Rename lh_xxx,sk_xxx tp OPENSSL_{LH,SK}_xxx

Rename sk_xxx to OPENSSL_sk_xxx and _STACK to OPENSSL_STACK
Rename lh_xxx API to OPENSSL_LH_xxx and LHASH_NODE to OPENSSL_LH_NODE
Make lhash stuff opaque.
Use typedefs for function pointers; makes the code simpler.
Remove CHECKED_xxx macros.
Add documentation; remove old X509-oriented doc.
Add API-compat names for entire old API

Reviewed-by: Dr. Stephen Henson <steve@openssl.org>

4 files changed, 268 insertions, 266 deletions

diff --git a/doc/crypto/lh_stats.pod b/doc/crypto/lh_stats.pod
index 12b4a16..bdc19b4 100644
--- a/doc/crypto/lh_stats.pod
+++ b/doc/crypto/lh_stats.pod
@@ -2,20 +2,21 @@
 
 =head1 NAME
 
-lh_stats, lh_node_stats, lh_node_usage_stats, lh_stats_bio,
-lh_node_stats_bio, lh_node_usage_stats_bio - LHASH statistics
+OPENSSL_LH_stats, OPENSSL_LH_node_stats, OPENSSL_LH_node_usage_stats,
+OPENSSL_LH_stats_bio,
+OPENSSL_LH_node_stats_bio, OPENSSL_LH_node_usage_stats_bio - LHASH statistics
 
 =head1 SYNOPSIS
 
  #include <openssl/lhash.h>
 
- void lh_stats(LHASH *table, FILE *out);
- void lh_node_stats(LHASH *table, FILE *out);
- void lh_node_usage_stats(LHASH *table, FILE *out);
+ void OPENSSL_LH_stats(LHASH *table, FILE *out);
+ void OPENSSL_LH_node_stats(LHASH *table, FILE *out);
+ void OPENSSL_LH_node_usage_stats(LHASH *table, FILE *out);
 
- void lh_stats_bio(LHASH *table, BIO *out);
- void lh_node_stats_bio(LHASH *table, BIO *out);
- void lh_node_usage_stats_bio(LHASH *table, BIO *out);
+ void OPENSSL_LH_stats_bio(LHASH *table, BIO *out);
+ void OPENSSL_LH_node_stats_bio(LHASH *table, BIO *out);
+ void OPENSSL_LH_node_usage_stats_bio(LHASH *table, BIO *out);
 
 =head1 DESCRIPTION
 
@@ -24,14 +25,14 @@ accessing the hash table.  This is mostly a legacy of Eric Young
 writing this library for the reasons of implementing what looked like
 a nice algorithm rather than for a particular software product.
 
-lh_stats() prints out statistics on the size of the hash table, how
+OPENSSL_LH_stats() prints out statistics on the size of the hash table, how
 many entries are in it, and the number and result of calls to the
 routines in this library.
 
-lh_node_stats() prints the number of entries for each 'bucket' in the
+OPENSSL_LH_node_stats() prints the number of entries for each 'bucket' in the
 hash table.
 
-lh_node_usage_stats() prints out a short summary of the state of the
+OPENSSL_LH_node_usage_stats() prints out a short summary of the state of the
 hash table.  It prints the 'load' and the 'actual load'.  The load is
 the average number of data items per 'bucket' in the hash table.  The
 'actual load' is the average number of items per 'bucket', but only
@@ -40,7 +41,7 @@ average number of searches that will need to find an item in the hash
 table, while the 'load' is the average number that will be done to
 record a miss.
 
-lh_stats_bio(), lh_node_stats_bio() and lh_node_usage_stats_bio()
+OPENSSL_LH_stats_bio(), OPENSSL_LH_node_stats_bio() and OPENSSL_LH_node_usage_stats_bio()
 are the same as the above, except that the output goes to a B<BIO>.
 
 =head1 RETURN VALUES
diff --git a/doc/crypto/lhash.pod b/doc/crypto/lhash.pod
index acc0821..9e29617 100644
--- a/doc/crypto/lhash.pod
+++ b/doc/crypto/lhash.pod
@@ -2,39 +2,45 @@
 
 =head1 NAME
 
-lh_new, lh_free, lh_insert, lh_delete, lh_retrieve, lh_doall, lh_doall_arg, lh_error - dynamic hash table
+DECLARE_LHASH_OF,
+OPENSSL_LH_COMPFUNC, OPENSSL_LH_HASHFUNC, OPENSSL_LH_DOALL_FUNC,
+LHASH_DOALL_ARG_FN_TYPE,
+lh_TYPE_new, lh_TYPE_free,
+lh_TYPE_insert, lh_TYPE_delete, lh_TYPE_retrieve,
+lh_TYPE_doall, lh_TYPE_doall_arg, lh_TYPE_error - dynamic hash table
 
 =head1 SYNOPSIS
 
  #include <openssl/lhash.h>
 
- DECLARE_LHASH_OF(<type>);
+ DECLARE_LHASH_OF(TYPE);
 
- LHASH *lh_<type>_new();
- void lh_<type>_free(LHASH_OF(<type> *table);
+ LHASH *lh_TYPE_new();
+ void lh_TYPE_free(LHASH_OF(TYPE *table);
 
- <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_insert(LHASH_OF(TYPE *table, TYPE *data);
+ TYPE *lh_TYPE_delete(LHASH_OF(TYPE *table, TYPE *data);
+ TYPE *lh_retrieve(LHASH_OFTYPE *table, TYPE *data);
 
- void lh_<type>_doall(LHASH_OF(<type> *table, LHASH_DOALL_FN_TYPE func);
- void lh_<type>_doall_arg(LHASH_OF(<type> *table, LHASH_DOALL_ARG_FN_TYPE func,
-          <type2>, <type2> *arg);
+ 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, TYPE *arg);
 
- int lh_<type>_error(LHASH_OF(<type> *table);
+ int lh_TYPE_error(LHASH_OF(TYPE) *table);
 
- typedef int (*LHASH_COMP_FN_TYPE)(const void *, const void *);
- typedef unsigned long (*LHASH_HASH_FN_TYPE)(const void *);
- typedef void (*LHASH_DOALL_FN_TYPE)(const void *);
+ typedef int (*OPENSSL_LH_COMPFUNC)(const void *, const void *);
+ typedef unsigned long (*OPENSSL_LH_HASHFUNC)(const void *);
+ typedef void (*OPENSSL_LH_DOALL_FUNC)(const void *);
  typedef void (*LHASH_DOALL_ARG_FN_TYPE)(const void *, const void *);
 
 =head1 DESCRIPTION
 
 This library implements type-checked dynamic hash tables. The hash
 table entries can be arbitrary structures. Usually they consist of key
-and value fields.
+and value fields.  In the description here, I<TYPE> is used a placeholder
+for any of the OpenSSL datatypes, such as I<SSL_SESSION>.
 
-lh_<type>_new() creates a new B<LHASH_OF(<type>> structure to store
+lh_TYPE_new() creates a new B<LHASH_OF(TYPE)> structure to store
 arbitrary data entries, and provides the 'hash' and 'compare'
 callbacks to be used in organising the table's entries.  The B<hash>
 callback takes a pointer to a table entry as its argument and returns
@@ -47,7 +53,7 @@ will contain items of some particular type and the B<hash> and
 B<compare> callbacks hash/compare these types, then the
 B<DECLARE_LHASH_HASH_FN> and B<IMPLEMENT_LHASH_COMP_FN> macros can be
 used to create callback wrappers of the prototypes required by
-lh_<type>_new().  These provide per-variable casts before calling the
+lh_TYPE_new().  These provide per-variable casts before calling the
 type-specific callbacks written by the application author.  These
 macros, as well as those used for the "doall" callbacks, are defined
 as;
@@ -104,25 +110,25 @@ as;
          /* ... */
  }
 
-lh_<type>_free() frees the B<LHASH_OF(<type>> structure
+lh_TYPE_free() frees the B<LHASH_OF(TYPE)> structure
 B<table>. Allocated hash table entries will not be freed; consider
-using lh_<type>_doall() to deallocate any remaining entries in the
+using lh_TYPE_doall() to deallocate any remaining entries in the
 hash table (see below).
 
-lh_<type>_insert() inserts the structure pointed to by B<data> into
+lh_TYPE_insert() inserts the structure pointed to by B<data> into
 B<table>.  If there already is an entry with the same key, the old
-value is replaced. Note that lh_<type>_insert() stores pointers, the
+value is replaced. Note that lh_TYPE_insert() stores pointers, the
 data are not copied.
 
-lh_<type>_delete() deletes an entry from B<table>.
+lh_TYPE_delete() deletes an entry from B<table>.
 
-lh_<type>_retrieve() looks up an entry in B<table>. Normally, B<data>
+lh_TYPE_retrieve() looks up an entry in B<table>. Normally, B<data>
 is a structure with the key field(s) set; the function will return a
 pointer to a fully populated structure.
 
-lh_<type>_doall() will, for every entry in the hash table, call
-B<func> with the data item as its parameter.  For lh_<type>_doall()
-and lh_<type>_doall_arg(), function pointer casting should be avoided
+lh_TYPE_doall() will, for every entry in the hash table, call
+B<func> with the data item as its parameter.  For lh_TYPE_doall()
+and lh_TYPE_doall_arg(), function pointer casting should be avoided
 in the callbacks (see B<NOTE>) - instead use the declare/implement
 macros to create type-checked wrappers that cast variables prior to
 calling your type-specific callbacks.  An example of this is
@@ -149,7 +155,7 @@ 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!
 
-lh_<type>_doall_arg() is the same as lh_<type>_doall() except that
+lh_TYPE_doall_arg() is the same as lh_TYPE_doall() except that
 B<func> will be called with B<arg> as the second argument and B<func>
 should be of type B<LHASH_DOALL_ARG_FN_TYPE> (a callback prototype
 that is passed both the table entry and an extra argument).  As with
@@ -169,27 +175,28 @@ that is provided by the caller):
  lh_STUFF_doall_arg(hashtable, LHASH_DOALL_ARG_FN(STUFF_print), BIO,
                     logging_bio);
 
-lh_<type>_error() can be used to determine if an error occurred in the last
-operation. lh_<type>_error() is a macro.
+
+lh_TYPE_error() can be used to determine if an error occurred in the last
+operation.
 
 =head1 RETURN VALUES
 
-lh_<type>_new() returns B<NULL> on error, otherwise a pointer to the new
+lh_TYPE_new() returns B<NULL> on error, otherwise a pointer to the new
 B<LHASH> structure.
 
-When a hash table entry is replaced, lh_<type>_insert() returns the value
+When a hash table entry is replaced, lh_TYPE_insert() returns the value
 being replaced. B<NULL> is returned on normal operation and on error.
 
-lh_<type>_delete() returns the entry being deleted.  B<NULL> is returned if
+lh_TYPE_delete() returns the entry being deleted.  B<NULL> is returned if
 there is no such value in the hash table.
 
-lh_<type>_retrieve() returns the hash table entry if it has been found,
+lh_TYPE_retrieve() returns the hash table entry if it has been found,
 B<NULL> otherwise.
 
-lh_<type>_error() returns 1 if an error occurred in the last operation, 0
+lh_TYPE_error() returns 1 if an error occurred in the last operation, 0
 otherwise.
 
-lh_<type>_free(), lh_<type>_doall() and lh_<type>_doall_arg() return no values.
+lh_TYPE_free(), lh_TYPE_doall() and lh_TYPE_doall_arg() return no values.
 
 =head1 NOTE
 
@@ -232,17 +239,12 @@ without any "const" qualifiers.
 
 =head1 BUGS
 
-lh_<type>_insert() returns B<NULL> both for success and error.
+lh_TYPE_insert() returns B<NULL> both for success and error.
 
 =head1 SEE ALSO
 
 L<lh_stats(3)>
 
-=head1 HISTORY
-
-In OpenSSL 1.0.0, the lhash interface was revamped for better
-type checking.
-
 =cut
 
 =head1 COPYRIGHT
diff --git a/doc/crypto/sk_X509_num.pod b/doc/crypto/sk_X509_num.pod
deleted file mode 100644
index 1f16e81..0000000
--- a/doc/crypto/sk_X509_num.pod
+++ /dev/null
@@ -1,213 +0,0 @@
-=pod
-
-=head1 NAME
-
-sk_X509_num, sk_X509_value, sk_X509_new, sk_X509_new_null, sk_X509_free,
-sk_X509_zero, sk_X509_delete, sk_X509_delete_ptr, sk_X509_push,
-sk_X509_unshift, sk_X509_pop, sk_X509_shift, sk_X509_pop_free, sk_X509_insert,
-sk_X509_set, sk_X509_find, sk_X509_find_ex, sk_X509_sort, sk_X509_is_sorted,
-sk_X509_dup, sk_X509_deep_copy, sk_X509_set_cmp_func - X509 stack
-
-=head1 SYNOPSIS
-
- #include <openssl/x509.h>
-
- int sk_X509_num(const STACK_OF(X509) *sk);
- X509 *sk_X509_value(const STACK_OF(X509) *sk, int idx);
- STACK_OF(X509) *sk_X509_new(int (*cmpf)(const X509 * const *a,
-                                         const X509 * const *b));
- STACK_OF(X509) *sk_X509_new_null(void);
- int (*sk_X509_set_cmp_func (STACK_OF(X509) *sk,
-                             int (*cmpf) (const X509 * const *a,
-                                          const X509 * const *b)))
-                             (const X509 * const *, const X509 * const *);
- void sk_X509_free(const STACK_OF(X509) *sk);
- void sk_X509_zero(const STACK_OF(X509) *sk);
- void sk_X509_pop_free(STACK_OF(X509) *sk, void (*func) (X509 *a));
- X509 *sk_X509_delete(STACK_OF(X509) *sk, int i);
- X509 *sk_X509_delete_ptr(STACK_OF(X509) *sk, X509 *ptr);
- int sk_X509_insert(STACK_OF(X509) *sk, X509 *ptr, int idx);
- int sk_X509_push(STACK_OF(X509) *sk, X509 *ptr);
- int sk_X509_unshift(STACK_OF(X509) *sk, X509 *ptr);
- X509 *sk_X509_pop(STACK_OF(X509) *sk);
- X509 *sk_X509_shift(STACK_OF(X509) *sk);
- X509 *sk_X509_set(STACK_OF(X509) *sk, int idx, X509 *ptr);
- int sk_X509_find(STACK_OF(X509) *sk, X509 *ptr);
- int sk_X509_find_ex(STACK_OF(X509) *sk, X509 *ptr);
- void sk_X509_sort(const STACK_OF(X509) *sk);
- int sk_X509_is_sorted(const STACK_OF(X509) *sk);
- STACK_OF(X509) *sk_X509_dup(STACK_OF(X509) *sk);
- STACK_OF(X509) *sk_X509_deep_copy(STACK_OF(X509) *sk,
-                                   X509 * (*copyfn) (const X509 *),
-                                   void (*freefn) (X509 *));
-
-=head1 DESCRIPTION
-
-sk_X509_num() returns the number of elements in B<sk> or -1 if B<sk> is
-B<NULL>.
-
-sk_X509_value() returns element B<idx> in B<sk>. Where B<idx> runs from 0
-to sk_X509_num(sk) - 1 inclusive. If B<idx> is out of range then B<NULL>
-is returned.
-
-sk_X509_new() allocates a new empty stack using comparison function B<cmpf>.
-If B<cmpf> is B<0> then no comparison function is used.
-
-sk_X509_new_null() allocates a new empty stack with no comparison function.
-
-sk_X509_set_cmp_func() sets the comparison function of B<sk> to B<cmpf>.
-The previous comparison function is returned or B<0> if there was
-no previous comparison function.
-
-sk_X509_free() frees up the B<sk> structure. It does B<not> free up any
-elements of B<sk>. After this call B<sk> is no longer valid.
-
-sk_X509_zero() sets the number of elements in B<sk> to zero. It does not free
-B<sk> so after this call B<sk> is still valid.
-
-sk_X509_pop_free() frees up all elements of B<sk> and B<sk> itself. The
-free function func() is called on each element to free it.
-
-sk_X509_delete() deletes element B<i> from B<sk>. It returns the deleted
-element or B<NULL> if B<i> is out of range.
-
-sk_X509_delete_ptr() deletes element matching B<ptr> from B<sk>. It returns
-the deleted element or B<NULL> if no element matching B<ptr> was found.
-
-sk_X509_insert() inserts B<ptr> into B<sk> at position B<idx>. Any existing
-elements at or after B<idx> are moved downwards. If B<idx> is out of range
-the new element is appended to B<sk>. sk_X509_insert() either returns the
-number of elements in B<sk> after the new element is inserted or zero if
-an error occurred: which will happen if there is a memory allocation failure.
-
-sk_X509_push() appends B<ptr> to B<sk> it is equivalent to:
-
- sk_X509_insert(sk, ptr, -1);
-
-sk_X509_unshift() inserts B<ptr> at the start of B<sk> it is equivalent to:
-
- sk_X509_insert(sk, ptr, 0);
-
-sk_X509_pop() returns and removes the last element from B<sk>.
-
-sk_X509_shift() returns and removes the first element from B<sk>.
-
-sk_X509_set() sets element B<idx> of B<sk> to B<ptr> replacing the current
-element. The new element value is returned or B<NULL> if an error occurred:
-this will only happen if B<sk> is B<NULL> or B<idx> is out of range.
-
-sk_X509_find() and int sk_X509_find_ex() search B<sk> using the supplied
-comparison function for an element matching B<ptr>. sk_X509_find() returns
-the index of the first matching element or B<-1> if there is no match.
-sk_X509_find_ex() returns a matching element or the nearest element that
-does not match B<ptr>. Note: if a comparison function is set then  B<sk> is
-sorted before the search which may change its order. If no comparison
-function is set then a linear search is made for a pointer matching B<ptr>
-and the stack is not reordered.
-
-sk_X509_sort() sorts B<sk> using the supplied comparison function.
-
-sk_X509_is_sorted() returns B<1> if B<sk> is sorted and B<0> otherwise.
-
-sk_X509_dup() returns a copy of B<sk>. Note the pointers in the copy
-are identical to the original.
-
-sk_X509_deep_copy() returns a new stack where each element has been copied.
-Copying is performed by the supplied copyfn() and freeing by freefn(). The
-function freefn() is only called if an error occurs.
-
-=head1 NOTES
-
-This manual page documents the functions which operate on a stack of
-B<X509> pointers. A stack can contain pointers to any structure with B<X509>
-replaced by the appropriate structure name.
-
-Care should be taken when accessing stacks in multi-threaded environments.
-Any operation which increases the size of a stack such as sk_X509_insert() or
-sk_push() can "grow" the size of an internal array and cause race conditions
-if the same stack is accessed in a different thread. Operations such as
-sk_find() and sk_sort() can also reorder the stack.
-
-Any comparison function supplied should use a metric suitable
-for use in a binary search operation. That is it should return zero, a
-positive or negative value if B<a> is equal to, greater than
-or less than B<b> respectively.
-
-Care should be taken when checking the return values of the functions
-sk_X509_find() and sk_X509_find_ex(). They return an index to the
-matching element. In particular B<0> indicates a matching first element.
-A failed search is indicated by a B<-1> return value.
-
-=head1 APPLICATION DEFINED STACKS
-
-Applications can create and use their own stacks by placing any of the macros
-described below in a header file.
-
-DEFINE_STACK_OF(NAME) creates set of functions for a stack of B<NAME>. This
-will mean that type B<NAME> is stored in each stack, the type is referenced by
-STACK_OF(NAME) and each function name begins with sk_NAME_. For example:
-
- NAME *sk_NAME_value(STACK_OF(NAME) *sk, int idx);
-
-DEFINE_STACK_OF_CONST(NAME) is identical to DEFINE_STACK_OF(NAME) except
-each element is constant for example:
-
- const NAME *sk_name_value(STACK_OF(NAME) *sk, int idx);
-
-DEFINE_SPECIAL_STACK_OF(FNAME, STNAME) defines a stack of B<STNAME> but
-each function uses B<FNAME>. For example:
-
- STNAME *sk_FNAME_value(STACK_OF(STNAME) *sk, int idx);
-
-=head1 RETURN VALUES
-
-sk_X509_num() returns the number of elements in the stack or B<-1> if the
-passed stack is B<NULL>.
-
-sk_X509_value() returns a pointer to a stack element or B<NULL> if the
-index is out of range.
-
-sk_X509_new() and sk_X509_new_null() return an empty stack or B<NULL> if
-an error occurs.
-
-sk_X509_set_cmp_func() returns the old comparison function or B<NULL> if
-there was no old comparison function.
-
-sk_X509_free(), sk_X509_zero(), sk_X509_pop_free() and sk_X509_sort() do
-not return values.
-
-sk_X509_pop(), sk_X509_shift(), sk_X509_delete() and sk_X509_delete_ptr()
-return a pointer to the deleted element or B<NULL> on error.
-
-sk_X509_insert(), sk_X509_push() and sk_X509_unshift() return the total
-number of elements in the stack and 0 if an error occurred.
-
-sk_X509_set() returns a pointer to the replacement element or B<NULL> on
-error.
-
-sk_X509_find() and sk_X509_find_ex() return an index to the found element
-or B<-1> on error.
-
-sk_X509_is_sorted() returns B<1> if the stack is sorted and B<0> if it is
-not.
-
-sk_X509_dup() and sk_X509_deep_copy() return a pointer to the copy of the
-stack.
-
-=head1 HISTORY
-
-Use of inline functions and application defined stacks first appeared in
-OpenSSL 1.1.0. Previous versions of OpenSSL implemented stacks as macros.
-
-=cut
-
-=head1 COPYRIGHT
-
-Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
-
-Licensed under the OpenSSL license (the "License").  You may not use
-this file except in compliance with the License.  You can obtain a copy
-in the file LICENSE in the source distribution or at
-L<https://www.openssl.org/source/license.html>.
-
-=cut
diff --git a/doc/crypto/stack.pod b/doc/crypto/stack.pod
new file mode 100644
index 0000000..1defff0
--- /dev/null
+++ b/doc/crypto/stack.pod
@@ -0,0 +1,212 @@
+=pod
+
+=head1 NAME
+
+DEFINE_STACK_OF, DEFINE_STACK_OF_CONST, DEFINE_SPECIAL_STACK_OF,
+sk_TYPE_num, sk_TYPE_value, sk_TYPE_new, sk_TYPE_new_null, sk_TYPE_free,
+sk_TYPE_zero, sk_TYPE_delete, sk_TYPE_delete_ptr, sk_TYPE_push,
+sk_TYPE_unshift, sk_TYPE_pop, sk_TYPE_shift, sk_TYPE_pop_free,
+sk_TYPE_insert, sk_TYPE_set, sk_TYPE_find, sk_TYPE_find_ex, sk_TYPE_sort,
+sk_TYPE_is_sorted, sk_TYPE_dup, sk_TYPE_deep_copy, sk_TYPE_set_cmp_func -
+stack container
+
+=head1 SYNOPSIS
+
+ #include <openssl/safestack.h>
+
+ #define STACK_OF(TYPE)
+ #define DEFINE_STACK_OF
+ #define DEFINE_STACK_OF_CONST
+ #define DEFINE_SPECIAL_STACK_OF
+
+ typedef int (*sk_TYPE_compfunc)(const TYPE *const *a, const TYPE *const *b);
+ typedef TYPE * (*sk_TYPE_copyfunc)(const TYPE *a);
+ typedef void (*sk_TYPE_freefunc)(TYPE *a);
+
+ int sk_TYPE_num(const STACK_OF(TYPE) *sk);
+ TYPE *sk_TYPE_value(const STACK_OF(TYPE) *sk, int idx);
+ STACK_OF(TYPE) *sk_TYPE_new(sk_TYPE_compfunc compare);
+ STACK_OF(TYPE) *sk_TYPE_new_null(void);
+ void sk_TYPE_free(const STACK_OF(TYPE) *sk);
+ void sk_TYPE_zero(const STACK_OF(TYPE) *sk);
+ TYPE *sk_TYPE_delete(STACK_OF(TYPE) *sk, int i);
+ TYPE *sk_TYPE_delete_ptr(STACK_OF(TYPE) *sk, TYPE *ptr);
+ int sk_TYPE_push(STACK_OF(TYPE) *sk, TYPE *ptr);
+ int sk_TYPE_unshift(STACK_OF(TYPE) *sk, TYPE *ptr);
+ TYPE *sk_TYPE_pop(STACK_OF(TYPE) *sk);
+ TYPE *sk_TYPE_shift(STACK_OF(TYPE) *sk);
+ void sk_TYPE_pop_free(STACK_OF(TYPE) *sk, sk_TYPE_freefunc freefunc);
+ int sk_TYPE_insert(STACK_OF(TYPE) *sk, TYPE *ptr, int idx);
+ TYPE *sk_TYPE_set(STACK_OF(TYPE) *sk, int idx, TYPE *ptr);
+ int sk_TYPE_find(STACK_OF(TYPE) *sk, TYPE *ptr);
+ int sk_TYPE_find_ex(STACK_OF(TYPE) *sk, TYPE *ptr);
+ void sk_TYPE_sort(const STACK_OF(TYPE) *sk);
+ int sk_TYPE_is_sorted(const STACK_OF(TYPE) *sk);
+ STACK_OF(TYPE) *sk_TYPE_dup(STACK_OF(TYPE) *sk);
+ STACK_OF(TYPE) *sk_TYPE_deep_copy(STACK_OF(TYPE) *sk,
+                                   sk_TYPE_copyfunc copyfunc,
+                                   sk_TYPE_freefunc freefunc);
+ sk_TYPE_compfunc (*sk_TYPE_set_cmp_func(STACK_OF(TYPE) *sk, sk_TYPE_compfunc compare);
+
+=head1 DESCRIPTION
+
+Applications can create and use their own stacks by placing any of the macros
+described below in a header file.  In the description below, I<TYPE> is used
+as a placeholder for any of the OpenSSL datatypes, such as I<X509>.
+
+DEFINE_STACK_OF(TYPE) creates set of functions for a stack of B<TYPE>. This
+will mean that type B<TYPE> is stored in each stack, the type is referenced by
+STACK_OF(TYPE) and each function name begins with I<sk_TYPE_>. For example:
+
+ TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx);
+
+DEFINE_STACK_OF_CONST(TYPE) is identical to DEFINE_STACK_OF(TYPE) except
+each element is constant. For example:
+
+ const TYPE *sk_TYPE_value(STACK_OF(TYPE) *sk, int idx);
+
+DEFINE_SPECIAL_STACK_OF(FUNCNAME, TYPE) defines a stack of B<TYPE> but
+each function uses B<FUNCNAME> in the function name. For example:
+
+ TYPE *sk_FUNCNAME_value(STACK_OF(TYPE) *sk, int idx);
+
+sk_TYPE_num() returns the number of elements in B<sk> or -1 if B<sk> is
+B<NULL>.
+
+sk_TYPE_value() returns element B<idx> in B<sk>, where B<idx> starts at
+zero. If B<idx> is out of range then B<NULL> is returned.
+
+sk_TYPE_new() allocates a new empty stack using comparison function B<compar>.
+If B<compar> is B<NULL> then no comparison function is used.
+
+sk_TYPE_new_null() allocates a new empty stack with no comparison function.
+
+sk_TYPE_set_cmp_func() sets the comparison function of B<sk> to B<compar>.
+The previous comparison function is returned or B<NULL> if there was
+no previous comparison function.
+
+sk_TYPE_free() frees up the B<sk> structure. It does B<not> free up any
+elements of B<sk>. After this call B<sk> is no longer valid.
+
+sk_TYPE_zero() sets the number of elements in B<sk> to zero. It does not free
+B<sk> so after this call B<sk> is still valid.
+
+sk_TYPE_pop_free() frees up all elements of B<sk> and B<sk> itself. The
+free function freefunc() is called on each element to free it.
+
+sk_TYPE_delete() deletes element B<i> from B<sk>. It returns the deleted
+element or B<NULL> if B<i> is out of range.
+
+sk_TYPE_delete_ptr() deletes element matching B<ptr> from B<sk>. It returns
+the deleted element or B<NULL> if no element matching B<ptr> was found.
+
+sk_TYPE_insert() inserts B<ptr> into B<sk> at position B<idx>. Any existing
+elements at or after B<idx> are moved downwards. If B<idx> is out of range
+the new element is appended to B<sk>. sk_TYPE_insert() either returns the
+number of elements in B<sk> after the new element is inserted or zero if
+an error (such as memory allocation failure) occurred.
+
+sk_TYPE_push() appends B<ptr> to B<sk> it is equivalent to:
+
+ sk_TYPE_insert(sk, ptr, -1);
+
+sk_TYPE_unshift() inserts B<ptr> at the start of B<sk> it is equivalent to:
+
+ sk_TYPE_insert(sk, ptr, 0);
+
+sk_TYPE_pop() returns and removes the last element from B<sk>.
+
+sk_TYPE_shift() returns and removes the first element from B<sk>.
+
+sk_TYPE_set() sets element B<idx> of B<sk> to B<ptr> replacing the current
+element. The new element value is returned or B<NULL> if an error occurred:
+this will only happen if B<sk> is B<NULL> or B<idx> is out of range.
+
+sk_TYPE_find() and sk_TYPE_find_ex() search B<sk> using the supplied
+comparison function for an element matching B<ptr>. sk_TYPE_find() returns
+the index of the first matching element or B<-1> if there is no match.
+sk_TYPE_find_ex() returns a matching element or the nearest element that
+does not match B<ptr>. Note: if a comparison function is set then  B<sk> is
+sorted before the search which may change its order. If no comparison
+function is set then a linear search is made for a pointer matching B<ptr>
+and the stack is not reordered.
+
+sk_TYPE_sort() sorts B<sk> using the supplied comparison function.
+
+sk_TYPE_is_sorted() returns B<1> if B<sk> is sorted and B<0> otherwise.
+
+sk_TYPE_dup() returns a copy of B<sk>. Note the pointers in the copy
+are identical to the original.
+
+sk_TYPE_deep_copy() returns a new stack where each element has been copied.
+Copying is performed by the supplied copyfunc() and freeing by freefunc(). The
+function freefunc() is only called if an error occurs.
+
+=head1 NOTES
+
+Care should be taken when accessing stacks in multi-threaded environments.
+Any operation which increases the size of a stack such as sk_TYPE_insert() or
+sk_push() can "grow" the size of an internal array and cause race conditions
+if the same stack is accessed in a different thread. Operations such as
+sk_find() and sk_sort() can also reorder the stack.
+
+Any comparison function supplied should use a metric suitable
+for use in a binary search operation. That is it should return zero, a
+positive or negative value if B<a> is equal to, greater than
+or less than B<b> respectively.
+
+Care should be taken when checking the return values of the functions
+sk_TYPE_find() and sk_TYPE_find_ex(). They return an index to the
+matching element. In particular B<0> indicates a matching first element.
+A failed search is indicated by a B<-1> return value.
+
+=head1 RETURN VALUES
+
+sk_TYPE_num() returns the number of elements in the stack or B<-1> if the
+passed stack is B<NULL>.
+
+sk_TYPE_value() returns a pointer to a stack element or B<NULL> if the
+index is out of range.
+
+sk_TYPE_new() and sk_TYPE_new_null() return an empty stack or B<NULL> if
+an error occurs.
+
+sk_TYPE_set_cmp_func() returns the old comparison function or B<NULL> if
+there was no old comparison function.
+
+sk_TYPE_free(), sk_TYPE_zero(), sk_TYPE_pop_free() and sk_TYPE_sort() do
+not return values.
+
+sk_TYPE_pop(), sk_TYPE_shift(), sk_TYPE_delete() and sk_TYPE_delete_ptr()
+return a pointer to the deleted element or B<NULL> on error.
+
+sk_TYPE_insert(), sk_TYPE_push() and sk_TYPE_unshift() return the total
+number of elements in the stack and 0 if an error occurred.
+
+sk_TYPE_set() returns a pointer to the replacement element or B<NULL> on
+error.
+
+sk_TYPE_find() and sk_TYPE_find_ex() return an index to the found element
+or B<-1> on error.
+
+sk_TYPE_is_sorted() returns B<1> if the stack is sorted and B<0> if it is
+not.
+
+sk_TYPE_dup() and sk_TYPE_deep_copy() return a pointer to the copy of the
+stack.
+
+=head1 HISTORY
+
+Before OpenSSL 1.1.0, this was implemented via macros and not inline functions
+and was not a public API.
+
+=head1 COPYRIGHT
+
+Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the OpenSSL license (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut