#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>

#include "pkgio.h"
#include "util.h"

static int create_hierarchy(int dirfd, image_entry_t *list)
{
	image_entry_t *ent;

	for (ent = list; ent != NULL; ent = ent->next) {
		if (S_ISDIR(ent->mode)) {
			if (mkdirat(dirfd, ent->name, 0755)) {
				if (errno == EEXIST)
					continue;
				fprintf(stderr, "mkdir %s: %s\n", ent->name,
					strerror(errno));
				return -1;
			}
		}
	}

	for (ent = list; ent != NULL; ent = ent->next) {
		if (S_ISLNK(ent->mode)) {
			if (symlinkat(ent->data.symlink.target,
				      dirfd, ent->name)) {
				fprintf(stderr, "symlink %s to %s: %s\n",
					ent->name, ent->data.symlink.target,
					strerror(errno));
				return -1;
			}
		}
	}

	return 0;
}

static image_entry_t *get_file_entry(image_entry_t *list, uint32_t id)
{
	while (list != NULL) {
		if (S_ISREG(list->mode) && list->data.file.id == id)
			return list;

		list = list->next;
	}

	return NULL;
}

static int unpack_files(int dirfd, image_entry_t *list, pkg_reader_t *rd)
{
	uint8_t buffer[2048];
	image_entry_t *meta;
	file_data_t frec;
	ssize_t ret;
	size_t diff;
	uint64_t i;
	int fd;

	for (;;) {
		ret = pkg_reader_read_payload(rd, &frec, sizeof(frec));
		if (ret == 0)
			break;
		if (ret < 0)
			return -1;
		if ((size_t)ret < sizeof(frec))
			goto fail_trunc;

		frec.id = le32toh(frec.id);

		meta = get_file_entry(list, frec.id);
		if (meta == NULL) {
			fprintf(stderr, "%s: missing meta information for "
				"file %u\n", pkg_reader_get_filename(rd),
				(unsigned int)frec.id);
			return -1;
		}

		fd = openat(dirfd, meta->name, O_WRONLY | O_CREAT | O_EXCL,
			    0644);
		if (fd < 0) {
			perror(meta->name);
			return -1;
		}

		for (i = 0; i < meta->data.file.size; i += ret) {
			if ((meta->data.file.size - i) <
			    (uint64_t)sizeof(buffer)) {
				diff = meta->data.file.size - i;
			} else {
				diff = sizeof(buffer);
			}

			ret = pkg_reader_read_payload(rd, buffer, diff);
			if (ret < 0)
				goto fail_fd;
			if ((size_t)ret < diff)
				goto fail_trunc;

			ret = write_retry(fd, buffer, diff);
			if (ret < 0) {
				perror(meta->name);
				goto fail_fd;
			}

			if ((size_t)ret < diff) {
				fprintf(stderr, "%s: truncated write\n",
					pkg_reader_get_filename(rd));
				goto fail_fd;
			}
		}

		close(fd);
	}

	return 0;
fail_fd:
	close(fd);
	return -1;
fail_trunc:
	fprintf(stderr, "%s: truncated file data record\n",
		pkg_reader_get_filename(rd));
	return -1;
}

static int change_permissions(int dirfd, image_entry_t *list, int flags)
{
	while (list != NULL) {
		if (S_ISLNK(list->mode)) {
			list = list->next;
			continue;
		}

		if (!(flags & UNPACK_NO_CHMOD) && !S_ISLNK(list->mode)) {
			if (fchmodat(dirfd, list->name,
				     list->mode & 07777, 0)) {
				fprintf(stderr, "%s: chmod: %s\n", list->name,
					strerror(errno));
				return -1;
			}
		}

		if (!(flags & UNPACK_NO_CHOWN)) {
			if (fchownat(dirfd, list->name, list->uid, list->gid,
				     AT_SYMLINK_NOFOLLOW)) {
				fprintf(stderr, "%s: chown: %s\n", list->name,
					strerror(errno));
				return -1;
			}
		}

		list = list->next;
	}

	return 0;
}

int pkg_unpack(int rootfd, int flags, pkg_reader_t *rd)
{
	image_entry_t *list = NULL;
	record_t *hdr;
	int ret;

	list = image_entry_list_from_package(rd);
	if (list == NULL)
		return -1;

	list = image_entry_sort(list);

	if (pkg_reader_rewind(rd))
		goto fail;

	if (create_hierarchy(rootfd, list))
		goto fail;

	for (;;) {
		ret = pkg_reader_get_next_record(rd);
		if (ret == 0)
			break;
		if (ret < 0)
			goto fail;

		hdr = pkg_reader_current_record_header(rd);

		if (hdr->magic == PKG_MAGIC_DATA) {
			if (unpack_files(rootfd, list, rd))
				goto fail;
		}
	}

	if (change_permissions(rootfd, list, flags))
		goto fail;

	image_entry_free_list(list);
	return 0;
fail:
	image_entry_free_list(list);
	return -1;
}