// SPDX-License-Identifier: GPL-2.0+
/*
 * EFI_FILE_PROTOCOL
 *
 * Copyright (c) 2017 Rob Clark
 */

#include <common.h>
#include <charset.h>
#include <efi_loader.h>
#include <log.h>
#include <malloc.h>
#include <mapmem.h>
#include <fs.h>
#include <part.h>

/* GUID for file system information */
const efi_guid_t efi_file_system_info_guid = EFI_FILE_SYSTEM_INFO_GUID;

/* GUID to obtain the volume label */
const efi_guid_t efi_system_volume_label_id = EFI_FILE_SYSTEM_VOLUME_LABEL_ID;

struct file_system {
        struct efi_simple_file_system_protocol base;
        struct efi_device_path *dp;
        struct blk_desc *desc;
        int part;
};
#define to_fs(x) container_of(x, struct file_system, base)

struct file_handle {
        struct efi_file_handle base;
        struct file_system *fs;
        loff_t offset;       /* current file position/cursor */
        int isdir;
        u64 open_mode;

        /* for reading a directory: */
        struct fs_dir_stream *dirs;
        struct fs_dirent *dent;

        char path[0];
};
#define to_fh(x) container_of(x, struct file_handle, base)

static const struct efi_file_handle efi_file_handle_protocol;

static char *basename(struct file_handle *fh)
{
        char *s = strrchr(fh->path, '/');
        if (s)
                return s + 1;
        return fh->path;
}

static int set_blk_dev(struct file_handle *fh)
{
        return fs_set_blk_dev_with_part(fh->fs->desc, fh->fs->part);
}

/**
 * is_dir() - check if file handle points to directory
 *
 * We assume that set_blk_dev(fh) has been called already.
 *
 * @fh:         file handle
 * Return:      true if file handle points to a directory
 */
static int is_dir(struct file_handle *fh)
{
        struct fs_dir_stream *dirs;

        dirs = fs_opendir(fh->path);
        if (!dirs)
                return 0;

        fs_closedir(dirs);

        return 1;
}

/*
 * Normalize a path which may include either back or fwd slashes,
 * double slashes, . or .. entries in the path, etc.
 */
static int sanitize_path(char *path)
{
        char *p;

        /* backslash to slash: */
        p = path;
        while ((p = strchr(p, '\\')))
                *p++ = '/';

        /* handle double-slashes: */
        p = path;
        while ((p = strstr(p, "//"))) {
                char *src = p + 1;
                memmove(p, src, strlen(src) + 1);
        }

        /* handle extra /.'s */
        p = path;
        while ((p = strstr(p, "/."))) {
                /*
                 * You'd be tempted to do this *after* handling ".."s
                 * below to avoid having to check if "/." is start of
                 * a "/..", but that won't have the correct results..
                 * for example, "/foo/./../bar" would get resolved to
                 * "/foo/bar" if you did these two passes in the other
                 * order
                 */
                if (p[2] == '.') {
                        p += 2;
                        continue;
                }
                char *src = p + 2;
                memmove(p, src, strlen(src) + 1);
        }

        /* handle extra /..'s: */
        p = path;
        while ((p = strstr(p, "/.."))) {
                char *src = p + 3;

                p--;

                /* find beginning of previous path entry: */
                while (true) {
                        if (p < path)
                                return -1;
                        if (*p == '/')
                                break;
                        p--;
                }

                memmove(p, src, strlen(src) + 1);
        }

        return 0;
}

/**
 * efi_create_file() - create file or directory
 *
 * @fh:                 file handle
 * @attributes:         attributes for newly created file
 * Returns:             0 for success
 */
static int efi_create_file(struct file_handle *fh, u64 attributes)
{
        loff_t actwrite;
        void *buffer = &actwrite;

        if (attributes & EFI_FILE_DIRECTORY)
                return fs_mkdir(fh->path);
        else
                return fs_write(fh->path, map_to_sysmem(buffer), 0, 0,
                                &actwrite);
}

/**
 * file_open() - open a file handle
 *
 * @fs:                 file system
 * @parent:             directory relative to which the file is to be opened
 * @file_name:          path of the file to be opened. '\', '.', or '..' may
 *                      be used as modifiers. A leading backslash indicates an
 *                      absolute path.
 * @open_mode:          bit mask indicating the access mode (read, write,
 *                      create)
 * @attributes:         attributes for newly created file
 * Returns:             handle to the opened file or NULL
 */
static struct efi_file_handle *file_open(struct file_system *fs,
                struct file_handle *parent, u16 *file_name, u64 open_mode,
                u64 attributes)
{
        struct file_handle *fh;
        char f0[MAX_UTF8_PER_UTF16] = {0};
        int plen = 0;
        int flen = 0;

        if (file_name) {
                utf16_to_utf8((u8 *)f0, file_name, 1);
                flen = u16_strlen(file_name);
        }

        /* we could have a parent, but also an absolute path: */
        if (f0[0] == '\\') {
                plen = 0;
        } else if (parent) {
                plen = strlen(parent->path) + 1;
        }

        /* +2 is for null and '/' */
        fh = calloc(1, sizeof(*fh) + plen + (flen * MAX_UTF8_PER_UTF16) + 2);

        fh->open_mode = open_mode;
        fh->base = efi_file_handle_protocol;
        fh->fs = fs;

        if (parent) {
                char *p = fh->path;
                int exists;

                if (plen > 0) {
                        strcpy(p, parent->path);
                        p += plen - 1;
                        *p++ = '/';
                }

                utf16_to_utf8((u8 *)p, file_name, flen);

                if (sanitize_path(fh->path))
                        goto error;

                /* check if file exists: */
                if (set_blk_dev(fh))
                        goto error;

                exists = fs_exists(fh->path);
                /* fs_exists() calls fs_close(), so open file system again */
                if (set_blk_dev(fh))
                        goto error;

                if (!exists) {
                        if (!(open_mode & EFI_FILE_MODE_CREATE) ||
                            efi_create_file(fh, attributes))
                                goto error;
                        if (set_blk_dev(fh))
                                goto error;
                }

                /* figure out if file is a directory: */
                fh->isdir = is_dir(fh);
        } else {
                fh->isdir = 1;
                strcpy(fh->path, "");
        }

        return &fh->base;

error:
        free(fh);
        return NULL;
}

static efi_status_t EFIAPI efi_file_open(struct efi_file_handle *file,
                struct efi_file_handle **new_handle,
                u16 *file_name, u64 open_mode, u64 attributes)
{
        struct file_handle *fh = to_fh(file);
        efi_status_t ret;

        EFI_ENTRY("%p, %p, \"%ls\", %llx, %llu", file, new_handle,
                  file_name, open_mode, attributes);

        /* Check parameters */
        if (!file || !new_handle || !file_name) {
                ret = EFI_INVALID_PARAMETER;
                goto out;
        }
        if (open_mode != EFI_FILE_MODE_READ &&
            open_mode != (EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE) &&
            open_mode != (EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE |
                         EFI_FILE_MODE_CREATE)) {
                ret = EFI_INVALID_PARAMETER;
                goto out;
        }
        /*
         * The UEFI spec requires that attributes are only set in create mode.
         * The SCT does not care about this and sets EFI_FILE_DIRECTORY in
         * read mode. EDK2 does not check that attributes are zero if not in
         * create mode.
         *
         * So here we only check attributes in create mode and do not check
         * that they are zero otherwise.
         */
        if ((open_mode & EFI_FILE_MODE_CREATE) &&
            (attributes & (EFI_FILE_READ_ONLY | ~EFI_FILE_VALID_ATTR))) {
                ret = EFI_INVALID_PARAMETER;
                goto out;
        }

        /* Open file */
        *new_handle = file_open(fh->fs, fh, file_name, open_mode, attributes);
        if (*new_handle) {
                EFI_PRINT("file handle %p\n", *new_handle);
                ret = EFI_SUCCESS;
        } else {
                ret = EFI_NOT_FOUND;
        }
out:
        return EFI_EXIT(ret);
}

static efi_status_t file_close(struct file_handle *fh)
{
        fs_closedir(fh->dirs);
        free(fh);
        return EFI_SUCCESS;
}

static efi_status_t EFIAPI efi_file_close(struct efi_file_handle *file)
{
        struct file_handle *fh = to_fh(file);
        EFI_ENTRY("%p", file);
        return EFI_EXIT(file_close(fh));
}

static efi_status_t EFIAPI efi_file_delete(struct efi_file_handle *file)
{
        struct file_handle *fh = to_fh(file);
        efi_status_t ret = EFI_SUCCESS;

        EFI_ENTRY("%p", file);

        if (set_blk_dev(fh) || fs_unlink(fh->path))
                ret = EFI_WARN_DELETE_FAILURE;

        file_close(fh);
        return EFI_EXIT(ret);
}

/**
 * efi_get_file_size() - determine the size of a file
 *
 * @fh:         file handle
 * @file_size:  pointer to receive file size
 * Return:      status code
 */
static efi_status_t efi_get_file_size(struct file_handle *fh,
                                      loff_t *file_size)
{
        if (set_blk_dev(fh))
                return EFI_DEVICE_ERROR;

        if (fs_size(fh->path, file_size))
                return EFI_DEVICE_ERROR;

        return EFI_SUCCESS;
}

static efi_status_t file_read(struct file_handle *fh, u64 *buffer_size,
                void *buffer)
{
        loff_t actread;
        efi_status_t ret;
        loff_t file_size;

        if (!buffer) {
                ret = EFI_INVALID_PARAMETER;
                return ret;
        }

        ret = efi_get_file_size(fh, &file_size);
        if (ret != EFI_SUCCESS)
                return ret;
        if (file_size < fh->offset) {
                ret = EFI_DEVICE_ERROR;
                return ret;
        }

        if (set_blk_dev(fh))
                return EFI_DEVICE_ERROR;
        if (fs_read(fh->path, map_to_sysmem(buffer), fh->offset,
                    *buffer_size, &actread))
                return EFI_DEVICE_ERROR;

        *buffer_size = actread;
        fh->offset += actread;

        return EFI_SUCCESS;
}

static efi_status_t dir_read(struct file_handle *fh, u64 *buffer_size,
                void *buffer)
{
        struct efi_file_info *info = buffer;
        struct fs_dirent *dent;
        u64 required_size;
        u16 *dst;

        if (set_blk_dev(fh))
                return EFI_DEVICE_ERROR;

        if (!fh->dirs) {
                assert(fh->offset == 0);
                fh->dirs = fs_opendir(fh->path);
                if (!fh->dirs)
                        return EFI_DEVICE_ERROR;
                fh->dent = NULL;
        }

        /*
         * So this is a bit awkward.  Since fs layer is stateful and we
         * can't rewind an entry, in the EFI_BUFFER_TOO_SMALL case below
         * we might have to return without consuming the dent.. so we
         * have to stash it for next call.
         */
        if (fh->dent) {
                dent = fh->dent;
        } else {
                dent = fs_readdir(fh->dirs);
        }

        if (!dent) {
                /* no more files in directory */
                *buffer_size = 0;
                return EFI_SUCCESS;
        }

        /* check buffer size: */
        required_size = sizeof(*info) +
                        2 * (utf8_utf16_strlen(dent->name) + 1);
        if (*buffer_size < required_size) {
                *buffer_size = required_size;
                fh->dent = dent;
                return EFI_BUFFER_TOO_SMALL;
        }
        if (!buffer)
                return EFI_INVALID_PARAMETER;
        fh->dent = NULL;

        *buffer_size = required_size;
        memset(info, 0, required_size);

        info->size = required_size;
        info->file_size = dent->size;
        info->physical_size = dent->size;

        if (dent->type == FS_DT_DIR)
                info->attribute |= EFI_FILE_DIRECTORY;

        dst = info->file_name;
        utf8_utf16_strcpy(&dst, dent->name);

        fh->offset++;

        return EFI_SUCCESS;
}

static efi_status_t EFIAPI efi_file_read(struct efi_file_handle *file,
                                         efi_uintn_t *buffer_size, void *buffer)
{
        struct file_handle *fh = to_fh(file);
        efi_status_t ret = EFI_SUCCESS;
        u64 bs;

        EFI_ENTRY("%p, %p, %p", file, buffer_size, buffer);

        if (!buffer_size) {
                ret = EFI_INVALID_PARAMETER;
                goto error;
        }

        bs = *buffer_size;
        if (fh->isdir)
                ret = dir_read(fh, &bs, buffer);
        else
                ret = file_read(fh, &bs, buffer);
        if (bs <= SIZE_MAX)
                *buffer_size = bs;
        else
                *buffer_size = SIZE_MAX;

error:
        return EFI_EXIT(ret);
}

/**
 * efi_file_write() - write to file
 *
 * This function implements the Write() service of the EFI_FILE_PROTOCOL.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification for
 * details.
 *
 * @file:               file handle
 * @buffer_size:        number of bytes to write
 * @buffer:             buffer with the bytes to write
 * Return:              status code
 */
static efi_status_t EFIAPI efi_file_write(struct efi_file_handle *file,
                                          efi_uintn_t *buffer_size,
                                          void *buffer)
{
        struct file_handle *fh = to_fh(file);
        efi_status_t ret = EFI_SUCCESS;
        loff_t actwrite;

        EFI_ENTRY("%p, %p, %p", file, buffer_size, buffer);

        if (!file || !buffer_size || !buffer) {
                ret = EFI_INVALID_PARAMETER;
                goto out;
        }
        if (fh->isdir) {
                ret = EFI_UNSUPPORTED;
                goto out;
        }
        if (!(fh->open_mode & EFI_FILE_MODE_WRITE)) {
                ret = EFI_ACCESS_DENIED;
                goto out;
        }

        if (!*buffer_size)
                goto out;

        if (set_blk_dev(fh)) {
                ret = EFI_DEVICE_ERROR;
                goto out;
        }
        if (fs_write(fh->path, map_to_sysmem(buffer), fh->offset, *buffer_size,
                     &actwrite)) {
                ret = EFI_DEVICE_ERROR;
                goto out;
        }
        *buffer_size = actwrite;
        fh->offset += actwrite;

out:
        return EFI_EXIT(ret);
}

/**
 * efi_file_getpos() - get current position in file
 *
 * This function implements the GetPosition service of the EFI file protocol.
 * See the UEFI spec for details.
 *
 * @file:       file handle
 * @pos:        pointer to file position
 * Return:      status code
 */
static efi_status_t EFIAPI efi_file_getpos(struct efi_file_handle *file,
                                           u64 *pos)
{
        efi_status_t ret = EFI_SUCCESS;
        struct file_handle *fh = to_fh(file);

        EFI_ENTRY("%p, %p", file, pos);

        if (fh->isdir) {
                ret = EFI_UNSUPPORTED;
                goto out;
        }

        *pos = fh->offset;
out:
        return EFI_EXIT(ret);
}

/**
 * efi_file_setpos() - set current position in file
 *
 * This function implements the SetPosition service of the EFI file protocol.
 * See the UEFI spec for details.
 *
 * @file:       file handle
 * @pos:        new file position
 * Return:      status code
 */
static efi_status_t EFIAPI efi_file_setpos(struct efi_file_handle *file,
                                           u64 pos)
{
        struct file_handle *fh = to_fh(file);
        efi_status_t ret = EFI_SUCCESS;

        EFI_ENTRY("%p, %llu", file, pos);

        if (fh->isdir) {
                if (pos != 0) {
                        ret = EFI_UNSUPPORTED;
                        goto error;
                }
                fs_closedir(fh->dirs);
                fh->dirs = NULL;
        }

        if (pos == ~0ULL) {
                loff_t file_size;

                ret = efi_get_file_size(fh, &file_size);
                if (ret != EFI_SUCCESS)
                        goto error;
                pos = file_size;
        }

        fh->offset = pos;

error:
        return EFI_EXIT(ret);
}

static efi_status_t EFIAPI efi_file_getinfo(struct efi_file_handle *file,
                                            const efi_guid_t *info_type,
                                            efi_uintn_t *buffer_size,
                                            void *buffer)
{
        struct file_handle *fh = to_fh(file);
        efi_status_t ret = EFI_SUCCESS;
        u16 *dst;

        EFI_ENTRY("%p, %pUl, %p, %p", file, info_type, buffer_size, buffer);

        if (!file || !info_type || !buffer_size ||
            (*buffer_size && !buffer)) {
                ret = EFI_INVALID_PARAMETER;
                goto error;
        }

        if (!guidcmp(info_type, &efi_file_info_guid)) {
                struct efi_file_info *info = buffer;
                char *filename = basename(fh);
                unsigned int required_size;
                loff_t file_size;

                /* check buffer size: */
                required_size = sizeof(*info) +
                                2 * (utf8_utf16_strlen(filename) + 1);
                if (*buffer_size < required_size) {
                        *buffer_size = required_size;
                        ret = EFI_BUFFER_TOO_SMALL;
                        goto error;
                }

                ret = efi_get_file_size(fh, &file_size);
                if (ret != EFI_SUCCESS)
                        goto error;

                memset(info, 0, required_size);

                info->size = required_size;
                info->file_size = file_size;
                info->physical_size = file_size;

                if (fh->isdir)
                        info->attribute |= EFI_FILE_DIRECTORY;

                dst = info->file_name;
                utf8_utf16_strcpy(&dst, filename);
        } else if (!guidcmp(info_type, &efi_file_system_info_guid)) {
                struct efi_file_system_info *info = buffer;
                struct disk_partition part;
                efi_uintn_t required_size;
                int r;

                if (fh->fs->part >= 1)
                        r = part_get_info(fh->fs->desc, fh->fs->part, &part);
                else
                        r = part_get_info_whole_disk(fh->fs->desc, &part);
                if (r < 0) {
                        ret = EFI_DEVICE_ERROR;
                        goto error;
                }
                required_size = sizeof(*info) + 2;
                if (*buffer_size < required_size) {
                        *buffer_size = required_size;
                        ret = EFI_BUFFER_TOO_SMALL;
                        goto error;
                }

                memset(info, 0, required_size);

                info->size = required_size;
                /*
                 * TODO: We cannot determine if the volume can be written to.
                 */
                info->read_only = false;
                info->volume_size = part.size * part.blksz;
                /*
                 * TODO: We currently have no function to determine the free
                 * space. The volume size is the best upper bound we have.
                 */
                info->free_space = info->volume_size;
                info->block_size = part.blksz;
                /*
                 * TODO: The volume label is not available in U-Boot.
                 */
                info->volume_label[0] = 0;
        } else if (!guidcmp(info_type, &efi_system_volume_label_id)) {
                if (*buffer_size < 2) {
                        *buffer_size = 2;
                        ret = EFI_BUFFER_TOO_SMALL;
                        goto error;
                }
                *(u16 *)buffer = 0;
        } else {
                ret = EFI_UNSUPPORTED;
        }

error:
        return EFI_EXIT(ret);
}

static efi_status_t EFIAPI efi_file_setinfo(struct efi_file_handle *file,
                                            const efi_guid_t *info_type,
                                            efi_uintn_t buffer_size,
                                            void *buffer)
{
        struct file_handle *fh = to_fh(file);
        efi_status_t ret = EFI_UNSUPPORTED;

        EFI_ENTRY("%p, %pUl, %zu, %p", file, info_type, buffer_size, buffer);

        if (!guidcmp(info_type, &efi_file_info_guid)) {
                struct efi_file_info *info = (struct efi_file_info *)buffer;
                char *filename = basename(fh);
                char *new_file_name, *pos;
                loff_t file_size;

                /* The buffer will always contain a file name. */
                if (buffer_size < sizeof(struct efi_file_info) + 2 ||
                    buffer_size < info->size) {
                        ret = EFI_BAD_BUFFER_SIZE;
                        goto out;
                }
                /* We cannot change the directory attribute */
                if (!fh->isdir != !(info->attribute & EFI_FILE_DIRECTORY)) {
                        ret = EFI_ACCESS_DENIED;
                        goto out;
                }
                /* Check for renaming */
                new_file_name = malloc(utf16_utf8_strlen(info->file_name) + 1);
                if (!new_file_name) {
                        ret = EFI_OUT_OF_RESOURCES;
                        goto out;
                }
                pos = new_file_name;
                utf16_utf8_strcpy(&pos, info->file_name);
                if (strcmp(new_file_name, filename)) {
                        /* TODO: we do not support renaming */
                        EFI_PRINT("Renaming not supported\n");
                        free(new_file_name);
                        ret = EFI_ACCESS_DENIED;
                        goto out;
                }
                free(new_file_name);
                /* Check for truncation */
                ret = efi_get_file_size(fh, &file_size);
                if (ret != EFI_SUCCESS)
                        goto out;
                if (file_size != info->file_size) {
                        /* TODO: we do not support truncation */
                        EFI_PRINT("Truncation not supported\n");
                        ret = EFI_ACCESS_DENIED;
                        goto out;
                }
                /*
                 * We do not care for the other attributes
                 * TODO: Support read only
                 */
                ret = EFI_SUCCESS;
        } else {
                /* TODO: We do not support changing the volume label */
                ret = EFI_UNSUPPORTED;
        }
out:
        return EFI_EXIT(ret);
}

static efi_status_t EFIAPI efi_file_flush(struct efi_file_handle *file)
{
        EFI_ENTRY("%p", file);
        return EFI_EXIT(EFI_SUCCESS);
}

static efi_status_t EFIAPI efi_file_open_ex(struct efi_file_handle *file,
                        struct efi_file_handle **new_handle,
                        u16 *file_name, u64 open_mode, u64 attributes,
                        struct efi_file_io_token *token)
{
        return EFI_UNSUPPORTED;
}

static efi_status_t EFIAPI efi_file_read_ex(struct efi_file_handle *file,
                        struct efi_file_io_token *token)
{
        return EFI_UNSUPPORTED;
}

static efi_status_t EFIAPI efi_file_write_ex(struct efi_file_handle *file,
                        struct efi_file_io_token *token)
{
        return EFI_UNSUPPORTED;
}

static efi_status_t EFIAPI efi_file_flush_ex(struct efi_file_handle *file,
                        struct efi_file_io_token *token)
{
        return EFI_UNSUPPORTED;
}

static const struct efi_file_handle efi_file_handle_protocol = {
        .rev = EFI_FILE_PROTOCOL_REVISION2,
        .open = efi_file_open,
        .close = efi_file_close,
        .delete = efi_file_delete,
        .read = efi_file_read,
        .write = efi_file_write,
        .getpos = efi_file_getpos,
        .setpos = efi_file_setpos,
        .getinfo = efi_file_getinfo,
        .setinfo = efi_file_setinfo,
        .flush = efi_file_flush,
        .open_ex = efi_file_open_ex,
        .read_ex = efi_file_read_ex,
        .write_ex = efi_file_write_ex,
        .flush_ex = efi_file_flush_ex,
};

/**
 * efi_file_from_path() - open file via device path
 *
 * @fp:         device path
 * @return:     EFI_FILE_PROTOCOL for the file or NULL
 */
struct efi_file_handle *efi_file_from_path(struct efi_device_path *fp)
{
        struct efi_simple_file_system_protocol *v;
        struct efi_file_handle *f;
        efi_status_t ret;

        v = efi_fs_from_path(fp);
        if (!v)
                return NULL;

        EFI_CALL(ret = v->open_volume(v, &f));
        if (ret != EFI_SUCCESS)
                return NULL;

        /* Skip over device-path nodes before the file path. */
        while (fp && !EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH))
                fp = efi_dp_next(fp);

        /*
         * Step through the nodes of the directory path until the actual file
         * node is reached which is the final node in the device path.
         */
        while (fp) {
                struct efi_device_path_file_path *fdp =
                        container_of(fp, struct efi_device_path_file_path, dp);
                struct efi_file_handle *f2;
                u16 *filename;

                if (!EFI_DP_TYPE(fp, MEDIA_DEVICE, FILE_PATH)) {
                        printf("bad file path!\n");
                        f->close(f);
                        return NULL;
                }

                filename = u16_strdup(fdp->str);
                if (!filename)
                        return NULL;
                EFI_CALL(ret = f->open(f, &f2, filename,
                                       EFI_FILE_MODE_READ, 0));
                free(filename);
                if (ret != EFI_SUCCESS)
                        return NULL;

                fp = efi_dp_next(fp);

                EFI_CALL(f->close(f));
                f = f2;
        }

        return f;
}

static efi_status_t EFIAPI
efi_open_volume(struct efi_simple_file_system_protocol *this,
                struct efi_file_handle **root)
{
        struct file_system *fs = to_fs(this);

        EFI_ENTRY("%p, %p", this, root);

        *root = file_open(fs, NULL, NULL, 0, 0);

        return EFI_EXIT(EFI_SUCCESS);
}

struct efi_simple_file_system_protocol *
efi_simple_file_system(struct blk_desc *desc, int part,
                       struct efi_device_path *dp)
{
        struct file_system *fs;

        fs = calloc(1, sizeof(*fs));
        fs->base.rev = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_REVISION;
        fs->base.open_volume = efi_open_volume;
        fs->desc = desc;
        fs->part = part;
        fs->dp = dp;

        return &fs->base;
}