/*
 * rd.c - Multiple ramdisk driver - gzip-loading version - v. 0.8 beta.
 * 
 * (C) Chad Page, Theodore Ts'o, et. al, 1995. 
 *
 * This ramdisk is designed to have filesystems created on it and
 * mounted just like a regular floppy disk.
 *  
 * It also does something suggested by Linus: use the buffer cache as
 * the ramdisk data.  This makes it possible to dynamically allocate
 * the ramdisk buffer - with some consequences I have to deal with as
 * I write this.
 * 
 * This code is based on the original ramdisk.c, written mostly by
 * Theodore Ts'o (TYT) in 1991.  The code was largely rewritten by
 * Chad Page to use the buffer cache to store the ramdisk data in
 * 1995; Theodore then took over the driver again, and cleaned it up
 * for inclusion in the mainline kernel.
 *
 * The original CRAMDISK code was written by Richard Lyons, and
 * adapted by Chad Page to use the new ramdisk interface.  Theodore
 * Ts'o rewrote it so that both the compressed ramdisk loader and the
 * kernel decompressor uses the same inflate.c codebase.  The ramdisk
 * loader now also loads into a dynamic (buffer cache based) ramdisk,
 * not the old static ramdisk.  Support for the old static ramdisk has
 * been completely removed.
 *
 * Loadable module support added by Tom Dyas.
 *
 * Further cleanups by Chad Page (page0588@sundance.sjsu.edu):
 *      Cosmetic changes in #ifdef MODULE, code movement, etc...
 *      When the ramdisk is rmmod'ed, free the protected buffers
 *      Default ramdisk size changed to 2.88MB
 *
 *  Added initrd: Werner Almesberger & Hans Lermen, Feb '96
 *
 * 4/25/96 : Made ramdisk size a parameter (default is now 4MB) 
 *              - Chad Page
 */

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/minix_fs.h>
#include <linux/ext2_fs.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/malloc.h>
#include <linux/ioctl.h>
#include <linux/fd.h>
#include <linux/module.h>

#include <asm/system.h>
#include <asm/segment.h>

extern void wait_for_keypress(void);

/*
 * 35 has been officially registered as the RAMDISK major number, but
 * so is the original MAJOR number of 1.  We're using 1 in
 * include/linux/major.h for now
 */
#define MAJOR_NR RAMDISK_MAJOR
#include <linux/blk.h>

/* The ramdisk size is now a parameter */
#define NUM_RAMDISKS 16         /* This cannot be overridden (yet) */ 

#ifndef MODULE
/* We don't have to load ramdisks or gunzip them in a module... */
#define RD_LOADER
#define BUILD_CRAMDISK

void rd_load(void);
static int crd_load(struct file *fp, struct file *outfp);

#ifdef CONFIG_BLK_DEV_INITRD
static int initrd_users = 0;
#endif
#endif

/*
 * Various static variables go here... mostly used within the ramdisk
 * code only.
 */

static int rd_length[NUM_RAMDISKS];
static int rd_blocksizes[NUM_RAMDISKS];

/*
 * Parameters for the boot-loading of the ramdisk.  These are set by
 * init/main.c (from arguments to the kernel command line) or from the
 * architecture-specific setup routine (from the stored bootsector
 * information). 
 */
int rd_size = 4096;             /* Size of the ramdisks */

#ifndef MODULE
int rd_doload = 0;          /* 1 = load ramdisk, 0 = don't load */
int rd_prompt = 1;          /* 1 = prompt for ramdisk, 0 = don't prompt */
int rd_image_start = 0;     /* starting block # of image */
#ifdef CONFIG_BLK_DEV_INITRD
unsigned long initrd_start,initrd_end;
int mount_initrd = 1;           /* zero if initrd should not be mounted */
#endif
#endif

/*
 * Basically, my strategy here is to set up a buffer-head which can't
 * be deleted, and make that my Ramdisk.  If the request is outside of
 * the allocated size, we must get rid of it...
 */
static void rd_request(void)
{
        unsigned int minor;
        int offset, len;

repeat:
        INIT_REQUEST;
        
        minor = MINOR(CURRENT->rq_dev);

        if (minor >= NUM_RAMDISKS) {
                end_request(0);
                goto repeat;
        }
        
        offset = CURRENT->sector << 9;
        len = CURRENT->current_nr_sectors << 9;

        if ((offset + len) > rd_length[minor]) {
                end_request(0);
                goto repeat;
        }

        /*
         * If we're reading, fill the buffer with 0's.  This is okay since
         * we're using protected buffers which should never get freed...
         *
         * If we're writing, we protect the buffer.
         */

        if (CURRENT->cmd == READ) 
                memset(CURRENT->buffer, 0, len); 
        else    
                set_bit(BH_Protected, &CURRENT->bh->b_state);

        end_request(1);
        goto repeat;
} 

static int rd_ioctl(struct inode *inode, struct file *file,
                    unsigned int cmd, unsigned long arg)
{
        int err;
        
        if (!inode || !inode->i_rdev)   
                return -EINVAL;

        switch (cmd) {
                case BLKFLSBUF:
                        if (!suser()) return -EACCES;
                        invalidate_buffers(inode->i_rdev);
                        break;
                case BLKGETSIZE:   /* Return device size */
                        if (!arg)  return -EINVAL;
                        err = verify_area(VERIFY_WRITE, (long *) arg,
                                          sizeof(long));
                        if (err)
                                return err;
                        put_user(rd_length[MINOR(inode->i_rdev)] / 512, 
                                 (long *) arg);
                        return 0;
                        
                default:
                        break;
        };

        return 0;
}


#ifdef CONFIG_BLK_DEV_INITRD

static int initrd_read(struct inode *inode,struct file *file,char *buf,
    int count)
{
        int left;

        left = initrd_end-initrd_start-file->f_pos;
        if (count > left) count = left;
        if (count <= 0) return 0;
        memcpy_tofs(buf,(char *) initrd_start+file->f_pos,count);
        file->f_pos += count;
        return count;
}


static void initrd_release(struct inode *inode,struct file *file)
{
        unsigned long i;

        if (--initrd_users) return;
        for (i = initrd_start; i < initrd_end; i += PAGE_SIZE)
                free_page(i);
        initrd_start = 0;
}


static struct file_operations initrd_fops = {
        NULL,           /* lseek */
        initrd_read,    /* read */
        NULL,           /* write */
        NULL,           /* readdir */
        NULL,           /* select */
        NULL,           /* ioctl */
        NULL,           /* mmap */
        NULL,           /* open */
        initrd_release, /* release */
        NULL            /* fsync */ 
};

#endif


static int rd_open(struct inode * inode, struct file * filp)
{
#ifdef CONFIG_BLK_DEV_INITRD
        if (DEVICE_NR(inode->i_rdev) == INITRD_MINOR) {
                if (!initrd_start) return -ENODEV;
                initrd_users++;
                filp->f_op = &initrd_fops;
                return 0;
        }
#endif

        if (DEVICE_NR(inode->i_rdev) >= NUM_RAMDISKS)
                return -ENXIO;

        MOD_INC_USE_COUNT;

        return 0;
}

#ifdef MODULE
static void rd_release(struct inode * inode, struct file * filp)
{
        MOD_DEC_USE_COUNT;
}
#endif

static struct file_operations fd_fops = {
        NULL,           /* lseek - default */
        block_read,     /* read - block dev read */
        block_write,    /* write - block dev write */
        NULL,           /* readdir - not here! */
        NULL,           /* select */
        rd_ioctl,       /* ioctl */
        NULL,           /* mmap */
        rd_open,        /* open */
#ifndef MODULE
        NULL,           /* no special release code... */
#else
        rd_release,     /* module needs to decrement use count */
#endif
        block_fsync             /* fsync */ 
};

/*
 * This is the registration and initialization section of the ramdisk
 * driver.
 */
int rd_init(void)
{
        int             i;

        if (register_blkdev(MAJOR_NR, "ramdisk", &fd_fops)) {
                printk("RAMDISK: Could not get major %d", MAJOR_NR);
                return -EIO;
        }

        blk_dev[MAJOR_NR].request_fn = &rd_request;

        for (i = 0; i < NUM_RAMDISKS; i++) {
                rd_length[i] = (rd_size * 1024);
                rd_blocksizes[i] = 1024;
        }

        blksize_size[MAJOR_NR] = rd_blocksizes;

        printk("Ramdisk driver initialized : %d ramdisks of %dK size\n",
	       NUM_RAMDISKS, rd_size);

        return 0;
}

/* loadable module support */

#ifdef MODULE

int init_module(void)
{
        int error = rd_init();
        if (!error)
                printk(KERN_INFO "RAMDISK: Loaded as module.\n");
        return error;
}

/*
 * Before freeing the module, invalidate all of the protected buffers!
 */
void cleanup_module(void)
{
        int i;

        for (i = 0 ; i < NUM_RAMDISKS; i++)
                invalidate_buffers(MKDEV(MAJOR_NR, i));

        unregister_blkdev( MAJOR_NR, "ramdisk" );
        blk_dev[MAJOR_NR].request_fn = 0;
}

#endif  /* MODULE */

/* End of non-loading portions of the ramdisk driver */

#ifdef RD_LOADER 
/*
 * This routine tries to a ramdisk image to load, and returns the
 * number of blocks to read for a non-compressed image, 0 if the image
 * is a compressed image, and -1 if an image with the right magic
 * numbers could not be found.
 *
 * We currently check for the following magic numbers:
 *      minix
 *      ext2
 *      gzip
 */
int
identify_ramdisk_image(kdev_t device, struct file *fp, int start_block)
{
        const int size = 512;
        struct minix_super_block *minixsb;
        struct ext2_super_block *ext2sb;
        int nblocks = -1;
        int max_blocks;
        unsigned char *buf;

        buf = kmalloc(size, GFP_KERNEL);
        if (buf == 0)
                return -1;

        minixsb = (struct minix_super_block *) buf;
        ext2sb = (struct ext2_super_block *) buf;
        memset(buf, 0xe5, size);

        /*
         * Read block 0 to test for gzipped kernel
         */
        if (fp->f_op->lseek)
                fp->f_op->lseek(fp->f_inode, fp,
				start_block * BLOCK_SIZE, 0);
        fp->f_pos = start_block * BLOCK_SIZE;
        
        fp->f_op->read(fp->f_inode, fp, buf, size);

        /*
         * If it matches the gzip magic numbers, return -1
         */
        if (buf[0] == 037 && ((buf[1] == 0213) || (buf[1] == 0236))) {
                printk(KERN_NOTICE
                       "RAMDISK: Compressed image found at block %d\n",
                       start_block);
                nblocks = 0;
                goto done;
        }

        /*
         * Read block 1 to test for minix and ext2 superblock
         */
        if (fp->f_op->lseek)
                fp->f_op->lseek(fp->f_inode, fp,
                                (start_block+1) * BLOCK_SIZE, 0);
        fp->f_pos = (start_block+1) * BLOCK_SIZE;

        fp->f_op->read(fp->f_inode, fp, buf, size);
                
        /* Try minix */
        if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
            minixsb->s_magic == MINIX_SUPER_MAGIC2) {
                printk(KERN_NOTICE
                       "RAMDISK: Minix filesystem found at block %d\n",
                       start_block);
                nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
                goto done;
        }

        /* Try ext2 */
        if (ext2sb->s_magic == EXT2_SUPER_MAGIC) {
                printk(KERN_NOTICE
                       "RAMDISK: Ext2 filesystem found at block %d\n",
                       start_block);
                nblocks = ext2sb->s_blocks_count;
                goto done;
        }
        printk(KERN_NOTICE
               "RAMDISK: Couldn't find valid ramdisk image "
	       "starting at %d.\n", start_block);
        
done:
        if (fp->f_op->lseek)
                fp->f_op->lseek(fp->f_inode, fp,
				start_block * BLOCK_SIZE, 0);
        fp->f_pos = start_block * BLOCK_SIZE;   

        if ((nblocks > 0) && blk_size[MAJOR(device)]) {
                max_blocks = blk_size[MAJOR(device)][MINOR(device)];
                max_blocks -= start_block;
                if (nblocks > max_blocks) {
                        printk(KERN_NOTICE
                               "RAMDISK: Restricting filesystem size "
                               "from %d to %d blocks.\n",
                               nblocks, max_blocks);
                        nblocks = max_blocks;
                }
        }
        kfree(buf);
        return nblocks;
}

/*
 * This routine loads in the ramdisk image.
 */
static void rd_load_image(kdev_t device,int offset)
{
        struct inode inode, out_inode;
        struct file infile, outfile;
        unsigned short fs;
        kdev_t ram_device;
        int nblocks, i;
        char *buf;
        unsigned short rotate = 0;
        char rotator[4] = { '|' , '/' , '-' , '\\' };

        ram_device = MKDEV(MAJOR_NR, 0);

        memset(&infile, 0, sizeof(infile));
        memset(&inode, 0, sizeof(inode));
        inode.i_rdev = device;
        infile.f_mode = 1; /* read only */
        infile.f_inode = &inode;

        memset(&outfile, 0, sizeof(outfile));
        memset(&out_inode, 0, sizeof(out_inode));
        out_inode.i_rdev = ram_device;
        outfile.f_mode = 3; /* read/write */
        outfile.f_inode = &out_inode;

        if (blkdev_open(&inode, &infile) != 0) return;
        if (blkdev_open(&out_inode, &outfile) != 0) return;

        fs = get_fs();
        set_fs(KERNEL_DS);
        
        nblocks = identify_ramdisk_image(device, &infile, offset);
        if (nblocks < 0)
                goto done;

        if (nblocks == 0) {
#ifdef BUILD_CRAMDISK
                if (crd_load(&infile, &outfile) == 0)
                        goto successful_load;
#else
                printk(KERN_NOTICE
                       "RAMDISK: Kernel does not support compressed "
                       "ramdisk images\n");
#endif
                goto done;
        }

        if (nblocks > (rd_length[0] >> BLOCK_SIZE_BITS)) {
                printk("RAMDISK: image too big! (%d/%d blocks)\n",
                       nblocks, rd_length[0] >> BLOCK_SIZE_BITS);
                goto done;
        }
                
        /*
         * OK, time to copy in the data
         */
        buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
        if (buf == 0) {
                printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
                goto done;
        }

        printk(KERN_NOTICE "RAMDISK: Loading %d blocks into ram disk... ",
               nblocks);
        for (i=0; i < nblocks; i++) {
                infile.f_op->read(infile.f_inode, &infile, buf,
                                  BLOCK_SIZE);
                outfile.f_op->write(outfile.f_inode, &outfile, buf,
                                    BLOCK_SIZE);
                if (!(i % 16)) {
                        printk("%c\b", rotator[rotate & 0x3]);
                        rotate++;
                }
        }
        printk("done.\n");
        kfree(buf);

successful_load:
        invalidate_buffers(device);
        ROOT_DEV = MKDEV(MAJOR_NR,0);

done:
        if (infile.f_op->release)
                infile.f_op->release(&inode, &infile);
        set_fs(fs);
}


void rd_load()
{
        if (rd_doload == 0)
                return;
        
        if (MAJOR(ROOT_DEV) != FLOPPY_MAJOR) return;

        if (rd_prompt) {
#ifdef CONFIG_BLK_DEV_FD
                floppy_eject();
#endif
                printk(KERN_NOTICE
                       "VFS: Insert root floppy disk to be loaded "
                       "into ramdisk and press ENTER\n");
                wait_for_keypress();
        }

        rd_load_image(ROOT_DEV,rd_image_start);

}


#ifdef CONFIG_BLK_DEV_INITRD
void initrd_load(void)
{
        rd_load_image(MKDEV(MAJOR_NR, INITRD_MINOR),0);
}
#endif

#endif /* RD_LOADER */

#ifdef BUILD_CRAMDISK

/*
 * gzip declarations
 */

#define OF(args)  args

#define memzero(s, n)     memset ((s), 0, (n))


typedef unsigned char  uch;
typedef unsigned short ush;
typedef unsigned long  ulg;

#define INBUFSIZ 4096
#define WSIZE 0x8000    /* window size--must be a power of two, and */
                        /*  at least 32K for zip's deflate method */

static uch *inbuf;
static uch *window;

static unsigned insize = 0;  /* valid bytes in inbuf */
static unsigned inptr = 0;   /* index of next byte to be */
                             /* processed in inbuf */
static unsigned outcnt = 0;  /* bytes in output buffer */
static exit_code = 0;
static long bytes_out = 0;
static struct file *crd_infp, *crd_outfp;

#define get_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf())
                
/* Diagnostic functions (stubbed out) */
#define Assert(cond,msg)
#define Trace(x)
#define Tracev(x)
#define Tracevv(x)
#define Tracec(c,x)
#define Tracecv(c,x)

#define STATIC static

static int  fill_inbuf(void);
static void flush_window(void);
static void *malloc(int size);
static void free(void *where);
static void error(char *m);
static void gzip_mark(void **);
static void gzip_release(void **);

#include "../../lib/inflate.c"

static void *malloc(int size)
{
        return kmalloc(size, GFP_KERNEL);
}

static void free(void *where)
{
        kfree(where);
}

static void gzip_mark(void **ptr)
{
}

static void gzip_release(void **ptr)
{
}


/* 
 * Fill the input buffer. This is called only when the buffer is empty
 * and at least one byte is really needed.
 */
static int fill_inbuf()
{
        if (exit_code) return -1;
        
        insize = crd_infp->f_op->read(crd_infp->f_inode, crd_infp,
                                      inbuf, INBUFSIZ);
        if (insize == 0) return -1;

        inptr = 1;

        return inbuf[0];
}

/* 
 * Write the output window window[0..outcnt-1] and update crc and
 * bytes_out.  (Used for the decompressed data only.)
 */
static void flush_window()
{
    ulg c = crc;         /* temporary variable */
    unsigned n;
    uch *in, ch;
    
    crd_outfp->f_op->write(crd_outfp->f_inode, crd_outfp, window,
                           outcnt);
    in = window;
    for (n = 0; n < outcnt; n++) {
            ch = *in++;
            c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
    }
    crc = c;
    bytes_out += (ulg)outcnt;
    outcnt = 0;
}

static void error(char *x)
{
        printk(KERN_ERR "%s", x);
        exit_code = 1;
}

static int
crd_load(struct file * fp, struct file *outfp)
{
        int result;
        
        crd_infp = fp;
        crd_outfp = outfp;
        inbuf = kmalloc(INBUFSIZ, GFP_KERNEL);
        if (inbuf == 0) {
                printk(KERN_ERR "RAMDISK: Couldn't allocate "
		       "gzip buffer\n");
                return -1;
        }
        window = kmalloc(WSIZE, GFP_KERNEL);
        if (window == 0) {
                printk(KERN_ERR "RAMDISK: Couldn't allocate "
		       "gzip window\n");
                kfree(inbuf);
                return -1;
        }
        makecrc();
        result = gunzip();
        kfree(inbuf);
        kfree(window);
        return result;
}

#endif  /* BUILD_CRAMDISK */