TYPE *const *b);
28 typedef TYPE * (*sk_TYPE_copyfunc)(const TYPE *a);
29 typedef void (*sk_TYPE_freefunc)(TYPE *a);
30
31 int sk_TYPE_num(const STACK_OF(TYPE) *sk);
32 TYPE *sk_TYPE_value(const STACK_OF(TYPE) *sk, int idx);
33 STACK_OF(TYPE) *sk_TYPE_new(sk_TYPE_compfunc compare);
34 STACK_OF(TYPE) *sk_TYPE_new_null(void);
35 int sk_TYPE_reserve(STACK_OF(TYPE) *sk, int n);
36 void sk_TYPE_free(const STACK_OF(TYPE) *sk);
37 void sk_TYPE_zero(const STACK_OF(TYPE) *sk);
38 TYPE *sk_TYPE_delete(STACK_OF(TYPE) *sk, int i);
39 TYPE *sk_TYPE_delete_ptr(STACK_OF(TYPE) *sk, TYPE *ptr);
40 int sk_TYPE_push(STACK_OF(TYPE) *sk, const TYPE *ptr);
41 int sk_TYPE_unshift(STACK_OF(TYPE) *sk, const TYPE *ptr);
42 TYPE *sk_TYPE_pop(STACK_OF(TYPE) *sk);
43 TYPE *sk_TYPE_shift(STACK_OF(TYPE) *sk);
44 void sk_TYPE_pop_free(STACK_OF(TYPE) *sk, sk_TYPE_freefunc freefunc);
45 int sk_TYPE_insert(STACK_OF(TYPE) *sk, TYPE *ptr, int idx);
46 TYPE *sk_TYPE_set(STACK_OF(TYPE) *sk, int idx, const TYPE *ptr);
47 int sk_TYPE_find(STACK_OF(TYPE) *sk, TYPE *ptr);
48 int sk_TYPE_find_ex(STACK_OF(TYPE) *sk, TYPE *ptr);
49 void sk_TYPE_sort(const STACK_OF(TYPE) *sk);
50 int sk_TYPE_is_sorted(const STACK_OF(TYPE) *sk);
51 STACK_OF(TYPE) *sk_TYPE_dup(const STACK_OF(TYPE) *sk);
52 STACK_OF(TYPE) *sk_TYPE_deep_copy(const STACK_OF(TYPE) *sk,
53                                   sk_TYPE_copyfunc copyfunc,
54                                   sk_TYPE_freefunc freefunc);
55 sk_TYPE_compfunc (*sk_TYPE_set_cmp_func(STACK_OF(TYPE) *sk,
56                                         sk_TYPE_compfunc compare));
57 STACK_OF(TYPE) *sk_TYPE_new_reserve(sk_TYPE_compfunc compare, int n);
58
59=head1 DESCRIPTION
60
61Applications can create and use their own stacks by placing any of the macros
62described below in a header file. These macros define typesafe inline
63functions that wrap around the utility B<OPENSSL_sk_> API.
64In the description here, I<TYPE> is used
65as a placeholder for any of the OpenSSL datatypes, such as I<X509>.
66
67STACK_OF() returns the name for a stack of the specified B<TYPE>.
68DEFINE_STACK_OF() creates set of functions for a stack of B<TYPE>. This
69will mean that type B<TYPE> is stored in each stack, the type is referenced by
70STACK_OF(TYPE) and each function name begins with I<sk_TYPE_>. For example:
71
72 TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx);
73
74DEFINE_STACK_OF_CONST() is identical to DEFINE_STACK_OF() except
75each element is constant. For example:
76
77 const TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx);
78
79DEFINE_SPECIAL_STACK_OF() defines a stack of B<TYPE> but
80each function uses B<FUNCNAME> in the function name. For example:
81
82 TYPE *sk_FUNCNAME_value(STACK_OF(TYPE) *sk, int idx);
83
84DEFINE_SPECIAL_STACK_OF_CONST() is similar except that each element is
85constant:
86
87 const TYPE *sk_FUNCNAME_value(STACK_OF(TYPE) *sk, int idx);
88
89sk_TYPE_num() returns the number of elements in B<sk> or -1 if B<sk> is
90B<NULL>.
91
92sk_TYPE_value() returns element B<idx> in B<sk>, where B<idx> starts at
93zero. If B<idx> is out of range then B<NULL> is returned.
94
95sk_TYPE_new() allocates a new empty stack using comparison function B<compare>.
96If B<compare> is B<NULL> then no comparison function is used. This function is
97equivalent to sk_TYPE_new_reserve(compare, 0).
98
99sk_TYPE_new_null() allocates a new empty stack with no comparison function. This
100function is equivalent to sk_TYPE_new_reserve(NULL, 0).
101
102sk_TYPE_reserve() allocates additional memory in the B<sk> structure
103such that the next B<n> calls to sk_TYPE_insert(), sk_TYPE_push()
104or sk_TYPE_unshift() will not fail or cause memory to be allocated
105or reallocated. If B<n> is zero, any excess space allocated in the
106B<sk> structure is freed. On error B<sk> is unchanged.
107
108sk_TYPE_new_reserve() allocates a new stack. The new stack will have additional
109memory allocated to hold B<n> elements if B<n> is positive. The next B<n> calls
110to sk_TYPE_insert(), sk_TYPE_push() or sk_TYPE_unshift() will not fail or cause
111memory to be allocated or reallocated. If B<n> is zero or less than zero, no
112memory is allocated. sk_TYPE_new_reserve() also sets the comparison function
113B<compare> to the newly created stack. If B<compare> is B<NULL> then no
114comparison function is used.
115
116sk_TYPE_set_cmp_func() sets the comparison function of B<sk> to B<compare>.
117The previous comparison function is returned or B<NULL> if there was
118no previous comparison function.
119
120sk_TYPE_free() frees up the B<sk> structure. It does B<not> free up any
121elements of B<sk>. After this call B<sk> is no longer valid.
122
123sk_TYPE_zero() sets the number of elements in B<sk> to zero. It does not free
124B<sk> so after this call B<sk> is still valid.
125
126sk_TYPE_pop_free() frees up all elements of B<sk> and B<sk> itself. The
127free function freefunc() is called on each element to free it.
128
129sk_TYPE_delete() deletes element B<i> from B<sk>. It returns the deleted
130element or B<NULL> if B<i> is out of range.
131
132sk_TYPE_delete_ptr() deletes element matching B<ptr> from B<sk>. It returns
133the deleted element or B<NULL> if no element matching B<ptr> was found.
134
135sk_TYPE_insert() inserts B<ptr> into B<sk> at position B<idx>. Any existing
136elements at or after B<idx> are moved downwards. If B<idx> is out of range
137the new element is appended to B<sk>. sk_TYPE_insert() either returns the
138number of elements in B<sk> after the new element is inserted or zero if
139an error (such as memory allocation failure) occurred.
140
141sk_TYPE_push() appends B<ptr> to B<sk> it is equivalent to:
142
143 sk_TYPE_insert(sk, ptr, -1);
144
145sk_TYPE_unshift() inserts B<ptr> at the start of B<sk> it is equivalent to:
146
147 sk_TYPE_insert(sk, ptr, 0);
148
149sk_TYPE_pop() returns and removes the last element from B<sk>.
150
151sk_TYPE_shift() returns and removes the first element from B<sk>.
152
153sk_TYPE_set() sets element B<idx> of B<sk> to B<ptr> replacing the current
154element. The new element value is returned or B<NULL> if an error occurred:
155this will only happen if B<sk> is B<NULL> or B<idx> is out of range.
156
157sk_TYPE_find() searches B<sk> for the element B<ptr>.  In the case
158where no comparison function has been specified, the function performs
159a linear search for a pointer equal to B<ptr>. The index of the first
160matching element is returned or B<-1> if there is no match. In the case
161where a comparison function has been specified, B<sk> is sorted then
162sk_TYPE_find() returns the index of a matching element or B<-1> if there
163is no match. Note that, in this case, the matching element returned is
164not guaranteed to be the first; the comparison function will usually
165compare the values pointed to rather than the pointers themselves and
166the order of elements in B<sk> could change.
167
168sk_TYPE_find_ex() operates like sk_TYPE_find() except when a comparison
169function has been specified and no matching element is found. Instead
170of returning B<-1>, sk_TYPE_find_ex() returns the index of the element
171either before or after the location where B<ptr> would be if it were
172present in B<sk>.
173
174sk_TYPE_sort() sorts B<sk> using the supplied comparison function.
175
176sk_TYPE_is_sorted() returns B<1> if B<sk> is sorted and B<0> otherwise.
177
178sk_TYPE_dup() returns a copy of B<sk>. Note the pointers in the copy
179are identical to the original.
180
181sk_TYPE_deep_copy() returns a new stack where each element has been copied.
182Copying is performed by the supplied copyfunc() and freeing by freefunc(). The
183function freefunc() is only called if an error occurs.
184
185=head1 NOTES
186
187Care should be taken when accessing stacks in multi-threaded environments.
188Any operation which increases the size of a stack such as sk_TYPE_insert() or
189sk_push() can "grow" the size of an internal array and cause race conditions
190if the same stack is accessed in a different thread. Operations such as
191sk_find() and sk_sort() can also reorder the stack.
192
193Any comparison function supplied should use a metric suitable
194for use in a binary search operation. That is it should return zero, a
195positive or negative value if B<a> is equal to, greater than
196or less than B<b> respectively.
197
198Care should be taken when checking the return values of the functions
199sk_TYPE_find() and sk_TYPE_find_ex(). They return an index to the
200matching element. In particular B<0> indicates a matching first element.
201A failed search is indicated by a B<-1> return value.
202
203STACK_OF(), DEFINE_STACK_OF(), DEFINE_STACK_OF_CONST(), and
204DEFINE_SPECIAL_STACK_OF() are implemented as macros.
205
206The underlying utility B<OPENSSL_sk_> API should not be used directly.
207It defines these functions: OPENSSL_sk_deep_copy(),
208OPENSSL_sk_delete(), OPENSSL_sk_delete_ptr(), OPENSSL_sk_dup(),
209OPENSSL_sk_find(), OPENSSL_sk_find_ex(), OPENSSL_sk_free(),
210OPENSSL_sk_insert(), OPENSSL_sk_is_sorted(), OPENSSL_sk_new(),
211OPENSSL_sk_new_null(), OPENSSL_sk_num(), OPENSSL_sk_pop(),
212OPENSSL_sk_pop_free(), OPENSSL_sk_push(), OPENSSL_sk_reserve(),
213OPENSSL_sk_set(), OPENSSL_sk_set_cmp_func(), OPENSSL_sk_shift(),
214OPENSSL_sk_sort(), OPENSSL_sk_unshift(), OPENSSL_sk_value(),
215OPENSSL_sk_zero().
216
217=head1 RETURN VALUES
218
219sk_TYPE_num() returns the number of elements in the stack or B<-1> if the
220passed stack is B<NULL>.
221
222sk_TYPE_value() returns a pointer to a stack element or B<NULL> if the
223index is out of range.
224
225sk_TYPE_new(), sk_TYPE_new_null() and sk_TYPE_new_reserve() return an empty
226stack or B<NULL> if an error occurs.
227
228sk_TYPE_reserve() returns B<1> on successful allocation of the required memory
229or B<0> on error.
230
231sk_TYPE_set_cmp_func() returns the old comparison function or B<NULL> if
232there was no old comparison function.
233
234sk_TYPE_free(), sk_TYPE_zero(), sk_TYPE_pop_free() and sk_TYPE_sort() do
235not return values.
236
237sk_TYPE_pop(), sk_TYPE_shift(), sk_TYPE_delete() and sk_TYPE_delete_ptr()
238return a pointer to the deleted element or B<NULL> on error.
239
240sk_TYPE_insert(), sk_TYPE_push() and sk_TYPE_unshift() return the total
241number of elements in the stack and 0 if an error occurred. sk_TYPE_push()
242further returns -1 if B<sk> is B<NULL>.
243
244sk_TYPE_set() returns a pointer to the replacement element or B<NULL> on
245error.
246
247sk_TYPE_find() and sk_TYPE_find_ex() return an index to the found element
248or B<-1> on error.
249
250sk_TYPE_is_sorted() returns B<1> if the stack is sorted and B<0> if it is
251not.
252
253sk_TYPE_dup() and sk_TYPE_deep_copy() return a pointer to the copy of the
254stack.
255
256=head1 HISTORY
257
258Before OpenSSL 1.1.0, this was implemented via macros and not inline functions
259and was not a public API.
260
261sk_TYPE_reserve() and sk_TYPE_new_reserve() were added in OpenSSL 1.1.1.
262
263=head1 COPYRIGHT
264
265Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
266
267Licensed under the OpenSSL license (the "License").  You may not use
268this file except in compliance with the License.  You can obtain a copy
269in the file LICENSE in the source distribution or at
270L<https://www.openssl.org/source/license.html>.
271
272=cut
273