New APIs: lvm-set-filter and lvm-clear-filter.

[libguestfs.git] / src / guestfs.pod

diff --git a/src/guestfs.pod b/src/guestfs.pod
index 0f60c8e..e876016 100644 (file)
--- a/src/guestfs.pod
+++ b/src/guestfs.pod
@@ -612,6 +612,27 @@ the error message was also unintuitive, but we have corrected this
 since.  Like the Bourne shell, we should have used C<guestfish -c
 command> to run commands.
 
+=item guestfish megabyte modifiers don't work right on all commands
+
+In recent guestfish you can use C<1M> to mean 1 megabyte (and
+similarly for other modifiers).  What guestfish actually does is to
+multiply the number part by the modifier part and pass the result to
+the C API.  However this doesn't work for a few APIs which aren't
+expecting bytes, but are already expecting some other unit
+(eg. megabytes).
+
+The most common is L</guestfs_lvcreate>.  The guestfish command:
+
+ lvcreate LV VG 100M
+
+does not do what you might expect.  Instead because
+L</guestfs_lvcreate> is already expecting megabytes, this tries to
+create a 100 I<terabyte> (100 megabytes * megabytes) logical volume.
+The error message you get from this is also a little obscure.
+
+This could be fixed in the generator by specially marking parameters
+and return values which take bytes or other units.
+
 =item Protocol limit of 256 characters for error messages
 
 This limit is both rather small and quite unnecessary.  We should be
@@ -1042,6 +1063,24 @@ The callback function C<cb> will be called when the child process
 becomes ready first time after it has been launched.  (This
 corresponds to a transition from LAUNCHING to the READY state).
 
+=head2 guestfs_set_close_callback
+
+ typedef void (*guestfs_close_cb) (guestfs_h *g, void *opaque);
+ void guestfs_set_close_callback (guestfs_h *g,
+                                  guestfs_close_cb cb,
+                                  void *opaque);
+
+The callback function C<cb> will be called while the handle
+is being closed (synchronously from L</guestfs_close>).
+
+Note that libguestfs installs an L<atexit(3)> handler to try to
+clean up handles that are open when the program exits.  This
+means that this callback might be called indirectly from
+L<exit(3)>, which can cause unexpected problems in higher-level
+languages (eg. if your HLL interpreter has already been cleaned
+up by the time this is called, and if your callback then jumps
+into some HLL function).
+
 =head1 BLOCK DEVICE NAMING
 
 In the kernel there is now quite a profusion of schemata for naming