+
+ /** Implements the F_GETLK and F_SETLK cases of fcntl syscall.
+ * If l_start = 0 and l_len = 0 the lock refers to the entire file.
+ struct flock {
+ short l_type; // lock type: F_UNLCK, F_RDLCK, F_WRLCK
+ short l_whence; // type of l_start: SEEK_SET, SEEK_CUR, SEEK_END
+ long l_start; // starting offset, bytes
+ long l_len; // len = 0 means until EOF
+ short l_pid; // lock owner
+ short l_xxx; // padding
+ };
+ */
+ private int sys_fcntl_lock(FD fd, int cmd, int arg)
+ throws FaultException, IOException {
+ if (arg == 0) { System.out.println("BAD ARG"); return -EINVAL; }
+ int word = memRead(arg);
+ int l_start = memRead(arg+4);
+ int l_len = memRead(arg+8);
+ int l_type = word>>16;
+ int l_whence = word&0x00ff;
+
+ Seekable s = fd.seekable();
+ if (s == null) return -EINVAL;
+
+ switch (l_whence) {
+ case SEEK_SET: break;
+ case SEEK_CUR: l_start += s.pos(); break;
+ case SEEK_END: l_start += s.length(); break;
+ default: return -1;
+ }
+
+ if (cmd != F_GETLK && cmd != F_SETLK) return -EINVAL;
+
+ if (cmd == F_GETLK) {
+ // Check if an l_type lock can be aquired. The only way to
+ // do this within the Java API is to try and create a lock.
+ Seekable.Lock lock = s.lock(l_start, l_len, l_type == F_RDLCK);
+
+ if (lock != null) {
+ // no lock exists
+ memWrite(arg, SEEK_SET|(F_UNLCK<<16));
+ lock.release();
+ }
+
+ return 0;
+ }
+
+ // now processing F_SETLK
+ if (cmd != F_SETLK) return -EINVAL;
+
+ if (l_type == F_UNLCK) {
+ // release all locks that fall within the boundaries given
+ for (int i=0; i < LOCK_MAX; i++) {
+ if (locks[i] == null || !s.equals(locks[i].seekable()))
+ continue;
+
+ int pos = (int)locks[i].position();
+ if (pos < l_start) continue;
+ if (l_start != 0 && l_len != 0) // start/len 0 means unlock all
+ if (pos + locks[i].size() > l_start + l_len)
+ continue;
+
+ locks[i].release();
+ locks[i] = null;
+ }
+ return 0;
+
+ } else if (l_type == F_RDLCK || l_type == F_WRLCK) {
+ // first see if a lock already exists
+ for (int i=0; i < LOCK_MAX; i++) {
+ if (locks[i] == null || !s.equals(locks[i].seekable()))
+ continue;
+ int pos = (int)locks[i].position();
+ int size = (int)locks[i].size();
+ if (l_start < pos && pos + size < l_start + l_len) {
+ // found a lock contained in the new requested lock
+ locks[i].release();
+ locks[i] = null;
+
+ } else if (l_start >= pos && pos + size >= l_start + l_len) {
+ // found a lock that contains the requested lock
+ if (locks[i].isShared() == (l_type == F_RDLCK)) {
+ memWrite(arg+4, pos);
+ memWrite(arg+8, size);
+ return 0;
+ } else {
+ locks[i].release();
+ locks[i] = null;
+ }
+ }
+ }
+
+ // create the lock
+ Seekable.Lock lock = s.lock(l_start, l_len, l_type == F_RDLCK);
+ if (lock == null) return -EAGAIN;
+
+ int i;
+ for (i=0; i < LOCK_MAX; i++)
+ if (locks[i] == null) break;
+ if (i == LOCK_MAX) return -ENOLCK;
+ locks[i] = lock;
+ return 0;
+
+ } else {
+ return -EINVAL;
+ }
+ }
+