#include <langinfo.h>
#include <iconv.h>

char* iconv_(char* s, char* from_charset, char* to_charset) {
        iconv_t cd = iconv_open(to_charset, from_charset);
        char* retval = s;
        if (cd != (iconv_t) (-1)) {
                size_t s_len = strlen(retval);
                /* the maximum expansion when converting happens when converting
                   tscii to utf-8; each tscii char can become up to 4 unicode chars
                   and each one of those unicode chars can be 3 bytes long */
                char *buf = alloca(4 * 3 * s_len);
                {
                        char *ptr = buf;
                        size_t ptr_len = 4 * 3 * s_len;
                        if ((iconv(cd, &s, &s_len, &ptr, &ptr_len)) != (size_t) (-1)) {
                                *ptr = 0;
                                retval = buf;
                        }
                }
                iconv_close(cd);
        }
        return strdup(retval);
}