#include "tar.h"

#include <mango/handle.h>
#include <mango/vm.h>
#include <string.h>

size_t getsize(const char *in)
{
	size_t size = 0;
	size_t j;
	size_t count = 1;

	for (j = 11; j > 0; j--, count *= 8) {
		size += ((in[j - 1] - '0') * count);
	}

	return size;
}

int tar_init(struct tar *tar, uintptr_t base)
{
	memset(tar, 0x0, sizeof *tar);
	tar->tar_entries = (struct tar_bin_header *)base;
	return 0;
}

int tar_open(struct tar *tar, const char *path, struct tar_file *out)
{
	while (*path == '/') {
		path++;
	}

	if (*path == '\0') {
		return -1;
	}

	struct tar_bin_header *bin_header = tar->tar_entries;
	struct tar_header header;
	for (size_t i = 0;; i++) {
		tar_header_decode(bin_header, &header);
		if (bin_header->filename[0] == 0) {
			break;
		}

		char *s = (char *)bin_header;
		s += sizeof *bin_header;

		if (!strcmp(bin_header->filename, path)) {
			out->f_header = header;
			out->f_data = s;
			return 0;
		}

		s += header.size;
		s += ((sizeof *bin_header)
		      - ((uintptr_t)s % (sizeof *bin_header)));

		bin_header = (struct tar_bin_header *)s;
	}

	return -1;
}

int tar_file_create_vm_object(const struct tar_file *file, kern_handle_t *out)
{
	const void *data = file->f_data;
	size_t len = file->f_header.size;
	kern_handle_t vmo = KERN_HANDLE_INVALID;

	kern_status_t status = vm_object_create(
		NULL,
		0,
		file->f_header.size,
		VM_PROT_READ | VM_PROT_EXEC | VM_PROT_USER,
		&vmo);
	if (status != KERN_OK) {
		return -1;
	}

	size_t nr_written = 0;
	status = vm_object_write(vmo, data, 0, len, &nr_written);
	if (status != KERN_OK || nr_written != len) {
		kern_handle_close(vmo);
		return -1;
	}

	*out = vmo;
	return 0;
}

int tar_header_decode(const struct tar_bin_header *in, struct tar_header *out)
{
	memcpy(out->filename, in->filename, sizeof out->filename);
	out->size = getsize(in->size);
	return 0;
}