// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2013, 2014
 * Phillip Lougher <phillip@squashfs.org.uk>
 */

#include <linux/bio.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/lz4.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "decompressor.h"
#include "page_actor.h"

#define LZ4_LEGACY      1

struct lz4_comp_opts {
        __le32 version;
        __le32 flags;
};

struct squashfs_lz4 {
        void *input;
        void *output;
};


static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
        void *buff, int len)
{
        struct lz4_comp_opts *comp_opts = buff;

        /* LZ4 compressed filesystems always have compression options */
        if (comp_opts == NULL || len < sizeof(*comp_opts))
                return ERR_PTR(-EIO);

        if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
                /* LZ4 format currently used by the kernel is the 'legacy'
                 * format */
                ERROR("Unknown LZ4 version\n");
                return ERR_PTR(-EINVAL);
        }

        return NULL;
}


static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
{
        int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
        struct squashfs_lz4 *stream;

        stream = kzalloc_obj(*stream);
        if (stream == NULL)
                goto failed;
        stream->input = vmalloc(block_size);
        if (stream->input == NULL)
                goto failed2;
        stream->output = vmalloc(block_size);
        if (stream->output == NULL)
                goto failed3;

        return stream;

failed3:
        vfree(stream->input);
failed2:
        kfree(stream);
failed:
        ERROR("Failed to initialise LZ4 decompressor\n");
        return ERR_PTR(-ENOMEM);
}


static void lz4_free(void *strm)
{
        struct squashfs_lz4 *stream = strm;

        if (stream) {
                vfree(stream->input);
                vfree(stream->output);
        }
        kfree(stream);
}


static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
        struct bio *bio, int offset, int length,
        struct squashfs_page_actor *output)
{
        struct bvec_iter_all iter_all = {};
        struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
        struct squashfs_lz4 *stream = strm;
        void *buff = stream->input, *data;
        int bytes = length, res;

        while (bio_next_segment(bio, &iter_all)) {
                int avail = min(bytes, ((int)bvec->bv_len) - offset);

                data = bvec_virt(bvec);
                memcpy(buff, data + offset, avail);
                buff += avail;
                bytes -= avail;
                offset = 0;
        }

        res = LZ4_decompress_safe(stream->input, stream->output,
                length, output->length);

        if (res < 0)
                return -EIO;

        bytes = res;
        data = squashfs_first_page(output);
        buff = stream->output;
        while (data) {
                if (bytes <= PAGE_SIZE) {
                        if (!IS_ERR(data))
                                memcpy(data, buff, bytes);
                        break;
                }
                if (!IS_ERR(data))
                        memcpy(data, buff, PAGE_SIZE);
                buff += PAGE_SIZE;
                bytes -= PAGE_SIZE;
                data = squashfs_next_page(output);
        }
        squashfs_finish_page(output);

        return res;
}

const struct squashfs_decompressor squashfs_lz4_comp_ops = {
        .init = lz4_init,
        .comp_opts = lz4_comp_opts,
        .free = lz4_free,
        .decompress = lz4_uncompress,
        .id = LZ4_COMPRESSION,
        .name = "lz4",
        .alloc_buffer = 0,
        .supported = 1
};