/*
 * (C) Copyright 2000-2010
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * (C) Copyright 2001 Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Andreas Heppel <aheppel@sysgo.de>
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <command.h>
#include <environment.h>
#include <linux/stddef.h>
#include <search.h>
#include <errno.h>
#include <malloc.h>

DECLARE_GLOBAL_DATA_PTR;

/************************************************************************
 * Default settings to be used when no valid environment is found
 */
#include <env_default.h>

struct hsearch_data env_htab = {
        .change_ok = env_flags_validate,
};

__weak uchar env_get_char_spec(int index)
{
        return *((uchar *)(gd->env_addr + index));
}

static uchar env_get_char_init(int index)
{
        /* if crc was bad, use the default environment */
        if (gd->env_valid)
                return env_get_char_spec(index);
        else
                return default_environment[index];
}

uchar env_get_char_memory(int index)
{
        return *env_get_addr(index);
}

uchar env_get_char(int index)
{
        /* if relocated to RAM */
        if (gd->flags & GD_FLG_RELOC)
                return env_get_char_memory(index);
        else
                return env_get_char_init(index);
}

const uchar *env_get_addr(int index)
{
        if (gd->env_valid)
                return (uchar *)(gd->env_addr + index);
        else
                return &default_environment[index];
}

/*
 * Read an environment variable as a boolean
 * Return -1 if variable does not exist (default to true)
 */
int getenv_yesno(const char *var)
{
        char *s = getenv(var);

        if (s == NULL)
                return -1;
        return (*s == '1' || *s == 'y' || *s == 'Y' || *s == 't' || *s == 'T') ?
                1 : 0;
}

/*
 * Look up the variable from the default environment
 */
char *getenv_default(const char *name)
{
        char *ret_val;
        unsigned long really_valid = gd->env_valid;
        unsigned long real_gd_flags = gd->flags;

        /* Pretend that the image is bad. */
        gd->flags &= ~GD_FLG_ENV_READY;
        gd->env_valid = 0;
        ret_val = getenv(name);
        gd->env_valid = really_valid;
        gd->flags = real_gd_flags;
        return ret_val;
}

void set_default_env(const char *s)
{
        int flags = 0;

        if (sizeof(default_environment) > ENV_SIZE) {
                puts("*** Error - default environment is too large\n\n");
                return;
        }

        if (s) {
                if (*s == '!') {
                        printf("*** Warning - %s, "
                                "using default environment\n\n",
                                s + 1);
                } else {
                        flags = H_INTERACTIVE;
                        puts(s);
                }
        } else {
                puts("Using default environment\n\n");
        }

        if (himport_r(&env_htab, (char *)default_environment,
                        sizeof(default_environment), '\0', flags, 0,
                        0, NULL) == 0)
                error("Environment import failed: errno = %d\n", errno);

        gd->flags |= GD_FLG_ENV_READY;
        gd->flags |= GD_FLG_ENV_DEFAULT;
}


/* [re]set individual variables to their value in the default environment */
int set_default_vars(int nvars, char * const vars[])
{
        /*
         * Special use-case: import from default environment
         * (and use \0 as a separator)
         */
        return himport_r(&env_htab, (const char *)default_environment,
                                sizeof(default_environment), '\0',
                                H_NOCLEAR | H_INTERACTIVE, 0, nvars, vars);
}

#ifdef CONFIG_ENV_AES
#include <aes.h>
/**
 * env_aes_cbc_get_key() - Get AES-128-CBC key for the environment
 *
 * This function shall return 16-byte array containing AES-128 key used
 * to encrypt and decrypt the environment. This function must be overriden
 * by the implementer as otherwise the environment encryption will not
 * work.
 */
__weak uint8_t *env_aes_cbc_get_key(void)
{
        return NULL;
}

static int env_aes_cbc_crypt(env_t *env, const int enc)
{
        unsigned char *data = env->data;
        uint8_t *key;
        uint8_t key_exp[AES_EXPAND_KEY_LENGTH];
        uint32_t aes_blocks;

        key = env_aes_cbc_get_key();
        if (!key)
                return -EINVAL;

        /* First we expand the key. */
        aes_expand_key(key, key_exp);

        /* Calculate the number of AES blocks to encrypt. */
        aes_blocks = ENV_SIZE / AES_KEY_LENGTH;

        if (enc)
                aes_cbc_encrypt_blocks(key_exp, data, data, aes_blocks);
        else
                aes_cbc_decrypt_blocks(key_exp, data, data, aes_blocks);

        return 0;
}
#else
static inline int env_aes_cbc_crypt(env_t *env, const int enc)
{
        return 0;
}
#endif

/*
 * Check if CRC is valid and (if yes) import the environment.
 * Note that "buf" may or may not be aligned.
 */
int env_import(const char *buf, int check)
{
        env_t *ep = (env_t *)buf;
        int ret;

        if (check) {
                uint32_t crc;

                memcpy(&crc, &ep->crc, sizeof(crc));

                if (crc32(0, ep->data, ENV_SIZE) != crc) {
                        set_default_env("!bad CRC");
                        return 0;
                }
        }

        /* Decrypt the env if desired. */
        ret = env_aes_cbc_crypt(ep, 0);
        if (ret) {
                error("Failed to decrypt env!\n");
                set_default_env("!import failed");
                return ret;
        }

        if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0, 0,
                        0, NULL)) {
                gd->flags |= GD_FLG_ENV_READY;
                return 1;
        }

        error("Cannot import environment: errno = %d\n", errno);

        set_default_env("!import failed");

        return 0;
}

/* Emport the environment and generate CRC for it. */
int env_export(env_t *env_out)
{
        char *res;
        ssize_t len;
        int ret;

        res = (char *)env_out->data;
        len = hexport_r(&env_htab, '\0', 0, &res, ENV_SIZE, 0, NULL);
        if (len < 0) {
                error("Cannot export environment: errno = %d\n", errno);
                return 1;
        }

        /* Encrypt the env if desired. */
        ret = env_aes_cbc_crypt(env_out, 1);
        if (ret)
                return ret;

        env_out->crc = crc32(0, env_out->data, ENV_SIZE);

        return 0;
}

void env_relocate(void)
{
#if defined(CONFIG_NEEDS_MANUAL_RELOC)
        env_reloc();
        env_htab.change_ok += gd->reloc_off;
#endif
        if (gd->env_valid == 0) {
#if defined(CONFIG_ENV_IS_NOWHERE) || defined(CONFIG_SPL_BUILD)
                /* Environment not changable */
                set_default_env(NULL);
#else
                bootstage_error(BOOTSTAGE_ID_NET_CHECKSUM);
                set_default_env("!bad CRC");
#endif
        } else {
                env_relocate_spec();
        }
}

#if defined(CONFIG_AUTO_COMPLETE) && !defined(CONFIG_SPL_BUILD)
int env_complete(char *var, int maxv, char *cmdv[], int bufsz, char *buf)
{
        ENTRY *match;
        int found, idx;

        idx = 0;
        found = 0;
        cmdv[0] = NULL;

        while ((idx = hmatch_r(var, idx, &match, &env_htab))) {
                int vallen = strlen(match->key) + 1;

                if (found >= maxv - 2 || bufsz < vallen)
                        break;

                cmdv[found++] = buf;
                memcpy(buf, match->key, vallen);
                buf += vallen;
                bufsz -= vallen;
        }

        qsort(cmdv, found, sizeof(cmdv[0]), strcmp_compar);

        if (idx)
                cmdv[found++] = "...";

        cmdv[found] = NULL;
        return found;
}
#endif