input/CdioParanoia: remove loop from Read()

The Read() method is not required to fill the whole buffer.  By
returning as soon as at least one byte was read, we allow faster
cancellation.

NEWS

@@ -3,6 +3,7 @@ ver 0.23.8 (not yet released)
   - curl: fix crash if web server does not understand WebDAV
 * input
   - cdio_paranoia: fix crash if no drive was found
+  - cdio_paranoia: faster cancellation
 * output
   - pipewire: fix crash with PipeWire 0.3.53
 * mixer

src/input/plugins/CdioParanoiaInputPlugin.cxx

@@ -288,13 +288,9 @@ size_t
 CdioParanoiaInputStream::Read(std::unique_lock<Mutex> &,
 			      void *ptr, size_t length)
 {
-	size_t nbytes = 0;
-	char *wptr = (char *) ptr;
-
-	while (length > 0) {
 	/* end of track ? */
 	if (IsEOF())
-			break;
+		return 0;
 
 	//current sector was changed ?
 	const int16_t *rbuf;
@@ -330,19 +326,13 @@ CdioParanoiaInputStream::Read(std::unique_lock<Mutex> &,
 	assert(diff >= 0 && diff < CDIO_CD_FRAMESIZE_RAW);
 
 	const size_t maxwrite = CDIO_CD_FRAMESIZE_RAW - diff;  //# of bytes pending in current buffer
-		const size_t len = std::min(length, maxwrite);
+	const std::size_t nbytes = std::min(length, maxwrite);
 
 	//skip diff bytes from this lsn
-		memcpy(wptr, ((const char *)rbuf) + diff, len);
-		//update pointer
-		wptr += len;
-		nbytes += len;
+	memcpy(ptr, ((const char *)rbuf) + diff, nbytes);
 
 	//update offset
-		offset += len;
-		//update length
-		length -= len;
-	}
+	offset += nbytes;
 
 	return nbytes;
 }