+/* A wrapper to manage the "stack frames" */
+typedef struct bignum_ctx_stack {
+ /* Array of indexes into the bignum stack */
+ unsigned int *indexes;
+ /* Number of stack frames, and the size of the allocated array */
+ unsigned int depth, size;
+} BN_STACK;
+static void BN_STACK_init(BN_STACK *);
+static void BN_STACK_finish(BN_STACK *);
+static int BN_STACK_push(BN_STACK *, unsigned int);
+static unsigned int BN_STACK_pop(BN_STACK *);
+
+/**********/
+/* BN_CTX */
+/**********/
+
+/* The opaque BN_CTX type */
+struct bignum_ctx {
+ /* The bignum bundles */
+ BN_POOL pool;
+ /* The "stack frames", if you will */
+ BN_STACK stack;
+ /* The number of bignums currently assigned */
+ unsigned int used;
+ /* Depth of stack overflow */
+ int err_stack;
+ /* Block "gets" until an "end" (compatibility behaviour) */
+ int too_many;
+};
+
+/* Enable this to find BN_CTX bugs */
+#ifdef BN_CTX_DEBUG
+static const char *ctxdbg_cur = NULL;
+static void ctxdbg(BN_CTX *ctx)
+{
+ unsigned int bnidx = 0, fpidx = 0;
+ BN_POOL_ITEM *item = ctx->pool.head;
+ BN_STACK *stack = &ctx->stack;
+ fprintf(stderr, "(%16p): ", ctx);
+ while (bnidx < ctx->used) {
+ fprintf(stderr, "%03x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
+ if (!(bnidx % BN_CTX_POOL_SIZE))
+ item = item->next;
+ }
+ fprintf(stderr, "\n");
+ bnidx = 0;
+ fprintf(stderr, " : ");
+ while (fpidx < stack->depth) {
+ while (bnidx++ < stack->indexes[fpidx])
+ fprintf(stderr, " ");
+ fprintf(stderr, "^^^ ");
+ bnidx++;
+ fpidx++;
+ }
+ fprintf(stderr, "\n");
+}
+
+# define CTXDBG_ENTRY(str, ctx) do { \
+ ctxdbg_cur = (str); \
+ fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
+ ctxdbg(ctx); \
+ } while(0)
+# define CTXDBG_EXIT(ctx) do { \
+ fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
+ ctxdbg(ctx); \
+ } while(0)
+# define CTXDBG_RET(ctx,ret)
+#else
+# define CTXDBG_ENTRY(str, ctx)
+# define CTXDBG_EXIT(ctx)
+# define CTXDBG_RET(ctx,ret)
+#endif
+
+
+BN_CTX *BN_CTX_new(void)
+{
+ BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
+ if (!ret) {
+ BNerr(BN_F_BN_CTX_NEW, ERR_R_MALLOC_FAILURE);
+ return NULL;
+ }
+ /* Initialise the structure */
+ BN_POOL_init(&ret->pool);
+ BN_STACK_init(&ret->stack);
+ ret->used = 0;
+ ret->err_stack = 0;
+ ret->too_many = 0;
+ return ret;
+}