+/** XXX: could use mmap? */
+void
+copy_in_bits (boost::filesystem::path from, boost::filesystem::path to, boost::function<void (float)> progress)
+{
+ FILE* f = fopen_boost (from, "rb");
+ if (!f) {
+ throw OpenFileError (from, errno, OpenFileError::READ);
+ }
+ FILE* t = fopen_boost (to, "wb");
+ if (!t) {
+ fclose (f);
+ throw OpenFileError (to, errno, OpenFileError::WRITE);
+ }
+
+ /* on the order of a second's worth of copying */
+ boost::uintmax_t const chunk = 20 * 1024 * 1024;
+
+ uint8_t* buffer = static_cast<uint8_t*> (malloc(chunk));
+ if (!buffer) {
+ throw std::bad_alloc ();
+ }
+
+ boost::uintmax_t const total = boost::filesystem::file_size (from);
+ boost::uintmax_t remaining = total;
+
+ while (remaining) {
+ boost::uintmax_t this_time = min (chunk, remaining);
+ size_t N = fread (buffer, 1, chunk, f);
+ if (N < this_time) {
+ fclose (f);
+ fclose (t);
+ free (buffer);
+ throw ReadFileError (from, errno);
+ }
+
+ N = fwrite (buffer, 1, this_time, t);
+ if (N < this_time) {
+ fclose (f);
+ fclose (t);
+ free (buffer);
+ throw WriteFileError (to, errno);
+ }
+
+ progress (1 - float(remaining) / total);
+ remaining -= this_time;
+ }
+
+ fclose (f);
+ fclose (t);
+ free (buffer);
+}
+