launch: Store drive information in guestfs_h

This is a NFC on its own, but provides a place-holder for drive metadata which
can be used after launch.

Fixes by RWMJ:

 - Fix the tests: this requires a new internal function 'debug-drives'
   that dumps out the g->drives information so it can be checked in
   two of the tests.  Previously these tests used 'debug-cmdline'.

 - Test file existence / use_cache_off in the add_drive_opts function,
   not when launching qemu in the child process.

 - Call free along error paths.

 - Add comments.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/guestfs.c b/src/guestfs.c
index f7ad9674..170d0d32 100644
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -206,6 +206,7 @@ guestfs_close (guestfs_h *g)
   g->events = NULL;
 
   guestfs___free_inspect_info (g);
+  guestfs___free_drives (&g->drives);
 
   /* Close sockets. */
   if (g->fd[0] >= 0)
@@ -994,3 +995,21 @@ guestfs___free_string_list (char **argv)
     free (argv[i]);
   free (argv);
 }
+
+void
+guestfs___free_drives (struct drive **drives)
+{
+  struct drive *i = *drives;
+  *drives = NULL;
+
+  while (i != NULL) {
+    struct drive *next = i->next;
+
+    free (i->path);
+    free (i->format);
+    free (i->iface);
+    free (i);
+
+    i = next;
+  }
+}