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. 182 183B<sk_I<TYPE>_find_ex>() operates like B<sk_I<TYPE>_find>() except when a 184comparison function has been specified and no matching element is found. 185Instead of returning B<-1>, B<sk_I<TYPE>_find_ex>() returns the index of the 186element either before or after the location where I<ptr> would be if it were 187present in I<sk>. The function also does not guarantee that the first matching 188element in the sorted stack is returned. 189 190B<sk_I<TYPE>_find_all>() operates like B<sk_I<TYPE>_find>() but it also 191sets the I<*pnum> to number of matching elements in the stack. In case 192no comparison function has been specified the I<*pnum> will be always set 193to 1 if matching element was found, 0 otherwise. 194 195B<sk_I<TYPE>_sort>() sorts I<sk> using the supplied comparison function. 196 197B<sk_I<TYPE>_is_sorted>() returns B<1> if I<sk> is sorted and B<0> otherwise. 198 199B<sk_I<TYPE>_dup>() returns a shallow copy of I<sk> 200or an empty stack if the passed stack is NULL. 201Note the pointers in the copy are identical to the original. 202 203B<sk_I<TYPE>_deep_copy>() returns a new stack where each element has been 204copied or an empty stack if the passed stack is NULL. 205Copying is performed by the supplied copyfunc() and freeing by freefunc(). 206The function freefunc() is only called if an error occurs. 207 208=head1 NOTES 209 210Care should be taken when accessing stacks in multi-threaded environments. 211Any operation which increases the size of a stack such as B<sk_I<TYPE>_insert>() 212or B<sk_I<TYPE>_push>() can "grow" the size of an internal array and cause race 213conditions if the same stack is accessed in a different thread. Operations such 214as B<sk_I<TYPE>_find>() and B<sk_I<TYPE>_sort>() can also reorder the stack. 215 216Any comparison function supplied should use a metric suitable 217for use in a binary search operation. That is it should return zero, a 218positive or negative value if I<a> is equal to, greater than 219or less than I<b> respectively. 220 221Care should be taken when checking the return values of the functions 222B<sk_I<TYPE>_find>() and B<sk_I<TYPE>_find_ex>(). They return an index to the 223matching element. In particular B<0> indicates a matching first element. 224A failed search is indicated by a B<-1> return value. 225 226STACK_OF(), DEFINE_STACK_OF(), DEFINE_STACK_OF_CONST(), and 227DEFINE_SPECIAL_STACK_OF() are implemented as macros. 228 229It is not an error to call B<sk_I<TYPE>_num>(), B<sk_I<TYPE>_value>(), 230B<sk_I<TYPE>_free>(), B<sk_I<TYPE>_zero>(), B<sk_I<TYPE>_pop_free>(), 231B<sk_I<TYPE>_delete>(), B<sk_I<TYPE>_delete_ptr>(), B<sk_I<TYPE>_pop>(), 232B<sk_I<TYPE>_shift>(), B<sk_I<TYPE>_find>(), B<sk_I<TYPE>_find_ex>(), 233and B<sk_I<TYPE>_find_all>() on a NULL stack, empty stack, or with 234an invalid index. An error is not raised in these conditions. 235 236The underlying utility B<OPENSSL_sk_> API should not be used directly. 237It defines these functions: OPENSSL_sk_deep_copy(), 238OPENSSL_sk_delete(), OPENSSL_sk_delete_ptr(), OPENSSL_sk_dup(), 239OPENSSL_sk_find(), OPENSSL_sk_find_ex(), OPENSSL_sk_find_all(), 240OPENSSL_sk_free(), OPENSSL_sk_insert(), OPENSSL_sk_is_sorted(), 241OPENSSL_sk_new(), OPENSSL_sk_new_null(), OPENSSL_sk_new_reserve(), 242OPENSSL_sk_num(), OPENSSL_sk_pop(), OPENSSL_sk_pop_free(), OPENSSL_sk_push(), 243OPENSSL_sk_reserve(), OPENSSL_sk_set(), OPENSSL_sk_set_cmp_func(), 244OPENSSL_sk_shift(), OPENSSL_sk_sort(), OPENSSL_sk_unshift(), 245OPENSSL_sk_value(), OPENSSL_sk_zero(). 246 247=head1 RETURN VALUES 248 249B<sk_I<TYPE>_num>() returns the number of elements in the stack or B<-1> if the 250passed stack is NULL. 251 252B<sk_I<TYPE>_value>() returns a pointer to a stack element or NULL if the 253index is out of range. 254 255B<sk_I<TYPE>_new>(), B<sk_I<TYPE>_new_null>() and B<sk_I<TYPE>_new_reserve>() 256return an empty stack or NULL if an error occurs. 257 258B<sk_I<TYPE>_reserve>() returns B<1> on successful allocation of the required 259memory or B<0> on error. 260 261B<sk_I<TYPE>_set_cmp_func>() returns the old comparison function or NULL if 262there was no old comparison function. 263 264B<sk_I<TYPE>_free>(), B<sk_I<TYPE>_zero>(), B<sk_I<TYPE>_pop_free>() and 265B<sk_I<TYPE>_sort>() do not return values. 266 267B<sk_I<TYPE>_pop>(), B<sk_I<TYPE>_shift>(), B<sk_I<TYPE>_delete>() and 268B<sk_I<TYPE>_delete_ptr>() return a pointer to the deleted element or NULL 269on error. 270 271B<sk_I<TYPE>_insert>(), B<sk_I<TYPE>_push>() and B<sk_I<TYPE>_unshift>() return 272the total number of elements in the stack and 0 if an error occurred. 273 274B<sk_I<TYPE>_set>() returns a pointer to the replacement element or NULL on 275error. 276 277B<sk_I<TYPE>_find>() and B<sk_I<TYPE>_find_ex>() return an index to the found 278element or B<-1> on error. 279 280B<sk_I<TYPE>_is_sorted>() returns B<1> if the stack is sorted and B<0> if it is 281not. 282 283B<sk_I<TYPE>_dup>() and B<sk_I<TYPE>_deep_copy>() return a pointer to the copy 284of the stack or NULL on error. 285 286=head1 HISTORY 287 288Before OpenSSL 1.1.0, this was implemented via macros and not inline functions 289and was not a public API. 290 291B<sk_I<TYPE>_reserve>() and B<sk_I<TYPE>_new_reserve>() were added in OpenSSL 2921.1.1. 293 294From OpenSSL 3.2.0, the B<sk_I<TYPE>_find>(), B<sk_I<TYPE>_find_ex>() 295and B<sk_I<TYPE>_find_all>() calls are read-only and do not sort the 296stack. To avoid any performance implications this change introduces, 297B<sk_I<TYPE>_sort>() should be called before these find operations. 298 299Before OpenSSL 3.3.0 B<sk_I<TYPE>_push>() returned -1 if I<sk> was NULL. It 300was changed to return 0 in this condition as for other errors. 301 302=head1 COPYRIGHT 303 304Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved. 305 306Licensed under the Apache License 2.0 (the "License"). You may not use 307this file except in compliance with the License. You can obtain a copy 308in the file LICENSE in the source distribution or at 309L<https://www.openssl.org/source/license.html>. 310 311=cut 312