// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
 * Phillip Lougher <phillip@squashfs.org.uk>
 *
 * zlib_wrapper.c
 */


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

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

static void *zlib_init(struct squashfs_sb_info *dummy, void *buff)
{
        z_stream *stream = kmalloc_obj(z_stream);
        if (stream == NULL)
                goto failed;
        stream->workspace = vmalloc(zlib_inflate_workspacesize());
        if (stream->workspace == NULL)
                goto failed;

        return stream;

failed:
        ERROR("Failed to allocate zlib workspace\n");
        kfree(stream);
        return ERR_PTR(-ENOMEM);
}


static void zlib_free(void *strm)
{
        z_stream *stream = strm;

        if (stream)
                vfree(stream->workspace);
        kfree(stream);
}


static int zlib_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);
        int zlib_init = 0, error = 0;
        z_stream *stream = strm;

        stream->avail_out = PAGE_SIZE;
        stream->next_out = squashfs_first_page(output);
        stream->avail_in = 0;

        if (IS_ERR(stream->next_out)) {
                error = PTR_ERR(stream->next_out);
                goto finish;
        }

        for (;;) {
                int zlib_err;

                if (stream->avail_in == 0) {
                        const void *data;
                        int avail;

                        if (!bio_next_segment(bio, &iter_all)) {
                                /* Z_STREAM_END must be reached. */
                                error = -EIO;
                                break;
                        }

                        avail = min(length, ((int)bvec->bv_len) - offset);
                        data = bvec_virt(bvec);
                        length -= avail;
                        stream->next_in = data + offset;
                        stream->avail_in = avail;
                        offset = 0;
                }

                if (stream->avail_out == 0) {
                        stream->next_out = squashfs_next_page(output);
                        if (IS_ERR(stream->next_out)) {
                                error = PTR_ERR(stream->next_out);
                                break;
                        } else if (stream->next_out != NULL)
                                stream->avail_out = PAGE_SIZE;
                }

                if (!zlib_init) {
                        zlib_err = zlib_inflateInit(stream);
                        if (zlib_err != Z_OK) {
                                error = -EIO;
                                break;
                        }
                        zlib_init = 1;
                }

                zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
                if (zlib_err == Z_STREAM_END)
                        break;
                if (zlib_err != Z_OK) {
                        error = -EIO;
                        break;
                }
        }

finish:
        squashfs_finish_page(output);

        if (!error)
                if (zlib_inflateEnd(stream) != Z_OK)
                        error = -EIO;

        return error ? error : stream->total_out;
}

const struct squashfs_decompressor squashfs_zlib_comp_ops = {
        .init = zlib_init,
        .free = zlib_free,
        .decompress = zlib_uncompress,
        .id = ZLIB_COMPRESSION,
        .name = "zlib",
        .alloc_buffer = 1,
        .supported = 1
};