Add infrastructure for reference counts.

OpenSSL has traditionally done reference counting with |int|s and the
|CRYPTO_add| function. Unless a special callback is installed (rare),
this is implemented by doing the reference count operations under a
lock.

This change adds infrastructure for handling reference counts and uses
atomic operations when C11 support is available.

Change-Id: Ia023ce432319efd00f77a7340da27d16ee4b63c3
Reviewed-on: https://boringssl-review.googlesource.com/4771
Reviewed-by: Adam Langley <agl@google.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/crypto/refcount_test.c b/crypto/refcount_test.c
new file mode 100644
index 00000000..53db90f6
--- /dev/null
+++ b/crypto/refcount_test.c
@@ -0,0 +1,59 @@
+/* Copyright (c) 2015, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include "internal.h"
+
+#include <stdio.h>
+
+#include <openssl/type_check.h>
+
+
+int main() {
+  CRYPTO_refcount_t count = 0;
+
+  CRYPTO_refcount_inc(&count);
+  if (count != 1) {
+    fprintf(stderr, "Incrementing reference count did not work.\n");
+    return 1;
+  }
+  if (!CRYPTO_refcount_dec_and_test_zero(&count) || count != 0) {
+    fprintf(stderr, "Decrementing reference count to zero did not work.\n");
+    return 1;
+  }
+
+  count = CRYPTO_REFCOUNT_MAX;
+  CRYPTO_refcount_inc(&count);
+  if (count != CRYPTO_REFCOUNT_MAX) {
+    fprintf(stderr, "Count did not saturate correctly when incrementing.\n");
+    return 1;
+  }
+  if (CRYPTO_refcount_dec_and_test_zero(&count) ||
+      count != CRYPTO_REFCOUNT_MAX) {
+    fprintf(stderr, "Count did not saturate correctly when decrementing.\n");
+    return 1;
+  }
+
+  count = 2;
+  if (CRYPTO_refcount_dec_and_test_zero(&count)) {
+    fprintf(stderr, "Decrementing two resulted in zero!\n");
+    return 1;
+  }
+  if (count != 1) {
+    fprintf(stderr, "Decrementing two did not produce one!");
+    return 1;
+  }
+
+  printf("PASS\n");
+  return 0;
+}