--- /dev/null
+/*
+ * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (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
+ * https://www.openssl.org/source/license.html
+ */
+
+#ifndef OSSL_INTERNAL_PRIORITY_QUEUE_H
+# define OSSL_INTERNAL_PRIORITY_QUEUE_H
+# pragma once
+
+# include <openssl/e_os2.h>
+
+# define PRIORITY_QUEUE_OF(type) OSSL_PRIORITY_QUEUE_ ## type
+
+# define DEFINE_PRIORITY_QUEUE_OF_INTERNAL(type, ctype) \
+ typedef struct ossl_priority_queue_st_ ## type PRIORITY_QUEUE_OF(type); \
+ static ossl_unused ossl_inline PRIORITY_QUEUE_OF(type) * \
+ ossl_pqueue_##type##_new(int (*compare)(const ctype *, const ctype *)) \
+ { \
+ return (PRIORITY_QUEUE_OF(type) *)ossl_pqueue_new( \
+ (int (*)(const void *, const void *))compare); \
+ } \
+ static ossl_unused ossl_inline void \
+ ossl_pqueue_##type##_free(PRIORITY_QUEUE_OF(type) *pq) \
+ { \
+ ossl_pqueue_free((OSSL_PQUEUE *)pq); \
+ } \
+ static ossl_unused ossl_inline void \
+ ossl_pqueue_##type##_pop_free(PRIORITY_QUEUE_OF(type) *pq, \
+ void (*freefunc)(ctype *)) \
+ { \
+ ossl_pqueue_pop_free((OSSL_PQUEUE *)pq, (void (*)(void *))freefunc);\
+ } \
+ static ossl_unused ossl_inline int \
+ ossl_pqueue_##type##_reserve(PRIORITY_QUEUE_OF(type) *pq, size_t n) \
+ { \
+ return ossl_pqueue_reserve((OSSL_PQUEUE *)pq, n); \
+ } \
+ static ossl_unused ossl_inline size_t \
+ ossl_pqueue_##type##_num(const PRIORITY_QUEUE_OF(type) *pq) \
+ { \
+ return ossl_pqueue_num((OSSL_PQUEUE *)pq); \
+ } \
+ static ossl_unused ossl_inline int \
+ ossl_pqueue_##type##_push(PRIORITY_QUEUE_OF(type) *pq, \
+ ctype *data, size_t *elem) \
+ { \
+ return ossl_pqueue_push((OSSL_PQUEUE *)pq, (void *)data, elem); \
+ } \
+ static ossl_unused ossl_inline ctype * \
+ ossl_pqueue_##type##_peek(const PRIORITY_QUEUE_OF(type) *pq) \
+ { \
+ return (type *)ossl_pqueue_peek((OSSL_PQUEUE *)pq); \
+ } \
+ static ossl_unused ossl_inline ctype * \
+ ossl_pqueue_##type##_pop(PRIORITY_QUEUE_OF(type) *pq) \
+ { \
+ return (type *)ossl_pqueue_pop((OSSL_PQUEUE *)pq); \
+ } \
+ static ossl_unused ossl_inline ctype * \
+ ossl_pqueue_##type##_remove(PRIORITY_QUEUE_OF(type) *pq, \
+ size_t elem) \
+ { \
+ return (type *)ossl_pqueue_remove((OSSL_PQUEUE *)pq, elem); \
+ } \
+ struct ossl_priority_queue_st_ ## type
+
+# define DEFINE_PRIORITY_QUEUE_OF(type) \
+ DEFINE_PRIORITY_QUEUE_OF_INTERNAL(type, type)
+
+typedef struct ossl_pqueue_st OSSL_PQUEUE;
+
+OSSL_PQUEUE *ossl_pqueue_new(int (*compare)(const void *, const void *));
+void ossl_pqueue_free(OSSL_PQUEUE *pq);
+void ossl_pqueue_pop_free(OSSL_PQUEUE *pq, void (*freefunc)(void *));
+int ossl_pqueue_reserve(OSSL_PQUEUE *pq, size_t n);
+
+size_t ossl_pqueue_num(const OSSL_PQUEUE *pq);
+int ossl_pqueue_push(OSSL_PQUEUE *pq, void *data, size_t *elem);
+void *ossl_pqueue_peek(const OSSL_PQUEUE *pq);
+void *ossl_pqueue_pop(OSSL_PQUEUE *pq);
+void *ossl_pqueue_remove(OSSL_PQUEUE *pq, size_t elem);
+
+#endif
--- /dev/null
+/*
+ * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (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
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/crypto.h>
+#include <openssl/err.h>
+#include <assert.h>
+#include "internal/priority_queue.h"
+#include "internal/safe_math.h"
+
+OSSL_SAFE_MATH_UNSIGNED(size_t, size_t)
+
+/*
+ * Fundamental operations:
+ * Binary Heap Fibonacci Heap
+ * Get smallest O(1) O(1)
+ * Delete any O(log n) O(log n) average but worst O(n)
+ * Insert O(log n) O(1)
+ *
+ * Not supported:
+ * Merge two structures O(log n) O(1)
+ * Decrease key O(log n) O(1)
+ * Increase key O(log n) ?
+ *
+ * The Fibonacci heap is quite a bit more complicated to implement and has
+ * larger overhead in practice. We favour the binary heap here. A multi-way
+ * (ternary or quaternary) heap might elicit a performance advantage via better
+ * cache access patterns.
+ */
+
+struct pq_heap_st {
+ void *data; /* User supplied data pointer */
+ size_t index; /* Constant index in elements[] */
+};
+
+struct pq_elem_st {
+ size_t posn; /* Current index in heap[] or link in free list */
+#ifndef NDEBUG
+ int used; /* Debug flag indicating that this is in use */
+#endif
+};
+
+struct ossl_pqueue_st
+{
+ struct pq_heap_st *heap;
+ struct pq_elem_st *elements;
+ int (*compare)(const void *, const void *);
+ size_t htop; /* Highest used heap element */
+ size_t hmax; /* Allocated heap & element space */
+ size_t freelist; /* Index into elements[], start of free element list */
+};
+
+/*
+ * The initial and maximum number of elements in the heap.
+ */
+static const size_t min_nodes = 8;
+static const size_t max_nodes =
+ SIZE_MAX / (sizeof(struct pq_heap_st) > sizeof(struct pq_elem_st)
+ ? sizeof(struct pq_heap_st) : sizeof(struct pq_elem_st));
+
+#ifndef NDEBUG
+/* Some basic sanity checking of the data structure */
+# define ASSERT_USED(pq, idx) \
+ assert(pq->elements[pq->heap[idx].index].used); \
+ assert(pq->elements[pq->heap[idx].index].posn == idx)
+# define ASSERT_ELEM_USED(pq, elem) \
+ assert(pq->elements[elem].used)
+#else
+# define ASSERT_USED(pq, idx)
+# define ASSERT_ELEM_USED(pq, elem)
+#endif
+
+/*
+ * Calculate the array growth based on the target size.
+ *
+ * The growth factor is a rational number and is defined by a numerator
+ * and a denominator. According to Andrew Koenig in his paper "Why Are
+ * Vectors Efficient?" from JOOP 11(5) 1998, this factor should be less
+ * than the golden ratio (1.618...).
+ *
+ * We use an expansion factor of 8 / 5 = 1.6
+ */
+static ossl_inline int compute_pqueue_growth(size_t target, size_t current)
+{
+ int err = 0;
+
+ while (current < target) {
+ if (current >= max_nodes)
+ return 0;
+
+ current = safe_muldiv_size_t(current, 8, 5, &err);
+ if (err)
+ return 0;
+ if (current >= max_nodes)
+ current = max_nodes;
+ }
+ return current;
+}
+
+static ossl_inline void pqueue_swap_elem(OSSL_PQUEUE *pq, size_t i, size_t j)
+{
+ struct pq_heap_st *h = pq->heap, t_h;
+ struct pq_elem_st *e = pq->elements;
+
+ ASSERT_USED(pq, i);
+ ASSERT_USED(pq, j);
+
+ t_h = h[i];
+ h[i] = h[j];
+ h[j] = t_h;
+
+ e[h[i].index].posn = i;
+ e[h[j].index].posn = j;
+}
+
+static ossl_inline void pqueue_move_elem(OSSL_PQUEUE *pq, size_t from, size_t to)
+{
+ struct pq_heap_st *h = pq->heap;
+ struct pq_elem_st *e = pq->elements;
+
+ ASSERT_USED(pq, from);
+
+ h[to] = h[from];
+ e[h[to].index].posn = to;
+}
+
+/*
+ * Force the specified element to the front of the heap. This breaks
+ * the heap partial ordering pre-condition.
+ */
+static ossl_inline void pqueue_force_bottom(OSSL_PQUEUE *pq, size_t n)
+{
+ ASSERT_USED(pq, n);
+ while (n > 0) {
+ const size_t p = (n - 1) / 2;
+
+ ASSERT_USED(pq, p);
+ pqueue_swap_elem(pq, n, p);
+ n = p;
+ }
+}
+
+/*
+ * Move an element down to its correct position to restore the partial
+ * order pre-condition.
+ */
+static ossl_inline void pqueue_move_down(OSSL_PQUEUE *pq, size_t n)
+{
+ struct pq_heap_st *h = pq->heap;
+
+ ASSERT_USED(pq, n);
+ while (n > 0) {
+ const size_t p = (n - 1) / 2;
+
+ ASSERT_USED(pq, p);
+ if (pq->compare(h[n].data, h[p].data) >= 0)
+ break;
+ pqueue_swap_elem(pq, n, p);
+ n = p;
+ }
+}
+
+/*
+ * Move an element up to its correct position to restore the partial
+ * order pre-condition.
+ */
+static ossl_inline void pqueue_move_up(OSSL_PQUEUE *pq, size_t n)
+{
+ struct pq_heap_st *h = pq->heap;
+ size_t p = n * 2 + 1;
+
+ ASSERT_USED(pq, n);
+ if (pq->htop > p + 1) {
+ ASSERT_USED(pq, p);
+ ASSERT_USED(pq, p + 1);
+ if (pq->compare(h[p].data, h[p + 1].data) > 0)
+ p++;
+ }
+ while (pq->htop > p && pq->compare(h[p].data, h[n].data) < 0) {
+ ASSERT_USED(pq, p);
+ pqueue_swap_elem(pq, n, p);
+ n = p;
+ p = n * 2 + 1;
+ if (pq->htop > p + 1) {
+ ASSERT_USED(pq, p + 1);
+ if (pq->compare(h[p].data, h[p + 1].data) > 0)
+ p++;
+ }
+ }
+}
+
+int ossl_pqueue_push(OSSL_PQUEUE *pq, void *data, size_t *elem)
+{
+ size_t n, m;
+
+ if (!ossl_pqueue_reserve(pq, 1))
+ return 0;
+
+ n = pq->htop++;
+ m = pq->freelist;
+ pq->freelist = pq->elements[m].posn;
+
+ pq->heap[n].data = data;
+ pq->heap[n].index = m;
+
+ pq->elements[m].posn = n;
+#ifndef NDEBUG
+ pq->elements[m].used = 1;
+#endif
+ pqueue_move_down(pq, n);
+ if (elem != NULL)
+ *elem = m;
+ return 1;
+}
+
+void *ossl_pqueue_peek(const OSSL_PQUEUE *pq)
+{
+ if (pq->htop > 0) {
+ ASSERT_USED(pq, 0);
+ return pq->heap->data;
+ }
+ return NULL;
+}
+
+void *ossl_pqueue_pop(OSSL_PQUEUE *pq)
+{
+ void *res;
+ size_t elem;
+
+ if (pq == NULL || pq->htop == 0)
+ return NULL;
+
+ ASSERT_USED(pq, 0);
+ res = pq->heap->data;
+ elem = pq->heap->index;
+
+ if (--pq->htop != 0) {
+ pqueue_move_elem(pq, pq->htop, 0);
+ pqueue_move_up(pq, 0);
+ }
+
+ pq->elements[elem].posn = pq->freelist;
+ pq->freelist = elem;
+#ifndef NDEBUG
+ pq->elements[elem].used = 0;
+#endif
+ return res;
+}
+
+void *ossl_pqueue_remove(OSSL_PQUEUE *pq, size_t elem)
+{
+ size_t n;
+
+ if (pq == NULL || elem >= pq->hmax || pq->htop == 0)
+ return 0;
+
+ ASSERT_ELEM_USED(pq, elem);
+ n = pq->elements[elem].posn;
+
+ ASSERT_USED(pq, n);
+
+ if (n == pq->htop - 1)
+ return pq->heap[--pq->htop].data;
+ if (n > 0)
+ pqueue_force_bottom(pq, n);
+ return ossl_pqueue_pop(pq);
+}
+
+static void pqueue_add_freelist(OSSL_PQUEUE *pq, size_t from)
+{
+ struct pq_elem_st *e = pq->elements;
+ size_t i;
+
+#ifndef NDEBUG
+ for (i = from; i < pq->hmax; i++)
+ e[i].used = 0;
+#endif
+ e[from].posn = pq->freelist;
+ for (i = from + 1; i < pq->hmax; i++)
+ e[i].posn = i - 1;
+ pq->freelist = pq->hmax - 1;
+}
+
+int ossl_pqueue_reserve(OSSL_PQUEUE *pq, size_t n)
+{
+ size_t new_max, cur_max;
+ struct pq_heap_st *h;
+ struct pq_elem_st *e;
+
+ if (pq == NULL)
+ return 0;
+ cur_max = pq->hmax;
+ if (pq->htop + n < cur_max)
+ return 1;
+
+ new_max = compute_pqueue_growth(n + cur_max, cur_max);
+ if (new_max == 0) {
+ ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);
+ return 0;
+ }
+
+ h = OPENSSL_realloc(pq->heap, new_max * sizeof(*pq->heap));
+ if (h == NULL) {
+ ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ pq->heap = h;
+
+ e = OPENSSL_realloc(pq->elements, new_max * sizeof(*pq->elements));
+ if (e == NULL) {
+ ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ pq->elements = e;
+
+ pq->hmax = new_max;
+ pqueue_add_freelist(pq, cur_max);
+ return 1;
+}
+
+OSSL_PQUEUE *ossl_pqueue_new(int (*compare)(const void *, const void *))
+{
+ OSSL_PQUEUE *pq;
+
+ if (compare == NULL)
+ return NULL;
+
+ pq = OPENSSL_malloc(sizeof(*pq));
+ if (pq == NULL) {
+ ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
+ return NULL;
+ }
+ pq->compare = compare;
+ pq->hmax = min_nodes;
+ pq->htop = 0;
+ pq->freelist = 0;
+ pq->heap = OPENSSL_malloc(sizeof(*pq->heap) * min_nodes);
+ pq->elements = OPENSSL_malloc(sizeof(*pq->elements) * min_nodes);
+ if (pq->heap == NULL || pq->elements == NULL) {
+ ossl_pqueue_free(pq);
+ ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
+ return NULL;
+ }
+ pqueue_add_freelist(pq, 0);
+ return pq;
+}
+
+void ossl_pqueue_free(OSSL_PQUEUE *pq)
+{
+ if (pq != NULL) {
+ OPENSSL_free(pq->heap);
+ OPENSSL_free(pq->elements);
+ OPENSSL_free(pq);
+ }
+}
+
+void ossl_pqueue_pop_free(OSSL_PQUEUE *pq, void (*freefunc)(void *))
+{
+ size_t i;
+
+ if (pq != NULL) {
+ for (i = 0; i < pq->htop; i++)
+ (*freefunc)(pq->heap[i].data);
+ ossl_pqueue_free(pq);
+ }
+}
+
+size_t ossl_pqueue_num(const OSSL_PQUEUE *pq)
+{
+ return pq != NULL ? pq->htop : 0;
+}
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