// SPDX-License-Identifier: GPL-2.0+
/*
 * storage_common.c -- Common definitions for mass storage functionality
 *
 * Copyright (C) 2003-2008 Alan Stern
 * Copyeight (C) 2009 Samsung Electronics
 * Author: Michal Nazarewicz (mina86@mina86.com)
 */

/*
 * This file requires the following identifiers used in USB strings to
 * be defined (each of type pointer to char):
 *  - fsg_string_interface    -- name of the interface
 */

/*
 * When USB_GADGET_DEBUG_FILES is defined the module param num_buffers
 * sets the number of pipeline buffers (length of the fsg_buffhd array).
 * The valid range of num_buffers is: num >= 2 && num <= 4.
 */

#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/kstrtox.h>
#include <linux/usb/composite.h>

#include "storage_common.h"

/* There is only one interface. */

struct usb_interface_descriptor fsg_intf_desc = {
        .bLength =              sizeof fsg_intf_desc,
        .bDescriptorType =      USB_DT_INTERFACE,

        .bNumEndpoints =        2,              /* Adjusted during fsg_bind() */
        .bInterfaceClass =      USB_CLASS_MASS_STORAGE,
        .bInterfaceSubClass =   USB_SC_SCSI,    /* Adjusted during fsg_bind() */
        .bInterfaceProtocol =   USB_PR_BULK,    /* Adjusted during fsg_bind() */
        .iInterface =           FSG_STRING_INTERFACE,
};
EXPORT_SYMBOL_GPL(fsg_intf_desc);

/*
 * Three full-speed endpoint descriptors: bulk-in, bulk-out, and
 * interrupt-in.
 */

struct usb_endpoint_descriptor fsg_fs_bulk_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        /* wMaxPacketSize set by autoconfiguration */
};
EXPORT_SYMBOL_GPL(fsg_fs_bulk_in_desc);

struct usb_endpoint_descriptor fsg_fs_bulk_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        /* wMaxPacketSize set by autoconfiguration */
};
EXPORT_SYMBOL_GPL(fsg_fs_bulk_out_desc);

struct usb_descriptor_header *fsg_fs_function[] = {
        (struct usb_descriptor_header *) &fsg_intf_desc,
        (struct usb_descriptor_header *) &fsg_fs_bulk_in_desc,
        (struct usb_descriptor_header *) &fsg_fs_bulk_out_desc,
        NULL,
};
EXPORT_SYMBOL_GPL(fsg_fs_function);


/*
 * USB 2.0 devices need to expose both high speed and full speed
 * descriptors, unless they only run at full speed.
 *
 * That means alternate endpoint descriptors (bigger packets).
 */
struct usb_endpoint_descriptor fsg_hs_bulk_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        /* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};
EXPORT_SYMBOL_GPL(fsg_hs_bulk_in_desc);

struct usb_endpoint_descriptor fsg_hs_bulk_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        /* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
        .bInterval =            1,      /* NAK every 1 uframe */
};
EXPORT_SYMBOL_GPL(fsg_hs_bulk_out_desc);


struct usb_descriptor_header *fsg_hs_function[] = {
        (struct usb_descriptor_header *) &fsg_intf_desc,
        (struct usb_descriptor_header *) &fsg_hs_bulk_in_desc,
        (struct usb_descriptor_header *) &fsg_hs_bulk_out_desc,
        NULL,
};
EXPORT_SYMBOL_GPL(fsg_hs_function);

struct usb_endpoint_descriptor fsg_ss_bulk_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        /* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(1024),
};
EXPORT_SYMBOL_GPL(fsg_ss_bulk_in_desc);

struct usb_ss_ep_comp_descriptor fsg_ss_bulk_in_comp_desc = {
        .bLength =              sizeof(fsg_ss_bulk_in_comp_desc),
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,

        /*.bMaxBurst =          DYNAMIC, */
};
EXPORT_SYMBOL_GPL(fsg_ss_bulk_in_comp_desc);

struct usb_endpoint_descriptor fsg_ss_bulk_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        /* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(1024),
};
EXPORT_SYMBOL_GPL(fsg_ss_bulk_out_desc);

struct usb_ss_ep_comp_descriptor fsg_ss_bulk_out_comp_desc = {
        .bLength =              sizeof(fsg_ss_bulk_in_comp_desc),
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,

        /*.bMaxBurst =          DYNAMIC, */
};
EXPORT_SYMBOL_GPL(fsg_ss_bulk_out_comp_desc);

struct usb_descriptor_header *fsg_ss_function[] = {
        (struct usb_descriptor_header *) &fsg_intf_desc,
        (struct usb_descriptor_header *) &fsg_ss_bulk_in_desc,
        (struct usb_descriptor_header *) &fsg_ss_bulk_in_comp_desc,
        (struct usb_descriptor_header *) &fsg_ss_bulk_out_desc,
        (struct usb_descriptor_header *) &fsg_ss_bulk_out_comp_desc,
        NULL,
};
EXPORT_SYMBOL_GPL(fsg_ss_function);


 /*-------------------------------------------------------------------------*/

/*
 * If the next two routines are called while the gadget is registered,
 * the caller must own fsg->filesem for writing.
 */

void fsg_lun_close(struct fsg_lun *curlun)
{
        if (curlun->filp) {
                LDBG(curlun, "close backing file\n");
                fput(curlun->filp);
                curlun->filp = NULL;
        }
}
EXPORT_SYMBOL_GPL(fsg_lun_close);

int fsg_lun_open(struct fsg_lun *curlun, const char *filename)
{
        int                             ro;
        struct file                     *filp = NULL;
        int                             rc = -EINVAL;
        struct inode                    *inode = NULL;
        loff_t                          size;
        loff_t                          num_sectors;
        loff_t                          min_sectors;
        unsigned int                    blkbits;
        unsigned int                    blksize;

        /* R/W if we can, R/O if we must */
        ro = curlun->initially_ro;
        if (!ro) {
                filp = filp_open(filename, O_RDWR | O_LARGEFILE, 0);
                if (PTR_ERR(filp) == -EROFS || PTR_ERR(filp) == -EACCES)
                        ro = 1;
        }
        if (ro)
                filp = filp_open(filename, O_RDONLY | O_LARGEFILE, 0);
        if (IS_ERR(filp)) {
                LINFO(curlun, "unable to open backing file: %s\n", filename);
                return PTR_ERR(filp);
        }

        if (!(filp->f_mode & FMODE_WRITE))
                ro = 1;

        inode = filp->f_mapping->host;
        if ((!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))) {
                LINFO(curlun, "invalid file type: %s\n", filename);
                goto out;
        }

        /*
         * If we can't read the file, it's no good.
         * If we can't write the file, use it read-only.
         */
        if (!(filp->f_mode & FMODE_CAN_READ)) {
                LINFO(curlun, "file not readable: %s\n", filename);
                goto out;
        }
        if (!(filp->f_mode & FMODE_CAN_WRITE))
                ro = 1;

        size = i_size_read(inode);
        if (size < 0) {
                LINFO(curlun, "unable to find file size: %s\n", filename);
                rc = (int) size;
                goto out;
        }

        if (curlun->cdrom) {
                blksize = 2048;
                blkbits = 11;
        } else if (S_ISBLK(inode->i_mode)) {
                blksize = bdev_logical_block_size(I_BDEV(inode));
                blkbits = blksize_bits(blksize);
        } else {
                blksize = 512;
                blkbits = 9;
        }

        num_sectors = size >> blkbits; /* File size in logic-block-size blocks */
        min_sectors = 1;
        if (curlun->cdrom) {
                min_sectors = 300;      /* Smallest track is 300 frames */
                if (num_sectors >= 256*60*75) {
                        num_sectors = 256*60*75 - 1;
                        LINFO(curlun, "file too big: %s\n", filename);
                        LINFO(curlun, "using only first %d blocks\n",
                                        (int) num_sectors);
                }
        }
        if (num_sectors < min_sectors) {
                LINFO(curlun, "file too small: %s\n", filename);
                rc = -ETOOSMALL;
                goto out;
        }

        if (fsg_lun_is_open(curlun))
                fsg_lun_close(curlun);

        curlun->blksize = blksize;
        curlun->blkbits = blkbits;
        curlun->ro = ro;
        curlun->filp = filp;
        curlun->file_length = size;
        curlun->num_sectors = num_sectors;
        LDBG(curlun, "open backing file: %s\n", filename);
        return 0;

out:
        fput(filp);
        return rc;
}
EXPORT_SYMBOL_GPL(fsg_lun_open);


/*-------------------------------------------------------------------------*/

/*
 * Sync the file data, don't bother with the metadata.
 * This code was copied from fs/buffer.c:sys_fdatasync().
 */
int fsg_lun_fsync_sub(struct fsg_lun *curlun)
{
        struct file     *filp = curlun->filp;

        if (curlun->ro || !filp)
                return 0;
        return vfs_fsync(filp, 1);
}
EXPORT_SYMBOL_GPL(fsg_lun_fsync_sub);

void store_cdrom_address(u8 *dest, int msf, u32 addr)
{
        if (msf) {
                /*
                 * Convert to Minutes-Seconds-Frames.
                 * Sector size is already set to 2048 bytes.
                 */
                addr += 2*75;           /* Lead-in occupies 2 seconds */
                dest[3] = addr % 75;    /* Frames */
                addr /= 75;
                dest[2] = addr % 60;    /* Seconds */
                addr /= 60;
                dest[1] = addr;         /* Minutes */
                dest[0] = 0;            /* Reserved */
        } else {
                /* Absolute sector */
                put_unaligned_be32(addr, dest);
        }
}
EXPORT_SYMBOL_GPL(store_cdrom_address);

/*-------------------------------------------------------------------------*/


ssize_t fsg_show_ro(struct fsg_lun *curlun, char *buf)
{
        return sprintf(buf, "%d\n", fsg_lun_is_open(curlun)
                                  ? curlun->ro
                                  : curlun->initially_ro);
}
EXPORT_SYMBOL_GPL(fsg_show_ro);

ssize_t fsg_show_nofua(struct fsg_lun *curlun, char *buf)
{
        return sprintf(buf, "%u\n", curlun->nofua);
}
EXPORT_SYMBOL_GPL(fsg_show_nofua);

ssize_t fsg_show_file(struct fsg_lun *curlun, struct rw_semaphore *filesem,
                      char *buf)
{
        char            *p;
        ssize_t         rc;

        down_read(filesem);
        if (fsg_lun_is_open(curlun)) {  /* Get the complete pathname */
                p = file_path(curlun->filp, buf, PAGE_SIZE - 1);
                if (IS_ERR(p))
                        rc = PTR_ERR(p);
                else {
                        rc = strlen(p);
                        memmove(buf, p, rc);
                        buf[rc] = '\n';         /* Add a newline */
                        buf[++rc] = 0;
                }
        } else {                                /* No file, return 0 bytes */
                *buf = 0;
                rc = 0;
        }
        up_read(filesem);
        return rc;
}
EXPORT_SYMBOL_GPL(fsg_show_file);

ssize_t fsg_show_cdrom(struct fsg_lun *curlun, char *buf)
{
        return sprintf(buf, "%u\n", curlun->cdrom);
}
EXPORT_SYMBOL_GPL(fsg_show_cdrom);

ssize_t fsg_show_removable(struct fsg_lun *curlun, char *buf)
{
        return sprintf(buf, "%u\n", curlun->removable);
}
EXPORT_SYMBOL_GPL(fsg_show_removable);

ssize_t fsg_show_inquiry_string(struct fsg_lun *curlun, char *buf)
{
        return sprintf(buf, "%s\n", curlun->inquiry_string);
}
EXPORT_SYMBOL_GPL(fsg_show_inquiry_string);

/*
 * The caller must hold fsg->filesem for reading when calling this function.
 */
static ssize_t _fsg_store_ro(struct fsg_lun *curlun, bool ro)
{
        if (fsg_lun_is_open(curlun)) {
                LDBG(curlun, "read-only status change prevented\n");
                return -EBUSY;
        }

        curlun->ro = ro;
        curlun->initially_ro = ro;
        LDBG(curlun, "read-only status set to %d\n", curlun->ro);

        return 0;
}

ssize_t fsg_store_ro(struct fsg_lun *curlun, struct rw_semaphore *filesem,
                     const char *buf, size_t count)
{
        ssize_t         rc;
        bool            ro;

        rc = kstrtobool(buf, &ro);
        if (rc)
                return rc;

        /*
         * Allow the write-enable status to change only while the
         * backing file is closed.
         */
        down_read(filesem);
        rc = _fsg_store_ro(curlun, ro);
        if (!rc)
                rc = count;
        up_read(filesem);

        return rc;
}
EXPORT_SYMBOL_GPL(fsg_store_ro);

ssize_t fsg_store_nofua(struct fsg_lun *curlun, const char *buf, size_t count)
{
        bool            nofua;
        int             ret;

        ret = kstrtobool(buf, &nofua);
        if (ret)
                return ret;

        /* Sync data when switching from async mode to sync */
        if (!nofua && curlun->nofua)
                fsg_lun_fsync_sub(curlun);

        curlun->nofua = nofua;

        return count;
}
EXPORT_SYMBOL_GPL(fsg_store_nofua);

ssize_t fsg_store_file(struct fsg_lun *curlun, struct rw_semaphore *filesem,
                       const char *buf, size_t count)
{
        int             rc = 0;

        if (curlun->prevent_medium_removal && fsg_lun_is_open(curlun)) {
                LDBG(curlun, "eject attempt prevented\n");
                return -EBUSY;                          /* "Door is locked" */
        }

        /* Remove a trailing newline */
        if (count > 0 && buf[count-1] == '\n')
                ((char *) buf)[count-1] = 0;            /* Ugh! */

        /* Load new medium */
        down_write(filesem);
        if (count > 0 && buf[0]) {
                /* fsg_lun_open() will close existing file if any. */
                rc = fsg_lun_open(curlun, buf);
                if (rc == 0)
                        curlun->unit_attention_data =
                                        SS_NOT_READY_TO_READY_TRANSITION;
        } else if (fsg_lun_is_open(curlun)) {
                fsg_lun_close(curlun);
                curlun->unit_attention_data = SS_MEDIUM_NOT_PRESENT;
        }
        up_write(filesem);
        return (rc < 0 ? rc : count);
}
EXPORT_SYMBOL_GPL(fsg_store_file);

ssize_t fsg_store_cdrom(struct fsg_lun *curlun, struct rw_semaphore *filesem,
                        const char *buf, size_t count)
{
        bool            cdrom;
        int             ret;

        ret = kstrtobool(buf, &cdrom);
        if (ret)
                return ret;

        down_read(filesem);
        ret = cdrom ? _fsg_store_ro(curlun, true) : 0;

        if (!ret) {
                curlun->cdrom = cdrom;
                ret = count;
        }
        up_read(filesem);

        return ret;
}
EXPORT_SYMBOL_GPL(fsg_store_cdrom);

ssize_t fsg_store_removable(struct fsg_lun *curlun, const char *buf,
                            size_t count)
{
        bool            removable;
        int             ret;

        ret = kstrtobool(buf, &removable);
        if (ret)
                return ret;

        curlun->removable = removable;

        return count;
}
EXPORT_SYMBOL_GPL(fsg_store_removable);

ssize_t fsg_store_inquiry_string(struct fsg_lun *curlun, const char *buf,
                                 size_t count)
{
        const size_t len = min(count, sizeof(curlun->inquiry_string));

        if (len == 0 || buf[0] == '\n') {
                curlun->inquiry_string[0] = 0;
        } else {
                snprintf(curlun->inquiry_string,
                         sizeof(curlun->inquiry_string), "%-28s", buf);
                if (curlun->inquiry_string[len-1] == '\n')
                        curlun->inquiry_string[len-1] = ' ';
        }

        return count;
}
EXPORT_SYMBOL_GPL(fsg_store_inquiry_string);

ssize_t fsg_store_forced_eject(struct fsg_lun *curlun, struct rw_semaphore *filesem,
                               const char *buf, size_t count)
{
        int ret;

        /*
         * Forcibly detach the backing file from the LUN
         * regardless of whether the host has allowed it.
         */
        curlun->prevent_medium_removal = 0;
        ret = fsg_store_file(curlun, filesem, "", 0);
        return ret < 0 ? ret : count;
}
EXPORT_SYMBOL_GPL(fsg_store_forced_eject);

MODULE_DESCRIPTION("Common definitions for mass storage functionality");
MODULE_LICENSE("GPL");