mman.c

#include <sys/mman.h>
#include <windows.h>
#include <errno.h>
#include <io.h>

#ifndef FILE_MAP_EXECUTE
#define FILE_MAP_EXECUTE 0x0020
#endif	/* FILE_MAP_EXECUTE */

static DWORD __map_mmap_prot_page(const int prot) {
    DWORD protect = 0;

    if(prot == PROT_NONE) return protect;

    if((prot & PROT_EXEC) != 0) {
        protect = ((prot & PROT_WRITE) != 0) ? 
                    PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ;
    } else {
        protect = ((prot & PROT_WRITE) != 0) ?
                    PAGE_READWRITE : PAGE_READONLY;
    }

    return protect;
}

static DWORD __map_mmap_prot_file(const int prot) {
	DWORD desiredAccess = 0;

	if(prot == PROT_NONE) return desiredAccess;

	if((prot & PROT_READ) != 0) desiredAccess |= FILE_MAP_READ;
	if((prot & PROT_WRITE) != 0) desiredAccess |= FILE_MAP_WRITE;
	if((prot & PROT_EXEC) != 0) desiredAccess |= FILE_MAP_EXECUTE;

	return desiredAccess;
}

void *mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t off) {
	HANDLE fm, h;

	void *map = MAP_FAILED;

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable: 4293)
#endif

	const DWORD dwFileOffsetLow = (sizeof(off_t) <= sizeof(DWORD)) ? 
			(DWORD)off : (DWORD)(off & 0xFFFFFFFFL);
	const DWORD dwFileOffsetHigh = (sizeof(off_t) <= sizeof(DWORD)) ?
			(DWORD)0 : (DWORD)((off >> 32) & 0xFFFFFFFFL);
	const DWORD protect = __map_mmap_prot_page(prot);
	const DWORD desiredAccess = __map_mmap_prot_file(prot);

	const off_t maxSize = off + (off_t)len;

	const DWORD dwMaxSizeLow = (sizeof(off_t) <= sizeof(DWORD)) ? 
			(DWORD)maxSize : (DWORD)(maxSize & 0xFFFFFFFFL);
	const DWORD dwMaxSizeHigh = (sizeof(off_t) <= sizeof(DWORD)) ?
			(DWORD)0 : (DWORD)((maxSize >> 32) & 0xFFFFFFFFL);

#ifdef _MSC_VER
#pragma warning(pop)
#endif

	errno = 0;

	if(len == 0 ||
	/* Unsupported flag combinations */
	(flags & MAP_FIXED) ||
	/* Usupported protection combinations */
	prot == PROT_EXEC) {
		errno = EINVAL;
		return MAP_FAILED;
	}

	h = ((flags & MAP_ANONYMOUS) == 0) ? (void *)fildes : INVALID_HANDLE_VALUE;

	if((flags & MAP_ANONYMOUS) == 0 && h == INVALID_HANDLE_VALUE) {
		errno = EBADF;
		return MAP_FAILED;
	}

	fm = CreateFileMappingW(h, NULL, protect, dwMaxSizeHigh, dwMaxSizeLow, NULL);

	if(!fm) {
		return MAP_FAILED;
	}

	map = MapViewOfFile(fm, desiredAccess, dwFileOffsetHigh, dwFileOffsetLow, len);

	CloseHandle(fm);

	if(!map) {
		return MAP_FAILED;
	}

	return map;
}

int munmap(void *addr, size_t len) {
	return UnmapViewOfFile(addr) ? 0 : -1;
}

int mprotect(void *addr, size_t len, int prot) {
	DWORD newProtect = __map_mmap_prot_page(prot);
	DWORD oldProtect = 0;

	return VirtualProtect(addr, len, newProtect, &oldProtect) ? 0 : -1;
}

int msync(void *addr, size_t len, int flags) {
	return FlushViewOfFile(addr, len) ? 0 : -1;
}

int mlock(const void *addr, size_t len) {
	//if (VirtualLock((LPVOID)addr, len)) return 0;

	errno = ENOSYS;
	return -1;
}

int munlock(const void *addr, size_t len) {
	//if (VirtualUnlock((LPVOID)addr, len)) return 0;

	errno = ENOSYS;
	return -1;
}