:: limine / common / protos / efi_boot_entry.c 4.0 KB raw

#include <protos/efi_boot_entry.h>

​

#if defined(UEFI)

​

#include <mm/pmm.h>

#include <efi.h>

#include <lib/config.h>

#include <lib/misc.h>

#include <stdbool.h>

​

static bool uefi_string_matches(CHAR16 *desc, size_t desc_max_chars, CHAR16 *target) {

    while (*target) {

        if (desc_max_chars == 0)

            return false;

        CHAR16 a = *desc >= L'a' && *desc <= L'z' ? *desc - 32 : *desc;

        CHAR16 b = *target >= L'a' && *target <= L'z' ? *target - 32 : *target;

        if (a != b)

            return false;

        desc++;

        target++;

        desc_max_chars--;

    }

    return desc_max_chars > 0 && *desc == L'\0';

}

​

static void format_boot_var(CHAR16 *out, UINT16 num) {

    out[0] = L'B';

    out[1] = L'o';

    out[2] = L'o';

    out[3] = L't';

    out[4] = L"0123456789ABCDEF"[(num >> 12) & 0xF];

    out[5] = L"0123456789ABCDEF"[(num >> 8) & 0xF];

    out[6] = L"0123456789ABCDEF"[(num >> 4) & 0xF];

    out[7] = L"0123456789ABCDEF"[(num >> 0) & 0xF];

    out[8] = L'\0';

}

​

static bool find_boot_entry(CHAR16 *entry, uint16_t *out) {

    EFI_STATUS status;

    uint16_t boot_order[128];

    size_t size = sizeof(boot_order);

    EFI_GUID global_variable = EFI_GLOBAL_VARIABLE;

​

    status = gRT->GetVariable(L"BootOrder", &global_variable, NULL, &size, boot_order);

​

    if (EFI_ERROR(status)) {

        panic(true, "efi_boot_entry: Failed to get BootOrder variable (%X)",

            (uint64_t)status);

    }

​

    size_t count = size / sizeof(uint16_t);

​

    for (size_t i = 0; i < count; i++) {

        CHAR16 var_name[9];

​

        format_boot_var(var_name, boot_order[i]);

​

        size_t buf_size = 0;

        /* Query for buf size */

        if (gRT->GetVariable(var_name, &global_variable, NULL, &buf_size, NULL)

                != EFI_BUFFER_TOO_SMALL) {

            continue;

        }

        size_t buf_alloc = buf_size;

        uint8_t *buf = ext_mem_alloc(buf_alloc);

        status = gRT->GetVariable(var_name, &global_variable, NULL, &buf_size, buf);

​

        if (EFI_ERROR(status)) {

            pmm_free(buf, buf_alloc);

            continue;

        }

        /* Get the description */

        if (buf_size < sizeof(uint32_t) + sizeof(uint16_t) + sizeof(CHAR16)) {

            pmm_free(buf, buf_alloc);

            continue;

        }

        size_t desc_offset = sizeof(uint32_t) + sizeof(uint16_t);

        CHAR16 *desc = (CHAR16 *)(buf + desc_offset);

        size_t desc_max_chars = (buf_size - desc_offset) / sizeof(CHAR16);

        if (uefi_string_matches(desc, desc_max_chars, entry)) {

            *out = boot_order[i];

            pmm_free(buf, buf_alloc);

            return true;

        }

        pmm_free(buf, buf_alloc);

    }

​

    return false;

}

​

noreturn void efi_boot_entry(char *config) {

    char *boot_entry = config_get_value(config, 0, "ENTRY");

​

    if (boot_entry == NULL) {

        panic(true, "efi_boot_entry: No entry specified");

    }

​

    /* Convert entry string to UTF-16 */

    CHAR16 boot_entry_utf16[128];

    size_t i;

​

    for (i = 0; i < sizeof(boot_entry_utf16) / sizeof(CHAR16) - 1 && boot_entry[i]; i++) {

        boot_entry_utf16[i] = (CHAR16)boot_entry[i];

    }

​

    boot_entry_utf16[i] = L'\0';

​

    /* Find the desired boot entry */

    uint16_t boot_next = 0;

​

    if (!find_boot_entry(boot_entry_utf16, &boot_next)) {

        panic(true, "efi_boot_entry: Failed to find boot entry '%s'", boot_entry);

    }

​

    EFI_GUID global_variable = EFI_GLOBAL_VARIABLE;

​

    /* Set BootNext to it */

    EFI_STATUS status = gRT->SetVariable(L"BootNext", &global_variable,

                                       EFI_VARIABLE_NON_VOLATILE |

                                       EFI_VARIABLE_BOOTSERVICE_ACCESS |

                                       EFI_VARIABLE_RUNTIME_ACCESS,

                                       sizeof(boot_next), &boot_next);

​

    if (status) {

        panic(true, "efi_boot_entry: Failed to set BootNext variable (%X)",

            (uint64_t)status);

    }

​

    /* Now reboot */

    gRT->ResetSystem(EfiResetWarm, EFI_SUCCESS, 0, NULL);

​

    panic(true, "efi_boot_entry: Failed to reboot");

}

​

#endif