streaming: create structure for loose 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 loose 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 35307d72295988f15c604bd1b8694c156defac3c..ac7b3026f5a6049f67cb96b0b1923d38506ba151 100644 (file)
--- a/streaming.c
+++ b/streaming.c
@@ -39,14 +39,6 @@ struct odb_read_stream {
        enum { z_unused, z_used, z_done, z_error } z_state;
 
        union {
-               struct {
-                       void *mapped;
-                       unsigned long mapsize;
-                       char hdr[32];
-                       int hdr_avail;
-                       int hdr_used;
-               } loose;
-
                struct {
                        struct packed_git *pack;
                        off_t pos;
@@ -165,11 +157,21 @@ static struct odb_read_stream *attach_stream_filter(struct odb_read_stream *st,
  *
  *****************************************************************/
 
-static ssize_t read_istream_loose(struct odb_read_stream *st, char *buf, size_t sz)
+struct odb_loose_read_stream {
+       struct odb_read_stream base;
+       void *mapped;
+       unsigned long mapsize;
+       char hdr[32];
+       int hdr_avail;
+       int hdr_used;
+};
+
+static ssize_t read_istream_loose(struct odb_read_stream *_st, char *buf, size_t sz)
 {
+       struct odb_loose_read_stream *st = (struct odb_loose_read_stream *)_st;
        size_t total_read = 0;
 
-       switch (st->z_state) {
+       switch (st->base.z_state) {
        case z_done:
                return 0;
        case z_error:
@@ -178,42 +180,43 @@ static ssize_t read_istream_loose(struct odb_read_stream *st, char *buf, size_t
                break;
        }
 
-       if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
-               size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
+       if (st->hdr_used < st->hdr_avail) {
+               size_t to_copy = st->hdr_avail - st->hdr_used;
                if (sz < to_copy)
                        to_copy = sz;
-               memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
-               st->u.loose.hdr_used += to_copy;
+               memcpy(buf, st->hdr + st->hdr_used, to_copy);
+               st->hdr_used += to_copy;
                total_read += to_copy;
        }
 
        while (total_read < sz) {
                int status;
 
-               st->z.next_out = (unsigned char *)buf + total_read;
-               st->z.avail_out = sz - total_read;
-               status = git_inflate(&st->z, Z_FINISH);
+               st->base.z.next_out = (unsigned char *)buf + total_read;
+               st->base.z.avail_out = sz - total_read;
+               status = git_inflate(&st->base.z, Z_FINISH);
 
-               total_read = st->z.next_out - (unsigned char *)buf;
+               total_read = st->base.z.next_out - (unsigned char *)buf;
 
                if (status == Z_STREAM_END) {
-                       git_inflate_end(&st->z);
-                       st->z_state = z_done;
+                       git_inflate_end(&st->base.z);
+                       st->base.z_state = z_done;
                        break;
                }
                if (status != Z_OK && (status != Z_BUF_ERROR || total_read < sz)) {
-                       git_inflate_end(&st->z);
-                       st->z_state = z_error;
+                       git_inflate_end(&st->base.z);
+                       st->base.z_state = z_error;
                        return -1;
                }
        }
        return total_read;
 }
 
-static int close_istream_loose(struct odb_read_stream *st)
+static int close_istream_loose(struct odb_read_stream *_st)
 {
-       close_deflated_stream(st);
-       munmap(st->u.loose.mapped, st->u.loose.mapsize);
+       struct odb_loose_read_stream *st = (struct odb_loose_read_stream *)_st;
+       close_deflated_stream(&st->base);
+       munmap(st->mapped, st->mapsize);
        return 0;
 }
 
@@ -222,7 +225,7 @@ static int open_istream_loose(struct odb_read_stream **out,
                              const struct object_id *oid)
 {
        struct object_info oi = OBJECT_INFO_INIT;
-       struct odb_read_stream *st;
+       struct odb_loose_read_stream *st;
        struct odb_source *source;
        unsigned long mapsize;
        void *mapped;
@@ -244,8 +247,8 @@ static int open_istream_loose(struct odb_read_stream **out,
         */
        CALLOC_ARRAY(st, 1);
 
-       switch (unpack_loose_header(&st->z, mapped, mapsize, st->u.loose.hdr,
-                                   sizeof(st->u.loose.hdr))) {
+       switch (unpack_loose_header(&st->base.z, mapped, mapsize, st->hdr,
+                                   sizeof(st->hdr))) {
        case ULHR_OK:
                break;
        case ULHR_BAD:
@@ -253,26 +256,26 @@ static int open_istream_loose(struct odb_read_stream **out,
                goto error;
        }
 
-       oi.sizep = &st->size;
-       oi.typep = &st->type;
+       oi.sizep = &st->base.size;
+       oi.typep = &st->base.type;
 
-       if (parse_loose_header(st->u.loose.hdr, &oi) < 0 || st->type < 0)
+       if (parse_loose_header(st->hdr, &oi) < 0 || st->base.type < 0)
                goto error;
 
-       st->u.loose.mapped = mapped;
-       st->u.loose.mapsize = mapsize;
-       st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
-       st->u.loose.hdr_avail = st->z.total_out;
-       st->z_state = z_used;
-       st->close = close_istream_loose;
-       st->read = read_istream_loose;
+       st->mapped = mapped;
+       st->mapsize = mapsize;
+       st->hdr_used = strlen(st->hdr) + 1;
+       st->hdr_avail = st->base.z.total_out;
+       st->base.z_state = z_used;
+       st->base.close = close_istream_loose;
+       st->base.read = read_istream_loose;
 
-       *out = st;
+       *out = &st->base;
 
        return 0;
 error:
-       git_inflate_end(&st->z);
-       munmap(st->u.loose.mapped, st->u.loose.mapsize);
+       git_inflate_end(&st->base.z);
+       munmap(st->mapped, st->mapsize);
        free(st);
        return -1;
 }