/*
 * Copyright 2017 Frank Hunleth
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "cfgfile.h"
#include "functions.h"
#include "requirement.h"
#include "mbr.h"
#include "gpt.h"
#include "uboot_env.h"
#include "util.h"
#include "archive_open.h"
#include "eval_math.h"
#include "3rdparty/semver.c/semver.h"
#include "monocypher-ed25519.h"

#include <stdlib.h>
#include <string.h>
#include <archive.h>
#include <archive_entry.h>

// Global variable for passing the top level cfg pointer through libconfuse
// This is needed for validating some of the function calls.
static cfg_t *toplevel_cfg;

/* function callback
 */
static int cb_func(enum fun_context_type ctype, cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    struct fun_context fctx;
    memset(&fctx, 0, sizeof(fctx));
    fctx.type = ctype;
    fctx.cfg = toplevel_cfg;
    fctx.task = cfg;

    // Convert to the normal argc/argv
    fctx.argc = argc + 1;
    if (fctx.argc > FUN_MAX_ARGS || fctx.argc < 1) {
        cfg_error(cfg, "Too many arguments passed to '%s'", opt->name);
        return -1;
    }

    fctx.argv[0] = opt->name;
    memcpy(&fctx.argv[1], argv, sizeof(const char *) * argc);

    if (fun_validate(&fctx) < 0) {
        cfg_error(cfg, last_error());
        return -1;
    }

    char str_argc[5];
    snprintf(str_argc, sizeof(str_argc), "%d", fctx.argc);

    cfg_addlist(cfg, "funlist", 2, str_argc, fctx.argv[0]);
    int i;
    for (i = 1; i < fctx.argc; i++)
        cfg_addlist(cfg, "funlist", 1, fctx.argv[i]);

    return 0;
}

static int cb_on_init_func(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    return cb_func(FUN_CONTEXT_INIT, cfg, opt, argc, argv);
}

static int cb_on_finish_func(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    return cb_func(FUN_CONTEXT_FINISH, cfg, opt, argc, argv);
}

static int cb_on_error_func(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    return cb_func(FUN_CONTEXT_ERROR, cfg, opt, argc, argv);
}

static int cb_on_resource_func(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    return cb_func(FUN_CONTEXT_FILE, cfg, opt, argc, argv);
}

/* requirement callback
 */
static int cb_task_require_func(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    struct fun_context fctx;
    memset(&fctx, 0, sizeof(fctx));
    fctx.cfg = toplevel_cfg;
    fctx.task = cfg;

    // Convert to the normal argc/argv
    fctx.argc = argc + 1;
    if (fctx.argc > FUN_MAX_ARGS || fctx.argc < 1) {
        cfg_error(cfg, "Too many arguments passed to '%s'", opt->name);
        return -1;
    }

    fctx.argv[0] = opt->name;
    memcpy(&fctx.argv[1], argv, sizeof(const char *) * argc);

    if (req_validate(&fctx) < 0) {
        cfg_error(cfg, last_error());
        return -1;
    }

    char str_argc[5];
    snprintf(str_argc, sizeof(str_argc), "%d", fctx.argc);

    cfg_addlist(cfg, "reqlist", 2, str_argc, fctx.argv[0]);
    int i;
    for (i = 1; i < fctx.argc; i++)
        cfg_addlist(cfg, "reqlist", 1, fctx.argv[i]);

    return 0;
}

static int check_param_count(cfg_t *cfg, cfg_opt_t *opt, int argc, int required)
{
    if (argc != required) {
        cfg_error(cfg, "'%s' requires %d parameters",
                  opt->name, required);
        return -1;
    }
    return 0;
}

static int define_helper(cfg_t *cfg, const char *key, const char *value, bool override)
{
    INFO("Defining '%s'='%s'", key, value);

    if (override || !get_environment(key)) {
        if (set_environment(key, value) < 0) {
            cfg_error(cfg, "set_environment failed");
            return -1;
        }
    } else {
        INFO("Not defining '%s'. Already set to '%s'", key, getenv(key));
    }
    return 0;
}

static int cb_define_bang(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    if (check_param_count(cfg, opt, argc, 2) < 0 ||
            define_helper(cfg, argv[0], argv[1], true) < 0)
        return -1;
    else
        return 0;
}

static int cb_define(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    if (check_param_count(cfg, opt, argc, 2) < 0 ||
            define_helper(cfg, argv[0], argv[1], false) < 0)
        return -1;
    else
        return 0;
}

static int cb_define_eval(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    if (check_param_count(cfg, opt, argc, 2) < 0)
        return -1;

    char result_str[24]; // Large enough to hold 64 bit int
    if (eval_math_str(argv[1], result_str, sizeof(result_str)) < 0) {
        cfg_error(cfg, "error evaluating '%s'", argv[1]);
        return -1;
    }

    return define_helper(cfg, argv[0], result_str, false);
}

static int cb_define_eval_bang(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    // Overriding version of define_eval
    if (check_param_count(cfg, opt, argc, 2) < 0)
        return -1;

    char result_str[24]; // Large enough to hold 64 bit int
    if (eval_math_str(argv[1], result_str, sizeof(result_str)) < 0) {
        cfg_error(cfg, "error evaluating '%s'", argv[1]);
        return -1;
    }

    return define_helper(cfg, argv[0], result_str, true);
}

static int cb_include(cfg_t *cfg, cfg_opt_t *opt, int argc, const char **argv)
{
    if (check_param_count(cfg, opt, argc, 1) < 0)
        return -1;

    const char *path = argv[0];
    if (path[0] == '\0') {
        cfg_error(cfg, "Cannot include the contents of an undefined variable");
        return -1;
    }

    char *updated_path;
    update_relative_path(cfg->filename, path, &updated_path);

    // The default cfg_include gives lexer errors for some bad inputs. E.g.,
    // specifying a directory. Check the file here to give better error
    // messages.
    if (!file_exists(updated_path)) {
        cfg_error(cfg, "Cannot include '%s': File not found", path);
        return -1;
    }

    if (!is_regular_file(updated_path)) {
        cfg_error(cfg, "Cannot include '%s': Not a regular file", path);
        return -1;
    }

    const char *newargv[2];
    newargv[0] = updated_path;
    newargv[1] = NULL;

    int rc = cfg_include(cfg, opt, 1, newargv);
    free(updated_path);

    return rc;
}

// libconfuse calls the validators every time an item is added
// to a section. The idiom is to validate the most recently
// added item each time. This one is also the last one in the list.
// It is a coding error if cfg_opt_getnsec returns error, so errors
// aren't checked. (They segfault.)
#define MOST_RECENTLY_ADDED_SECTION(opt) \
    cfg_opt_getnsec(opt, cfg_opt_size(opt) - 1)

// Automatically add environment variables when we validate a file resource
//
// Currently we generate:
//   FWUP_SIZE_<resource_name> - The size of the resource
static int add_file_resource_variables(const char *path, cfg_t *sec)
{
    int rc = 0;

    // FWUP_SIZE_<resource_name>
    if (path) {
        // Create the Variable Name
        //  strlen("FWUP_SIZE_") == 10
        size_t key_len = strlen(cfg_title(sec)) + 10 + 1;
        char *key = (char *) malloc(key_len);

        snprintf(key, key_len, "FWUP_SIZE_%s", cfg_title(sec));
        for (size_t i = 0; i < key_len; i++) {
            switch (key[i]) {
            case '-':
            case '/':
            case '.':
                key[i] = '_';
                break;
            default:
                break;
            }
        }

        struct stat st;

        // Special files may not have length
        // Only return an error if we fail to set the variable
        // after we know its size
        if (stat(path, &st) == 0) {
            char size_str[24]; // Large enough to hold 64 bit int
            snprintf(size_str, 24, "%" PRId64, (int64_t) st.st_size);

            INFO("Defining '%s'='%s'", key, size_str);

            if (set_environment(key, size_str) < 0)
                rc = -1;
        }
        free(key);
    }

    return rc;
}

static int cb_validate_require_fwup_version(cfg_t *cfg, cfg_opt_t *opt)
{
    semver_t current_version;
    if (semver_parse(VERSION, &current_version) < 0)
        fwup_errx(EXIT_FAILURE, "Invalid fwup version: " VERSION);

    semver_t version_req;
    const char *version_req_str = cfg_opt_getnstr(opt, 0);
    if (semver_parse(version_req_str, &version_req)) {
        cfg_error(cfg, "Invalid version '%s' passed to require-fwup-version", version_req_str);
        semver_free(&current_version);
        return -1;
    }

    int rc;
    if (semver_lte(version_req, current_version)) {
        // Required version is less than or equal to this version, so ok.
        rc = 0;
    } else {
        cfg_error(cfg, "fwup version '%s' required. This is fwup version '%s'.", version_req_str, VERSION);
        rc = -1;
    }

    semver_free(&current_version);
    semver_free(&version_req);
    return rc;
}

static int cb_validate_file_resource(cfg_t *cfg, cfg_opt_t *opt)
{
    cfg_t *sec = MOST_RECENTLY_ADDED_SECTION(opt);
    const char *path = cfg_getstr(sec, "host-path");
    const char *contents = cfg_getstr(sec, "contents");
    if (!path && !contents) {
        cfg_error(cfg, "host-path or contents must be set for file-resource '%s'", cfg_title(sec));
        return -1;
    }
    if (path && contents) {
        cfg_error(cfg, "only one of host-path or contents should be set for file-resource '%s'", cfg_title(sec));
        return -1;
    }

    return add_file_resource_variables(path, sec);
}

static int cb_validate_mbr(cfg_t *cfg, cfg_opt_t *opt)
{
    cfg_t *sec = MOST_RECENTLY_ADDED_SECTION(opt);

    const char *path = cfg_getstr(sec, "bootstrap-code-host-path");
    const char *bootstrap_hex = cfg_getstr(sec, "bootstrap-code");
    if (path && !bootstrap_hex) {
        FILE *fp = fopen(path, "rb");
        if (!fp) {
            cfg_error(cfg, "mbr bootstrap code path '%s' required, but can't be read", path);
            return -1;
        }

        uint8_t bootstrap[440];
        if (fread(bootstrap, 1, sizeof(bootstrap), fp) != sizeof(bootstrap)) {
            cfg_error(cfg, "mbr bootstrap code in '%s' should be %d bytes", path, sizeof(bootstrap));
            fclose(fp);
            return -1;
        }
        fclose(fp);

        char bootstrap_str[sizeof(bootstrap) * 2 + 1];
        bytes_to_hex(bootstrap, bootstrap_str, sizeof(bootstrap));
        cfg_setstr(sec, "bootstrap-code", bootstrap_str);
    }
    if (mbr_verify_cfg(sec) < 0) {
        cfg_error(cfg, last_error());
        return -1;
    }

    return 0;
}

static int cb_validate_gpt(cfg_t *cfg, cfg_opt_t *opt)
{
    cfg_t *sec = MOST_RECENTLY_ADDED_SECTION(opt);

    if (gpt_verify_cfg(sec) < 0) {
        cfg_error(cfg, last_error());
        return -1;
    }

    return 0;
}

static int cb_validate_uboot(cfg_t *cfg, cfg_opt_t *opt)
{
    cfg_t *sec = MOST_RECENTLY_ADDED_SECTION(opt);

    if (uboot_env_verify_cfg(sec) < 0) {
        cfg_error(cfg, last_error());
        return -1;
    }

    return 0;
}

static int cb_validate_on_resource(cfg_t *cfg, cfg_opt_t *opt)
{
    cfg_t *sec = MOST_RECENTLY_ADDED_SECTION(opt);

    const char *resource_name = cfg_title(sec);

    cfg_t *resource;
    unsigned int i = 0;
    while ((resource = cfg_getnsec(toplevel_cfg, "file-resource", i)) != NULL) {
        if (strcmp(cfg_title(resource), resource_name) == 0)
            return 0;
        i++;
    }

    cfg_error(cfg, "unknown resource: %s", resource_name);
    return -1;
}

// libconfuse v3.0 ignore unknown options
#ifdef CFGF_IGNORE_UNKNOWN
#define CFG_IGNORE_UNKNOWN \
    CFG_STR("__unknown", 0, CFGF_NONE),
#else
#define CFG_IGNORE_UNKNOWN
#endif

static cfg_opt_t file_resource_opts[] = {
    CFG_FUNC("include", &cb_include),
    CFG_STR("host-path", 0, CFGF_NONE),
    CFG_BOOL("skip-holes", cfg_false, CFGF_NONE),

#if (SIZEOF_INT == 4 && SIZEOF_OFF_T > 4)
    // If we're on a 32-bit machine that has large file offsets,
    // use "doubles" to store offsets in the config file to get
    // more bits. This enables support of updates well past
    // gigabytes. Search for "length" (with quotes) to verify
    // that the other uses of the parameter are ok.
    CFG_FLOAT_LIST("length", 0, CFGF_NONE),
#else
    CFG_INT_LIST("length", 0, CFGF_NONE),
#endif
    CFG_STR("contents", 0, CFGF_NONE),
    CFG_STR("blake2b-256", 0, CFGF_NONE),
    CFG_STR("sha256", 0, CFGF_NONE), // Old hash for files - use blake2b-256 now
    CFG_INT("assert-size-lte", -1, CFGF_NONE),
    CFG_INT("assert-size-gte", -1, CFGF_NONE),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};
static cfg_opt_t mbr_partition_opts[] = {
    CFG_STR("block-offset", 0, CFGF_NONE), // Special case: use a string to support unsigned 32-bit offsets on 32-bit machines
    CFG_INT("block-count", INT32_MAX, CFGF_NONE),
    CFG_INT("type", -1, CFGF_NONE),
    CFG_BOOL("boot", cfg_false, CFGF_NONE),
    CFG_BOOL("expand", cfg_false, CFGF_NONE),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};
static cfg_opt_t mbr_osii_opts[] = {
    CFG_INT("os-major", 0, CFGF_NONE),
    CFG_INT("os-minor", 0, CFGF_NONE),
    CFG_INT("start-block-offset", 0, CFGF_NONE),
    CFG_INT("ddr-load-address", 0, CFGF_NONE),
    CFG_INT("entry-point", 0, CFGF_NONE),
    CFG_INT("image-size-blocks", 0, CFGF_NONE),
    CFG_INT("attribute", 0xf, CFGF_NONE),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};
static cfg_opt_t mbr_opts[] = {
    CFG_STR("bootstrap-code-host-path", 0, CFGF_NONE),
    CFG_STR("bootstrap-code", 0, CFGF_NONE),
    CFG_BOOL("include-osip", cfg_false, CFGF_NONE),
    CFG_INT("osip-major", 1, CFGF_NONE),
    CFG_INT("osip-minor", 0, CFGF_NONE),
    CFG_INT("osip-num-pointers", 1, CFGF_NONE),
    CFG_STR("signature", 0, CFGF_NONE), // Special case: use a string to support unsigned 32-bit offsets on 32-bit machines
    CFG_SEC("partition", mbr_partition_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_SEC("osii", mbr_osii_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};
static cfg_opt_t gpt_partition_opts[] = {
    CFG_STR("block-offset", 0, CFGF_NONE), // Special case: use a string to support unsigned 32-bit offsets on 32-bit machines
    CFG_INT("block-count", INT32_MAX, CFGF_NONE),
    CFG_STR("type", 0, CFGF_NONE), // UUID
    CFG_STR("guid", 0, CFGF_NONE), // UUID
    CFG_STR("name", "", CFGF_NONE),
    CFG_STR("flags", "0", CFGF_NONE), // Special case: use a string to support unsigned 64-bit number
    CFG_BOOL("expand", cfg_false, CFGF_NONE),
    CFG_BOOL("boot", cfg_false, CFGF_NONE),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};
static cfg_opt_t gpt_opts[] = {
    CFG_STR("guid", 0, CFGF_NONE), // UUID
    CFG_SEC("partition", gpt_partition_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};
static cfg_opt_t uboot_environment_opts[] = {
    CFG_INT("block-offset", -1, CFGF_NONE),
    CFG_INT("block-count", INT32_MAX, CFGF_NONE),
    CFG_INT("block-offset-redund", -1, CFGF_NONE),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};

#define CFG_ON_EVENT_FUNCTIONS(CB) \
    CFG_STR_LIST("funlist", 0, CFGF_NONE), \
    CFG_FUNC("include", &cb_include), \
    CFG_FUNC("raw_memset", CB), \
    CFG_FUNC("raw_write", CB), \
    CFG_FUNC("fat_mkfs", CB), \
    CFG_FUNC("fat_attrib", CB), \
    CFG_FUNC("fat_write", CB), \
    CFG_FUNC("fat_cp", CB), \
    CFG_FUNC("fat_mv", CB), \
    CFG_FUNC("fat_mv!", CB), \
    CFG_FUNC("fat_rm", CB), \
    CFG_FUNC("fat_rm!", CB), \
    CFG_FUNC("fat_mkdir", CB), \
    CFG_FUNC("fat_setlabel", CB), \
    CFG_FUNC("fat_touch", CB), \
    CFG_FUNC("gpt_write", CB), \
    CFG_FUNC("mbr_write", CB), \
    CFG_FUNC("trim", CB), \
    CFG_FUNC("uboot_clearenv", CB), \
    CFG_FUNC("uboot_recover", CB), \
    CFG_FUNC("uboot_setenv", CB), \
    CFG_FUNC("uboot_unsetenv", CB), \
    CFG_FUNC("error", CB), \
    CFG_FUNC("info", CB), \
    CFG_FUNC("path_write", CB), \
    CFG_FUNC("pipe_write", CB), \
    CFG_FUNC("execute", CB)

static cfg_opt_t task_on_init_opts[] = {
    CFG_ON_EVENT_FUNCTIONS(cb_on_init_func),
    CFG_END()
};
static cfg_opt_t task_on_finish_opts[] = {
    CFG_ON_EVENT_FUNCTIONS(cb_on_finish_func),
    CFG_END()
};
static cfg_opt_t task_on_error_opts[] = {
    CFG_ON_EVENT_FUNCTIONS(cb_on_error_func),
    CFG_END()
};
static cfg_opt_t task_on_resource_opts[] = {
    CFG_BOOL("verify-on-the-fly", cfg_false, CFGF_NONE), // Deprecated
    CFG_STR("delta-source-raw-offset", 0, CFGF_NONE), // Special case: use a string to support unsigned 32-bit offsets on 32-bit machines
    CFG_INT("delta-source-raw-count", INT32_MAX, CFGF_NONE),
    CFG_STR("delta-source-fat-offset", 0, CFGF_NONE), // Special case: use a string to support unsigned 32-bit offsets on 32-bit machines
    CFG_STR("delta-source-fat-path", 0, CFGF_NONE),
    CFG_ON_EVENT_FUNCTIONS(cb_on_resource_func),
    CFG_END()
};
static cfg_opt_t task_opts[] = {
    CFG_FUNC("include", &cb_include), \

    CFG_STR_LIST("reqlist", 0, CFGF_NONE), // Internal - use functions below
    CFG_FUNC("require-partition-offset", cb_task_require_func),
    CFG_FUNC("require-fat-file-exists", cb_task_require_func),
    CFG_FUNC("require-uboot-variable", cb_task_require_func),
    CFG_FUNC("require-path-on-device", cb_task_require_func),
    CFG_FUNC("require-path-at-offset", cb_task_require_func),
    CFG_FUNC("require-fat-file-match", cb_task_require_func),

    CFG_INT("require-partition1-offset", -1, CFGF_NONE), // Deprecated
    CFG_BOOL("require-unmounted-destination", cfg_false, CFGF_NONE), // Deprecated
    CFG_BOOL("verify-on-the-fly", cfg_false, CFGF_NONE), // Deprecated
    CFG_SEC("on-init", task_on_init_opts, CFGF_NONE),
    CFG_SEC("on-finish", task_on_finish_opts, CFGF_NONE),
    CFG_SEC("on-error", task_on_error_opts, CFGF_NONE),
    CFG_SEC("on-resource", task_on_resource_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};
static cfg_opt_t opts[] = {
    CFG_STR("meta-product", 0, CFGF_NONE),
    CFG_STR("meta-description", 0, CFGF_NONE),
    CFG_STR("meta-version", 0, CFGF_NONE),
    CFG_STR("meta-author", 0, CFGF_NONE),
    CFG_STR("meta-platform", 0, CFGF_NONE),
    CFG_STR("meta-architecture", 0, CFGF_NONE),
    CFG_STR("meta-creation-date", 0, CFGF_NONE),
    CFG_STR("meta-fwup-version", 0, CFGF_NONE),
    CFG_STR("meta-vcs-identifier", 0, CFGF_NONE),
    CFG_STR("meta-misc", 0, CFGF_NONE),
    CFG_STR("meta-uuid", 0, CFGF_NONE),

    CFG_STR("require-fwup-version", "0", CFGF_NONE),
    CFG_FUNC("define", cb_define),
    CFG_FUNC("define!", cb_define_bang),
    CFG_FUNC("define-eval", cb_define_eval),
    CFG_FUNC("define-eval!", cb_define_eval_bang),
    CFG_SEC("file-resource", file_resource_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_SEC("mbr", mbr_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_SEC("gpt", gpt_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_SEC("task", task_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_SEC("uboot-environment", uboot_environment_opts, CFGF_MULTI | CFGF_TITLE | CFGF_NO_TITLE_DUPES),
    CFG_FUNC("include", &cb_include),
    CFG_IGNORE_UNKNOWN
    CFG_END()
};

int cfgfile_parse_file(const char *filename, cfg_t **cfg)
{
    if (fwup_verbose) {
        extern char **environ;
        int e = 0;

        INFO("Config environment:");
        while (environ[e] != NULL) {
            INFO(" %s", environ[e]);
            e++;
        }
    }

    int rc = 0;

    // Patch over a trivially easy error to make of not escaping the $
    // on the FWUP_META_UUID variable. This variable needs to be resolved
    // at "apply" time since it can't be calculated at creation time without
    // affecting itself.
    set_environment("FWUP_META_UUID", "${FWUP_META_UUID}");

    // libconfuse 3.0 note: This function is called when creating
    // archives. If there's an unknown option, we want to throw an
    // error so that the user can fix it. I.e., don't pass
    // CFGF_IGNORE_UNKNOWN here.
    toplevel_cfg = cfg_init(opts, 0);

    // Set a validating callback function for sections
    cfg_set_validate_func(toplevel_cfg, "require-fwup-version", cb_validate_require_fwup_version);
    cfg_set_validate_func(toplevel_cfg, "file-resource", cb_validate_file_resource);
    cfg_set_validate_func(toplevel_cfg, "mbr", cb_validate_mbr);
    cfg_set_validate_func(toplevel_cfg, "gpt", cb_validate_gpt);
    cfg_set_validate_func(toplevel_cfg, "uboot-environment", cb_validate_uboot);
    cfg_set_validate_func(toplevel_cfg, "task|on-resource", cb_validate_on_resource);

    if (strcmp(filename, "-") == 0) {
        if (cfg_parse_fp(toplevel_cfg, stdin) != 0)
            ERR_CLEANUP_MSG("Error parsing configuration from stdin");
    } else {
        switch (cfg_parse(toplevel_cfg, filename)) {
        case CFG_SUCCESS:
            break;
        case CFG_FILE_ERROR:
            ERR_CLEANUP_MSG("Error opening configuration file '%s'", filename);
        default:
        case CFG_PARSE_ERROR:
            ERR_CLEANUP_MSG("Error parsing configuration file '%s'", filename);
        }
    }
    *cfg = toplevel_cfg;
    return 0;

cleanup:
    cfg_free(toplevel_cfg);
    return rc;
}

/**
 * Helper function for reading all data in a file in the archive
 *
 * @param a the archive
 * @param ae the archive entry so that we can figure out the size if in seeking mode
 * @param buffer where to save the malloc'd buffer pointer
 * @param max_size read no more than this. If more exists, the rest isn't read.
 * @param size_read how much was actually read
 * @return 0 on success
 */
int archive_read_all_data(struct archive *a, struct archive_entry *ae, char **buffer, off_t max_size, off_t *size_read)
{
    if (archive_entry_size_is_set(ae)) {
        // Reading off disk case - we know the size a priori
        off_t total_size = archive_entry_size(ae);
        if (total_size < 0)
            return -1;

        // Only read up to max_size or as much as we have.
        if (total_size < max_size)
            max_size = total_size;
    }

    char *buf = (char *) malloc(max_size + 1);

    off_t size_left = max_size;
    while (size_left > 0) {
        off_t len = archive_read_data(a, &buf[max_size - size_left], size_left);
        if (len <= 0)
            break;
        size_left -= len;
    }

    *size_read = max_size - size_left;
    buf[*size_read] = 0; // NULL terminate for convenience
    *buffer = buf;

    return 0;
}

int cfgfile_parse_fw_ae(struct archive *a,
                        struct archive_entry *ae,
                        cfg_t **cfg,
                        unsigned char *meta_conf_signature,
                        unsigned char * const *public_keys)
{
    int rc = 0;
    char *meta_conf = NULL;
    off_t max_meta_conf_size = 50000;
    off_t total_size;

    if (archive_read_all_data(a, ae, &meta_conf, max_meta_conf_size, &total_size) < 0)
        ERR_CLEANUP_MSG("Error reading meta.conf from archive.\n"
                        "Check for file corruption or libarchive built without zlib support");
    if (total_size < 10 || total_size >= max_meta_conf_size)
        ERR_CLEANUP_MSG("Unexpected meta.conf size: %d", total_size);

    // Check the signature on meta.conf if it has been signed
    if (*public_keys) {
        if (!meta_conf_signature)
            ERR_CLEANUP_MSG("Expecting signed firmware archive.");

        bool worked = false;
        while (*public_keys) {
            if (crypto_ed25519_check(meta_conf_signature, *public_keys, (const uint8_t *) meta_conf, total_size) == 0) {
                worked = true;
                break;
            }
            public_keys++;
        }
        if (!worked)
            ERR_CLEANUP_MSG("Firmware archive's meta.conf fails digital signature verification.");
    } else if (meta_conf_signature) {
        INFO("Firmware archive is signed, but signature verification is off.");
    }

    // Parse the configuration, but do minimal validity checking of configuration
    // since many things are only used on the creation of the firmware update.
#ifdef CFGF_IGNORE_UNKNOWN
    // libconfuse 3.0 - ignore unknown options so that new options don't necessarily cause
    // the firmware update to fail. For example, this allows metadata to be added to the
    // meta.conf file in future firmware updates. Without it, the new metadata option
    // would result in libconfuse throwing a parse error.
    *cfg = cfg_init(opts, CFGF_IGNORE_UNKNOWN);
#else
#warning It is highly recommended to compile against libconfuse 3.0+.
#warning Forward compatibility with .fw files from future fwup versions may be more limited without this.
#warning If you are just creating .fw files, then you may ignore this warning. If not, consider
#warning building a statically linked version of fwup if your distro does not have a newer version.
#warning See scripts/download_deps.sh.
    *cfg = cfg_init(opts, 0);
#endif
    cfg_set_validate_func(*cfg, "require-fwup-version", cb_validate_require_fwup_version);

    // Set automatically determined metadata

    // fwup 1.2 and later base the creation date off meta.conf timestamp which
    // may or may not be accurate. Set it here. If it's overridden, then we have
    // an older .fw file and that's ok.
    time_t creation_time = 0;
    if (archive_entry_mtime_is_set(ae))
        creation_time = archive_entry_mtime(ae);
    char str[64];
    time_t_to_string(creation_time, str, sizeof(str));
    cfg_setstr(*cfg, "meta-creation-date", str);

    // meta-uuid is always calculated and cannot be overriden
    calculate_fwup_uuid(meta_conf, total_size, str);
    cfg_setstr(*cfg, "meta-uuid", str);
    set_environment("FWUP_META_UUID", str);

    if (cfg_parse_buf(*cfg, meta_conf) != 0)
        ERR_CLEANUP_MSG("Unexpected error parsing meta.conf");

    // Verify that meta-uuid wasn't changed when loading the file.
    if (strcmp(str, cfg_getstr(*cfg, "meta-uuid")) != 0 ||
        strcmp(str, get_environment("FWUP_META_UUID")) != 0)
        ERR_CLEANUP_MSG("meta.conf isn't allowed to change 'meta-uuid' or '$FWUP_META_UUID'");

cleanup:
    if (meta_conf)
        free(meta_conf);

    return rc;
}

int cfgfile_parse_fw_meta_conf(const char *filename, cfg_t **cfg, unsigned char * const *public_keys)
{
    int rc = 0;
    unsigned char *meta_conf_signature = NULL;
    struct archive *a = archive_read_new();
    archive_read_support_format_zip(a);
    rc = fwup_archive_open_filename(a, filename, NULL);
    if (rc != ARCHIVE_OK)
        ERR_CLEANUP_MSG("%s", archive_error_string(a));

    struct archive_entry *ae;
    rc = archive_read_next_header(a, &ae);
    if (rc != ARCHIVE_OK)
        ERR_CLEANUP_MSG("Corrupt archive '%s'", filename);

    if (strcmp(archive_entry_pathname(ae), "meta.conf.ed25519") == 0) {
        off_t total_size;
        if (archive_read_all_data(a, ae, (char **) &meta_conf_signature, 64, &total_size) < 0)
            ERR_CLEANUP_MSG("Error reading meta.conf.ed25519 from archive.\n"
                            "Check for file corruption or libarchive built without zlib support");

        if (total_size != 64)
            ERR_CLEANUP_MSG("Unexpected meta.conf.ed25519 size: %d", total_size);

        rc = archive_read_next_header(a, &ae);
        if (rc != ARCHIVE_OK)
            ERR_CLEANUP_MSG("Expecting more than meta.conf.ed25519 in archive");
    }
    if (strcmp(archive_entry_pathname(ae), "meta.conf") != 0)
        ERR_CLEANUP_MSG("Expecting meta.conf to be at beginning of %s", filename);

    OK_OR_CLEANUP(cfgfile_parse_fw_ae(a, ae, cfg, meta_conf_signature, public_keys));

cleanup:
    archive_read_free(a);
    if (meta_conf_signature)
        free(meta_conf_signature);

    return rc;
}

void cfgfile_free(cfg_t *cfg)
{
    cfg_free(cfg);
}