More documentation.

diff --git a/guestfs.pod b/guestfs.pod
index 63bd14c..1791545 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);
 


@@ -40,32 +42,249 @@ 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.
 
 contribute the language bindings).  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.
+

 =head1 CONNECTION MANAGEMENT
 
 =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);
+
+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

 
 

+ guestfs_h *guestfs_create (void);

 
 

+Create a connection handle.

 
 

+You have to call C<guestfs_add_drive> on the handle at least once.
+See CONFIGURATION MANAGEMENT section below.

 
 

+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.
+
+=head2 guestfs_launch, guestfs_wait_ready
+
+ int guestfs_launch (guestfs_h *handle);
+ int guestfs_wait_ready (guestfs_h *handle);
+
+Internally libguestfs is implemented by running a virtual machine
+using L<qemu(1)>.  These calls are necessary in order to boot the
+virtual machine.  More discussion of this is available in the section
+STATE MACHINE AND LOW-LEVEL EVENT API below.
+
+You should call these two functions after configuring the handle
+(eg. adding drives) but before performing any actions.

 
 =head1 CONFIGURATION MANAGEMENT
 
 
 =head1 CONFIGURATION MANAGEMENT
 

+The configuration functions allow you to configure which drive images
+will be examined or modified, and set other aspects of the L<qemu(1)>
+virtual machine that we will be running.  You need to call only
+C<guestfs_add_drive> at least once for each guest image that you want
+to examine.
+
+=head2 guestfs_add_drive

 
 

+ int guestfs_add_drive (guestfs_h *handle, const char *filename);

 
 

+This function adds a virtual machine disk image C<filename> to the
+guest.  The first time you call this function, the disk appears as IDE
+disk 0 (C</dev/sda>) in the guest, the second time as C</dev/sdb>, and
+so on.

 
 

+You don't necessarily need to be root when using libguestfs.  However
+you obviously do need sufficient permissions to access the filename
+for whatever operations you want to perform (ie. read access if you
+just want to read the image or write access if you want to modify the
+image).

 
 

+This is equivalent to the qemu parameter C<-drive file=filename>.

 
 

-=head1 HIGH-LEVEL API
+=head2 guestfs_add_cdrom

 
 

+ int guestfs_add_cdrom (guestfs_h *handle, const char *filename);

 
 

+This function adds a virtual CD-ROM disk image to the guest.

 
 

+This is equivalent to the qemu parameter C<-cdrom filename>.

 
 

+=head2 guestfs_config

 
 

+ int guestfs_config (guestfs_h *handle,
+                     const char *qemu_param, const char *qemu_value);

 
 

+This can be used to add arbitrary qemu command line parameters
+of the form C<-param value>.  Actually it's not quite arbitrary - we
+prevent you from setting some parameters which would interfere with
+parameters that we use.

 
 

+The first character of C<qemu_param> string must be a C<-> (dash).

 
 

+C<qemu_value> can be NULL.

 
 =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) (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.
+
+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);
+
+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 VERBOSE MESSAGES
+
+=head2 guestfs_set_verbose
+
+ void guestfs_set_verbose (guestfs_h *handle, int verbose);
+
+If C<verbose> is true, this turns on verbose messages (to C<stderr>).
+
+Verbose messages are disabled unless the environment variable
+C<LIBGUESTFS_DEBUG> is defined and set to C<1>.
+
+=head2 guestfs_get_verbose
+
+ int guestfs_get_verbose (guestfs_h *handle);
+
+This returns the verbose messages flag.
+
+=head1 HIGH-LEVEL API ACTIONS
+
+=head2 guestfs_sync
+
+ int guestfs_sync (guestfs_h *handle);
+
+This syncs the disk, so that any writes are flushed through to the
+underlying disk image.
+
+You should always call this if you have modified a disk image, before
+calling C<guestfs_close>.
+
+XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+
+Documentation will be auto-generated from here, including for
+guestfs_sync.
+
+XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+
+ do_[action] ([parameters])
+ {
+   guestfs_set_reply_callback (handle, [action]_cb, data);
+   guestfs_nb_[action] (handle, [parameters ...]);
+
+   guestfs_main_loop_run (); /* --> blocks, then calls my_cb */
+ }
+
+ [action]_cb (guestfs_h *handle, void *data)
+ {
+   retval = guestfs_nb_[action]_r (handle);
+   /* ... */
+   guestfs_main_loop_quit ();
+   return retval;
+ }
+
+XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+
+
+

 
 
 
 
 
 


@@ -79,6 +298,23 @@ 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:


@@ -172,7 +408,7 @@ For example:
    /* returns immediately */
  }
  
    /* returns immediately */
  }
  

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

  {
    retval = guestfs_nb_[action]_r (handle);
    /* ... */
  {
    retval = guestfs_nb_[action]_r (handle);
    /* ... */


@@ -184,7 +420,7 @@ high-level API.
 
 =head2 guestfs_set_reply_callback
 
 
 =head2 guestfs_set_reply_callback
 

- void guestfs_set_reply_callback (guestfs_handle h,
+ void guestfs_set_reply_callback (guestfs_h *handle,

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


@@ -197,7 +433,7 @@ callback.
 
 =head2 guestfs_set_log_message_callback
 
 
 =head2 guestfs_set_log_message_callback
 

- void guestfs_set_log_message_callback (guestfs_handle h,
+ 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 +447,7 @@ discarded.
 
 =head2 guestfs_set_subprocess_quit_callback
 
 
 =head2 guestfs_set_subprocess_quit_callback
 

- void guestfs_set_subprocess_quit_callback (guestfs_handle h,
+ 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 +456,15 @@ 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);
+ 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.