Method copyFile

3ds/source/io.cpp:186–259

}

Result io::copyFile(
    FS_Archive srcArch, FS_Archive dstArch, const std::u16string& srcPath, const std::u16string& dstPath, ProgressSink& sink, u8* buffer)
{
    u32 size = 0;
    FSStream input(srcArch, srcPath, FS_OPEN_READ);
    if (input.good()) {
        size = input.size() > BUFFER_SIZE ? BUFFER_SIZE : input.size();
    }
    else {
        Logging::error("Failed to open source file {} during copy with result {}.", StringUtils::UTF16toUTF8(srcPath), input.result());
        return input.result();
    }

    FSStream output(dstArch, dstPath, FS_OPEN_WRITE, input.size());
    if (!output.good()) {
        Logging::error("Failed to open destination file {} during copy with result {}.", StringUtils::UTF16toUTF8(dstPath), output.result());
        input.close();
        return output.result();
    }

    size_t slashpos = srcPath.rfind(StringUtils::UTF8toUTF16("/"));
    sink.startFile(srcPath.substr(slashpos + 1, srcPath.length() - slashpos - 1), input.size());

    Result res = 0;
    u32 offset = 0;
    u32 chunk  = size; // shrinks toward the readable-data boundary on RES_FS_PAST_DATA
    do {
        if (sink.cancelled()) {
            break;
        }
        u32 rd = input.read(buffer, chunk);
        if (R_FAILED(input.result())) {
            // Sparse extdata: this offset+chunk runs past the file's real data. Halve
            // the request to recover any readable prefix at this offset; once even a
            // single byte can't be read here, we've hit the true end of data — stop
            // this file cleanly and keep the backup going.
            if ((u32)input.result() == RES_FS_PAST_DATA) {
                if (chunk > 1) {
                    chunk /= 2;
                    continue;
                }
                Logging::info("Reached end of readable data for {} at offset {} (sparse extdata); backing up {} bytes.",
                    StringUtils::UTF16toUTF8(srcPath), offset, offset);
                break;
            }
            res = input.result();
            Logging::error("Read failure during copy of {} with result 0x{:08X}.", StringUtils::UTF16toUTF8(srcPath), (u32)res);
            break;
        }
        if (rd == 0) {
            break;
        }
        u32 wt = output.write(buffer, rd);
        if (R_FAILED(output.result())) {
            res = output.result();
            Logging::error("Write failure during copy of {} with result 0x{:08X}.", StringUtils::UTF16toUTF8(dstPath), (u32)res);
            break;
        }