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

#include <common.h>
#include <charset.h>
#include <malloc.h>
#include <efi_loader.h>
#include <asm/unaligned.h>

static const struct efi_boot_services *bs;
static const struct efi_runtime_services *rs;

/*
 * bootmgr implements the logic of trying to find a payload to boot
 * based on the BootOrder + BootXXXX variables, and then loading it.
 *
 * TODO detecting a special key held (f9?) and displaying a boot menu
 * like you would get on a PC would be clever.
 *
 * TODO if we had a way to write and persist variables after the OS
 * has started, we'd also want to check OsIndications to see if we
 * should do normal or recovery boot.
 */


/**
 * efi_deserialize_load_option() - parse serialized data
 *
 * Parse serialized data describing a load option and transform it to the
 * efi_load_option structure.
 *
 * @lo:         pointer to target
 * @data:       serialized data
 */
void efi_deserialize_load_option(struct efi_load_option *lo, u8 *data)
{
        lo->attributes = get_unaligned_le32(data);
        data += sizeof(u32);

        lo->file_path_length = get_unaligned_le16(data);
        data += sizeof(u16);

        /* FIXME */
        lo->label = (u16 *)data;
        data += (u16_strlen(lo->label) + 1) * sizeof(u16);

        /* FIXME */
        lo->file_path = (struct efi_device_path *)data;
        data += lo->file_path_length;

        lo->optional_data = data;
}

/**
 * efi_serialize_load_option() - serialize load option
 *
 * Serialize efi_load_option structure into byte stream for BootXXXX.
 *
 * @data:       buffer for serialized data
 * @lo:         load option
 * Return:      size of allocated buffer
 */
unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8 **data)
{
        unsigned long label_len;
        unsigned long size;
        u8 *p;

        label_len = (u16_strlen(lo->label) + 1) * sizeof(u16);

        /* total size */
        size = sizeof(lo->attributes);
        size += sizeof(lo->file_path_length);
        size += label_len;
        size += lo->file_path_length;
        if (lo->optional_data)
                size += (utf8_utf16_strlen((const char *)lo->optional_data)
                                           + 1) * sizeof(u16);
        p = malloc(size);
        if (!p)
                return 0;

        /* copy data */
        *data = p;
        memcpy(p, &lo->attributes, sizeof(lo->attributes));
        p += sizeof(lo->attributes);

        memcpy(p, &lo->file_path_length, sizeof(lo->file_path_length));
        p += sizeof(lo->file_path_length);

        memcpy(p, lo->label, label_len);
        p += label_len;

        memcpy(p, lo->file_path, lo->file_path_length);
        p += lo->file_path_length;

        if (lo->optional_data) {
                utf8_utf16_strcpy((u16 **)&p, (const char *)lo->optional_data);
                p += sizeof(u16); /* size of trailing \0 */
        }
        return size;
}

/**
 * get_var() - get UEFI variable
 *
 * It is the caller's duty to free the returned buffer.
 *
 * @name:       name of variable
 * @vendor:     vendor GUID of variable
 * @size:       size of allocated buffer
 * Return:      buffer with variable data or NULL
 */
static void *get_var(u16 *name, const efi_guid_t *vendor,
                     efi_uintn_t *size)
{
        efi_guid_t *v = (efi_guid_t *)vendor;
        efi_status_t ret;
        void *buf = NULL;

        *size = 0;
        EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
        if (ret == EFI_BUFFER_TOO_SMALL) {
                buf = malloc(*size);
                EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
        }

        if (ret != EFI_SUCCESS) {
                free(buf);
                *size = 0;
                return NULL;
        }

        return buf;
}

/**
 * try_load_entry() - try to load image for boot option
 *
 * Attempt to load load-option number 'n', returning device_path and file_path
 * if successful. This checks that the EFI_LOAD_OPTION is active (enabled)
 * and that the specified file to boot exists.
 *
 * @n:          number of the boot option, e.g. 0x0a13 for Boot0A13
 * @handle:     on return handle for the newly installed image
 * Return:      status code
 */
static efi_status_t try_load_entry(u16 n, efi_handle_t *handle)
{
        struct efi_load_option lo;
        u16 varname[] = L"Boot0000";
        u16 hexmap[] = L"0123456789ABCDEF";
        void *load_option;
        efi_uintn_t size;
        efi_status_t ret;

        varname[4] = hexmap[(n & 0xf000) >> 12];
        varname[5] = hexmap[(n & 0x0f00) >> 8];
        varname[6] = hexmap[(n & 0x00f0) >> 4];
        varname[7] = hexmap[(n & 0x000f) >> 0];

        load_option = get_var(varname, &efi_global_variable_guid, &size);
        if (!load_option)
                return EFI_LOAD_ERROR;

        efi_deserialize_load_option(&lo, load_option);

        if (lo.attributes & LOAD_OPTION_ACTIVE) {
                u32 attributes;

                debug("%s: trying to load \"%ls\" from %pD\n",
                      __func__, lo.label, lo.file_path);

                ret = EFI_CALL(efi_load_image(true, efi_root, lo.file_path,
                                              NULL, 0, handle));
                if (ret != EFI_SUCCESS) {
                        printf("Loading from Boot%04X '%ls' failed\n", n,
                               lo.label);
                        goto error;
                }

                attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
                             EFI_VARIABLE_RUNTIME_ACCESS;
                size = sizeof(n);
                ret = EFI_CALL(efi_set_variable(
                                L"BootCurrent",
                                (efi_guid_t *)&efi_global_variable_guid,
                                attributes, size, &n));
                if (ret != EFI_SUCCESS) {
                        if (EFI_CALL(efi_unload_image(*handle))
                            != EFI_SUCCESS)
                                printf("Unloading image failed\n");
                        goto error;
                }

                printf("Booting: %ls\n", lo.label);
        } else {
                ret = EFI_LOAD_ERROR;
        }

error:
        free(load_option);

        return ret;
}

/**
 * efi_bootmgr_load() - try to load from BootNext or BootOrder
 *
 * Attempt to load from BootNext or in the order specified by BootOrder
 * EFI variable, the available load-options, finding and returning
 * the first one that can be loaded successfully.
 *
 * @handle:     on return handle for the newly installed image
 * Return:      status code
 */
efi_status_t efi_bootmgr_load(efi_handle_t *handle)
{
        u16 bootnext, *bootorder;
        efi_uintn_t size;
        int i, num;
        efi_status_t ret;

        bs = systab.boottime;
        rs = systab.runtime;

        /* BootNext */
        bootnext = 0;
        size = sizeof(bootnext);
        ret = EFI_CALL(efi_get_variable(L"BootNext",
                                        (efi_guid_t *)&efi_global_variable_guid,
                                        NULL, &size, &bootnext));
        if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
                /* BootNext does exist here */
                if (ret == EFI_BUFFER_TOO_SMALL || size != sizeof(u16))
                        printf("BootNext must be 16-bit integer\n");

                /* delete BootNext */
                ret = EFI_CALL(efi_set_variable(
                                        L"BootNext",
                                        (efi_guid_t *)&efi_global_variable_guid,
                                        EFI_VARIABLE_NON_VOLATILE, 0,
                                        &bootnext));

                /* load BootNext */
                if (ret == EFI_SUCCESS) {
                        if (size == sizeof(u16)) {
                                ret = try_load_entry(bootnext, handle);
                                if (ret == EFI_SUCCESS)
                                        return ret;
                                printf("Loading from BootNext failed, falling back to BootOrder\n");
                        }
                } else {
                        printf("Deleting BootNext failed\n");
                }
        }

        /* BootOrder */
        bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
        if (!bootorder) {
                printf("BootOrder not defined\n");
                ret = EFI_NOT_FOUND;
                goto error;
        }

        num = size / sizeof(uint16_t);
        for (i = 0; i < num; i++) {
                debug("%s: trying to load Boot%04X\n", __func__, bootorder[i]);
                ret = try_load_entry(bootorder[i], handle);
                if (ret == EFI_SUCCESS)
                        break;
        }

        free(bootorder);

error:
        return ret;
}