streaming: read loose objects incrementally

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/streaming.c b/streaming.c
index 4fdd567a36a3f6b22a934838b46f6b2cd71fc3ec..06029266443f3e49516abbdaf8afbb4663de9f98 100644 (file)
--- a/streaming.c
+++ b/streaming.c
@@ -61,8 +61,11 @@ struct git_istream {
                } incore;
 
                struct {
-                       int fd; /* open for reading */
-                       /* NEEDSWORK: what else? */
+                       void *mapped;
+                       unsigned long mapsize;
+                       char hdr[32];
+                       int hdr_avail;
+                       int hdr_used;
                } loose;
 
                struct {
@@ -150,9 +153,85 @@ static void close_deflated_stream(struct git_istream *st)
  *
  *****************************************************************/
 
+static read_method_decl(loose)
+{
+       size_t total_read = 0;
+
+       switch (st->z_state) {
+       case z_done:
+               return 0;
+       case z_error:
+               return -1;
+       default:
+               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 (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;
+               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);
+
+               total_read = st->z.next_out - (unsigned char *)buf;
+
+               if (status == Z_STREAM_END) {
+                       git_inflate_end(&st->z);
+                       st->z_state = z_done;
+                       break;
+               }
+               if (status != Z_OK && status != Z_BUF_ERROR) {
+                       git_inflate_end(&st->z);
+                       st->z_state = z_error;
+                       return -1;
+               }
+       }
+       return total_read;
+}
+
+static close_method_decl(loose)
+{
+       close_deflated_stream(st);
+       munmap(st->u.loose.mapped, st->u.loose.mapsize);
+       return 0;
+}
+
+static struct stream_vtbl loose_vtbl = {
+       close_istream_loose,
+       read_istream_loose,
+};
+
 static open_method_decl(loose)
 {
-       return -1; /* for now */
+       st->u.loose.mapped = map_sha1_file(sha1, &st->u.loose.mapsize);
+       if (!st->u.loose.mapped)
+               return -1;
+       if (unpack_sha1_header(&st->z,
+                              st->u.loose.mapped,
+                              st->u.loose.mapsize,
+                              st->u.loose.hdr,
+                              sizeof(st->u.loose.hdr)) < 0) {
+               git_inflate_end(&st->z);
+               munmap(st->u.loose.mapped, st->u.loose.mapsize);
+               return -1;
+       }
+
+       parse_sha1_header(st->u.loose.hdr, &st->size);
+       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->vtbl = &loose_vtbl;
+       return 0;
 }