273 lines
11 KiB
Plaintext
273 lines
11 KiB
Plaintext
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=pod
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=head1 NAME
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DEFINE_STACK_OF, DEFINE_STACK_OF_CONST, DEFINE_SPECIAL_STACK_OF,
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DEFINE_SPECIAL_STACK_OF_CONST,
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sk_TYPE_num, sk_TYPE_value, sk_TYPE_new, sk_TYPE_new_null,
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sk_TYPE_reserve, sk_TYPE_free, sk_TYPE_zero, sk_TYPE_delete,
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sk_TYPE_delete_ptr, sk_TYPE_push, sk_TYPE_unshift, sk_TYPE_pop,
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sk_TYPE_shift, sk_TYPE_pop_free, sk_TYPE_insert, sk_TYPE_set,
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sk_TYPE_find, sk_TYPE_find_ex, sk_TYPE_sort, sk_TYPE_is_sorted,
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sk_TYPE_dup, sk_TYPE_deep_copy, sk_TYPE_set_cmp_func, sk_TYPE_new_reserve
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- stack container
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=head1 SYNOPSIS
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=for comment generic
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#include <openssl/safestack.h>
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STACK_OF(TYPE)
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DEFINE_STACK_OF(TYPE)
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DEFINE_STACK_OF_CONST(TYPE)
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DEFINE_SPECIAL_STACK_OF(FUNCTYPE, TYPE)
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DEFINE_SPECIAL_STACK_OF_CONST(FUNCTYPE, TYPE)
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typedef int (*sk_TYPE_compfunc)(const TYPE *const *a, const TYPE *const *b);
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typedef TYPE * (*sk_TYPE_copyfunc)(const TYPE *a);
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typedef void (*sk_TYPE_freefunc)(TYPE *a);
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int sk_TYPE_num(const STACK_OF(TYPE) *sk);
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TYPE *sk_TYPE_value(const STACK_OF(TYPE) *sk, int idx);
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STACK_OF(TYPE) *sk_TYPE_new(sk_TYPE_compfunc compare);
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STACK_OF(TYPE) *sk_TYPE_new_null(void);
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int sk_TYPE_reserve(STACK_OF(TYPE) *sk, int n);
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void sk_TYPE_free(const STACK_OF(TYPE) *sk);
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void sk_TYPE_zero(const STACK_OF(TYPE) *sk);
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TYPE *sk_TYPE_delete(STACK_OF(TYPE) *sk, int i);
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TYPE *sk_TYPE_delete_ptr(STACK_OF(TYPE) *sk, TYPE *ptr);
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int sk_TYPE_push(STACK_OF(TYPE) *sk, const TYPE *ptr);
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int sk_TYPE_unshift(STACK_OF(TYPE) *sk, const TYPE *ptr);
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TYPE *sk_TYPE_pop(STACK_OF(TYPE) *sk);
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TYPE *sk_TYPE_shift(STACK_OF(TYPE) *sk);
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void sk_TYPE_pop_free(STACK_OF(TYPE) *sk, sk_TYPE_freefunc freefunc);
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int sk_TYPE_insert(STACK_OF(TYPE) *sk, TYPE *ptr, int idx);
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TYPE *sk_TYPE_set(STACK_OF(TYPE) *sk, int idx, const TYPE *ptr);
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int sk_TYPE_find(STACK_OF(TYPE) *sk, TYPE *ptr);
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int sk_TYPE_find_ex(STACK_OF(TYPE) *sk, TYPE *ptr);
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void sk_TYPE_sort(const STACK_OF(TYPE) *sk);
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int sk_TYPE_is_sorted(const STACK_OF(TYPE) *sk);
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STACK_OF(TYPE) *sk_TYPE_dup(const STACK_OF(TYPE) *sk);
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STACK_OF(TYPE) *sk_TYPE_deep_copy(const STACK_OF(TYPE) *sk,
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sk_TYPE_copyfunc copyfunc,
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sk_TYPE_freefunc freefunc);
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sk_TYPE_compfunc (*sk_TYPE_set_cmp_func(STACK_OF(TYPE) *sk,
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sk_TYPE_compfunc compare));
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STACK_OF(TYPE) *sk_TYPE_new_reserve(sk_TYPE_compfunc compare, int n);
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=head1 DESCRIPTION
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Applications can create and use their own stacks by placing any of the macros
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described below in a header file. These macros define typesafe inline
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functions that wrap around the utility B<OPENSSL_sk_> API.
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In the description here, I<TYPE> is used
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as a placeholder for any of the OpenSSL datatypes, such as I<X509>.
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STACK_OF() returns the name for a stack of the specified B<TYPE>.
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DEFINE_STACK_OF() creates set of functions for a stack of B<TYPE>. This
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will mean that type B<TYPE> is stored in each stack, the type is referenced by
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STACK_OF(TYPE) and each function name begins with I<sk_TYPE_>. For example:
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TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx);
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DEFINE_STACK_OF_CONST() is identical to DEFINE_STACK_OF() except
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each element is constant. For example:
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const TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx);
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DEFINE_SPECIAL_STACK_OF() defines a stack of B<TYPE> but
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each function uses B<FUNCNAME> in the function name. For example:
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TYPE *sk_FUNCNAME_value(STACK_OF(TYPE) *sk, int idx);
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DEFINE_SPECIAL_STACK_OF_CONST() is similar except that each element is
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constant:
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const TYPE *sk_FUNCNAME_value(STACK_OF(TYPE) *sk, int idx);
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sk_TYPE_num() returns the number of elements in B<sk> or -1 if B<sk> is
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B<NULL>.
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sk_TYPE_value() returns element B<idx> in B<sk>, where B<idx> starts at
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zero. If B<idx> is out of range then B<NULL> is returned.
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sk_TYPE_new() allocates a new empty stack using comparison function B<compare>.
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If B<compare> is B<NULL> then no comparison function is used. This function is
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equivalent to sk_TYPE_new_reserve(compare, 0).
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sk_TYPE_new_null() allocates a new empty stack with no comparison function. This
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function is equivalent to sk_TYPE_new_reserve(NULL, 0).
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sk_TYPE_reserve() allocates additional memory in the B<sk> structure
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such that the next B<n> calls to sk_TYPE_insert(), sk_TYPE_push()
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or sk_TYPE_unshift() will not fail or cause memory to be allocated
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or reallocated. If B<n> is zero, any excess space allocated in the
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B<sk> structure is freed. On error B<sk> is unchanged.
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sk_TYPE_new_reserve() allocates a new stack. The new stack will have additional
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memory allocated to hold B<n> elements if B<n> is positive. The next B<n> calls
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to sk_TYPE_insert(), sk_TYPE_push() or sk_TYPE_unshift() will not fail or cause
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memory to be allocated or reallocated. If B<n> is zero or less than zero, no
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memory is allocated. sk_TYPE_new_reserve() also sets the comparison function
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B<compare> to the newly created stack. If B<compare> is B<NULL> then no
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comparison function is used.
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sk_TYPE_set_cmp_func() sets the comparison function of B<sk> to B<compare>.
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The previous comparison function is returned or B<NULL> if there was
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no previous comparison function.
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sk_TYPE_free() frees up the B<sk> structure. It does B<not> free up any
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elements of B<sk>. After this call B<sk> is no longer valid.
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sk_TYPE_zero() sets the number of elements in B<sk> to zero. It does not free
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B<sk> so after this call B<sk> is still valid.
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sk_TYPE_pop_free() frees up all elements of B<sk> and B<sk> itself. The
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free function freefunc() is called on each element to free it.
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sk_TYPE_delete() deletes element B<i> from B<sk>. It returns the deleted
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element or B<NULL> if B<i> is out of range.
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sk_TYPE_delete_ptr() deletes element matching B<ptr> from B<sk>. It returns
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the deleted element or B<NULL> if no element matching B<ptr> was found.
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sk_TYPE_insert() inserts B<ptr> into B<sk> at position B<idx>. Any existing
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elements at or after B<idx> are moved downwards. If B<idx> is out of range
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the new element is appended to B<sk>. sk_TYPE_insert() either returns the
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number of elements in B<sk> after the new element is inserted or zero if
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an error (such as memory allocation failure) occurred.
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sk_TYPE_push() appends B<ptr> to B<sk> it is equivalent to:
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sk_TYPE_insert(sk, ptr, -1);
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sk_TYPE_unshift() inserts B<ptr> at the start of B<sk> it is equivalent to:
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sk_TYPE_insert(sk, ptr, 0);
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sk_TYPE_pop() returns and removes the last element from B<sk>.
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sk_TYPE_shift() returns and removes the first element from B<sk>.
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sk_TYPE_set() sets element B<idx> of B<sk> to B<ptr> replacing the current
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element. The new element value is returned or B<NULL> if an error occurred:
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this will only happen if B<sk> is B<NULL> or B<idx> is out of range.
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sk_TYPE_find() searches B<sk> for the element B<ptr>. In the case
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where no comparison function has been specified, the function performs
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a linear search for a pointer equal to B<ptr>. The index of the first
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matching element is returned or B<-1> if there is no match. In the case
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where a comparison function has been specified, B<sk> is sorted then
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sk_TYPE_find() returns the index of a matching element or B<-1> if there
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is no match. Note that, in this case, the matching element returned is
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not guaranteed to be the first; the comparison function will usually
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compare the values pointed to rather than the pointers themselves and
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the order of elements in B<sk> could change.
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sk_TYPE_find_ex() operates like sk_TYPE_find() except when a comparison
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function has been specified and no matching element is found. Instead
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of returning B<-1>, sk_TYPE_find_ex() returns the index of the element
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either before or after the location where B<ptr> would be if it were
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present in B<sk>.
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sk_TYPE_sort() sorts B<sk> using the supplied comparison function.
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sk_TYPE_is_sorted() returns B<1> if B<sk> is sorted and B<0> otherwise.
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sk_TYPE_dup() returns a copy of B<sk>. Note the pointers in the copy
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are identical to the original.
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sk_TYPE_deep_copy() returns a new stack where each element has been copied.
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Copying is performed by the supplied copyfunc() and freeing by freefunc(). The
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function freefunc() is only called if an error occurs.
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=head1 NOTES
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Care should be taken when accessing stacks in multi-threaded environments.
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Any operation which increases the size of a stack such as sk_TYPE_insert() or
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sk_push() can "grow" the size of an internal array and cause race conditions
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if the same stack is accessed in a different thread. Operations such as
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sk_find() and sk_sort() can also reorder the stack.
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Any comparison function supplied should use a metric suitable
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for use in a binary search operation. That is it should return zero, a
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positive or negative value if B<a> is equal to, greater than
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or less than B<b> respectively.
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Care should be taken when checking the return values of the functions
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sk_TYPE_find() and sk_TYPE_find_ex(). They return an index to the
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matching element. In particular B<0> indicates a matching first element.
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A failed search is indicated by a B<-1> return value.
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STACK_OF(), DEFINE_STACK_OF(), DEFINE_STACK_OF_CONST(), and
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DEFINE_SPECIAL_STACK_OF() are implemented as macros.
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The underlying utility B<OPENSSL_sk_> API should not be used directly.
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It defines these functions: OPENSSL_sk_deep_copy(),
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OPENSSL_sk_delete(), OPENSSL_sk_delete_ptr(), OPENSSL_sk_dup(),
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OPENSSL_sk_find(), OPENSSL_sk_find_ex(), OPENSSL_sk_free(),
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OPENSSL_sk_insert(), OPENSSL_sk_is_sorted(), OPENSSL_sk_new(),
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OPENSSL_sk_new_null(), OPENSSL_sk_num(), OPENSSL_sk_pop(),
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OPENSSL_sk_pop_free(), OPENSSL_sk_push(), OPENSSL_sk_reserve(),
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OPENSSL_sk_set(), OPENSSL_sk_set_cmp_func(), OPENSSL_sk_shift(),
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OPENSSL_sk_sort(), OPENSSL_sk_unshift(), OPENSSL_sk_value(),
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OPENSSL_sk_zero().
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=head1 RETURN VALUES
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sk_TYPE_num() returns the number of elements in the stack or B<-1> if the
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passed stack is B<NULL>.
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sk_TYPE_value() returns a pointer to a stack element or B<NULL> if the
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index is out of range.
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sk_TYPE_new(), sk_TYPE_new_null() and sk_TYPE_new_reserve() return an empty
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stack or B<NULL> if an error occurs.
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sk_TYPE_reserve() returns B<1> on successful allocation of the required memory
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or B<0> on error.
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sk_TYPE_set_cmp_func() returns the old comparison function or B<NULL> if
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there was no old comparison function.
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sk_TYPE_free(), sk_TYPE_zero(), sk_TYPE_pop_free() and sk_TYPE_sort() do
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not return values.
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sk_TYPE_pop(), sk_TYPE_shift(), sk_TYPE_delete() and sk_TYPE_delete_ptr()
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return a pointer to the deleted element or B<NULL> on error.
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sk_TYPE_insert(), sk_TYPE_push() and sk_TYPE_unshift() return the total
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number of elements in the stack and 0 if an error occurred. sk_TYPE_push()
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further returns -1 if B<sk> is B<NULL>.
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sk_TYPE_set() returns a pointer to the replacement element or B<NULL> on
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error.
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sk_TYPE_find() and sk_TYPE_find_ex() return an index to the found element
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or B<-1> on error.
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sk_TYPE_is_sorted() returns B<1> if the stack is sorted and B<0> if it is
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not.
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sk_TYPE_dup() and sk_TYPE_deep_copy() return a pointer to the copy of the
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stack.
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=head1 HISTORY
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Before OpenSSL 1.1.0, this was implemented via macros and not inline functions
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and was not a public API.
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sk_TYPE_reserve() and sk_TYPE_new_reserve() were added in OpenSSL 1.1.1.
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=head1 COPYRIGHT
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Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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