/*
 * Copyright 2008, Ingo Weinhold, ingo_weinhold@gmx.de. All rights reserved.
 * Distributed under the terms of the MIT License.
 */

#include <sys/mman.h>

#include <errno.h>
#include <fcntl.h>
#include <string.h>

#include <OS.h>

#include <syscall_utils.h>
#include <syscalls.h>
#include <vm_defs.h>


static const char* kSharedMemoryDir = "/boot/var/shared_memory/";


static bool
append_string(char*& path, size_t& bytesLeft, const char* toAppend, size_t size)
{
	if (bytesLeft <= size)
		return false;

	memcpy(path, toAppend, size);
	path += size;
	path[0] = '\0';
	bytesLeft -= size;

	return true;
}


static bool
append_string(char*& path, size_t& bytesLeft, const char* toAppend)
{
	return append_string(path, bytesLeft, toAppend, strlen(toAppend));
}


static status_t
shm_name_to_path(const char* name, char* path, size_t pathSize)
{
	if (name == NULL)
		return B_BAD_VALUE;

	// skip leading slashes
	while (*name == '/')
		name++;

	if (*name == '\0')
		return B_BAD_VALUE;

	// create the path; replace occurrences of '/' by "%s" and '%' by "%%"
	if (!append_string(path, pathSize, kSharedMemoryDir))
		return ENAMETOOLONG;

	while (const char* found = strpbrk(name, "%/")) {
		// append section that doesn't need escaping
		if (found != name) {
			if (!append_string(path, pathSize, name, found - name))
				return ENAMETOOLONG;
		}

		// append escaped char
		const char* append = (*found == '%' ? "%%" : "%s");
		if (!append_string(path, pathSize, append, 2))
			return ENAMETOOLONG;
		name = found + 1;
	}

	// append remaining string
	if (!append_string(path, pathSize, name))
		return ENAMETOOLONG;

	return B_OK;
}


// #pragma mark -


void*
mmap(void* address, size_t length, int protection, int flags, int fd,
	off_t offset)
{
	// offset and length must be page-aligned
	if (length == 0 || offset % B_PAGE_SIZE != 0) {
		errno = B_BAD_VALUE;
		return MAP_FAILED;
	}

	// check anonymous mapping
	if ((flags & MAP_ANONYMOUS) != 0) {
		fd = -1;
	} else if (fd < 0) {
		errno = EBADF;
		return MAP_FAILED;
	}

	// either MAP_SHARED or MAP_PRIVATE must be specified
	if (((flags & MAP_SHARED) != 0) == ((flags & MAP_PRIVATE) != 0)) {
		errno = B_BAD_VALUE;
		return MAP_FAILED;
	}

	// translate mapping, address specification, and protection
	int mapping = (flags & MAP_SHARED) != 0
		? REGION_NO_PRIVATE_MAP : REGION_PRIVATE_MAP;

	uint32 addressSpec = B_ANY_ADDRESS;
	if ((flags & MAP_FIXED) != 0)
		addressSpec = B_EXACT_ADDRESS;

	uint32 areaProtection = 0;
	if ((protection & PROT_READ) != 0)
		areaProtection |= B_READ_AREA;
	if ((protection & PROT_WRITE) != 0)
		areaProtection |= B_WRITE_AREA;
	if ((protection & PROT_EXEC) != 0)
		areaProtection |= B_EXECUTE_AREA;

	// ask the kernel to map
	area_id area = _kern_map_file("mmap area", &address, addressSpec,
		length, areaProtection, mapping, true, fd, offset);
	if (area < 0) {
		errno = area;
		return MAP_FAILED;
	}

	return address;
}


int
munmap(void* address, size_t length)
{
	RETURN_AND_SET_ERRNO(_kern_unmap_memory(address, length));
}


int
mprotect(void* address, size_t length, int protection)
{
	RETURN_AND_SET_ERRNO(_kern_set_memory_protection(address, length,
		protection));
}


int
msync(void* address, size_t length, int flags)
{
	RETURN_AND_SET_ERRNO(_kern_sync_memory(address, length, flags));
}


int
posix_madvise(void* address, size_t length, int advice)
{
	RETURN_AND_SET_ERRNO(_kern_memory_advice(address, length, advice));
}


int
shm_open(const char* name, int openMode, mode_t permissions)
{
	char path[PATH_MAX];
	status_t error = shm_name_to_path(name, path, sizeof(path));
	if (error != B_OK)
		RETURN_AND_SET_ERRNO(error);

	return open(path, openMode, permissions);
}


int
shm_unlink(const char* name)
{
	char path[PATH_MAX];
	status_t error = shm_name_to_path(name, path, sizeof(path));
	if (error != B_OK)
		RETURN_AND_SET_ERRNO(error);

	return unlink(path);
}