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

#define LOG_CATEGORY LOGC_EFI

#include <common.h>
#include <charset.h>
#include <log.h>
#include <malloc.h>
#include <efi_loader.h>
#include <efi_variable.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.
 */

/**
 * 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
 * @load_options:       load options set on the loaded image protocol
 * Return:              status code
 */
static efi_status_t try_load_entry(u16 n, efi_handle_t *handle,
                                   void **load_options)
{
        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 = efi_get_var(varname, &efi_global_variable_guid, &size);
        if (!load_option)
                return EFI_LOAD_ERROR;

        ret = efi_deserialize_load_option(&lo, load_option, &size);
        if (ret != EFI_SUCCESS) {
                log_warning("Invalid load option for %ls\n", varname);
                goto error;
        }

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

                log_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) {
                        log_warning("Loading %ls '%ls' failed\n",
                                    varname, lo.label);
                        goto error;
                }

                attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
                             EFI_VARIABLE_RUNTIME_ACCESS;
                ret = efi_set_variable_int(L"BootCurrent",
                                           &efi_global_variable_guid,
                                           attributes, sizeof(n), &n, false);
                if (ret != EFI_SUCCESS)
                        goto unload;
                /* try to register load file2 for initrd's */
                if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD)) {
                        ret = efi_initrd_register();
                        if (ret != EFI_SUCCESS)
                                goto unload;
                }

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

        /* Set load options */
        if (size) {
                *load_options = malloc(size);
                if (!*load_options) {
                        ret = EFI_OUT_OF_RESOURCES;
                        goto error;
                }
                memcpy(*load_options, lo.optional_data, size);
                ret = efi_set_load_options(*handle, size, *load_options);
        } else {
                *load_options = NULL;
        }

error:
        free(load_option);

        return ret;

unload:
        if (EFI_CALL(efi_unload_image(*handle)) != EFI_SUCCESS)
                log_err("Unloading image failed\n");
        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
 * @load_options:       load options set on the loaded image protocol
 * Return:              status code
 */
efi_status_t efi_bootmgr_load(efi_handle_t *handle, void **load_options)
{
        u16 bootnext, *bootorder;
        efi_uintn_t size;
        int i, num;
        efi_status_t ret;

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

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

                /* delete BootNext */
                ret = efi_set_variable_int(L"BootNext",
                                           &efi_global_variable_guid,
                                           0, 0, NULL, false);

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

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

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

        free(bootorder);

error:
        return ret;
}