Scanning directories on the host filing system.

§1. All of this abstracts the code already found in the platform definitions.

typedef struct scan_directory {
    void *directory_handle;
    char directory_name_written_out[4*MAX_FILENAME_LENGTH];
    CLASS_DEFINITION
} scan_directory;

• The structure scan_directory is private to this section.

§2. The directory name going out has to be transcoded from flat Unicode to whatever the locale encoding is; the filenames coming back have to be transcoded the other way.

scan_directory *Directories::open(pathname *P) {
    scan_directory *D = CREATE(scan_directory);
    TEMPORARY_TEXT(pn);
    WRITE_TO(pn, "%p", P);
    Str::copy_to_locale_string(D->directory_name_written_out, pn, 4*MAX_FILENAME_LENGTH);
    DISCARD_TEXT(pn);
    D->directory_handle = Platform::opendir(D->directory_name_written_out);
    if (D->directory_handle == NULL) return NULL;
    return D;
}

int Directories::next(scan_directory *D, text_stream *leafname) {
    char leafname_Cs[MAX_FILENAME_LENGTH];
    int rv = TRUE;
    while (rv) {
        rv = Platform::readdir(D->directory_handle, D->directory_name_written_out, leafname_Cs);
        if (leafname_Cs[0] != '.') break;
    }
    Str::clear(leafname);
    if (rv) Streams::write_locale_string(leafname, leafname_Cs);
    return rv;
}

void Directories::close(scan_directory *D) {
    Platform::closedir(D->directory_handle);
}