source: trunk-3.0/docs/htmldocs/Samba3-Developers-Guide/vfs.html@ 102

Last change on this file since 102 was 44, checked in by Paul Smedley, 18 years ago

Update source to 3.0.25b
File size: 27.6 KB
Line 
1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 10. VFS Modules</title><link rel="stylesheet" href="samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.71.0"><link rel="start" href="index.html" title="SAMBA Developers Guide"><link rel="up" href="pt03.html" title="Part III. Samba Subsystems"><link rel="prev" href="rpc-plugin.html" title="Chapter 9. RPC Pluggable Modules"><link rel="next" href="parsing.html" title="Chapter 11. The smb.conf file"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 10. VFS Modules</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="rpc-plugin.html">Prev</a> </td><th width="60%" align="center">Part III. Samba Subsystems</th><td width="20%" align="right"> <a accesskey="n" href="parsing.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="vfs"></a>Chapter 10. VFS Modules</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Alexander</span> <span class="surname">Bokovoy</span></h3><div class="affiliation"><div class="address"><p><code class="email">&lt;<a href="mailto:ab@samba.org">ab@samba.org</a>&gt;</code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Stefan</span> <span class="surname">Metzmacher</span></h3><div class="affiliation"><div class="address"><p><code class="email">&lt;<a href="mailto:metze@samba.org">metze@samba.org</a>&gt;</code></p></div></div></div></div><div><p class="pubdate"> 27 May 2003 </p></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="vfs.html#id324691">The Samba (Posix) VFS layer</a></span></dt><dd><dl><dt><span class="sect2"><a href="vfs.html#id324696">The general interface</a></span></dt><dt><span class="sect2"><a href="vfs.html#id324766">Possible VFS operation layers</a></span></dt></dl></dd><dt><span class="sect1"><a href="vfs.html#id324811">The Interaction between the Samba VFS subsystem and the modules</a></span></dt><dd><dl><dt><span class="sect2"><a href="vfs.html#id324817">Initialization and registration</a></span></dt><dt><span class="sect2"><a href="vfs.html#id324954">How the Modules handle per connection data</a></span></dt></dl></dd><dt><span class="sect1"><a href="vfs.html#id325112">Upgrading to the New VFS Interface</a></span></dt><dd><dl><dt><span class="sect2"><a href="vfs.html#id325117">Upgrading from 2.2.* and 3.0aplha modules</a></span></dt></dl></dd><dt><span class="sect1"><a href="vfs.html#id325448">Some Notes</a></span></dt><dd><dl><dt><span class="sect2"><a href="vfs.html#id325454">Implement TRANSPARENT functions</a></span></dt><dt><span class="sect2"><a href="vfs.html#id325472">Implement OPAQUE functions</a></span></dt></dl></dd></dl></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id324691"></a>The Samba (Posix) VFS layer</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id324696"></a>The general interface</h3></div></div></div><p>
2Each VFS operation has a vfs_op_type, a function pointer and a handle pointer in the
3struct vfs_ops and tree macros to make it easier to call the operations.
4(Take a look at <code class="filename">include/vfs.h</code> and <code class="filename">include/vfs_macros.h</code>.)
5</p><pre class="programlisting">
6typedef enum _vfs_op_type {
7 SMB_VFS_OP_NOOP = -1,
8
9 ...
10
11 /* File operations */
12
13 SMB_VFS_OP_OPEN,
14 SMB_VFS_OP_CLOSE,
15 SMB_VFS_OP_READ,
16 SMB_VFS_OP_WRITE,
17 SMB_VFS_OP_LSEEK,
18 SMB_VFS_OP_SENDFILE,
19
20 ...
21
22 SMB_VFS_OP_LAST
23} vfs_op_type;
24</pre><p>This struct contains the function and handle pointers for all operations.</p><pre class="programlisting">
25struct vfs_ops {
26 struct vfs_fn_pointers {
27 ...
28
29 /* File operations */
30
31 int (*open)(struct vfs_handle_struct *handle,
32 struct connection_struct *conn,
33 const char *fname, int flags, mode_t mode);
34 int (*close)(struct vfs_handle_struct *handle,
35 struct files_struct *fsp, int fd);
36 ssize_t (*read)(struct vfs_handle_struct *handle,
37 struct files_struct *fsp, int fd, void *data, size_t n);
38 ssize_t (*write)(struct vfs_handle_struct *handle,
39 struct files_struct *fsp, int fd,
40 const void *data, size_t n);
41 SMB_OFF_T (*lseek)(struct vfs_handle_struct *handle,
42 struct files_struct *fsp, int fd,
43 SMB_OFF_T offset, int whence);
44 ssize_t (*sendfile)(struct vfs_handle_struct *handle,
45 int tofd, files_struct *fsp, int fromfd,
46 const DATA_BLOB *header, SMB_OFF_T offset, size_t count);
47
48 ...
49 } ops;
50
51 struct vfs_handles_pointers {
52 ...
53
54 /* File operations */
55
56 struct vfs_handle_struct *open;
57 struct vfs_handle_struct *close;
58 struct vfs_handle_struct *read;
59 struct vfs_handle_struct *write;
60 struct vfs_handle_struct *lseek;
61 struct vfs_handle_struct *sendfile;
62
63 ...
64 } handles;
65};
66</pre><p>
67This macros SHOULD be used to call any vfs operation.
68DO NOT ACCESS conn-&gt;vfs.ops.* directly !!!
69</p><pre class="programlisting">
70...
71
72/* File operations */
73#define SMB_VFS_OPEN(conn, fname, flags, mode) \
74 ((conn)-&gt;vfs.ops.open((conn)-&gt;vfs.handles.open,\
75 (conn), (fname), (flags), (mode)))
76#define SMB_VFS_CLOSE(fsp, fd) \
77 ((fsp)-&gt;conn-&gt;vfs.ops.close(\
78 (fsp)-&gt;conn-&gt;vfs.handles.close, (fsp), (fd)))
79#define SMB_VFS_READ(fsp, fd, data, n) \
80 ((fsp)-&gt;conn-&gt;vfs.ops.read(\
81 (fsp)-&gt;conn-&gt;vfs.handles.read,\
82 (fsp), (fd), (data), (n)))
83#define SMB_VFS_WRITE(fsp, fd, data, n) \
84 ((fsp)-&gt;conn-&gt;vfs.ops.write(\
85 (fsp)-&gt;conn-&gt;vfs.handles.write,\
86 (fsp), (fd), (data), (n)))
87#define SMB_VFS_LSEEK(fsp, fd, offset, whence) \
88 ((fsp)-&gt;conn-&gt;vfs.ops.lseek(\
89 (fsp)-&gt;conn-&gt;vfs.handles.lseek,\
90 (fsp), (fd), (offset), (whence)))
91#define SMB_VFS_SENDFILE(tofd, fsp, fromfd, header, offset, count) \
92 ((fsp)-&gt;conn-&gt;vfs.ops.sendfile(\
93 (fsp)-&gt;conn-&gt;vfs.handles.sendfile,\
94 (tofd), (fsp), (fromfd), (header), (offset), (count)))
95
96...
97</pre></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id324766"></a>Possible VFS operation layers</h3></div></div></div><p>
98These values are used by the VFS subsystem when building the conn-&gt;vfs
99and conn-&gt;vfs_opaque structs for a connection with multiple VFS modules.
100Internally, Samba differentiates only opaque and transparent layers at this process.
101Other types are used for providing better diagnosing facilities.
102</p><p>
103Most modules will provide transparent layers. Opaque layer is for modules
104which implement actual file system calls (like DB-based VFS). For example,
105default POSIX VFS which is built in into Samba is an opaque VFS module.
106</p><p>
107Other layer types (logger, splitter, scanner) were designed to provide different
108degree of transparency and for diagnosing VFS module behaviour.
109</p><p>
110Each module can implement several layers at the same time provided that only
111one layer is used per each operation.
112</p><pre class="programlisting">
113typedef enum _vfs_op_layer {
114 SMB_VFS_LAYER_NOOP = -1, /* - For using in VFS module to indicate end of array */
115 /* of operations description */
116 SMB_VFS_LAYER_OPAQUE = 0, /* - Final level, does not call anything beyond itself */
117 SMB_VFS_LAYER_TRANSPARENT, /* - Normal operation, calls underlying layer after */
118 /* possibly changing passed data */
119 SMB_VFS_LAYER_LOGGER, /* - Logs data, calls underlying layer, logging may not */
120 /* use Samba VFS */
121 SMB_VFS_LAYER_SPLITTER, /* - Splits operation, calls underlying layer _and_ own facility, */
122 /* then combines result */
123 SMB_VFS_LAYER_SCANNER /* - Checks data and possibly initiates additional */
124 /* file activity like logging to files _inside_ samba VFS */
125} vfs_op_layer;
126</pre></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id324811"></a>The Interaction between the Samba VFS subsystem and the modules</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id324817"></a>Initialization and registration</h3></div></div></div><p>
127As each Samba module a VFS module should have a
128</p><pre class="programlisting">NTSTATUS vfs_example_init(void);</pre><p> function if it's staticly linked to samba or
129</p><pre class="programlisting">NTSTATUS init_module(void);</pre><p> function if it's a shared module.
130</p><p>
131This should be the only non static function inside the module.
132Global variables should also be static!
133</p><p>
134The module should register its functions via the
135</p><pre class="programlisting">
136NTSTATUS smb_register_vfs(int version, const char *name, vfs_op_tuple *vfs_op_tuples);
137</pre><p> function.
138</p><div class="variablelist"><dl><dt><span class="term">version</span></dt><dd><p>should be filled with SMB_VFS_INTERFACE_VERSION</p></dd><dt><span class="term">name</span></dt><dd><p>this is the name witch can be listed in the
139<code class="literal">vfs objects</code> parameter to use this module.</p></dd><dt><span class="term">vfs_op_tuples</span></dt><dd><p>
140this is an array of vfs_op_tuple's.
141(vfs_op_tuples is descripted in details below.)
142</p></dd></dl></div><p>
143For each operation the module wants to provide it has a entry in the
144vfs_op_tuple array.
145</p><pre class="programlisting">
146typedef struct _vfs_op_tuple {
147 void* op;
148 vfs_op_type type;
149 vfs_op_layer layer;
150} vfs_op_tuple;
151</pre><div class="variablelist"><dl><dt><span class="term">op</span></dt><dd><p>the function pointer to the specified function.</p></dd><dt><span class="term">type</span></dt><dd><p>the vfs_op_type of the function to specified witch operation the function provides.</p></dd><dt><span class="term">layer</span></dt><dd><p>the vfs_op_layer in whitch the function operates.</p></dd></dl></div><p>A simple example:</p><pre class="programlisting">
152static vfs_op_tuple example_op_tuples[] = {
153 {SMB_VFS_OP(example_connect), SMB_VFS_OP_CONNECT, SMB_VFS_LAYER_TRANSPARENT},
154 {SMB_VFS_OP(example_disconnect), SMB_VFS_OP_DISCONNECT, SMB_VFS_LAYER_TRANSPARENT},
155
156 {SMB_VFS_OP(example_rename), SMB_VFS_OP_RENAME, SMB_VFS_LAYER_OPAQUE},
157
158 /* This indicates the end of the array */
159 {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
160};
161
162NTSTATUS init_module(void)
163{
164 return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "example", example_op_tuples);
165}
166</pre></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id324954"></a>How the Modules handle per connection data</h3></div></div></div><p>Each VFS function has as first parameter a pointer to the modules vfs_handle_struct.
167</p><pre class="programlisting">
168typedef struct vfs_handle_struct {
169 struct vfs_handle_struct *next, *prev;
170 const char *param;
171 struct vfs_ops vfs_next;
172 struct connection_struct *conn;
173 void *data;
174 void (*free_data)(void **data);
175} vfs_handle_struct;
176</pre><div class="variablelist"><dl><dt><span class="term">param</span></dt><dd><p>this is the module parameter specified in the <code class="literal">vfs objects</code> parameter.</p><p>e.g. for 'vfs objects = example:test' param would be "test".</p></dd><dt><span class="term">vfs_next</span></dt><dd><p>This vfs_ops struct contains the information for calling the next module operations.
177Use the SMB_VFS_NEXT_* macros to call a next module operations and
178don't access handle-&gt;vfs_next.ops.* directly!</p></dd><dt><span class="term">conn</span></dt><dd><p>This is a pointer back to the connection_struct to witch the handle belongs.</p></dd><dt><span class="term">data</span></dt><dd><p>This is a pointer for holding module private data.
179You can alloc data with connection life time on the handle-&gt;conn-&gt;mem_ctx TALLOC_CTX.
180But you can also manage the memory allocation yourself.</p></dd><dt><span class="term">free_data</span></dt><dd><p>This is a function pointer to a function that free's the module private data.
181If you talloc your private data on the TALLOC_CTX handle-&gt;conn-&gt;mem_ctx,
182you can set this function pointer to NULL.</p></dd></dl></div><p>Some useful MACROS for handle private data.
183</p><pre class="programlisting">
184#define SMB_VFS_HANDLE_GET_DATA(handle, datap, type, ret) { \
185 if (!(handle)||((datap=(type *)(handle)-&gt;data)==NULL)) { \
186 DEBUG(0,("%s() failed to get vfs_handle-&gt;data!\n",FUNCTION_MACRO)); \
187 ret; \
188 } \
189}
190
191#define SMB_VFS_HANDLE_SET_DATA(handle, datap, free_fn, type, ret) { \
192 if (!(handle)) { \
193 DEBUG(0,("%s() failed to set handle-&gt;data!\n",FUNCTION_MACRO)); \
194 ret; \
195 } else { \
196 if ((handle)-&gt;free_data) { \
197 (handle)-&gt;free_data(&amp;(handle)-&gt;data); \
198 } \
199 (handle)-&gt;data = (void *)datap; \
200 (handle)-&gt;free_data = free_fn; \
201 } \
202}
203
204#define SMB_VFS_HANDLE_FREE_DATA(handle) { \
205 if ((handle) &amp;&amp; (handle)-&gt;free_data) { \
206 (handle)-&gt;free_data(&amp;(handle)-&gt;data); \
207 } \
208}
209</pre><p>How SMB_VFS_LAYER_TRANSPARENT functions can call the SMB_VFS_LAYER_OPAQUE functions.</p><p>The easiest way to do this is to use the SMB_VFS_OPAQUE_* macros.
210</p><pre class="programlisting">
211...
212/* File operations */
213#define SMB_VFS_OPAQUE_OPEN(conn, fname, flags, mode) \
214 ((conn)-&gt;vfs_opaque.ops.open(\
215 (conn)-&gt;vfs_opaque.handles.open,\
216 (conn), (fname), (flags), (mode)))
217#define SMB_VFS_OPAQUE_CLOSE(fsp, fd) \
218 ((fsp)-&gt;conn-&gt;vfs_opaque.ops.close(\
219 (fsp)-&gt;conn-&gt;vfs_opaque.handles.close,\
220 (fsp), (fd)))
221#define SMB_VFS_OPAQUE_READ(fsp, fd, data, n) \
222 ((fsp)-&gt;conn-&gt;vfs_opaque.ops.read(\
223 (fsp)-&gt;conn-&gt;vfs_opaque.handles.read,\
224 (fsp), (fd), (data), (n)))
225#define SMB_VFS_OPAQUE_WRITE(fsp, fd, data, n) \
226 ((fsp)-&gt;conn-&gt;vfs_opaque.ops.write(\
227 (fsp)-&gt;conn-&gt;vfs_opaque.handles.write,\
228 (fsp), (fd), (data), (n)))
229#define SMB_VFS_OPAQUE_LSEEK(fsp, fd, offset, whence) \
230 ((fsp)-&gt;conn-&gt;vfs_opaque.ops.lseek(\
231 (fsp)-&gt;conn-&gt;vfs_opaque.handles.lseek,\
232 (fsp), (fd), (offset), (whence)))
233#define SMB_VFS_OPAQUE_SENDFILE(tofd, fsp, fromfd, header, offset, count) \
234 ((fsp)-&gt;conn-&gt;vfs_opaque.ops.sendfile(\
235 (fsp)-&gt;conn-&gt;vfs_opaque.handles.sendfile,\
236 (tofd), (fsp), (fromfd), (header), (offset), (count)))
237...
238</pre><p>How SMB_VFS_LAYER_TRANSPARENT functions can call the next modules functions.</p><p>The easiest way to do this is to use the SMB_VFS_NEXT_* macros.
239</p><pre class="programlisting">
240...
241/* File operations */
242#define SMB_VFS_NEXT_OPEN(handle, conn, fname, flags, mode) \
243 ((handle)-&gt;vfs_next.ops.open(\
244 (handle)-&gt;vfs_next.handles.open,\
245 (conn), (fname), (flags), (mode)))
246#define SMB_VFS_NEXT_CLOSE(handle, fsp, fd) \
247 ((handle)-&gt;vfs_next.ops.close(\
248 (handle)-&gt;vfs_next.handles.close,\
249 (fsp), (fd)))
250#define SMB_VFS_NEXT_READ(handle, fsp, fd, data, n) \
251 ((handle)-&gt;vfs_next.ops.read(\
252 (handle)-&gt;vfs_next.handles.read,\
253 (fsp), (fd), (data), (n)))
254#define SMB_VFS_NEXT_WRITE(handle, fsp, fd, data, n) \
255 ((handle)-&gt;vfs_next.ops.write(\
256 (handle)-&gt;vfs_next.handles.write,\
257 (fsp), (fd), (data), (n)))
258#define SMB_VFS_NEXT_LSEEK(handle, fsp, fd, offset, whence) \
259 ((handle)-&gt;vfs_next.ops.lseek(\
260 (handle)-&gt;vfs_next.handles.lseek,\
261 (fsp), (fd), (offset), (whence)))
262#define SMB_VFS_NEXT_SENDFILE(handle, tofd, fsp, fromfd, header, offset, count) \
263 ((handle)-&gt;vfs_next.ops.sendfile(\
264 (handle)-&gt;vfs_next.handles.sendfile,\
265 (tofd), (fsp), (fromfd), (header), (offset), (count)))
266...
267</pre></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id325112"></a>Upgrading to the New VFS Interface</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id325117"></a>Upgrading from 2.2.* and 3.0aplha modules</h3></div></div></div><div class="orderedlist"><ol type="1"><li><p>
268Add "vfs_handle_struct *handle, " as first parameter to all vfs operation functions.
269e.g. example_connect(connection_struct *conn, const char *service, const char *user);
270-&gt; example_connect(vfs_handle_struct *handle, connection_struct *conn, const char *service, const char *user);
271</p></li><li><p>
272Replace "default_vfs_ops." with "smb_vfs_next_".
273e.g. default_vfs_ops.connect(conn, service, user);
274-&gt; smb_vfs_next_connect(conn, service, user);
275</p></li><li><p>
276Uppercase all "smb_vfs_next_*" functions.
277e.g. smb_vfs_next_connect(conn, service, user);
278-&gt; SMB_VFS_NEXT_CONNECT(conn, service, user);
279</p></li><li><p>
280Add "handle, " as first parameter to all SMB_VFS_NEXT_*() calls.
281e.g. SMB_VFS_NEXT_CONNECT(conn, service, user);
282-&gt; SMB_VFS_NEXT_CONNECT(handle, conn, service, user);
283</p></li><li><p>
284(Only for 2.2.* modules)
285Convert the old struct vfs_ops example_ops to
286a vfs_op_tuple example_op_tuples[] array.
287e.g.
288</p><pre class="programlisting">
289struct vfs_ops example_ops = {
290 /* Disk operations */
291 example_connect, /* connect */
292 example_disconnect, /* disconnect */
293 NULL, /* disk free *
294 /* Directory operations */
295 NULL, /* opendir */
296 NULL, /* readdir */
297 NULL, /* mkdir */
298 NULL, /* rmdir */
299 NULL, /* closedir */
300 /* File operations */
301 NULL, /* open */
302 NULL, /* close */
303 NULL, /* read */
304 NULL, /* write */
305 NULL, /* lseek */
306 NULL, /* sendfile */
307 NULL, /* rename */
308 NULL, /* fsync */
309 example_stat, /* stat */
310 example_fstat, /* fstat */
311 example_lstat, /* lstat */
312 NULL, /* unlink */
313 NULL, /* chmod */
314 NULL, /* fchmod */
315 NULL, /* chown */
316 NULL, /* fchown */
317 NULL, /* chdir */
318 NULL, /* getwd */
319 NULL, /* utime */
320 NULL, /* ftruncate */
321 NULL, /* lock */
322 NULL, /* symlink */
323 NULL, /* readlink */
324 NULL, /* link */
325 NULL, /* mknod */
326 NULL, /* realpath */
327 NULL, /* fget_nt_acl */
328 NULL, /* get_nt_acl */
329 NULL, /* fset_nt_acl */
330 NULL, /* set_nt_acl */
331
332 NULL, /* chmod_acl */
333 NULL, /* fchmod_acl */
334
335 NULL, /* sys_acl_get_entry */
336 NULL, /* sys_acl_get_tag_type */
337 NULL, /* sys_acl_get_permset */
338 NULL, /* sys_acl_get_qualifier */
339 NULL, /* sys_acl_get_file */
340 NULL, /* sys_acl_get_fd */
341 NULL, /* sys_acl_clear_perms */
342 NULL, /* sys_acl_add_perm */
343 NULL, /* sys_acl_to_text */
344 NULL, /* sys_acl_init */
345 NULL, /* sys_acl_create_entry */
346 NULL, /* sys_acl_set_tag_type */
347 NULL, /* sys_acl_set_qualifier */
348 NULL, /* sys_acl_set_permset */
349 NULL, /* sys_acl_valid */
350 NULL, /* sys_acl_set_file */
351 NULL, /* sys_acl_set_fd */
352 NULL, /* sys_acl_delete_def_file */
353 NULL, /* sys_acl_get_perm */
354 NULL, /* sys_acl_free_text */
355 NULL, /* sys_acl_free_acl */
356 NULL /* sys_acl_free_qualifier */
357};
358</pre><p>
359-&gt;
360</p><pre class="programlisting">
361static vfs_op_tuple example_op_tuples[] = {
362 {SMB_VFS_OP(example_connect), SMB_VFS_OP_CONNECT, SMB_VFS_LAYER_TRANSPARENT},
363 {SMB_VFS_OP(example_disconnect), SMB_VFS_OP_DISCONNECT, SMB_VFS_LAYER_TRANSPARENT},
364
365 {SMB_VFS_OP(example_fstat), SMB_VFS_OP_FSTAT, SMB_VFS_LAYER_TRANSPARENT},
366 {SMB_VFS_OP(example_stat), SMB_VFS_OP_STAT, SMB_VFS_LAYER_TRANSPARENT},
367 {SMB_VFS_OP(example_lstat), SMB_VFS_OP_LSTAT, SMB_VFS_LAYER_TRANSPARENT},
368
369 {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
370};
371</pre><p>
372</p></li><li><p>
373Move the example_op_tuples[] array to the end of the file.
374</p></li><li><p>
375Add the init_module() function at the end of the file.
376e.g.
377</p><pre class="programlisting">
378NTSTATUS init_module(void)
379{
380 return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,"example",example_op_tuples);
381}
382</pre><p>
383</p></li><li><p>
384Check if your vfs_init() function does more then just prepare the vfs_ops structs or
385remember the struct smb_vfs_handle_struct.
386</p><table class="simplelist" border="0" summary="Simple list"><tr><td>If NOT you can remove the vfs_init() function.</td></tr><tr><td>If YES decide if you want to move the code to the example_connect() operation or to the init_module(). And then remove vfs_init().
387 e.g. a debug class registration should go into init_module() and the allocation of private data should go to example_connect().</td></tr></table><p>
388</p></li><li><p>
389(Only for 3.0alpha* modules)
390Check if your vfs_done() function contains needed code.
391</p><table class="simplelist" border="0" summary="Simple list"><tr><td>If NOT you can remove the vfs_done() function.</td></tr><tr><td>If YES decide if you can move the code to the example_disconnect() operation. Otherwise register a SMB_EXIT_EVENT with smb_register_exit_event(); (Described in the <a href="modules.html" title="Chapter 8. Modules">modules section</a>) And then remove vfs_done(). e.g. the freeing of private data should go to example_disconnect().
392</td></tr></table><p>
393</p></li><li><p>
394Check if you have any global variables left.
395Decide if it wouldn't be better to have this data on a connection basis.
396</p><table class="simplelist" border="0" summary="Simple list"><tr><td>If NOT leave them as they are. (e.g. this could be the variable for the private debug class.)</td></tr><tr><td>If YES pack all this data into a struct. You can use handle-&gt;data to point to such a struct on a per connection basis.</td></tr></table><p>
397
398 e.g. if you have such a struct:
399</p><pre class="programlisting">
400struct example_privates {
401 char *some_string;
402 int db_connection;
403};
404</pre><p>
405first way of doing it:
406</p><pre class="programlisting">
407static int example_connect(vfs_handle_struct *handle,
408 connection_struct *conn, const char *service,
409 const char* user)
410{
411 struct example_privates *data = NULL;
412
413 /* alloc our private data */
414 data = (struct example_privates *)talloc_zero(conn-&gt;mem_ctx, sizeof(struct example_privates));
415 if (!data) {
416 DEBUG(0,("talloc_zero() failed\n"));
417 return -1;
418 }
419
420 /* init out private data */
421 data-&gt;some_string = talloc_strdup(conn-&gt;mem_ctx,"test");
422 if (!data-&gt;some_string) {
423 DEBUG(0,("talloc_strdup() failed\n"));
424 return -1;
425 }
426
427 data-&gt;db_connection = open_db_conn();
428
429 /* and now store the private data pointer in handle-&gt;data
430 * we don't need to specify a free_function here because
431 * we use the connection TALLOC context.
432 * (return -1 if something failed.)
433 */
434 VFS_HANDLE_SET_DATA(handle, data, NULL, struct example_privates, return -1);
435
436 return SMB_VFS_NEXT_CONNECT(handle,conn,service,user);
437}
438
439static int example_close(vfs_handle_struct *handle, files_struct *fsp, int fd)
440{
441 struct example_privates *data = NULL;
442
443 /* get the pointer to our private data
444 * return -1 if something failed
445 */
446 SMB_VFS_HANDLE_GET_DATA(handle, data, struct example_privates, return -1);
447
448 /* do something here...*/
449 DEBUG(0,("some_string: %s\n",data-&gt;some_string));
450
451 return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
452}
453</pre><p>
454second way of doing it:
455</p><pre class="programlisting">
456static void free_example_privates(void **datap)
457{
458 struct example_privates *data = (struct example_privates *)*datap;
459
460 SAFE_FREE(data-&gt;some_string);
461 SAFE_FREE(data);
462
463 *datap = NULL;
464
465 return;
466}
467
468static int example_connect(vfs_handle_struct *handle,
469 connection_struct *conn, const char *service,
470 const char* user)
471{
472 struct example_privates *data = NULL;
473
474 /* alloc our private data */
475 data = (struct example_privates *)malloc(sizeof(struct example_privates));
476 if (!data) {
477 DEBUG(0,("malloc() failed\n"));
478 return -1;
479 }
480
481 /* init out private data */
482 data-&gt;some_string = strdup("test");
483 if (!data-&gt;some_string) {
484 DEBUG(0,("strdup() failed\n"));
485 return -1;
486 }
487
488 data-&gt;db_connection = open_db_conn();
489
490 /* and now store the private data pointer in handle-&gt;data
491 * we need to specify a free_function because we used malloc() and strdup().
492 * (return -1 if something failed.)
493 */
494 SMB_VFS_HANDLE_SET_DATA(handle, data, free_example_privates, struct example_privates, return -1);
495
496 return SMB_VFS_NEXT_CONNECT(handle,conn,service,user);
497}
498
499static int example_close(vfs_handle_struct *handle, files_struct *fsp, int fd)
500{
501 struct example_privates *data = NULL;
502
503 /* get the pointer to our private data
504 * return -1 if something failed
505 */
506 SMB_VFS_HANDLE_GET_DATA(handle, data, struct example_privates, return -1);
507
508 /* do something here...*/
509 DEBUG(0,("some_string: %s\n",data-&gt;some_string));
510
511 return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
512}
513</pre><p>
514</p></li><li><p>
515To make it easy to build 3rd party modules it would be usefull to provide
516configure.in, (configure), install.sh and Makefile.in with the module.
517(Take a look at the example in <code class="filename">examples/VFS</code>.)
518</p><p>
519The configure script accepts <code class="option">--with-samba-source</code> to specify
520the path to the samba source tree.
521It also accept <code class="option">--enable-developer</code> which lets the compiler
522give you more warnings.
523</p><p>
524The idea is that you can extend this
525<code class="filename">configure.in</code> and <code class="filename">Makefile.in</code> scripts
526for your module.
527</p></li><li><p>
528Compiling &amp; Testing...
529</p><table class="simplelist" border="0" summary="Simple list"><tr><td><strong class="userinput"><code>./configure <code class="option">--enable-developer</code></code></strong> ...</td></tr><tr><td><strong class="userinput"><code>make</code></strong></td></tr><tr><td>Try to fix all compiler warnings</td></tr><tr><td><strong class="userinput"><code>make</code></strong></td></tr><tr><td>Testing, Testing, Testing ...</td></tr></table><p>
530</p></li></ol></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id325448"></a>Some Notes</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id325454"></a>Implement TRANSPARENT functions</h3></div></div></div><p>
531Avoid writing functions like this:
532
533</p><pre class="programlisting">
534static int example_close(vfs_handle_struct *handle, files_struct *fsp, int fd)
535{
536 return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
537}
538</pre><p>
539
540Overload only the functions you really need to!
541</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id325472"></a>Implement OPAQUE functions</h3></div></div></div><p>
542If you want to just implement a better version of a
543default samba opaque function
544(e.g. like a disk_free() function for a special filesystem)
545it's ok to just overload that specific function.
546</p><p>
547If you want to implement a database filesystem or
548something different from a posix filesystem.
549Make sure that you overload every vfs operation!!!
550</p><p>
551Functions your FS does not support should be overloaded by something like this:
552e.g. for a readonly filesystem.
553</p><pre class="programlisting">
554static int example_rename(vfs_handle_struct *handle, connection_struct *conn,
555 char *oldname, char *newname)
556{
557 DEBUG(10,("function rename() not allowed on vfs 'example'\n"));
558 errno = ENOSYS;
559 return -1;
560}
561</pre></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="rpc-plugin.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="pt03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="parsing.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 9. RPC Pluggable Modules </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 11. The smb.conf file</td></tr></table></div></body></html>
Note: See TracBrowser for help on using the repository browser.