aligned: aligned memory alloc/realloc/free

1 files changed, 139 insertions, 0 deletions

diff --git a/src/common/aligned.c b/src/common/aligned.c
new file mode 100644
index 000000000..763dfd0e7
--- /dev/null
+++ b/src/common/aligned.c
@@ -0,0 +1,139 @@
+// Copyright (c) 2017-2018, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <string.h>
+#include "aligned.h"
+
+static inline int is_power_of_2(size_t n) { return n && (n & (n-1)) == 0; }
+
+#define MAGIC 0xaa0817161500ff81
+#define MAGIC_FREED 0xaa0817161500ff82
+
+static void local_abort(const char *msg)
+{
+  fprintf(stderr, "%s\n", msg);
+#ifdef NDEBUG
+  _exit(1);
+#else
+  abort();
+#endif
+}
+
+typedef struct
+{
+  uint64_t magic;
+  void *raw;
+  size_t bytes;
+  size_t align;
+} control;
+
+void *aligned_malloc(size_t bytes, size_t align)
+{
+  void *raw, *ptr;
+  control *ctrl;
+
+  if (!is_power_of_2(align))
+    return NULL;
+  if (bytes > (size_t)-1 - align)
+    return NULL;
+  if (bytes + align > (size_t)-1 - sizeof(control))
+    return NULL;
+
+  raw = malloc(bytes + sizeof(control) + align);
+  if (!raw)
+    return NULL;
+  ptr = (void*)(((uintptr_t)raw + align + sizeof(control) - 1) & ~(align-1));
+  ctrl = ((control*)ptr) - 1;
+  ctrl->magic = MAGIC;
+  ctrl->raw = raw;
+  ctrl->bytes = bytes;
+  ctrl->align = align;
+  return ptr;
+}
+
+void *aligned_realloc(void *ptr, size_t bytes, size_t align)
+{
+  void *raw, *ptr2;
+  control *ctrl, *ctrl2;
+
+  if (!ptr)
+    return aligned_malloc(bytes, align);
+  if (!bytes)
+  {
+     aligned_free(ptr);
+     return NULL;
+  }
+  if (!is_power_of_2(align))
+    return NULL;
+
+  ctrl = ((control*)ptr) - 1;
+  if (ctrl->magic == MAGIC_FREED)
+    local_abort("Double free detected");
+  if (ctrl->magic != MAGIC)
+    local_abort("Freeing unallocated memory");
+  if (ctrl->align != align)
+    return NULL;
+  if (ctrl->bytes >= bytes)
+    return ptr;
+
+  if (ctrl->bytes > (size_t)-1 - ctrl->align)
+    return NULL;
+  if (ctrl->bytes + ctrl->align > (size_t)-1 - sizeof(control))
+    return NULL;
+
+  raw = malloc(bytes + sizeof(control) + ctrl->align);
+  if (!raw)
+    return NULL;
+  ptr2 = (void*)(((uintptr_t)raw + ctrl->align + sizeof(control) - 1) & ~(ctrl->align-1));
+  memcpy(ptr2, ptr, ctrl->bytes);
+  ctrl2 = ((control*)ptr2) - 1;
+  ctrl2->magic = MAGIC;
+  ctrl2->raw = raw;
+  ctrl2->bytes = bytes;
+  ctrl2->align = ctrl->align;
+  ctrl->magic = MAGIC_FREED;
+  free(ctrl->raw);
+  return ptr2;
+}
+
+void aligned_free(void *ptr)
+{
+  if (!ptr)
+    return;
+  control *ctrl = ((control*)ptr) - 1;
+  if (ctrl->magic == MAGIC_FREED)
+    local_abort("Double free detected");
+  if (ctrl->magic != MAGIC)
+    local_abort("Freeing unallocated memory");
+  ctrl->magic = MAGIC_FREED;
+  free(ctrl->raw);
+}