streaming: create structure for filtered object streams

As explained in a preceding commit, we want to get rid of the union of
stream-type specific data in `struct odb_read_stream`. Create a new
structure for filtered object streams to move towards this design.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/streaming.c b/streaming.c
index 788f04e83ef6c8da14796a56f94ec8f6d0d95ec7..199cca5abb0eaab67530d08e4268ad46633c7d2a 100644 (file)
--- a/streaming.c
+++ b/streaming.c
@@ -19,16 +19,6 @@ typedef ssize_t (*read_istream_fn)(struct odb_read_stream *, char *, size_t);
 
 #define FILTER_BUFFER (1024*16)
 
-struct filtered_istream {
-       struct odb_read_stream *upstream;
-       struct stream_filter *filter;
-       char ibuf[FILTER_BUFFER];
-       char obuf[FILTER_BUFFER];
-       int i_end, i_ptr;
-       int o_end, o_ptr;
-       int input_finished;
-};
-
 struct odb_read_stream {
        close_istream_fn close;
        read_istream_fn read;
@@ -37,10 +27,6 @@ struct odb_read_stream {
        unsigned long size; /* inflated size of full object */
        git_zstream z;
        enum { z_unused, z_used, z_done, z_error } z_state;
-
-       union {
-               struct filtered_istream filtered;
-       } u;
 };
 
 /*****************************************************************
@@ -62,16 +48,28 @@ static void close_deflated_stream(struct odb_read_stream *st)
  *
  *****************************************************************/
 
-static int close_istream_filtered(struct odb_read_stream *st)
+struct odb_filtered_read_stream {
+       struct odb_read_stream base;
+       struct odb_read_stream *upstream;
+       struct stream_filter *filter;
+       char ibuf[FILTER_BUFFER];
+       char obuf[FILTER_BUFFER];
+       int i_end, i_ptr;
+       int o_end, o_ptr;
+       int input_finished;
+};
+
+static int close_istream_filtered(struct odb_read_stream *_fs)
 {
-       free_stream_filter(st->u.filtered.filter);
-       return close_istream(st->u.filtered.upstream);
+       struct odb_filtered_read_stream *fs = (struct odb_filtered_read_stream *)_fs;
+       free_stream_filter(fs->filter);
+       return close_istream(fs->upstream);
 }
 
-static ssize_t read_istream_filtered(struct odb_read_stream *st, char *buf,
+static ssize_t read_istream_filtered(struct odb_read_stream *_fs, char *buf,
                                     size_t sz)
 {
-       struct filtered_istream *fs = &(st->u.filtered);
+       struct odb_filtered_read_stream *fs = (struct odb_filtered_read_stream *)_fs;
        size_t filled = 0;
 
        while (sz) {
@@ -131,19 +129,17 @@ static ssize_t read_istream_filtered(struct odb_read_stream *st, char *buf,
 static struct odb_read_stream *attach_stream_filter(struct odb_read_stream *st,
                                                    struct stream_filter *filter)
 {
-       struct odb_read_stream *ifs = xmalloc(sizeof(*ifs));
-       struct filtered_istream *fs = &(ifs->u.filtered);
+       struct odb_filtered_read_stream *fs;
 
-       ifs->close = close_istream_filtered;
-       ifs->read = read_istream_filtered;
+       CALLOC_ARRAY(fs, 1);
+       fs->base.close = close_istream_filtered;
+       fs->base.read = read_istream_filtered;
        fs->upstream = st;
        fs->filter = filter;
-       fs->i_end = fs->i_ptr = 0;
-       fs->o_end = fs->o_ptr = 0;
-       fs->input_finished = 0;
-       ifs->size = -1; /* unknown */
-       ifs->type = st->type;
-       return ifs;
+       fs->base.size = -1; /* unknown */
+       fs->base.type = st->type;
+
+       return &fs->base;
 }
 
 /*****************************************************************