--- /dev/null
+#ifndef _BABELTRACE_MMAP_ALIGN_H
+#define _BABELTRACE_MMAP_ALIGN_H
+
+/*
+ * BabelTrace mmap-align.h - mmap alignment header
+ *
+ * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ */
+
+#include <babeltrace/align.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+
+/*
+ * This header implements a wrapper over mmap (mmap_align) that memory
+ * maps a file region that is not necessarily multiple of the page size.
+ * It returns a structure (instead of a pointer) that contains the mmap
+ * pointer (page-aligned) and a pointer to the offset requested within
+ * that page. Note: in the current implementation, the "addr" parameter
+ * cannot be forced, so we allocate at an address chosen by the OS.
+ */
+
+struct mmap_align {
+ void *page_aligned_addr; /* mmap address, aligned to floor */
+ size_t page_aligned_length; /* mmap length, containing range */
+
+ void *addr; /* virtual mmap address */
+ size_t length; /* virtual mmap length */
+};
+
+static inline
+struct mmap_align *mmap_align(size_t length, int prot,
+ int flags, int fd, off_t offset)
+{
+ struct mmap_align *mma;
+ off_t page_aligned_offset; /* mmap offset, aligned to floor */
+
+ mma = malloc(sizeof(*mma));
+ if (!mma)
+ return MAP_FAILED;
+ mma->length = length;
+ page_aligned_offset = ALIGN_FLOOR(offset, PAGE_SIZE);
+ /*
+ * Page aligned length needs to contain the requested range.
+ * E.g., for a small range that fits within a single page, we might
+ * require a 2 pages page_aligned_length if the range crosses a page
+ * boundary.
+ */
+ mma->page_aligned_length = ALIGN(length + offset - page_aligned_offset, PAGE_SIZE);
+ mma->page_aligned_addr = mmap(NULL, mma->page_aligned_length,
+ prot, flags, fd, page_aligned_offset);
+ if (mma->page_aligned_addr == (void *) -1UL) {
+ free(mma);
+ return MAP_FAILED;
+ }
+ mma->addr = mma->page_aligned_addr + (offset - page_aligned_offset);
+ return mma;
+}
+
+static inline
+int munmap_align(struct mmap_align *mma)
+{
+ void *page_aligned_addr;
+ size_t page_aligned_length;
+
+ page_aligned_addr = mma->page_aligned_addr;
+ page_aligned_length = mma->page_aligned_length;
+ free(mma);
+ return munmap(page_aligned_addr, page_aligned_length);
+}
+
+static inline
+void *mmap_align_addr(struct mmap_align *mma)
+{
+ return mma->addr;
+}
+
+/*
+ * Helper for special-cases, normally unused.
+ */
+static inline
+void mmap_align_set_addr(struct mmap_align *mma, void *addr)
+{
+ mma->addr = addr;
+}
+
+#endif /* _BABELTRACE_MMAP_ALIGN_H */