/*
 * 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.dwAllocationGranularity;
        }
        return page_size;
}
int git__page_size(size_t *page_size)
{
        *page_size = get_page_size();
        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 page_size = get_page_size();
        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 / page_size) * page_size;
        page_offset = offset - page_start;
        if (page_offset != 0) { /* offset must be multiple of page size */
                errno = EINVAL;
                giterr_set(GITERR_OS, "Failed to mmap. Offset must be multiple of page size");
                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