/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
 * fs_reader.c
 *
 * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
 */
#define SQFS_BUILDING_DLL
#include "internal.h"

static void dir_reader_destroy(sqfs_object_t *obj)
{
	sqfs_dir_reader_t *rd = (sqfs_dir_reader_t *)obj;

	sqfs_destroy(rd->meta_inode);
	sqfs_destroy(rd->meta_dir);
	free(rd);
}

static sqfs_object_t *dir_reader_copy(const sqfs_object_t *obj)
{
	const sqfs_dir_reader_t *rd = (const sqfs_dir_reader_t *)obj;
	sqfs_dir_reader_t *copy  = malloc(sizeof(*copy));

	if (copy == NULL)
		return NULL;

	memcpy(copy, rd, sizeof(*copy));

	copy->meta_inode = sqfs_copy(rd->meta_inode);
	if (copy->meta_inode == NULL)
		goto fail_mino;

	copy->meta_dir = sqfs_copy(rd->meta_dir);
	if (copy->meta_dir == NULL)
		goto fail_mdir;

	return (sqfs_object_t *)copy;
fail_mdir:
	sqfs_destroy(copy->meta_inode);
fail_mino:
	free(copy);
	return NULL;
}

sqfs_dir_reader_t *sqfs_dir_reader_create(const sqfs_super_t *super,
					  sqfs_compressor_t *cmp,
					  sqfs_file_t *file,
					  sqfs_u32 flags)
{
	sqfs_dir_reader_t *rd;
	sqfs_u64 start, limit;

	if (flags != 0)
		return NULL;

	rd = calloc(1, sizeof(*rd));
	if (rd == NULL)
		return NULL;

	start = super->inode_table_start;
	limit = super->directory_table_start;

	rd->meta_inode = sqfs_meta_reader_create(file, cmp, start, limit);

	if (rd->meta_inode == NULL) {
		free(rd);
		return NULL;
	}

	start = super->directory_table_start;
	limit = super->id_table_start;

	if (super->fragment_table_start < limit)
		limit = super->fragment_table_start;

	if (super->export_table_start < limit)
		limit = super->export_table_start;

	rd->meta_dir = sqfs_meta_reader_create(file, cmp, start, limit);

	if (rd->meta_dir == NULL) {
		sqfs_destroy(rd->meta_inode);
		free(rd);
		return NULL;
	}

	((sqfs_object_t *)rd)->destroy = dir_reader_destroy;
	((sqfs_object_t *)rd)->copy = dir_reader_copy;
	rd->super = super;
	return rd;
}

int sqfs_dir_reader_open_dir(sqfs_dir_reader_t *rd,
			     const sqfs_inode_generic_t *inode,
			     sqfs_u32 flags)
{
	sqfs_u64 block_start;
	size_t size, offset;

	if (flags != 0)
		return SQFS_ERROR_UNSUPPORTED;

	if (inode->base.type == SQFS_INODE_DIR) {
		size = inode->data.dir.size;
		offset = inode->data.dir.offset;
		block_start = inode->data.dir.start_block;
	} else if (inode->base.type == SQFS_INODE_EXT_DIR) {
		size = inode->data.dir_ext.size;
		offset = inode->data.dir_ext.offset;
		block_start = inode->data.dir_ext.start_block;
	} else {
		return SQFS_ERROR_NOT_DIR;
	}

	memset(&rd->hdr, 0, sizeof(rd->hdr));
	rd->size = size;
	rd->entries = 0;

	block_start += rd->super->directory_table_start;

	rd->dir_block_start = block_start;
	rd->dir_offset = offset;
	rd->start_size = size;

	if (rd->size <= sizeof(rd->hdr))
		return 0;

	return sqfs_meta_reader_seek(rd->meta_dir, block_start, offset);
}

int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_entry_t **out)
{
	sqfs_dir_entry_t *ent;
	size_t count;
	int err;

	if (!rd->entries) {
		if (rd->size <= sizeof(rd->hdr))
			return 1;

		err = sqfs_meta_reader_read_dir_header(rd->meta_dir, &rd->hdr);
		if (err)
			return err;

		rd->size -= sizeof(rd->hdr);
		rd->entries = rd->hdr.count + 1;
	}

	if (rd->size <= sizeof(*ent)) {
		rd->size = 0;
		rd->entries = 0;
		return 1;
	}

	err = sqfs_meta_reader_read_dir_ent(rd->meta_dir, &ent);
	if (err)
		return err;

	count = sizeof(*ent) + strlen((const char *)ent->name);

	if (count > rd->size) {
		rd->size = 0;
		rd->entries = 0;
	} else {
		rd->size -= count;
		rd->entries -= 1;
	}

	rd->inode_offset = ent->offset;
	*out = ent;
	return 0;
}

int sqfs_dir_reader_rewind(sqfs_dir_reader_t *rd)
{
	memset(&rd->hdr, 0, sizeof(rd->hdr));
	rd->size = rd->start_size;
	rd->entries = 0;

	if (rd->size <= sizeof(rd->hdr))
		return 0;

	return sqfs_meta_reader_seek(rd->meta_dir, rd->dir_block_start,
				     rd->dir_offset);
}

int sqfs_dir_reader_find(sqfs_dir_reader_t *rd, const char *name)
{
	sqfs_dir_entry_t *ent;
	int ret;

	if (rd->size != rd->start_size) {
		ret = sqfs_dir_reader_rewind(rd);
		if (ret)
			return ret;
	}

	do {
		ret = sqfs_dir_reader_read(rd, &ent);
		if (ret < 0)
			return ret;
		if (ret > 0)
			return SQFS_ERROR_NO_ENTRY;

		ret = strcmp((const char *)ent->name, name);
		free(ent);
	} while (ret < 0);

	return ret == 0 ? 0 : SQFS_ERROR_NO_ENTRY;
}

int sqfs_dir_reader_get_inode(sqfs_dir_reader_t *rd,
			      sqfs_inode_generic_t **inode)
{
	sqfs_u64 block_start;

	block_start = rd->hdr.start_block;

	return sqfs_meta_reader_read_inode(rd->meta_inode, rd->super,
					   block_start, rd->inode_offset,
					   inode);
}

int sqfs_dir_reader_get_root_inode(sqfs_dir_reader_t *rd,
				   sqfs_inode_generic_t **inode)
{
	sqfs_u64 block_start = rd->super->root_inode_ref >> 16;
	sqfs_u16 offset = rd->super->root_inode_ref & 0xFFFF;

	return sqfs_meta_reader_read_inode(rd->meta_inode, rd->super,
					   block_start, offset, inode);
}