Many non-daemon functions are now auto-generated.

[libguestfs.git] / guestfs.pod

diff --git a/guestfs.pod b/guestfs.pod
index 63bd14c..8fdc93d 100644 (file)
--- a/guestfs.pod
+++ b/guestfs.pod
@@ -6,12 +6,14 @@ guestfs - Library for accessing and modifying virtual machine images
 
 =head1 SYNOPSIS
 
 
 =head1 SYNOPSIS
 

- guestfs_h handle = guestfs_create ();
+ #include <guestfs.h>
+ 
+ guestfs_h *handle = guestfs_create ();

  guestfs_add_drive (handle, "guest.img");
  guestfs_launch (handle);
  guestfs_wait_ready (handle);
  guestfs_mount (handle, "/dev/sda1", "/");
  guestfs_add_drive (handle, "guest.img");
  guestfs_launch (handle);
  guestfs_wait_ready (handle);
  guestfs_mount (handle, "/dev/sda1", "/");

- guestfs_touch_file (handle, "/hello");
+ guestfs_touch (handle, "/hello");

  guestfs_sync (handle);
  guestfs_close (handle);
 
  guestfs_sync (handle);
  guestfs_close (handle);
 


@@ -32,44 +34,167 @@ schemes, qcow, qcow2, vmdk.
 
 Libguestfs provides ways to enumerate guest storage (eg. partitions,
 LVs, what filesystem is in each LV, etc.).  It can also run commands
 
 Libguestfs provides ways to enumerate guest storage (eg. partitions,
 LVs, what filesystem is in each LV, etc.).  It can also run commands

-in the context of the guest.  Also you can mount guest filesystems on
-the host (requires root privs and NFS).
+in the context of the guest.  Also you can access filesystems over FTP.

 
 Libguestfs is a library that can be linked with C and C++ management
 
 Libguestfs is a library that can be linked with C and C++ management

-programs (or management programs written in other languages, if people
-contribute the language bindings).  You can also use it from shell
-scripts or the command line.
+programs (or management programs written in OCaml or Perl).
+You can also use it from shell scripts or the command line.

 
 

-=head1 CONNECTION MANAGEMENT
+You don't need to be root to use libguestfs, although obviously you do
+need enough permissions to access the disk images.

 
 

+=head1 CONNECTION MANAGEMENT

 
 

+If you are using the high-level API, then you should call the
+functions in the following order:

 
 

+ guestfs_h *handle = guestfs_create ();
+ 
+ guestfs_add_drive (handle, "guest.img");
+ /* call guestfs_add_drive additional times if the guest has
+  * multiple disks
+  */
+ 
+ guestfs_launch (handle);
+ guestfs_wait_ready (handle);

 
 

+ /* now you can examine what partitions, LVs etc are available
+  * you have to mount / at least
+  */ 
+ guestfs_mount (handle, "/dev/sda1", "/");

 
 

+ /* now you can perform actions on the guest disk image */
+ guestfs_touch (handle, "/hello");
+ 
+ /* you only need to call guestfs_sync if you have made
+  * changes to the guest image
+  */
+ guestfs_sync (handle);
+ 
+ guestfs_close (handle);

 
 

-=head1 CONFIGURATION MANAGEMENT
+C<guestfs_wait_ready> and all of the actions including C<guestfs_sync>
+are blocking calls.  You can use the low-level event API to do
+non-blocking operations instead.

 
 

+All functions that return integers, return C<-1> on error.  See
+section ERROR HANDLING below for how to handle errors.

 
 

+=head2 guestfs_h *

 
 

+C<guestfs_h> is the opaque type representing a connection handle.
+Create a handle by calling C<guestfs_create>.  Call C<guestfs_close>
+to free the handle and release all resources used.

 
 

+Handles and operations on handles are not thread safe.  However you
+can use a separate handle for each thread (but not on the same disk
+image).

 
 

+=head2 guestfs_create

 
 

-=head1 HIGH-LEVEL API
+ guestfs_h *guestfs_create (void);

 
 

+Create a connection handle.

 
 

+You have to call C<guestfs_add_drive> on the handle at least once.

 
 

+This function returns a non-NULL pointer to a handle on success or
+NULL on error.

 
 

+After configuring the handle, you have to call C<guestfs_launch> and
+C<guestfs_wait_ready>.

 
 

+You may also want to configure error handling for the handle.  See
+ERROR HANDLING section below.

 
 

+=head2 guestfs_close

 
 

+ void guestfs_close (guestfs_h *handle);

 
 

+This closes the connection handle and frees up all resources used.

 
 =head1 ERROR HANDLING
 
 
 =head1 ERROR HANDLING
 

+The convention in all functions that return C<int> is that they return
+C<-1> to indicate an error.  You can get additional information on
+errors by calling C<guestfs_set_error_handler>.  The default error
+handler prints the information string to C<stderr>.
+
+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
+handler using C<guestfs_set_out_of_memory_handler>.
+
+=head2 guestfs_set_error_handler
+
+ typedef void (*guestfs_error_handler_cb) (guestfs_h *handle,
+                                           void *data,
+                                           const char *msg);
+ void guestfs_set_error_handler (guestfs_h *handle,
+                                 guestfs_error_handler_cb cb,
+                                 void *data);
+
+The callback C<cb> will be called if there is an error.  The
+parameters passed to the callback are an opaque data pointer and the
+error message string.
+
+Note that the message string C<msg> is freed as soon as the callback
+function returns, so if you want to stash it somewhere you must make
+your own copy.
+
+The default handler prints messages on C<stderr>.
+
+If you set C<cb> to C<NULL> then I<no> handler is called and the error
+message is completely discarded.
+
+=head2 guestfs_get_error_handler
+
+ guestfs_error_handler_cb guestfs_get_error_handler (guestfs_h *handle,
+                                                     void **data_rtn);
+
+Returns the current error handler callback.

 
 

+=head2 guestfs_set_out_of_memory_handler 

 
 

+ typedef void (*guestfs_abort_cb) (void);
+ int guestfs_set_out_of_memory_handler (guestfs_h *handle,
+                                        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 default is to call L<abort(3)>.
+
+You cannot set C<cb> to C<NULL>.  You can't ignore out of memory
+situations.
+
+=head2 guestfs_get_out_of_memory_handler
+
+ guestfs_abort_fn guestfs_get_out_of_memory_handler (guestfs_h *handle);
+
+This returns the current out of memory handler.
+
+=head1 PATH
+
+Libguestfs needs a kernel and initrd.img, which it finds by looking
+along an internal path.
+
+By default it looks for these in the directory C<$libdir/guestfs>
+(eg. C</usr/local/lib/guestfs> or C</usr/lib64/guestfs>).
+
+Use C<guestfs_set_path> or set the environment variable
+C<LIBGUESTFS_PATH> to change the directories that libguestfs will
+search in.  The value is a colon-separated list of paths.  The current
+directory is I<not> searched unless the path contains an empty element
+or C<.>.  For example C<LIBGUESTFS_PATH=:/usr/lib/guestfs> would
+search the current directory and then C</usr/lib/guestfs>.
+
+=head1 HIGH-LEVEL API ACTIONS
+
+@ACTIONS@
+
+=head1 STRUCTURES
+
+@STRUCTS@

 
 =head1 STATE MACHINE AND LOW-LEVEL EVENT API
 
 
 =head1 STATE MACHINE AND LOW-LEVEL EVENT API
 


@@ -79,6 +204,23 @@ and most of this discussion won't make sense unless you understand
 that the complexity is dealing with the (asynchronous) actions of the
 child process.
 
 that the complexity is dealing with the (asynchronous) actions of the
 child process.
 

+                            child process
+  ___________________       _________________________
+ /                   \     /                         \
+ | main program      |     | qemu +-----------------+|
+ |                   |     |      | Linux kernel    ||
+ +-------------------+     |      +-----------------+|
+ | libguestfs     <-------------->| guestfsd        ||
+ |                   |     |      +-----------------+|
+ \___________________/     \_________________________/
+
+The diagram above shows libguestfs communicating with the guestfsd
+daemon running inside the qemu child process.  There are several
+points of failure here: qemu can fail to start, the virtual machine
+inside qemu can fail to boot, guestfsd can fail to start or not
+establish communication, any component can start successfully but fail
+asynchronously later, and so on.
+

 =head2 STATE MACHINE
 
 libguestfs uses a state machine to model the child process:
 =head2 STATE MACHINE
 
 libguestfs uses a state machine to model the child process:


@@ -154,6 +296,8 @@ this function with C<cb> set to C<NULL>.
 
 =head2 NON-BLOCKING ACTIONS
 
 
 =head2 NON-BLOCKING ACTIONS
 

+XXX NOT IMPLEMENTED YET XXX
+

 C<guestfs_set_reply_callback> is the most interesting callback to
 play with, since it allows you to perform actions without blocking.
 
 C<guestfs_set_reply_callback> is the most interesting callback to
 play with, since it allows you to perform actions without blocking.
 


@@ -172,19 +316,19 @@ For example:
    /* returns immediately */
  }
  
    /* returns immediately */
  }
  

- my_cb (guestfs_h handle, void *data)
+ my_cb (guestfs_h *handle, void *data, XDR *xdr)

  {
  {

-   retval = guestfs_nb_[action]_r (handle);
+   retval = guestfs_nb_[action]_r (handle, xdr);

    /* ... */
  }
 
 There are C<guestfs_nb_*> and C<guestfs_nb_*_r> functions
    /* ... */
  }
 
 There are C<guestfs_nb_*> and C<guestfs_nb_*_r> functions

-corresponding to (very nearly) every C<guestfs_*> action in the
-high-level API.
+corresponding to every C<guestfs_*> action in the high-level API.

 
 =head2 guestfs_set_reply_callback
 
 
 =head2 guestfs_set_reply_callback
 

- void guestfs_set_reply_callback (guestfs_handle h,
+ typedef void (*guestfs_reply_cb) (guestfs_h *g, void *opaque, XDR *xdr);
+ void guestfs_set_reply_callback (guestfs_h *handle,

                                   guestfs_reply_cb cb,
                                   void *opaque);
 
                                   guestfs_reply_cb cb,
                                   void *opaque);
 


@@ -192,12 +336,15 @@ The callback function C<cb> will be called whenever a reply is
 received from the child process.  (This corresponds to a transition
 from the BUSY state to the READY state).
 
 received from the child process.  (This corresponds to a transition
 from the BUSY state to the READY state).
 

-Note (I<important!>) that high-level API calls overwrite this
-callback.
+Note that the C<xdr> that you get in the callback is in C<XDR_DECODE>
+mode, and you need to consume it before you return from the callback
+function (since it gets destroyed after).

 
 =head2 guestfs_set_log_message_callback
 
 
 =head2 guestfs_set_log_message_callback
 

- void guestfs_set_log_message_callback (guestfs_handle h,
+ typedef void (*guestfs_log_message_cb) (guestfs_h *g, void *opaque,
+                                         char *buf, int len);
+ void guestfs_set_log_message_callback (guestfs_h *handle,

                                         guestfs_log_message_cb cb,
                                         void *opaque);
 
                                         guestfs_log_message_cb cb,
                                         void *opaque);
 


@@ -211,7 +358,8 @@ discarded.
 
 =head2 guestfs_set_subprocess_quit_callback
 
 
 =head2 guestfs_set_subprocess_quit_callback
 

- void guestfs_set_subprocess_quit_callback (guestfs_handle h,
+ typedef void (*guestfs_subprocess_quit_cb) (guestfs_h *g, void *opaque);
+ void guestfs_set_subprocess_quit_callback (guestfs_h *handle,

                                             guestfs_subprocess_quit_cb cb,
                                             void *opaque);
 
                                             guestfs_subprocess_quit_cb cb,
                                             void *opaque);
 


@@ -220,15 +368,16 @@ quits, either asynchronously or if killed by
 C<guestfs_kill_subprocess>.  (This corresponds to a transition from
 any state to the CONFIG state).
 
 C<guestfs_kill_subprocess>.  (This corresponds to a transition from
 any state to the CONFIG state).
 

-=head2 guestfs_set_ready_callback
+=head2 guestfs_set_launch_done_callback

 
 

- void guestfs_set_ready_callback (guestfs_handle h,
-                                  guestfs_ready_cb cb,
-                                  void *opaque);
+ typedef void (*guestfs_launch_done_cb) (guestfs_h *g, void *opaque);
+ void guestfs_set_launch_done_callback (guestfs_h *handle,
+                                        guestfs_ready_cb cb,
+                                        void *opaque);

 
 The callback function C<cb> will be called when the child process
 
 The callback function C<cb> will be called when the child process

-becomes ready.  (This corresponds to a transition from I<either>
-LAUNCHING I<or> BUSY to the READY state).
+becomes ready first time after it has been launched.  (This
+corresponds to a transition from LAUNCHING to the READY state).

 
 You can use this instead of C<guestfs_wait_ready> to implement a
 non-blocking wait for the child process to finish booting up.
 
 You can use this instead of C<guestfs_wait_ready> to implement a
 non-blocking wait for the child process to finish booting up.


@@ -241,9 +390,9 @@ two are provided for you:
 
 =over 4
 
 
 =over 4
 

-=item libguestfs-poll
+=item libguestfs-select

 
 

-A simple main loop that is implemented using L<poll(2)>.
+A simple main loop that is implemented using L<select(2)>.

 
 This is the default main loop unless you call C<guestfs_set_main_loop>
 or C<guestfs_glib_set_main_loop>.
 
 This is the default main loop unless you call C<guestfs_set_main_loop>
 or C<guestfs_glib_set_main_loop>.


@@ -320,16 +469,31 @@ function, eg. C<g_main_loop_quit>.  In those cases, ignore this call.
 
 =head2 WRITING A CUSTOM MAIN LOOP
 
 
 =head2 WRITING A CUSTOM MAIN LOOP
 

-This isn't documented.  Please see the libguestfs-poll and libguestfs-glib
-implementations.
+This isn't documented.  Please see the libguestfs-select and
+libguestfs-glib implementations.

 
 

-=head1 SEE ALSO
+=head1 ENVIRONMENT VARIABLES

 
 

-L<qemu(1)>
+=over 4

 
 

+=item LIBGUESTFS_DEBUG

 
 

+Set C<LIBGUESTFS_DEBUG=1> to enable verbose messages.  This
+has the same effect as calling C<guestfs_set_verbose (handle, 1)>.

 
 

+=item LIBGUESTFS_PATH
+
+Set the path that libguestfs uses to search for kernel and initrd.img.
+See the discussion of paths in section PATH above.
+
+=back
+
+=head1 SEE ALSO

 
 

+L<guestfish(1)>,
+L<qemu(1)>,
+L<febootstrap(1)>,
+L<http://et.redhat.com/~rjones/libguestfs>.

 
 =head1 AUTHORS
 
 
 =head1 AUTHORS