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_find_all, sk_TYPE_sort, 12sk_TYPE_is_sorted, sk_TYPE_dup, sk_TYPE_deep_copy, sk_TYPE_set_cmp_func, 13sk_TYPE_new_reserve, 14OPENSSL_sk_deep_copy, OPENSSL_sk_delete, OPENSSL_sk_delete_ptr, 15OPENSSL_sk_dup, OPENSSL_sk_find, OPENSSL_sk_find_ex, OPENSSL_sk_find_all, 16OPENSSL_sk_free, OPENSSL_sk_insert, OPENSSL_sk_is_sorted, OPENSSL_sk_new, 17OPENSSL_sk_new_null, OPENSSL_sk_new_reserve, OPENSSL_sk_num, OPENSSL_sk_pop, 18OPENSSL_sk_pop_free, OPENSSL_sk_push, OPENSSL_sk_reserve, OPENSSL_sk_set, 19OPENSSL_sk_set_cmp_func, OPENSSL_sk_shift, OPENSSL_sk_sort, 20OPENSSL_sk_unshift, OPENSSL_sk_value, OPENSSL_sk_zero 21- stack container 22 23=head1 SYNOPSIS 24 25=for openssl generic 26 27 #include <openssl/safestack.h> 28 29 STACK_OF(TYPE) 30 DEFINE_STACK_OF(TYPE) 31 DEFINE_STACK_OF_CONST(TYPE) 32 DEFINE_SPECIAL_STACK_OF(FUNCTYPE, TYPE) 33 DEFINE_SPECIAL_STACK_OF_CONST(FUNCTYPE, TYPE) 34 35 typedef int (*sk_TYPE_compfunc)(const TYPE *const *a, const TYPE *const *b); 36 typedef TYPE * (*sk_TYPE_copyfunc)(const TYPE *a); 37 typedef void (*sk_TYPE_freefunc)(TYPE *a); 38 39 int sk_TYPE_num(const STACK_OF(TYPE) *sk); 40 TYPE *sk_TYPE_value(const STACK_OF(TYPE) *sk, int idx); 41 STACK_OF(TYPE) *sk_TYPE_new(sk_TYPE_compfunc compare); 42 STACK_OF(TYPE) *sk_TYPE_new_null(void); 43 int sk_TYPE_reserve(STACK_OF(TYPE) *sk, int n); 44 void sk_TYPE_free(STACK_OF(TYPE) *sk); 45 void sk_TYPE_zero(STACK_OF(TYPE) *sk); 46 TYPE *sk_TYPE_delete(STACK_OF(TYPE) *sk, int i); 47 TYPE *sk_TYPE_delete_ptr(STACK_OF(TYPE) *sk, TYPE *ptr); 48 int sk_TYPE_push(STACK_OF(TYPE) *sk, const TYPE *ptr); 49 int sk_TYPE_unshift(STACK_OF(TYPE) *sk, const TYPE *ptr); 50 TYPE *sk_TYPE_pop(STACK_OF(TYPE) *sk); 51 TYPE *sk_TYPE_shift(STACK_OF(TYPE) *sk); 52 void sk_TYPE_pop_free(STACK_OF(TYPE) *sk, sk_TYPE_freefunc freefunc); 53 int sk_TYPE_insert(STACK_OF(TYPE) *sk, TYPE *ptr, int idx); 54 TYPE *sk_TYPE_set(STACK_OF(TYPE) *sk, int idx, const TYPE *ptr); 55 int sk_TYPE_find(STACK_OF(TYPE) *sk, TYPE *ptr); 56 int sk_TYPE_find_ex(STACK_OF(TYPE) *sk, TYPE *ptr); 57 int sk_TYPE_find_all(STACK_OF(TYPE) *sk, TYPE *ptr, int *pnum); 58 void sk_TYPE_sort(const STACK_OF(TYPE) *sk); 59 int sk_TYPE_is_sorted(const STACK_OF(TYPE) *sk); 60 STACK_OF(TYPE) *sk_TYPE_dup(const STACK_OF(TYPE) *sk); 61 STACK_OF(TYPE) *sk_TYPE_deep_copy(const STACK_OF(TYPE) *sk, 62 sk_TYPE_copyfunc copyfunc, 63 sk_TYPE_freefunc freefunc); 64 sk_TYPE_compfunc (*sk_TYPE_set_cmp_func(STACK_OF(TYPE) *sk, 65 sk_TYPE_compfunc compare)); 66 STACK_OF(TYPE) *sk_TYPE_new_reserve(sk_TYPE_compfunc compare, int n); 67 68=head1 DESCRIPTION 69 70Applications can create and use their own stacks by placing any of the macros 71described below in a header file. These macros define typesafe inline 72functions that wrap around the utility B<OPENSSL_sk_> API. 73In the description here, B<I<TYPE>> is used 74as a placeholder for any of the OpenSSL datatypes, such as B<X509>. 75 76The STACK_OF() macro returns the name for a stack of the specified B<I<TYPE>>. 77This is an opaque pointer to a structure declaration. 78This can be used in every header file that references the stack. 79There are several B<DEFINE...> macros that create static inline functions 80for all of the functions described on this page. 81This should normally be used in one source file, and the stack manipulation 82is wrapped with application-specific functions. 83 84DEFINE_STACK_OF() creates set of functions for a stack of B<I<TYPE>> elements. 85The type is referenced by 86B<STACK_OF>(B<I<TYPE>>) and each function name begins with B<sk_I<TYPE>_>. 87DEFINE_STACK_OF_CONST() is identical to DEFINE_STACK_OF() except 88each element is constant. 89 90 /* DEFINE_STACK_OF(TYPE) */ 91 TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx); 92 /* DEFINE_STACK_OF_CONST(TYPE) */ 93 const TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx); 94 95DEFINE_SPECIAL_STACK_OF() and DEFINE_SPECIAL_STACK_OF_CONST() are similar 96except B<FUNCNAME> is used in the function names: 97 98 /* DEFINE_SPECIAL_STACK_OF(TYPE, FUNCNAME) */ 99 TYPE *sk_FUNCNAME_value(STACK_OF(TYPE) *sk, int idx); 100 /* DEFINE_SPECIAL_STACK_OF(TYPE, FUNCNAME) */ 101 const TYPE *sk_FUNCNAME_value(STACK_OF(TYPE) *sk, int idx); 102 103B<sk_I<TYPE>_num>() returns the number of elements in I<sk> or -1 if I<sk> is 104NULL. 105 106B<sk_I<TYPE>_value>() returns element I<idx> in I<sk>, where I<idx> starts at 107zero. If I<idx> is out of range then NULL is returned. 108 109B<sk_I<TYPE>_new>() allocates a new empty stack using comparison function 110I<compare>. If I<compare> is NULL then no comparison function is used. This 111function is equivalent to B<sk_I<TYPE>_new_reserve>(I<compare>, 0). 112 113B<sk_I<TYPE>_new_null>() allocates a new empty stack with no comparison 114function. This function is equivalent to B<sk_I<TYPE>_new_reserve>(NULL, 0). 115 116B<sk_I<TYPE>_reserve>() allocates additional memory in the I<sk> structure 117such that the next I<n> calls to B<sk_I<TYPE>_insert>(), B<sk_I<TYPE>_push>() 118or B<sk_I<TYPE>_unshift>() will not fail or cause memory to be allocated 119or reallocated. If I<n> is zero, any excess space allocated in the 120I<sk> structure is freed. On error I<sk> is unchanged. 121 122B<sk_I<TYPE>_new_reserve>() allocates a new stack. The new stack will have 123additional memory allocated to hold I<n> elements if I<n> is positive. 124The next I<n> calls to B<sk_I<TYPE>_insert>(), B<sk_I<TYPE>_push>() or 125B<sk_I<TYPE>_unshift>() will not fail or cause memory to be allocated or 126reallocated. If I<n> is zero or less than zero, no memory is allocated. 127B<sk_I<TYPE>_new_reserve>() also sets the comparison function I<compare> 128to the newly created stack. If I<compare> is NULL then no comparison 129function is used. 130 131B<sk_I<TYPE>_set_cmp_func>() sets the comparison function of I<sk> to 132I<compare>. The previous comparison function is returned or NULL if there 133was no previous comparison function. 134 135B<sk_I<TYPE>_free>() frees up the I<sk> structure. It does I<not> free up any 136elements of I<sk>. After this call I<sk> is no longer valid. 137 138B<sk_I<TYPE>_zero>() sets the number of elements in I<sk> to zero. It does not 139free I<sk> so after this call I<sk> is still valid. 140 141B<sk_I<TYPE>_pop_free>() frees up all elements of I<sk> and I<sk> itself. The 142free function freefunc() is called on each element to free it. 143 144B<sk_I<TYPE>_delete>() deletes element I<i> from I<sk>. It returns the deleted 145element or NULL if I<i> is out of range. 146 147B<sk_I<TYPE>_delete_ptr>() deletes element matching I<ptr> from I<sk>. It 148returns the deleted element or NULL if no element matching I<ptr> was found. 149 150B<sk_I<TYPE>_insert>() inserts I<ptr> into I<sk> at position I<idx>. Any 151existing elements at or after I<idx> are moved downwards. If I<idx> is out 152of range the new element is appended to I<sk>. B<sk_I<TYPE>_insert>() either 153returns the number of elements in I<sk> after the new element is inserted or 154zero if an error (such as memory allocation failure) occurred. 155 156B<sk_I<TYPE>_push>() appends I<ptr> to I<sk> it is equivalent to: 157 158 sk_TYPE_insert(sk, ptr, -1); 159 160B<sk_I<TYPE>_unshift>() inserts I<ptr> at the start of I<sk> it is equivalent 161to: 162 163 sk_TYPE_insert(sk, ptr, 0); 164 165B<sk_I<TYPE>_pop>() returns and removes the last element from I<sk>. 166 167B<sk_I<TYPE>_shift>() returns and removes the first element from I<sk>. 168 169B<sk_I<TYPE>_set>() sets element I<idx> of I<sk> to I<ptr> replacing the current 170element. The new element value is returned or NULL if an error occurred: 171this will only happen if I<sk> is NULL or I<idx> is out of range. 172 173B<sk_I<TYPE>_find>() searches I<sk> for the element I<ptr>. In the case 174where no comparison function has been specified, the function performs 175a linear search for a pointer equal to I<ptr>. The index of the first 176matching element is returned or B<-1> if there is no match. In the case 177where a comparison function has been specified, I<sk> is sorted and 178B<sk_I<TYPE>_find>() returns the index of a matching element or B<-1> if there 179is no match. Note that, in this case the comparison function will usually 180compare the values pointed to rather than the pointers themselves and 181the order of elements in I<sk> can change. Note that because the stack may be 182sorted as the result of a B<sk_I<TYPE>_find>() call, if a lock is being used to 183synchronise access to the stack across multiple threads, then that lock must be 184a "write" lock. 185 186B<sk_I<TYPE>_find_ex>() operates like B<sk_I<TYPE>_find>() except when a 187comparison function has been specified and no matching element is found. 188Instead of returning B<-1>, B<sk_I<TYPE>_find_ex>() returns the index of the 189element either before or after the location where I<ptr> would be if it were 190present in I<sk>. The function also does not guarantee that the first matching 191element in the sorted stack is returned. 192 193B<sk_I<TYPE>_find_all>() operates like B<sk_I<TYPE>_find>() but it also 194sets the I<*pnum> to number of matching elements in the stack. In case 195no comparison function has been specified the I<*pnum> will be always set 196to 1 if matching element was found, 0 otherwise. 197 198B<sk_I<TYPE>_sort>() sorts I<sk> using the supplied comparison function. 199 200B<sk_I<TYPE>_is_sorted>() returns B<1> if I<sk> is sorted and B<0> otherwise. 201 202B<sk_I<TYPE>_dup>() returns a shallow copy of I<sk> 203or an empty stack if the passed stack is NULL. 204Note the pointers in the copy are identical to the original. 205 206B<sk_I<TYPE>_deep_copy>() returns a new stack where each element has been 207copied or an empty stack if the passed stack is NULL. 208Copying is performed by the supplied copyfunc() and freeing by freefunc(). 209The function freefunc() is only called if an error occurs. 210 211=head1 NOTES 212 213Care should be taken when accessing stacks in multi-threaded environments. 214Any operation which increases the size of a stack such as B<sk_I<TYPE>_insert>() 215or B<sk_I<TYPE>_push>() can "grow" the size of an internal array and cause race 216conditions if the same stack is accessed in a different thread. Operations such 217as B<sk_I<TYPE>_find>() and B<sk_I<TYPE>_sort>() can also reorder the stack. 218 219Any comparison function supplied should use a metric suitable 220for use in a binary search operation. That is it should return zero, a 221positive or negative value if I<a> is equal to, greater than 222or less than I<b> respectively. 223 224Care should be taken when checking the return values of the functions 225B<sk_I<TYPE>_find>() and B<sk_I<TYPE>_find_ex>(). They return an index to the 226matching element. In particular B<0> indicates a matching first element. 227A failed search is indicated by a B<-1> return value. 228 229STACK_OF(), DEFINE_STACK_OF(), DEFINE_STACK_OF_CONST(), and 230DEFINE_SPECIAL_STACK_OF() are implemented as macros. 231 232It is not an error to call B<sk_I<TYPE>_num>(), B<sk_I<TYPE>_value>(), 233B<sk_I<TYPE>_free>(), B<sk_I<TYPE>_zero>(), B<sk_I<TYPE>_pop_free>(), 234B<sk_I<TYPE>_delete>(), B<sk_I<TYPE>_delete_ptr>(), B<sk_I<TYPE>_pop>(), 235B<sk_I<TYPE>_shift>(), B<sk_I<TYPE>_find>(), B<sk_I<TYPE>_find_ex>(), 236and B<sk_I<TYPE>_find_all>() on a NULL stack, empty stack, or with 237an invalid index. An error is not raised in these conditions. 238 239The underlying utility B<OPENSSL_sk_> API should not be used directly. 240It defines these functions: OPENSSL_sk_deep_copy(), 241OPENSSL_sk_delete(), OPENSSL_sk_delete_ptr(), OPENSSL_sk_dup(), 242OPENSSL_sk_find(), OPENSSL_sk_find_ex(), OPENSSL_sk_find_all(), 243OPENSSL_sk_free(), OPENSSL_sk_insert(), OPENSSL_sk_is_sorted(), 244OPENSSL_sk_new(), OPENSSL_sk_new_null(), OPENSSL_sk_new_reserve(), 245OPENSSL_sk_num(), OPENSSL_sk_pop(), OPENSSL_sk_pop_free(), OPENSSL_sk_push(), 246OPENSSL_sk_reserve(), OPENSSL_sk_set(), OPENSSL_sk_set_cmp_func(), 247OPENSSL_sk_shift(), OPENSSL_sk_sort(), OPENSSL_sk_unshift(), 248OPENSSL_sk_value(), OPENSSL_sk_zero(). 249 250=head1 RETURN VALUES 251 252B<sk_I<TYPE>_num>() returns the number of elements in the stack or B<-1> if the 253passed stack is NULL. 254 255B<sk_I<TYPE>_value>() returns a pointer to a stack element or NULL if the 256index is out of range. 257 258B<sk_I<TYPE>_new>(), B<sk_I<TYPE>_new_null>() and B<sk_I<TYPE>_new_reserve>() 259return an empty stack or NULL if an error occurs. 260 261B<sk_I<TYPE>_reserve>() returns B<1> on successful allocation of the required 262memory or B<0> on error. 263 264B<sk_I<TYPE>_set_cmp_func>() returns the old comparison function or NULL if 265there was no old comparison function. 266 267B<sk_I<TYPE>_free>(), B<sk_I<TYPE>_zero>(), B<sk_I<TYPE>_pop_free>() and 268B<sk_I<TYPE>_sort>() do not return values. 269 270B<sk_I<TYPE>_pop>(), B<sk_I<TYPE>_shift>(), B<sk_I<TYPE>_delete>() and 271B<sk_I<TYPE>_delete_ptr>() return a pointer to the deleted element or NULL 272on error. 273 274B<sk_I<TYPE>_insert>(), B<sk_I<TYPE>_push>() and B<sk_I<TYPE>_unshift>() return 275the total number of elements in the stack and 0 if an error occurred. 276B<sk_I<TYPE>_push>() further returns -1 if I<sk> is NULL. 277 278B<sk_I<TYPE>_set>() returns a pointer to the replacement element or NULL on 279error. 280 281B<sk_I<TYPE>_find>() and B<sk_I<TYPE>_find_ex>() return an index to the found 282element or B<-1> on error. 283 284B<sk_I<TYPE>_is_sorted>() returns B<1> if the stack is sorted and B<0> if it is 285not. 286 287B<sk_I<TYPE>_dup>() and B<sk_I<TYPE>_deep_copy>() return a pointer to the copy 288of the stack or NULL on error. 289 290=head1 HISTORY 291 292Before OpenSSL 1.1.0, this was implemented via macros and not inline functions 293and was not a public API. 294 295B<sk_I<TYPE>_reserve>() and B<sk_I<TYPE>_new_reserve>() were added in OpenSSL 2961.1.1. 297 298=head1 COPYRIGHT 299 300Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved. 301 302Licensed under the Apache License 2.0 (the "License"). You may not use 303this file except in compliance with the License. You can obtain a copy 304in the file LICENSE in the source distribution or at 305L<https://www.openssl.org/source/license.html>. 306 307=cut 308