Add Erlang bindings.

[libguestfs.git] / src / guestfs.pod

diff --git a/src/guestfs.pod b/src/guestfs.pod
index db9d8f0..7ff313d 100644 (file)
--- a/src/guestfs.pod
+++ b/src/guestfs.pod
@@ -42,8 +42,8 @@ FUSE.
 
 Libguestfs is a library that can be linked with C and C++ management
 programs (or management programs written in OCaml, Perl, Python, Ruby,
 
 Libguestfs is a library that can be linked with C and C++ management
 programs (or management programs written in OCaml, Perl, Python, Ruby,

-Java, PHP, Haskell or C#).  You can also use it from shell scripts or the
-command line.
+Java, PHP, Erlang, Haskell or C#).  You can also use it from shell
+scripts or the command line.

 
 You don't need to be root to use libguestfs, although obviously you do
 need enough permissions to access the disk images.
 
 You don't need to be root to use libguestfs, although obviously you do
 need enough permissions to access the disk images.


@@ -719,6 +719,10 @@ used.
 The C# bindings are highly experimental.  Please read the warnings
 at the top of C<csharp/Libguestfs.cs>.
 
 The C# bindings are highly experimental.  Please read the warnings
 at the top of C<csharp/Libguestfs.cs>.
 

+=item B<Erlang>
+
+See L<guestfs-erlang(3)>.
+

 =item B<Haskell>
 
 This is the only language binding that is working but incomplete.
 =item B<Haskell>
 
 This is the only language binding that is working but incomplete.


@@ -1344,8 +1348,6 @@ been printed to C<stderr> before the program exits.
 For other programs the caller will almost certainly want to install an
 alternate error handler or do error handling in-line like this:
 
 For other programs the caller will almost certainly want to install an
 alternate error handler or do error handling in-line like this:
 

- g = guestfs_create ();
- 

  /* This disables the default behaviour of printing errors
     on stderr. */
  guestfs_set_error_handler (g, NULL, NULL);
  /* This disables the default behaviour of printing errors
     on stderr. */
  guestfs_set_error_handler (g, NULL, NULL);


@@ -1354,9 +1356,12 @@ alternate error handler or do error handling in-line like this:
    /* Examine the error message and print it etc. */
    char *msg = guestfs_last_error (g);
    int errnum = guestfs_last_errno (g);
    /* Examine the error message and print it etc. */
    char *msg = guestfs_last_error (g);
    int errnum = guestfs_last_errno (g);

-   fprintf (stderr, "%s\n", msg);
+   fprintf (stderr, "%s", msg);
+   if (errnum != 0)
+     fprintf (stderr, ": %s", strerror (errnum));
+   fprintf (stderr, "\n");

    /* ... */
    /* ... */

-  }
+ }

 
 Out of memory errors are handled differently.  The default action is
 to call L<abort(3)>.  If this is undesirable, then you can set a
 
 Out of memory errors are handled differently.  The default action is
 to call L<abort(3)>.  If this is undesirable, then you can set a


@@ -1452,8 +1457,8 @@ Returns the current error handler callback.
 =head2 guestfs_set_out_of_memory_handler
 
  typedef void (*guestfs_abort_cb) (void);
 =head2 guestfs_set_out_of_memory_handler
 
  typedef void (*guestfs_abort_cb) (void);

- int guestfs_set_out_of_memory_handler (guestfs_h *g,
-                                        guestfs_abort_cb);
+ void guestfs_set_out_of_memory_handler (guestfs_h *g,
+                                         guestfs_abort_cb);

 
 The callback C<cb> will be called if there is an out of memory
 situation.  I<Note this callback must not return>.
 
 The callback C<cb> will be called if there is an out of memory
 situation.  I<Note this callback must not return>.


@@ -1832,6 +1837,21 @@ If no callback is registered: the messages are sent to stderr.  You
 can override the printing of trace messages to stderr by setting up a
 callback.
 
 can override the printing of trace messages to stderr by setting up a
 callback.
 

+=item GUESTFS_EVENT_ENTER
+(payload type: function name)
+
+The callback function is called whenever a libguestfs function
+is entered.
+
+The payload is a string which contains the name of the function
+that we are entering (not including C<guestfs_> prefix).
+
+Note that libguestfs functions can call themselves, so you may
+see many events from a single call.  A few libguestfs functions
+do not generate this event.
+
+If no callback is registered: the event is ignored.
+

 =back
 
 =head3 guestfs_set_event_callback
 =back
 
 =head3 guestfs_set_event_callback


@@ -2227,6 +2247,99 @@ callback to receive these messages.
 
 =head1 INTERNALS
 
 
 =head1 INTERNALS
 

+=head2 APPLIANCE BOOT PROCESS
+
+This process has evolved and continues to evolve.  The description
+here corresponds only to the current version of libguestfs and is
+provided for information only.
+
+In order to follow the stages involved below, enable libguestfs
+debugging (set the environment variable C<LIBGUESTFS_DEBUG=1>).
+
+=over 4
+
+=item Create the appliance
+
+C<febootstrap-supermin-helper> is invoked to create the kernel, a
+small initrd and the appliance.
+
+The appliance is cached in C</var/tmp/.guestfs-E<lt>UIDE<gt>> (or in
+another directory if C<TMPDIR> is set).
+
+For a complete description of how the appliance is created and cached,
+read the L<febootstrap(8)> and L<febootstrap-supermin-helper(8)> man
+pages.
+
+=item Start qemu and boot the kernel
+
+qemu is invoked to boot the kernel.
+
+=item Run the initrd
+
+C<febootstrap-supermin-helper> builds a small initrd.  The initrd is
+not the appliance.  The purpose of the initrd is to load enough kernel
+modules in order that the appliance itself can be mounted and started.
+
+The initrd is a cpio archive called
+C</var/tmp/.guestfs-E<lt>UIDE<gt>/initrd>.
+
+When the initrd has started you will see messages showing that kernel
+modules are being loaded, similar to this:
+
+ febootstrap: ext2 mini initrd starting up
+ febootstrap: mounting /sys
+ febootstrap: internal insmod libcrc32c.ko
+ febootstrap: internal insmod crc32c-intel.ko
+
+=item Find and mount the appliance device
+
+The appliance is a sparse file containing an ext2 filesystem which
+contains a familiar (although reduced in size) Linux operating system.
+It would normally be called C</var/tmp/.guestfs-E<lt>UIDE<gt>/root>.
+
+The regular disks being inspected by libguestfs are the first
+devices exposed by qemu (eg. as C</dev/vda>).
+
+The last disk added to qemu is the appliance itself (eg. C</dev/vdb>
+if there was only one regular disk).
+
+Thus the final job of the initrd is to locate the appliance disk,
+mount it, and switch root into the appliance, and run C</init> from
+the appliance.
+
+If this works successfully you will see messages such as:
+
+ febootstrap: picked /sys/block/vdb/dev as root device
+ febootstrap: creating /dev/root as block special 252:16
+ febootstrap: mounting new root on /root
+ febootstrap: chroot
+ Starting /init script ...
+
+Note that C<Starting /init script ...> indicates that the appliance's
+init script is now running.
+
+=item Initialize the appliance
+
+The appliance itself now initializes itself.  This involves starting
+certain processes like C<udev>, possibly printing some debug
+information, and finally running the daemon (C<guestfsd>).
+
+=item The daemon
+
+Finally the daemon (C<guestfsd>) runs inside the appliance.  If it
+runs you should see:
+
+ verbose daemon enabled
+
+The daemon expects to see a named virtio-serial port exposed by qemu
+and connected on the other end to the library.
+
+The daemon connects to this port (and hence to the library) and sends
+a four byte message C<GUESTFS_LAUNCH_FLAG>, which initiates the
+communication protocol (see below).
+
+=back
+

 =head2 COMMUNICATION PROTOCOL
 
 Don't rely on using this protocol directly.  This section documents
 =head2 COMMUNICATION PROTOCOL
 
 Don't rely on using this protocol directly.  This section documents


@@ -2789,6 +2902,8 @@ will work with libguestfs.
 
 =item C<csharp>
 
 
 =item C<csharp>
 

+=item C<erlang>
+

 =item C<haskell>
 
 =item C<java>
 =item C<haskell>
 
 =item C<java>


@@ -2817,6 +2932,11 @@ about the stable branch policy.
 
 =item *
 
 
 =item *
 

+Check C<make && make check> works on at least Fedora, Debian and
+Ubuntu.
+
+=item *
+

 Finalize RELEASE-NOTES.
 
 =item *
 Finalize RELEASE-NOTES.
 
 =item *


@@ -2961,6 +3081,16 @@ be reached in practice.  See the source code for more information.
 
 =over 4
 
 
 =over 4
 

+=item FEBOOTSTRAP_KERNEL
+
+=item FEBOOTSTRAP_MODULES
+
+These two environment variables allow the kernel that libguestfs uses
+in the appliance to be selected.  If C<$FEBOOTSTRAP_KERNEL> is not
+set, then the most recent host kernel is chosen.  For more information
+about kernel selection, see L<febootstrap-supermin-helper(8)>.  This
+feature is only available in febootstrap E<ge> 3.8.
+

 =item LIBGUESTFS_APPEND
 
 Pass additional options to the guest kernel.
 =item LIBGUESTFS_APPEND
 
 Pass additional options to the guest kernel.


@@ -3011,6 +3141,7 @@ enough.
 =head1 SEE ALSO
 
 L<guestfs-examples(3)>,
 =head1 SEE ALSO
 
 L<guestfs-examples(3)>,

+L<guestfs-erlang(3)>,

 L<guestfs-java(3)>,
 L<guestfs-ocaml(3)>,
 L<guestfs-perl(3)>,
 L<guestfs-java(3)>,
 L<guestfs-ocaml(3)>,
 L<guestfs-perl(3)>,


@@ -3036,6 +3167,7 @@ L<virt-tar-out(1)>,
 L<virt-win-reg(1)>,
 L<qemu(1)>,
 L<febootstrap(1)>,
 L<virt-win-reg(1)>,
 L<qemu(1)>,
 L<febootstrap(1)>,

+L<febootstrap-supermin-helper(8)>,

 L<hivex(3)>,
 L<http://libguestfs.org/>.
 
 L<hivex(3)>,
 L<http://libguestfs.org/>.