libdpkg: Refactor parsedb_new() out from parsedb_open()

lib/dpkg/parse.c

@@ -502,29 +502,42 @@ parse_get_type(struct parsedb_state *ps, enum parsedbflags flags)
 }
 
 /**
- * Open a file for RFC-822 parsing.
+ * Create a new deb822 parser context.
  */
 struct parsedb_state *
-parsedb_open(const char *filename, enum parsedbflags flags)
+parsedb_new(const char *filename, int fd, enum parsedbflags flags)
 {
   struct parsedb_state *ps;
-  struct stat st;
-  int fd;
 
   ps = m_malloc(sizeof(*ps));
   ps->filename = filename;
   ps->type = parse_get_type(ps, flags);
   ps->flags = flags;
+  ps->fd = fd;
   ps->lno = 0;
   ps->pkg = NULL;
   ps->pkgbin = NULL;
 
+  return ps;
+}
+
+/**
+ * Open a file for deb822 parsing.
+ */
+struct parsedb_state *
+parsedb_open(const char *filename, enum parsedbflags flags)
+{
+  struct parsedb_state *ps;
+  struct stat st;
+  int fd;
+
   fd = open(filename, O_RDONLY);
   if (fd == -1)
     ohshite(_("failed to open package info file `%.255s' for reading"),
             filename);
 
-  ps->fd = fd;
+  ps = parsedb_new(filename, fd, flags);
+
   push_cleanup(cu_closefd, ~ehflag_normaltidy, NULL, 0, 1, &ps->fd);
 
   if (fstat(ps->fd, &st) == -1)

lib/dpkg/parsedump.h

@@ -69,6 +69,8 @@ struct field_state {
 	int *fieldencountered;
 };
 
+struct parsedb_state *
+parsedb_new(const char *filename, int fd, enum parsedbflags flags);
 struct parsedb_state *
 parsedb_open(const char *filename, enum parsedbflags flags);
 void