public static FileDesc loadFile(Path root, Path file, int blocSize)
throws NoSuchAlgorithmException, FileNotFoundException, IOException {
MessageDigest md = MessageDigest.getInstance("SHA-512");
MessageDigest fileMd = MessageDigest.getInstance("SHA-512");
FileDesc desc = new FileDesc(file.toString(), null, null);
List<Bloc> list = new ArrayList<Bloc>();
try (FileInputStream fis = new FileInputStream(root.resolve(file).toString())) {
byte[] buf = new byte[blocSize];
byte[] h;
int s;
while ((s = fis.read(buf)) != -1) {
int c;
while (s < buf.length && (c = fis.read()) != -1) buf[s++] = (byte) c;
fileMd.update(buf, 0, s);
// padding
byte p = 0;
while (s < buf.length) buf[s++] = ++p;
h = md.digest(buf);
Bloc bloc = new Bloc(RollingChecksum.compute(buf), new Hash(h));
list.add(bloc);
}
h = fileMd.digest();
desc.fileHash = new Hash(h);
desc.blocs = list.toArray(new Bloc[0]);
}
return desc;
}
/** @return matching bloc B bloc -> A bloc */
public static Map<Integer, Integer> diff(FileDesc a, FileDesc b) {
Map<Integer, List<IndexedHash>> blocA = new HashMap<Integer, List<IndexedHash>>();
int i = 0;
for (Bloc bloc : a.blocs) {
List<IndexedHash> l = blocA.get(bloc.roll);
if (l == null) {
l = new ArrayList<IndexedHash>();
blocA.put(bloc.roll, l);
}
l.add(new IndexedHash(i++, bloc.hash));
}
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
loop:
for (i = 0; i < b.blocs.length; i++) {
Bloc blocB = b.blocs[i];
List<IndexedHash> list = blocA.get(blocB.roll);
if (list != null) {
for (IndexedHash bloc : list) {
if (blocB.hash.equals(bloc.h)) {
map.put(i, bloc.i);
continue loop;
}
}
}
}
return map;
}