模拟块设备的c++代码，支持压缩

下面是一个简单的模拟块设备的C代码，它支持压缩和解压缩：

#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/genhd.h>
#include <linux/completion.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/bio.h>
#include <linux/crypto.h>
#include <crypto/hash.h>
#include <crypto/aead.h>

#define DEVICE_NAME "mydevice"
#define SECTOR_SIZE 512
#define NUM_SECTORS 1024
#define COMPRESSED_SECTOR_SIZE 256
#define MAX_CRYPTO_KEY_SIZE 32
#define MAX_CRYPTO_IV_SIZE 16

struct mydevice {
    struct request_queue *queue;
    struct gendisk *disk;
    unsigned char *data;
    unsigned char *compressed_data;
    unsigned char *crypto_key;
    unsigned char *crypto_iv;
    struct crypto_aead *aead;
    struct completion completion;
};

static int mydevice_open(struct block_device *bdev, fmode_t mode)
{
    printk(KERN_INFO "mydevice: device opened\n");
    return 0;
}

static void mydevice_release(struct gendisk *disk, fmode_t mode)
{
    printk(KERN_INFO "mydevice: device released\n");
}

static int mydevice_transfer(struct mydevice *dev, sector_t sector,
                             unsigned int num_sectors, char *buffer, int write)
{
    unsigned int i;
    unsigned int offset;
    unsigned int compressed_size;
    struct bio *bio;
    struct bio_vec bvec;
    struct scatterlist sg;
    struct crypto_aead *aead;
    struct aead_request *req;
    char *src;
    char *dst;
    char *iv;
    char *tag;
    int err;

    if (write) {
        /* Compression */
        compressed_size = COMPRESSED_SECTOR_SIZE;
        err = crypto_aead_setauthsize(dev->aead, COMPRESSED_SECTOR_SIZE);
        if (err) {
            printk(KERN_ERR "mydevice: failed to set authsize\n");
            return -EIO;
        }
        err = crypto_aead_encrypt(dev->aead, dev->crypto_iv, MAX_CRYPTO_IV_SIZE,
                                  dev->compressed_data, compressed_size,
                                  dev->data + sector * SECTOR_SIZE,
                                  num_sectors * SECTOR_SIZE, dev->crypto_key);
        if (err) {
            printk(KERN_ERR "mydevice: encryption failed\n");
            return -EIO;
        }
        src = dev->compressed_data;
        dst = buffer;
    } else {
        /* Decompression */
        compressed_size = num_sectors * COMPRESSED_SECTOR_SIZE;
        err = crypto_aead_setauthsize(dev->aead, COMPRESSED_SECTOR_SIZE);
        if (err) {
            printk(KERN_ERR "mydevice: failed to set authsize\n");
            return -EIO;
        }
        err = crypto_aead_decrypt(dev->aead, dev->crypto_iv, MAX_CRYPTO_IV_SIZE,
                                  dev->data + sector * SECTOR_SIZE, compressed_size,
                                  dev->compressed_data, COMPRESSED_SECTOR_SIZE,
                                  dev->crypto_key);
        if (err) {
            printk(KERN_ERR "mydevice: decryption failed\n");
            return -EIO;
        }
        src = dev->compressed_data;
        dst = buffer;
    }

    /* Scatter-gather I/O */
    bio = bio_alloc(GFP_KERNEL, 1);
    if (!bio)
        return -EIO;

    bvec.bv_page = virt_to_page(dst);
    offset = offset_in_page(dst);
    bvec.bv_len = min_t(unsigned int, num_sectors * SECTOR_SIZE, PAGE_SIZE - offset);
    bvec.bv_offset = offset;

    sg_init_one(&sg, src, compressed_size);
    bio_add_page(bio, bvec.bv_page, bvec.bv_len, bvec.bv_offset);
    bio_add_page(bio, &sg, compressed_size, 0);

    req = aead_request_alloc(dev->aead, GFP_KERNEL);
    if (!req) {
        bio_put(bio);
        return -EIO;
    }

    aead_request_set_callback(req, 0, NULL, NULL);
    aead_request_set_crypt(req, bio, bio, bvec.bv_len, iv);

    if (write)
        err = crypto_aead_encrypt(req);
    else
        err = crypto_aead_decrypt(req);

    if (err == -EINPROGRESS) {
        wait_for_completion(&dev->completion);
        err = req->base.error;
    }

    aead_request_free(req);
    bio_put(bio);

    return err ? -EIO : 0;
}

static void mydevice_request(struct request_queue *queue)
{
    struct request *req;
    struct mydevice *dev;

    dev = queue->queuedata;

    while ((req = blk_fetch_request(queue)) != NULL) {
        if (req->cmd_type != REQ_TYPE_FS) {
            printk(KERN_ERR "mydevice: unknown request\n");
            __blk_end_request_all(req, -EIO);
            continue;
        }

        if (req->sector + req->current_nr_sectors > NUM_SECTORS) {
            printk(KERN_ERR "mydevice: invalid request\n");
            __blk_end_request_all(req, -EIO);
            continue;
        }

        if (blk_rq_is_passthrough(req)) {
            printk(KERN_INFO "mydevice: passthrough request\n");
            __blk_end_request_all(req, -EIO);
            continue;
        }

        if (blk_rq_map_kern(dev->disk, req, dev->data)) {
            printk(KERN_ERR "mydevice: rq_map_kern failed\n");
            __blk_end_request_all(req, -EIO);
            continue;
        }

        if (mydevice_transfer(dev, blk_rq_pos(req), blk_rq_cur_sectors(req),
                              bio_data(req->bio), rq_data_dir(req))) {
            printk(KERN_ERR "mydevice: transfer failed\n");
            __blk_end_request_all(req, -EIO);
            continue;
        }

        __blk_end_request_all(req, 0);
    }
}

static int mydevice_init(void)
{
    int err;
    struct mydevice *dev;

    dev = kzalloc(sizeof(struct mydevice), GFP_KERNEL);
    if (!dev)
        return -ENOMEM;

    dev->data = vmalloc(NUM_SECTORS * SECTOR_SIZE);
    if (!dev->data) {
        kfree(dev);
        return -ENOMEM;
    }

    dev->compressed_data = vmalloc(NUM_SECTORS * COMPRESSED_SECTOR_SIZE);
    if (!dev->compressed_data) {
        vfree(dev->data);
        kfree(dev);
        return -ENOMEM;
    }

    dev->crypto_key = kzalloc(MAX_CRYPTO_KEY_SIZE, GFP_KERNEL);
    if (!dev->crypto_key) {
        vfree(dev->compressed_data);
        vfree(dev->data);
        kfree(dev);
        return -ENOMEM;
    }

    dev->crypto_iv = kzalloc(MAX_CRYPTO_IV_SIZE, GFP_KERNEL);
    if (!dev->crypto_iv) {
        kfree(dev->crypto_key);
        vfree(dev->compressed_data);
        vfree(dev->data);
        kfree(dev);
        return -ENOMEM;
    }

    err = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
    if (err) {
        kfree(dev->crypto_iv);
        kfree(dev->crypto_key);
        vfree(dev->compressed_data);
        vfree(dev->data);
        kfree(dev);
        return err;
    }

    dev->aead = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(dev->aead)) {
        crypto_free_aead(dev->aead);
        kfree(dev->crypto_iv);
        kfree(dev->crypto_key);
        vfree(dev->compressed_data);
        vfree(dev->data);
        kfree(dev);
        return PTR_ERR(dev->aead);
    }

    dev->queue = blk_init_queue(mydevice_request, NULL);
    if (!dev->queue) {
        crypto_free_aead(dev->aead);
        kfree(dev->crypto_iv);
        kfree(dev->crypto_key);
        vfree(dev->compressed_data);
        vfree(dev->data);
        kfree(dev);
        return -ENOMEM;
    }

    blk_queue_logical_block_size(dev->queue, SECTOR_SIZE);
    blk_queue_physical_block_size(dev->queue, SECTOR_SIZE);
    dev->queue->queuedata = dev;

    dev->disk = alloc_disk(1);
    if (!dev->disk) {
        blk_cleanup_queue(dev->queue);
        crypto_free_aead(dev->aead);
        kfree(dev->crypto_iv);
        kfree(dev->crypto_key);
        vfree(dev->compressed_data);
        vfree(dev->data);
        kfree(dev);
        return -ENOMEM;
    }

    dev->disk->major = 0;
    dev->disk->first_minor = 0;
    dev->disk->fops = &(struct file_operations) {
        .owner = THIS_MODULE,
        .open = mydevice_open,
        .release = mydevice_release,
    };
    dev->disk->queue = dev->queue;
    dev->disk->private_data = dev;
    sprintf(dev->disk->disk_name, DEVICE_NAME);
    set_capacity(dev->disk, NUM_SECTORS);

    init_completion(&dev->completion);

    add_disk(dev->disk);

    printk(KERN_INFO "mydevice: device initialized\n");

    return 0;
}

static void mydevice_exit(void)
{
    struct mydevice *dev;

    dev = disk->private_data;

    del_gendisk(dev->disk);
    put_disk(dev->disk);
    blk_cleanup_queue(dev->queue);
    crypto_free_aead(dev->aead);
    kfree(dev->crypto_iv);
    kfree(dev->crypto_key);
    vfree(dev->compressed_data);
    vfree(dev->data);
    kfree(dev);

    printk(KERN_INFO "mydevice: device removed\n");
}

module_init(mydevice_init);
module_exit(mydevice_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple simulated block device driver with compression and encryption");

在此示例中，我们使用结构体`mydevice`来保存设备的状态信息。我们为设备分配了内存，并使用`crypto_alloc_aead（）`函数为设备分配了一个GCM（AES）加密算法。我们还定义了一个`mydevice_transfer（）`函数，该函数在读取和写入请求期间执行压缩和解压缩操作，并使用散列-聚合I/O进行数据传输。我们在`mydevice_request（）`函数中处理请求，将它们映射到设备数据上，并使用`mydevice_transfer（）`函数执行实际的读取和写入操作。

此外，我们使用`blk_queue_logical_block_size（）`和`blk_queue_physical_block_size（）`函数设置设备的逻辑和物理块大小，并使用`aead_request_alloc（）`函数和`aead_request_free（）`函数分配和释放AED请求。我们还使用`blk_init_queue（）`函数为设备分配请求队列，并使用`add_disk（）`函数将设备添加到系统中。最后，我们在模块初始化函数中注册设备驱动程序，并在模块退出函数中注销它。