o_stream_send_istream(): Don't do backwards copying if the area doesn't really overlap.

--HG--
branch : HEAD

diff --git a/src/lib/ostream-file.c b/src/lib/ostream-file.c
index 6f9456338196c2c1e28c8b803cf0cdc3c39ac292..187648a5cb33cba38a4da08ca8d7a27ebe30764a 100644 (file)
--- a/src/lib/ostream-file.c
+++ b/src/lib/ostream-file.c
@@ -776,7 +776,7 @@ static off_t o_stream_file_send_istream(struct ostream_private *outstream,
 {
        struct file_ostream *foutstream = (struct file_ostream *)outstream;
        const struct stat *st;
-       off_t ret;
+       off_t in_abs_offset, ret;
        int in_fd;
 
        in_fd = i_stream_get_fd(instream);
@@ -791,16 +791,17 @@ static off_t o_stream_file_send_istream(struct ostream_private *outstream,
                }
                i_assert(instream->v_offset <= (uoff_t)st->st_size);
 
-               ret = (off_t)outstream->ostream.offset -
-                       (off_t)(instream->real_stream->abs_start_offset +
-                               instream->v_offset);
+               in_abs_offset = instream->real_stream->abs_start_offset +
+                       instream->v_offset;
+               ret = (off_t)outstream->ostream.offset - in_abs_offset;
                if (ret == 0) {
                        /* copying data over itself. we don't really
                           need to do that, just fake it. */
                        return st->st_size - instream->v_offset;
                }
-               if (ret > 0) {
+               if (ret > 0 && st->st_size > ret) {
                        /* overlapping */
+                       i_assert(instream->seekable);
                        return io_stream_copy_backwards(outstream, instream,
                                                        st->st_size);
                }