lib-mail: istream-qp-decoder: For efficiency, avoid copying data between decode buffe...

Instead, use the decode buffer directly as stream buffer.

diff --git a/src/lib-mail/istream-qp-decoder.c b/src/lib-mail/istream-qp-decoder.c
index 3dfdd74dacdebd07c613e4482d237d48f220c936..f41c12fb2cd4d72626a5f746da9a2c6537d3d2b8 100644 (file)
--- a/src/lib-mail/istream-qp-decoder.c
+++ b/src/lib-mail/istream-qp-decoder.c
@@ -32,24 +32,42 @@ static ssize_t i_stream_qp_decoder_read(struct istream_private *stream)
        struct qp_decoder_istream *bstream =
                (struct qp_decoder_istream *)stream;
        const unsigned char *data;
-       size_t size, avail, error_pos;
+       size_t size, error_pos;
        const char *error;
        int ret;
 
        for (;;) {
+               /* remove skipped data from buffer */
+               if (stream->skip > 0) {
+                       i_assert(stream->skip <= bstream->buf->used);
+                       buffer_delete(bstream->buf, 0, stream->skip);
+                       stream->pos -= stream->skip;
+                       stream->skip = 0;
+               }
+
+               stream->buffer = bstream->buf->data;
+
+               i_assert(stream->pos <= bstream->buf->used);
+               if (stream->pos >= bstream->istream.max_buffer_size) {
+                       /* stream buffer still at maximum */
+                       return -2;
+               }
+
                /* if something is already decoded, return as much of it as
                   we can */
                if (bstream->buf->used > 0) {
-                       i_stream_try_alloc(stream, bstream->buf->used, &avail);
-                       if (avail == 0)
-                               return -2;
-                       size = I_MIN(avail, bstream->buf->used);
-                       memcpy(stream->w_buffer + stream->pos,
-                              bstream->buf->data, size);
-                       buffer_delete(bstream->buf, 0, size);
-                       stream->pos += size;
-                       return size;
+                       size_t new_pos, bytes;
+
+                       /* only return up to max_buffer_size bytes, even when buffer
+                          actually has more, as not to confuse the caller */
+                       new_pos = I_MIN
+                               (bstream->buf->used, bstream->istream.max_buffer_size);
+                       bytes = new_pos - stream->pos;
+                       stream->pos = new_pos;
+
+                       return (ssize_t)bytes;
                }
+
                /* need to read more input */
                ret = i_stream_read_data(stream->parent, &data, &size, 0);
                if (ret <= 0) {