1 files changed, 34 insertions, 0 deletions
diff --git a/format/packfile/ingest/use.go b/format/packfile/ingest/use.go
new file mode 100644
index 00000000..97f8757a
--- /dev/null
+++ b/format/packfile/ingest/use.go
@@ -0,0 +1,34 @@
+package ingest
+
+import (
+	"fmt"
+	"hash/crc32"
+)
+
+// use consumes n unread bytes and updates accounting/checksum state.
+func (scanner *streamScanner) use(n int) error {
+	if n < 0 || n > scanner.n-scanner.off {
+		return fmt.Errorf("packfile/ingest: invalid consume length %d", n)
+	}
+
+	if n == 0 {
+		return nil
+	}
+
+	chunk := scanner.buf[scanner.off : scanner.off+n]
+	if scanner.hashEnabled {
+		_, err := scanner.hash.Write(chunk)
+		if err != nil {
+			return err
+		}
+	}
+
+	if scanner.inEntryCRC {
+		scanner.entryCRC = crc32.Update(scanner.entryCRC, crc32.IEEETable, chunk)
+	}
+
+	scanner.off += n
+	scanner.consumed += uint64(n)
+
+	return nil
+}