InputStream: make offset_type unsigned

src/decoder/plugins/OpusDecoderPlugin.cxx

@@ -187,8 +187,6 @@ LoadEOSPacket(InputStream &is, Decoder *decoder, int serialno,
 		return -1;
 
 	const auto old_offset = is.GetOffset();
-	if (old_offset < 0)
-		return -1;
 
 	/* create temporary Ogg objects for seeking and parsing the
 	   EOS packet */
@@ -335,7 +333,6 @@ MPDOpusDecoder::Seek(OggSyncState &oy, double where_s)
 	assert(eos_granulepos > 0);
 	assert(input_stream.IsSeekable());
 	assert(input_stream.KnownSize());
-	assert(input_stream.GetOffset() >= 0);
 
 	const ogg_int64_t where_granulepos(where_s * opus_sample_rate);
 

src/input/AsyncInputStream.cxx

@@ -116,9 +116,6 @@ AsyncInputStream::Seek(offset_type new_offset, Error &error)
 	if (!IsSeekable())
 		return false;
 
-	if (new_offset < 0)
-		return false;
-
 	/* check if we can fast-forward the buffer */
 
 	while (new_offset > offset) {

src/input/InputStream.hxx

@@ -35,7 +35,7 @@ struct Tag;
 
 class InputStream {
 public:
-	typedef int64_t offset_type;
+	typedef uint64_t offset_type;
 
 private:
 	/**
@@ -236,8 +236,6 @@ public:
 
 	void AddOffset(offset_type delta) {
 		assert(ready);
-		assert(offset >= 0);
-		assert(delta >= 0);
 
 		offset += delta;
 	}
@@ -253,7 +251,6 @@ public:
 	offset_type GetRest() const {
 		assert(ready);
 		assert(KnownSize());
-		assert(offset >= 0);
 
 		return size - offset;
 	}

src/input/plugins/CdioParanoiaInputPlugin.cxx

@@ -274,7 +274,7 @@ input_cdio_open(const char *uri,
 bool
 CdioParanoiaInputStream::Seek(offset_type new_offset, Error &error)
 {
-	if (new_offset < 0 || new_offset > size) {
+	if (new_offset > size) {
 		error.Format(cdio_domain, "Invalid offset to seek %ld (%ld)",
 			     (long int)new_offset, (long int)size);
 		return false;

src/input/plugins/FileInputPlugin.cxx

@@ -101,13 +101,13 @@ input_file_open(const char *filename,
 bool
 FileInputStream::Seek(offset_type new_offset, Error &error)
 {
-	new_offset = (offset_type)lseek(fd, (off_t)new_offset, SEEK_SET);
-	if (new_offset < 0) {
+	auto result = lseek(fd, (off_t)new_offset, SEEK_SET);
+	if (result < 0) {
 		error.SetErrno("Failed to seek");
 		return false;
 	}
 
-	offset = new_offset;
+	offset = (offset_type)result;
 	return true;
 }