/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#include "map.h"

#include <errno.h>

#ifndef NO_MMAP

static DWORD get_page_size(void)

{

	static DWORD page_size;

	SYSTEM_INFO sys;

	if (!page_size) {

		GetSystemInfo(&sys);

		page_size = sys.dwPageSize;

	}

	return page_size;

}

static DWORD get_allocation_granularity(void)

{

	static DWORD granularity;

	SYSTEM_INFO sys;

	if (!granularity) {

		GetSystemInfo(&sys);

		granularity = sys.dwAllocationGranularity;

	}

	return granularity;

}

int git__page_size(size_t *page_size)

{

	*page_size = get_page_size();

	return 0;

}

int git__mmap_alignment(size_t *page_size)

{

	*page_size = get_allocation_granularity();

	return 0;

}

int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, git_off_t offset)

{

	HANDLE fh = (HANDLE)_get_osfhandle(fd);

	DWORD alignment = get_allocation_granularity();

	DWORD fmap_prot = 0;

	DWORD view_prot = 0;

	DWORD off_low = 0;

	DWORD off_hi = 0;

	git_off_t page_start;

	git_off_t page_offset;

	GIT_MMAP_VALIDATE(out, len, prot, flags);

	out->data = NULL;

	out->len = 0;

	out->fmh = NULL;

	if (fh == INVALID_HANDLE_VALUE) {

		errno = EBADF;

		giterr_set(GITERR_OS, "failed to mmap. Invalid handle value");

		return -1;

	}

	if (prot & GIT_PROT_WRITE)

		fmap_prot |= PAGE_READWRITE;

	else if (prot & GIT_PROT_READ)

		fmap_prot |= PAGE_READONLY;

	if (prot & GIT_PROT_WRITE)

		view_prot |= FILE_MAP_WRITE;

	if (prot & GIT_PROT_READ)

		view_prot |= FILE_MAP_READ;

	page_start = (offset / alignment) * alignment;

	page_offset = offset - page_start;

	if (page_offset != 0) { /* offset must be multiple of the allocation granularity */

		errno = EINVAL;

		giterr_set(GITERR_OS, "failed to mmap. Offset must be multiple of allocation granularity");

		return -1;

	}

	out->fmh = CreateFileMapping(fh, NULL, fmap_prot, 0, 0, NULL);

	if (!out->fmh || out->fmh == INVALID_HANDLE_VALUE) {

		giterr_set(GITERR_OS, "failed to mmap. Invalid handle value");

		out->fmh = NULL;

		return -1;

	}

	assert(sizeof(git_off_t) == 8);

	off_low = (DWORD)(page_start);

	off_hi = (DWORD)(page_start >> 32);

	out->data = MapViewOfFile(out->fmh, view_prot, off_hi, off_low, len);

	if (!out->data) {

		giterr_set(GITERR_OS, "failed to mmap. No data written");

		CloseHandle(out->fmh);

		out->fmh = NULL;

		return -1;

	}

	out->len = len;

	return 0;

}

int p_munmap(git_map *map)

{

	int error = 0;

	assert(map != NULL);

	if (map->data) {

		if (!UnmapViewOfFile(map->data)) {

			giterr_set(GITERR_OS, "failed to munmap. Could not unmap view of file");

			error = -1;

		}

		map->data = NULL;

	}

	if (map->fmh) {

		if (!CloseHandle(map->fmh)) {

			giterr_set(GITERR_OS, "failed to munmap. Could not close handle");

			error = -1;

		}

		map->fmh = NULL;

	}

	return error;

}

#endif