lib: istream-sized - consistently set stream_errno=EINVAL if stream is too large

Earlier it was sometimes done and sometimes not, depending on whether the
parent istream happened to stop at the expected boundary.

diff --git a/src/lib/istream-sized.c b/src/lib/istream-sized.c
index e5b4cf136b67e79079d51aa77f4f58a64bb265aa..6a6438506cd62a09edd9cc46f4959221d65e3cc7 100644 (file)
--- a/src/lib/istream-sized.c
+++ b/src/lib/istream-sized.c
@@ -43,6 +43,22 @@ i_stream_create_sized_default_error_callback(
        }
 }
 
+static ssize_t
+i_stream_sized_parent_read(struct istream_private *stream, size_t *pos_r)
+{
+       ssize_t ret;
+
+       do {
+               if ((ret = i_stream_read(stream->parent)) == -2)
+                       break;
+
+               stream->istream.stream_errno = stream->parent->stream_errno;
+               stream->istream.eof = stream->parent->eof;
+               stream->buffer = i_stream_get_data(stream->parent, pos_r);
+       } while (*pos_r <= stream->pos && ret > 0);
+       return ret;
+}
+
 static ssize_t i_stream_sized_read(struct istream_private *stream)
 {
        struct sized_istream *sstream =
@@ -53,12 +69,6 @@ static ssize_t i_stream_sized_read(struct istream_private *stream)
        ssize_t ret;
        size_t pos;
 
-       if (stream->istream.v_offset +
-           (stream->pos - stream->skip) >= sstream->size) {
-               stream->istream.eof = TRUE;
-               return -1;
-       }
-
        i_stream_seek(stream->parent, sstream->istream.parent_start_offset +
                      stream->istream.v_offset);
 
@@ -68,14 +78,17 @@ static ssize_t i_stream_sized_read(struct istream_private *stream)
        stream->buffer = i_stream_get_data(stream->parent, &pos);
        if (pos > stream->pos)
                ret = 0;
-       else do {
-               if ((ret = i_stream_read(stream->parent)) == -2)
+       else {
+               if ((ret = i_stream_sized_parent_read(stream, &pos)) == -2)
                        return -2;
+       }
 
-               stream->istream.stream_errno = stream->parent->stream_errno;
-               stream->istream.eof = stream->parent->eof;
-               stream->buffer = i_stream_get_data(stream->parent, &pos);
-       } while (pos <= stream->pos && ret > 0);
+       left = sstream->size - stream->istream.v_offset;
+       if (pos == left && ret != -1) {
+               /* we have exactly the wanted amount of data left, but we
+                  don't know yet if there is more data in parent. */
+               ret = i_stream_sized_parent_read(stream, &pos);
+       }
 
        memset(&data, 0, sizeof(data));
        data.v_offset = stream->istream.v_offset;
@@ -83,14 +96,13 @@ static ssize_t i_stream_sized_read(struct istream_private *stream)
        data.wanted_size = sstream->size;
        data.eof = stream->istream.eof;
 
-       left = sstream->size - stream->istream.v_offset;
-       if (pos == left)
-               stream->istream.eof = TRUE;
-       else if (pos > left) {
+       if (pos == left) {
+               /* we may or may not be finished, depending on whether
+                  parent is at EOF. */
+       } else if (pos > left) {
+               /* parent has more data available than expected */
                error = sstream->error_callback(&data, sstream->error_context);
                io_stream_set_error(&stream->iostream, "%s", error);
-               pos = left;
-               stream->istream.eof = TRUE;
                stream->istream.stream_errno = EINVAL;
                return -1;
        } else if (!stream->istream.eof) {