#include <string.h>

extern "C"
{
    char** environ = nullptr;

    char* getenv(const char* key)
    {
        char** env = environ;
        size_t len = strlen(key);

        while (*env)
        {
            // Retrieve an environment variable from environ.
            char* var = *(env++);

            // Check for an equals sign, else we just skip this one.
            char* delim = strchr(var, '=');
            if (!delim) continue;

            // Get the length of this variable's key (the part before the equals sign)
            size_t key_length = strcspn(var, "=");
            if (len != key_length) continue;

            // If the keys match, we found it! Return the value (which is just after the equals sign)
            if (!memcmp(key, var, key_length)) { return delim + 1; }
        }

        return nullptr;
    }
}