minecraft-pi-reborn/launcher/src/bootstrap.c

#define _FILE_OFFSET_BITS 64

#include <libreborn/libreborn.h>

#include "util.h"
#include "bootstrap.h"
#include "patchelf.h"
#include "crash-report.h"

#define MCPI_BINARY "minecraft-pi"
#define QEMU_BINARY "qemu-arm"

#ifndef __ARM_ARCH
#define USE_QEMU
#endif

#define REQUIRED_PAGE_SIZE 4096
#define _STR(x) #x
#define STR(x) _STR(x)

// Exit Handler
static void exit_handler(__attribute__((unused)) int signal_id) {
    // Pass Signal To Child
    murder_children();
    while (wait(NULL) > 0) {}
    _exit(EXIT_SUCCESS);
}

// Debug Information
static void run_debug_command(const char *const command[], const char *prefix) {
    int status = 0;
    char *output = run_command(command, &status, NULL);
    if (output != NULL) {
        // Remove Newline
        size_t length = strlen(output);
        if (length > 0 && output[length - 1] == '\n') {
            output[length - 1] = '\0';
        }

        // Print
        DEBUG("%s: %s", prefix, output);
        free(output);
    }
    if (!is_exit_status_success(status)) {
        ERR("Unable To Gather Debug Information");
    }
}
static void print_debug_information() {
    // System Information
    const char *const command[] = {"uname", "-a", NULL};
    run_debug_command(command, "System Information");

    // Version
    DEBUG("Reborn Version: v%s", MCPI_VERSION);

    // Architecture
    const char *arch = "Unknown";
#ifdef __x86_64__
    arch = "AMD64";
#elif defined(__aarch64__)
    arch = "ARM64";
#elif defined(__arm__)
    arch = "ARM32";
#endif
    DEBUG("Reborn Target Architecture: %s", arch);
}

// Pre-Bootstrap
void pre_bootstrap(int argc, char *argv[]) {
    // Set Debug Tag
    reborn_debug_tag = "(Launcher) ";

    // Disable stdout Buffering
    setvbuf(stdout, NULL, _IONBF, 0);

    // Print Version
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "--version") == 0 || strcmp(argv[i], "-v") == 0) {
            // Print
            printf("Reborn v%s\n", MCPI_VERSION);
            fflush(stdout);
            exit(EXIT_SUCCESS);
        }
    }

    // Setup Logging
    setup_log_file();

    // --debug
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "--debug") == 0) {
            set_and_print_env("MCPI_DEBUG", "1");
            break;
        }
    }

    // Set Default Native Component Environment
#define set_variable_default(name) set_and_print_env("MCPI_NATIVE_" name, getenv(name));
    for_each_special_environmental_variable(set_variable_default);

    // GTK Dark Mode
#ifndef MCPI_SERVER_MODE
    set_and_print_env("GTK_THEME", "Adwaita:dark");
#endif

    // Configure PATH
    {
        // Get Binary Directory
        char *binary_directory = get_binary_directory();

        // Add Library Directory
        char *new_path = NULL;
        safe_asprintf(&new_path, "%s/bin", binary_directory);
        // Add Existing PATH
        {
            char *value = getenv("PATH");
            if (value != NULL && strlen(value) > 0) {
                string_append(&new_path, ":%s", value);
            }
        }
        // Set And Free
        set_and_print_env("PATH", new_path);
        free(new_path);

        // Free Binary Directory
        free(binary_directory);
    }

    // --copy-sdk
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "--copy-sdk") == 0) {
            char *binary_directory = get_binary_directory();
            copy_sdk(binary_directory, 0);
            free(binary_directory);
            fflush(stdout);
            exit(EXIT_SUCCESS);
        }
    }

    // Setup Crash Reports
    setup_crash_report();

    // AppImage
#ifdef MCPI_IS_APPIMAGE_BUILD
    {
        char *owd = getenv("OWD");
        if (owd != NULL && chdir(owd) != 0) {
            ERR("AppImage: Unable To Fix Current Directory: %s", strerror(errno));
        }
    }
#endif

    // Install Signal Handlers
    struct sigaction act_sigint;
    memset((void *) &act_sigint, 0, sizeof (struct sigaction));
    act_sigint.sa_flags = SA_RESTART;
    act_sigint.sa_handler = &exit_handler;
    sigaction(SIGINT, &act_sigint, NULL);
    struct sigaction act_sigterm;
    memset((void *) &act_sigterm, 0, sizeof (struct sigaction));
    act_sigterm.sa_flags = SA_RESTART;
    act_sigterm.sa_handler = &exit_handler;
    sigaction(SIGTERM, &act_sigterm, NULL);

    // Check Page Size (Not Needed When Using QEMU)
#ifndef USE_QEMU
    long page_size = sysconf(_SC_PAGESIZE);
    if (page_size != REQUIRED_PAGE_SIZE) {
        ERR("Invalid page size! A page size of %ld bytes is required, but the system size is %ld bytes.", (long) REQUIRED_PAGE_SIZE, page_size);
    }
#endif

    // Debug Information
    print_debug_information();
}

// Bootstrap
void bootstrap(int argc, char *argv[]) {
    INFO("Configuring Game...");

    // Get Binary Directory
    char *binary_directory = get_binary_directory();
    DEBUG("Binary Directory: %s", binary_directory);

    // Copy SDK
    copy_sdk(binary_directory, 1);

    // Set MCPI_REBORN_ASSETS_PATH
    {
        char *assets_path = realpath("/proc/self/exe", NULL);
        ALLOC_CHECK(assets_path);
        chop_last_component(&assets_path);
        string_append(&assets_path, "/data");
        set_and_print_env("MCPI_REBORN_ASSETS_PATH", assets_path);
        free(assets_path);
    }

    // Resolve Binary Path & Set MCPI_DIRECTORY
    char *resolved_path = NULL;
    {
        // Log
        DEBUG("Resolving File Paths...");

        // Resolve Full Binary Path
        char *full_path = NULL;
        safe_asprintf(&full_path, "%s/" MCPI_BINARY, binary_directory);
        resolved_path = realpath(full_path, NULL);
        ALLOC_CHECK(resolved_path);
        free(full_path);
    }

    // Fix MCPI Dependencies
    char new_mcpi_exe_path[] = MCPI_PATCHED_DIR "/XXXXXX";
    {
        // Log
        DEBUG("Patching ELF Dependencies...");

        // Find Linker
        char *linker = NULL;
        // Select Linker
#ifdef MCPI_USE_PREBUILT_ARMHF_TOOLCHAIN
        // Use ARM Sysroot Linker
        safe_asprintf(&linker, "%s/sysroot/lib/ld-linux-armhf.so.3", binary_directory);
#else
        // Use Current Linker
        linker = patch_get_interpreter();
#endif

        // Patch
        patch_mcpi_elf_dependencies(resolved_path, new_mcpi_exe_path, linker);

        // Free Linker Path
        if (linker != NULL) {
            free(linker);
        }

        // Verify
        if (!starts_with(new_mcpi_exe_path, MCPI_PATCHED_DIR)) {
            IMPOSSIBLE();
        }
    }

    // Set MCPI_VANILLA_ASSETS_PATH
    {
        char *assets_path = strdup(resolved_path);
        ALLOC_CHECK(assets_path);
        chop_last_component(&assets_path);
        string_append(&assets_path, "/data");
        set_and_print_env("MCPI_VANILLA_ASSETS_PATH", assets_path);
        free(assets_path);
    }

    // Free Resolved Path
    free(resolved_path);

    // Configure Library Search Path
    {
        // Log
        DEBUG("Setting Linker Search Paths...");

        // Prepare
        char *transitive_ld_path = NULL;
        char *mcpi_ld_path = NULL;

        // Library Search Path For Native Components
        {
            // Add Native Library Directory
            safe_asprintf(&transitive_ld_path, "%s/lib/native", binary_directory);

            // Add Host LD_LIBRARY_PATH
            {
                char *value = getenv("LD_LIBRARY_PATH");
                if (value != NULL && strlen(value) > 0) {
                    string_append(&transitive_ld_path, ":%s", value);
                }
            }

            // Set
            set_and_print_env("MCPI_NATIVE_LD_LIBRARY_PATH", transitive_ld_path);
            free(transitive_ld_path);
        }

        // Library Search Path For ARM Components
        {
            // Add ARM Library Directory
            safe_asprintf(&mcpi_ld_path, "%s/lib/arm", binary_directory);

            // Add ARM Sysroot Libraries (Ensure Priority) (Ignore On Actual ARM System)
#ifdef MCPI_USE_PREBUILT_ARMHF_TOOLCHAIN
            string_append(&mcpi_ld_path, ":%s/sysroot/lib:%s/sysroot/lib/arm-linux-gnueabihf:%s/sysroot/usr/lib:%s/sysroot/usr/lib/arm-linux-gnueabihf", binary_directory, binary_directory, binary_directory, binary_directory);
#endif

            // Add Host LD_LIBRARY_PATH
            {
                char *value = getenv("LD_LIBRARY_PATH");
                if (value != NULL && strlen(value) > 0) {
                    string_append(&mcpi_ld_path, ":%s", value);
                }
            }

            // Set
            set_and_print_env("MCPI_ARM_LD_LIBRARY_PATH", mcpi_ld_path);
            free(mcpi_ld_path);
        }
    }

    // Configure Preloaded Objects
    {
        // Log
        DEBUG("Locating Mods...");

        // Native Components
        char *host_ld_preload = getenv("LD_PRELOAD");
        set_and_print_env("MCPI_NATIVE_LD_PRELOAD", host_ld_preload);

        // ARM Components
        bootstrap_mods(binary_directory);
    }

    // Free Binary Directory
    free(binary_directory);

    // Start Game
    INFO("Starting Game...");

    // Arguments
    int argv_start = 1; // argv = &new_args[argv_start]
    const char *new_args[argv_start /* 1 Potential Prefix Argument (QEMU) */ + argc + 1 /* NULL-Terminator */]; //

    // Copy Existing Arguments
    for (int i = 1; i < argc; i++) {
        new_args[i + argv_start] = argv[i];
    }
    // NULL-Terminator
    new_args[argv_start + argc] = NULL;

    // Set Executable Argument
    new_args[argv_start] = new_mcpi_exe_path;

    // Non-ARM Systems Need QEMU
#ifdef USE_QEMU
    argv_start--;
    new_args[argv_start] = QEMU_BINARY;
    // Use 4k Page Size
    set_and_print_env("QEMU_PAGESIZE", STR(REQUIRED_PAGE_SIZE));
#endif

    // Setup Environment
    setup_exec_environment(1);

    // Pass LD_* Variables Through QEMU
#ifdef USE_QEMU
    char *qemu_set_env = NULL;
#define pass_variable_through_qemu(name) string_append(&qemu_set_env, "%s%s=%s", qemu_set_env == NULL ? "" : ",", name, getenv(name));
    for_each_special_environmental_variable(pass_variable_through_qemu);
    set_and_print_env("QEMU_SET_ENV", qemu_set_env);
    free(qemu_set_env);
    // Treat QEMU Itself As A Native Component
    setup_exec_environment(0);
#endif

    // Run
    const char **new_argv = &new_args[argv_start];
    safe_execvpe(new_argv, (const char *const *) environ);
}