Add draft about new registry subsystem

(This used to be commit 6d310e98e0d8654a95de98fcd4aa55e3c681157d)

2 files changed, 211 insertions, 0 deletions

diff --git a/docs/docbook/devdoc/dev-doc.xml b/docs/docbook/devdoc/dev-doc.xml
index 7000d09c988..e112a0f9e1e 100644
--- a/docs/docbook/devdoc/dev-doc.xml
+++ b/docs/docbook/devdoc/dev-doc.xml
@@ -20,6 +20,7 @@
 <!ENTITY contributing SYSTEM "contributing.xml">
 <!ENTITY vfs SYSTEM "vfs.xml">
 <!ENTITY windows-deb SYSTEM "windows-debug.xml">
+<!ENTITY registry SYSTEM "registry.xml">
 ]>
 
 <book id="Samba-Developers-Guide">
@@ -82,6 +83,7 @@ url="http://www.fsf.org/licenses/gpl.txt">http://www.fsf.org/licenses/gpl.txt</u
 &rpc-plugin;
 &vfs;
 &packagers;
+&registry;
 &contributing;
 
 </book>
diff --git a/docs/docbook/devdoc/registry.xml b/docs/docbook/devdoc/registry.xml
new file mode 100644
index 00000000000..b331ebce7f9
--- /dev/null
+++ b/docs/docbook/devdoc/registry.xml
@@ -0,0 +1,209 @@
+<chapter id="registry">
+	<chapterinfo>
+		&author.jelmer;
+		<pubdate>24 September 2003</pubdate>
+	</chapterinfo>
+
+	<title>The registry subsystem</title>
+
+	<sect1><title>Planned backends</title>
+	
+<para>
+	The new registry subsystem will work with several different backends: 
+</para>
+
+<itemizedlist>
+	<listitem><para>NT4 (NT4 registry files)</para></listitem>
+	<listitem><para>TDB (Samba TDB files)</para></listitem>
+	<listitem><para>RPC (Remote Registry over RPC, reg pipe)</para></listitem>
+	<listitem><para>wine (Wine Registry Files)</para></listitem>
+	<listitem><para>gconf (The GNOME configuration backend)</para></listitem>
+</itemizedlist>
+
+</sect1>
+
+<sect1><title>Data structures</title>
+
+<para>
+The following structure describes a registry key:
+</para>
+
+<programlisting>
+typedef struct reg_key_s {
+  char *name;         /* Name of the key                    */
+  smb_ucs2_t *class_name; /* Name of key class */
+  int type;           /* One of REG_ROOT_KEY or REG_SUB_KEY */
+  NTTIME last_mod; /* Time last modified                 */
+  struct reg_key_s *owner;
+  struct key_list_s *sub_keys; /* NULL indicates keys not available in memory, function should be called */
+  struct val_list_s *values; /* NULL indicates values not available in memory, function should be called */
+  SEC_DESC *security;
+  REG_HANDLE *handle; /* Pointer to REG_HANDLE this key belongs to */
+  void *backend_data; /* Pointer used by the backend */
+} REG_KEY;
+</programlisting>
+
+<para>The following structure describes a registry value:</para>
+
+<programlisting>
+typedef struct val_key_s {
+  char *name; /* NULL if name not available */
+  int data_type;
+  int data_len;
+  void *data_blk;    /* Might want a separate block */
+  REG_HANDLE *handle; /* Pointer to REG_HANDLE this key belongs to */
+  void *backend_data;
+} REG_VAL;
+</programlisting>
+
+<para>The following structures are used for lists of subkeys or values:</para>
+
+<programlisting>
+/* container for registry subkey names */
+typedef struct key_list_s {
+	TALLOC_CTX	*ctx;
+	uint32      num_subkeys;
+	REG_KEY     **subkeys;
+} REG_KEY_LIST;
+
+/* container for registry values */
+typedef struct val_list_s {
+	TALLOC_CTX *ctx;
+    uint32 num_vals;
+    REG_VAL **vals;
+} REG_VAL_LIST;
+</programlisting>
+
+<para>
+And this structure is used for an instance of a registry (a registry file that's opened, a remote registry pipe we're connected to, etc).
+</para>
+
+<programlisting>
+typedef struct reg_handle_s {
+	REGISTRY_OPS *functions;
+	REG_KEY *root; /* NULL if not available */
+	void *backend_data;
+} REG_HANDLE;
+</programlisting>
+
+</sect1>
+
+<sect1>
+	<title>External interface</title>
+
+<programlisting>
+REG_HANDLE *reg_open(char *backend, char *location, BOOL try_full_load);
+REG_KEY *reg_open_key(REG_KEY *parent, char *name);
+REG_VAL *reg_key_get_val(REG_KEY *key, char *name);
+REG_VAL_LIST *reg_key_get_vals(REG_KEY *key);
+REG_KEY_LIST *reg_key_get_subkeys(REG_KEY *key);
+BOOL reg_key_del(REG_KEY *key);
+BOOL reg_val_del(REG_VAL *val);
+BOOL reg_key_add(REG_KEY *parent, REG_KEY *key);
+BOOL reg_val_add(REG_KEY *parent, REG_VAL *val):
+BOOL reg_val_update(REG_VAL *val);
+BOOL reg_key_update(REG_KEY *key);
+void reg_free_key(REG_KEY *key);
+void reg_free_val(REG_VAL *val);
+void reg_free(REG_HANDLE *h);
+void reg_free_key_list(REG_KEY_LIST *list):
+void reg_free_val_list(REG_VAL_LIST *list):
+</programlisting>
+
+</sect1>
+
+<sect1>
+	<title>Utility functions</title>
+
+	<para>The following helper functions are available:</para>
+
+	<programlisting>
+void reg_key_list_init( REG_KEY_LIST *ctr );
+int reg_key_list_addkey( REG_KEY_LIST *ctr, const char *keyname );
+int reg_key_list_numkeys( REG_KEY_LIST *ctr );
+char* reg_key_list_specific_key( REG_KEY_LIST *ctr, uint32 key_index );
+void reg_key_list_destroy( REG_KEY_LIST *ctr );
+void reg_val_list_init( REG_VAL_LIST *ctr );
+int reg_val_list_numvals( REG_VAL_LIST *ctr );
+void free_registry_value( REG_VAL *val );
+uint8* regval_data_p( REG_VAL *val );
+int regval_size( REG_VAL *val );
+char* regval_name( REG_VAL *val );
+uint32 regval_type( REG_VAL *val );
+TALLOC_CTX* reg_val_list_getctx( REG_VAL_LIST *val );
+int reg_val_list_addvalue( REG_VAL_LIST *ctr, const char *name, uint16 type,
+                         const char *data_p, size_t size );
+int reg_val_list_copyvalue( REG_VAL_LIST *ctr, REG_VAL *val );
+int reg_val_list_delvalue( REG_VAL_LIST *ctr, const char *name );
+void reg_val_list_destroy( REG_VAL_LIST *ctr );
+</programlisting>
+
+</sect1>
+
+<sect1>
+	<title>Writing backends</title>
+
+<para>There are basically two ways of reading data from the registry: loading 
+it all into memory and then working in this copy in memory, or 
+re-reading/re-opening it every time necessary.</para>
+
+<para>This interface aims to support both types. </para>
+
+<para>A registry backend should provide the following functions:</para>
+
+<programlisting>
+typedef struct {
+	REG_HANDLE *(*open_registry) (const char *location, BOOL try_complete_load);
+	REG_KEY *(*open_root_key) (REG_HANDLE *);
+	REG_KEY *(*open_key_rel) (REG_KEY *parent, const char *name);
+	/* if open_key_abs is set to NULL, a default implementation will be provided. */
+	REG_KEY *(*open_key_abs) (REG_HANDLE *, const char *name);
+	REG_KEY_LIST *(*get_subkeys) (REG_KEY *);
+    REG_VAL_LIST *(*get_values) (REG_KEY *);
+	BOOL (*add_key)(REG_KEY *, REG_KEY *);
+	BOOL (*update_key)(REG_KEY *);
+	BOOL (*del_key)(REG_KEY *);
+	BOOL (*add_value)(REG_KEY *, REG_VAL *);
+	BOOL (*update_value)(REG_VAL *);
+	BOOL (*del_value)(REG_VAL *);
+	REG_VAL *(*get_value) (REG_KEY *, const char *name);
+	/* It is not guaranteed that no data has been stored before save() 
+	 * has been called. This function is only useful for backends that 
+	 * store the data in memory and then write out the whole registry at once */
+	BOOL (*save)(REG_HANDLE *, const char *location);
+	BOOL (*close_registry) (REG_HANDLE *);
+	void (*free_key)(REG_KEY *);
+	void (*free_value)(REG_VAL *);
+} REGISTRY_OPS;
+</programlisting>
+
+<para>open_root_key() is optional. It's only called if the 
+	<parameter>root</parameter> field of the REG_HANDLE struct is NULL.</para>
+
+<para>open_key_abs() is optional. If it's NULL, the frontend will 
+	provide a replacement, using open_key_rel().</para>
+
+<para>get_values() and get_value() are optional. They're only called if 
+the <parameter>values</parameter> field of the REG_KEY struct is NULL.</para>
+
+<para>get_subkeys() and get_key() are optional. THey're only called 
+	if the <parameter>subkeys</parameter> field of the REG_KEY struct is NULL.</para>
+
+</sect1>
+
+<sect1><title>Memory allocation</title>
+
+<para>Okay, so who's responsible for what parts of the memory? </para>
+
+<para>The memory is basically maintained by the backends. When the user 
+is finished using a particular structure, it should call the related free
+function for the structure it's freeing.</para>
+
+<para>The backend should then decide what to do with the structure. It may 
+choose to free it, or, if it's maintaining single copies of everything in 
+memory, may choose to ignore the free and free it when the registry is closed.
+</para>
+
+</sect1>
+
+</chapter>