Add OS utility header

Provide abstractions for the locking allocator (allocate and free
locked pages) to decouple it from the platform dependent code. Should
make it easy to write a Windows version using VirtualAlloc+VirtualLock.

Exposes max mlock limit as a build.h toggle

1 files changed, 40 insertions, 0 deletions

diff --git a/src/lib/utils/os_utils.h b/src/lib/utils/os_utils.h
new file mode 100644
index 000000000..0030f88c9
--- /dev/null
+++ b/src/lib/utils/os_utils.h
@@ -0,0 +1,40 @@
+/*
+* OS specific utility functions
+* (C) 2015 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#ifndef BOTAN_OS_UTILS_H__
+#define BOTAN_OS_UTILS_H__
+
+#include <botan/types.h>
+
+namespace Botan {
+
+namespace OS {
+
+/*
+* Returns the maximum amount of memory (in bytes) we could/should
+* hyptothetically allocate. Reads "BOTAN_MLOCK_POOL_SIZE" from
+* environment which can be set to zero.
+*/
+size_t get_memory_locking_limit();
+
+/*
+* Request so many bytes of page-aligned RAM locked into memory OS
+* calls (mlock, VirtualLock, or similar). Returns null on failure. The
+* memory returned is zeroed. Free it with free_locked_pages.
+*/
+void* allocate_locked_pages(size_t length);
+
+/*
+* Free memory allocated by allocate_locked_pages
+*/
+void free_locked_pages(void* ptr, size_t length);
+
+}
+
+}
+
+#endif