4
\chapter{Bacula FD Plugin API}
5
To write a Bacula plugin, you create a dynamic shared object program (or dll on
6
Win32) with a particular name and two exported entry points, place it in the
7
{\bf Plugins Directory}, which is defined in the {\bf bacula-fd.conf} file in
8
the {\bf Client} resource, and when the FD starts, it will load all the plugins
9
that end with {\bf -fd.so} (or {\bf -fd.dll} on Win32) found in that directory.
11
\section{Normal vs Command Plugins}
12
In general, there are two ways that plugins are called. The first way, is when
13
a particular event is detected in Bacula, it will transfer control to each
14
plugin that is loaded in turn informing the plugin of the event. This is very
15
similar to how a {\bf RunScript} works, and the events are very similar. Once
16
the plugin gets control, it can interact with Bacula by getting and setting
17
Bacula variables. In this way, it behaves much like a RunScript. Currently
18
very few Bacula variables are defined, but they will be implemented as the need
19
arrises, and it is very extensible.
21
We plan to have plugins register to receive events that they normally would
22
not receive, such as an event for each file examined for backup or restore.
23
This feature is not yet implemented.
25
The second type of plugin, which is more useful and fully implemented in the
26
current version is what we call a command plugin. As with all plugins, it gets
27
notified of important events as noted above (details described below), but in
28
addition, this kind of plugin can accept a command line, which is a:
31
Plugin = <command-string>
34
directive that is placed in the Include section of a FileSet and is very
35
similar to the "File = " directive. When this Plugin directive is encountered
36
by Bacula during backup, it passes the "command" part of the Plugin directive
37
only to the plugin that is explicitly named in the first field of that command
38
string. This allows that plugin to backup any file or files on the system that
39
it wants. It can even create "virtual files" in the catalog that contain data
40
to be restored but do not necessarily correspond to actual files on the
43
The important features of the command plugin entry points are:
45
\item It is triggered by a "Plugin =" directive in the FileSet
46
\item Only a single plugin is called that is named on the "Plugin =" directive.
47
\item The full command string after the "Plugin =" is passed to the plugin
48
so that it can be told what to backup/restore.
52
\section{Loading Plugins}
53
Once the File daemon loads the plugins, it asks the OS for the
54
two entry points (loadPlugin and unloadPlugin) then calls the
55
{\bf loadPlugin} entry point (see below).
57
Bacula passes information to the plugin through this call and it gets
58
back information that it needs to use the plugin. Later, Bacula
59
will call particular functions that are defined by the
60
{\bf loadPlugin} interface.
62
When Bacula is finished with the plugin
63
(when Bacula is going to exit), it will call the {\bf unloadPlugin}
66
The two entry points are:
69
bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs)
76
both these external entry points to the shared object are defined as C entry
77
points to avoid name mangling complications with C++. However, the shared
78
object can actually be written in any language (preferrably C or C++) providing
79
that it follows C language calling conventions.
81
The definitions for {\bf bRC} and the arguments are {\bf
82
src/filed/fd-plugins.h} and so this header file needs to be included in
83
your plugin. It along with {\bf src/lib/plugins.h} define basically the whole
84
plugin interface. Within this header file, it includes the following
88
#include <sys/types.h>
91
#include "lib/plugins.h"
95
Aside from the {\bf bc\_types.h} and {\bf confit.h} headers, the plugin
96
definition uses the minimum code from Bacula. The bc\_types.h file is required
97
to ensure that the data type defintions in arguments correspond to the Bacula
100
The return codes are defined as:
104
bRC_Stop = 1, /* Stop calling other plugins */
105
bRC_Error = 2, /* Some kind of error */
106
bRC_More = 3, /* More files to backup */
111
At a future point in time, we hope to make the Bacula libbac.a into a
112
shared object so that the plugin can use much more of Bacula's
113
infrastructure, but for this first cut, we have tried to minimize the
114
dependence on Bacula.
117
As previously mentioned, the {\bf loadPlugin} entry point in the plugin
118
is called immediately after Bacula loads the plugin when the File daemon
119
itself is first starting. This entry point is only called once during the
120
execution of the File daemon. In calling the
121
plugin, the first two arguments are information from Bacula that
122
is passed to the plugin, and the last two arguments are information
123
about the plugin that the plugin must return to Bacula. The call is:
126
bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs)
129
and the arguments are:
133
This is information about Bacula in general. Currently, the only value
134
defined in the bInfo structure is the version, which is the Bacula plugin
135
interface version, currently defined as 1. The {\bf size} is set to the
136
byte size of the structure. The exact definition of the bInfo structure
137
as of this writing is:
140
typedef struct s_baculaInfo {
147
The bFuncs structure defines the callback entry points within Bacula
148
that the plugin can use register events, get Bacula values, set
149
Bacula values, and send messages to the Job output or debug output.
151
The exact definition as of this writing is:
153
typedef struct s_baculaFuncs {
156
bRC (*registerBaculaEvents)(bpContext *ctx, ...);
157
bRC (*getBaculaValue)(bpContext *ctx, bVariable var, void *value);
158
bRC (*setBaculaValue)(bpContext *ctx, bVariable var, void *value);
159
bRC (*JobMessage)(bpContext *ctx, const char *file, int line,
160
int type, utime_t mtime, const char *fmt, ...);
161
bRC (*DebugMessage)(bpContext *ctx, const char *file, int line,
162
int level, const char *fmt, ...);
163
void *(*baculaMalloc)(bpContext *ctx, const char *file, int line,
165
void (*baculaFree)(bpContext *ctx, const char *file, int line, void *mem);
169
We will discuss these entry points and how to use them a bit later when
170
describing the plugin code.
174
When the loadPlugin entry point is called, the plugin must initialize
175
an information structure about the plugin and return a pointer to
176
this structure to Bacula.
178
The exact definition as of this writing is:
181
typedef struct s_pluginInfo {
184
const char *plugin_magic;
185
const char *plugin_license;
186
const char *plugin_author;
187
const char *plugin_date;
188
const char *plugin_version;
189
const char *plugin_description;
195
\item [version] is the current Bacula defined plugin interface version, currently
196
set to 1. If the interface version differs from the current version of
197
Bacula, the plugin will not be run (not yet implemented).
198
\item [plugin\_magic] is a pointer to the text string "*FDPluginData*", a
199
sort of sanity check. If this value is not specified, the plugin
200
will not be run (not yet implemented).
201
\item [plugin\_license] is a pointer to a text string that describes the
202
plugin license. Bacula will only accept compatible licenses (not yet
204
\item [plugin\_author] is a pointer to the text name of the author of the program.
205
This string can be anything but is generally the author's name.
206
\item [plugin\_date] is the pointer text string containing the date of the plugin.
207
This string can be anything but is generally some human readable form of
209
\item [plugin\_version] is a pointer to a text string containing the version of
210
the plugin. The contents are determined by the plugin writer.
211
\item [plugin\_description] is a pointer to a string describing what the
212
plugin does. The contents are determined by the plugin writer.
215
The pInfo structure must be defined in static memory because Bacula does not
216
copy it and may refer to the values at any time while the plugin is
217
loaded. All values must be supplied or the plugin will not run (not yet
218
implemented). All text strings must be either ASCII or UTF-8 strings that
219
are terminated with a zero byte.
222
When the loadPlugin entry point is called, the plugin must initialize
223
an entry point structure about the plugin and return a pointer to
224
this structure to Bacula. This structure contains pointer to each
225
of the entry points that the plugin must provide for Bacula. When
226
Bacula is actually running the plugin, it will call the defined
227
entry points at particular times. All entry points must be defined.
229
The pFuncs structure must be defined in static memory because Bacula does not
230
copy it and may refer to the values at any time while the plugin is
233
The exact definition as of this writing is:
236
typedef struct s_pluginFuncs {
239
bRC (*newPlugin)(bpContext *ctx);
240
bRC (*freePlugin)(bpContext *ctx);
241
bRC (*getPluginValue)(bpContext *ctx, pVariable var, void *value);
242
bRC (*setPluginValue)(bpContext *ctx, pVariable var, void *value);
243
bRC (*handlePluginEvent)(bpContext *ctx, bEvent *event, void *value);
244
bRC (*startBackupFile)(bpContext *ctx, struct save_pkt *sp);
245
bRC (*endBackupFile)(bpContext *ctx);
246
bRC (*startRestoreFile)(bpContext *ctx, const char *cmd);
247
bRC (*endRestoreFile)(bpContext *ctx);
248
bRC (*pluginIO)(bpContext *ctx, struct io_pkt *io);
249
bRC (*createFile)(bpContext *ctx, struct restore_pkt *rp);
250
bRC (*setFileAttributes)(bpContext *ctx, struct restore_pkt *rp);
251
bRC (*checkFile)(bpContext *ctx, char *fname);
255
The details of the entry points will be presented in
256
separate sections below.
260
\item [size] is the byte size of the structure.
261
\item [version] is the plugin interface version currently set to 3.
264
Sample code for loadPlugin:
266
bfuncs = lbfuncs; /* set Bacula funct pointers */
268
*pinfo = &pluginInfo; /* return pointer to our info */
269
*pfuncs = &pluginFuncs; /* return pointer to our functions */
274
where pluginInfo and pluginFuncs are statically defined structures.
275
See bpipe-fd.c for details.
281
\section{Plugin Entry Points}
282
This section will describe each of the entry points (subroutines) within
283
the plugin that the plugin must provide for Bacula, when they are called
284
and their arguments. As noted above, pointers to these subroutines are
285
passed back to Bacula in the pFuncs structure when Bacula calls the
286
loadPlugin() externally defined entry point.
288
\subsection{newPlugin(bpContext *ctx)}
289
This is the entry point that Bacula will call
290
when a new "instance" of the plugin is created. This typically
291
happens at the beginning of a Job. If 10 Jobs are running
292
simultaneously, there will be at least 10 instances of the
295
The bpContext structure will be passed to the plugin, and
296
during this call, if the plugin needs to have its private
297
working storage that is associated with the particular
298
instance of the plugin, it should create it from the heap
299
(malloc the memory) and store a pointer to
300
its private working storage in the {\bf pContext} variable.
301
Note: since Bacula is a multi-threaded program, you must not
302
keep any variable data in your plugin unless it is truely meant
303
to apply globally to the whole plugin. In addition, you must
304
be aware that except the first and last call to the plugin
305
(loadPlugin and unloadPlugin) all the other calls will be
306
made by threads that correspond to a Bacula job. The
307
bpContext that will be passed for each thread will remain the
308
same throughout the Job thus you can keep your privat Job specific
309
data in it ({\bf bContext}).
312
typedef struct s_bpContext {
313
void *pContext; /* Plugin private context */
314
void *bContext; /* Bacula private context */
319
This context pointer will be passed as the first argument to all
320
the entry points that Bacula calls within the plugin. Needless
321
to say, the plugin should not change the bContext variable, which
322
is Bacula's private context pointer for this instance (Job) of this
325
\subsection{freePlugin(bpContext *ctx)}
326
This entry point is called when the
327
this instance of the plugin is no longer needed (the Job is
328
ending), and the plugin should release all memory it may
329
have allocated for this particular instance (Job) i.e. the pContext.
330
This is not the final termination
331
of the plugin signaled by a call to {\bf unloadPlugin}.
332
Any other instances (Job) will
333
continue to run, and the entry point {\bf newPlugin} may be called
334
again if other jobs start.
336
\subsection{getPluginValue(bpContext *ctx, pVariable var, void *value)}
337
Bacula will call this entry point to get
338
a value from the plugin. This entry point is currently not called.
340
\subsection{setPluginValue(bpContext *ctx, pVariable var, void *value)}
341
Bacula will call this entry point to set
342
a value in the plugin. This entry point is currently not called.
344
\subsection{handlePluginEvent(bpContext *ctx, bEvent *event, void *value)}
345
This entry point is called when Bacula
346
encounters certain events (discussed below). This is, in fact, the
347
main way that most plugins get control when a Job runs and how
348
they know what is happening in the job. It can be likened to the
349
{\bf RunScript} feature that calls external programs and scripts,
350
and is very similar to the Bacula Python interface.
351
When the plugin is called, Bacula passes it the pointer to an event
352
structure (bEvent), which currently has one item, the eventType:
355
typedef struct s_bEvent {
360
which defines what event has been triggered, and for each event,
361
Bacula will pass a pointer to a value associated with that event.
362
If no value is associated with a particular event, Bacula will
363
pass a NULL pointer, so the plugin must be careful to always check
364
value pointer prior to dereferencing it.
366
The current list of events are:
372
bEventStartBackupJob = 3,
373
bEventEndBackupJob = 4,
374
bEventStartRestoreJob = 5,
375
bEventEndRestoreJob = 6,
376
bEventStartVerifyJob = 7,
377
bEventEndVerifyJob = 8,
378
bEventBackupCommand = 9,
379
bEventRestoreCommand = 10,
386
Most of the above are self-explanatory.
389
\item [bEventJobStart] is called whenever a Job starts. The value
390
passed is a pointer to a string that contains: "Jobid=nnn
391
Job=job-name". Where nnn will be replaced by the JobId and job-name
392
will be replaced by the Job name. The variable is temporary so if you
393
need the values, you must copy them.
395
\item [bEventJobEnd] is called whenever a Job ends. No value is passed.
397
\item [bEventStartBackupJob] is called when a Backup Job begins. No value
400
\item [bEventEndBackupJob] is called when a Backup Job ends. No value is
403
\item [bEventStartRestoreJob] is called when a Restore Job starts. No value
406
\item [bEventEndRestoreJob] is called when a Restore Job ends. No value is
409
\item [bEventStartVerifyJob] is called when a Verify Job starts. No value
412
\item [bEventEndVerifyJob] is called when a Verify Job ends. No value
415
\item [bEventBackupCommand] is called prior to the bEventStartBackupJob and
416
the plugin is passed the command string (everything after the equal sign
417
in "Plugin =" as the value.
419
Note, if you intend to backup a file, this is an important first point to
420
write code that copies the command string passed into your pContext area
421
so that you will know that a backup is being performed and you will know
422
the full contents of the "Plugin =" command (i.e. what to backup and
423
what virtual filename the user wants to call it.
425
\item [bEventRestoreCommand] is called prior to the bEventStartRestoreJob and
426
the plugin is passed the command string (everything after the equal sign
427
in "Plugin =" as the value.
429
See the notes above concerning backup and the command string. This is the
430
point at which Bacula passes you the original command string that was
431
specified during the backup, so you will want to save it in your pContext
432
area for later use when Bacula calls the plugin again.
434
\item [bEventLevel] is called when the level is set for a new Job. The value
435
is a 32 bit integer stored in the void*, which represents the Job Level code.
437
\item [bEventSince] is called when the since time is set for a new Job. The
438
value is a time\_t time at which the last job was run.
441
During each of the above calls, the plugin receives either no specific value or
442
only one value, which in some cases may not be sufficient. However, knowing
443
the context of the event, the plugin can call back to the Bacula entry points
444
it was passed during the {\bf loadPlugin} call and get to a number of Bacula
445
variables. (at the current time few Bacula variables are implemented, but it
446
easily extended at a future time and as needs require).
448
\subsection{startBackupFile(bpContext *ctx, struct save\_pkt *sp)}
449
This entry point is called only if your plugin is a command plugin, and
450
it is called when Bacula encounters the "Plugin = " directive in
451
the Include section of the FileSet.
452
Called when beginning the backup of a file. Here Bacula provides you
453
with a pointer to the {\bf save\_pkt} structure and you must fill in
454
this packet with the "attribute" data of the file.
458
int32_t pkt_size; /* size of this packet */
459
char *fname; /* Full path and filename */
460
char *link; /* Link name if any */
461
struct stat statp; /* System stat() packet for file */
462
int32_t type; /* FT_xx for this file */
463
uint32_t flags; /* Bacula internal flags */
464
bool portable; /* set if data format is portable */
465
char *cmd; /* command */
466
int32_t pkt_end; /* end packet sentinel */
470
The second argument is a pointer to the {\bf save\_pkt} structure for the file
471
to be backed up. The plugin is responsible for filling in all the fields
472
of the {\bf save\_pkt}. If you are backing up
473
a real file, then generally, the statp structure can be filled in by doing
474
a {\bf stat} system call on the file.
476
If you are backing up a database or
477
something that is more complex, you might want to create a virtual file.
478
That is a file that does not actually exist on the filesystem, but represents
479
say an object that you are backing up. In that case, you need to ensure
480
that the {\bf fname} string that you pass back is unique so that it
481
does not conflict with a real file on the system, and you need to
482
artifically create values in the statp packet.
484
Example programs such as {\bf bpipe-fd.c} show how to set these fields. You
485
must take care not to store pointers the stack in the pointer fields such as
486
fname and link, because when you return from your function, your stack entries
487
will be destroyed. The solution in that case is to malloc() and return the
488
pointer to it. In order to not have memory leaks, you should store a pointer to
489
all memory allocated in your pContext structure so that in subsequent calls or
490
at termination, you can release it back to the system.
492
Once the backup has begun, Bacula will call your plugin at the {\bf pluginIO}
493
entry point to "read" the data to be backed up. Please see the {\bf bpipe-fd.c}
494
plugin for how to do I/O.
496
Example of filling in the save\_pkt as used in bpipe-fd.c:
499
struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext;
500
time_t now = time(NULL);
501
sp->fname = p_ctx->fname;
502
sp->statp.st_mode = 0700 | S_IFREG;
503
sp->statp.st_ctime = now;
504
sp->statp.st_mtime = now;
505
sp->statp.st_atime = now;
506
sp->statp.st_size = -1;
507
sp->statp.st_blksize = 4096;
508
sp->statp.st_blocks = 1;
509
p_ctx->backup = true;
513
Note: the filename to be created has already been created from the
514
command string previously sent to the plugin and is in the plugin
515
context (p\_ctx->fname) and is a malloc()ed string. This example
516
creates a regular file (S\_IFREG), with various fields being created.
518
In general, the sequence of commands issued from Bacula to the plugin
519
to do a backup while processing the "Plugin = " directive are:
522
\item generate a bEventBackupCommand event to the specified plugin
523
and pass it the command string.
524
\item make a startPluginBackup call to the plugin, which
525
fills in the data needed in save\_pkt to save as the file
526
attributes and to put on the Volume and in the catalog.
527
\item call Bacula's internal save\_file() subroutine to save the specified
528
file. The plugin will then be called at pluginIO() to "open"
529
the file, and then to read the file data.
530
Note, if you are dealing with a virtual file, the "open" operation
531
is something the plugin does internally and it doesn't necessarily
532
mean opening a file on the filesystem. For example in the case of
533
the bpipe-fd.c program, it initiates a pipe to the requested program.
534
Finally when the plugin signals to Bacula that all the data was read,
535
Bacula will call the plugin with the "close" pluginIO() function.
539
\subsection{endBackupFile(bpContext *ctx)}
540
Called at the end of backing up a file for a command plugin. If the plugin's
541
work is done, it should return bRC\_OK. If the plugin wishes to create another
542
file and back it up, then it must return bRC\_More (not yet implemented). This
543
is probably a good time to release any malloc()ed memory you used to pass back
546
\subsection{startRestoreFile(bpContext *ctx, const char *cmd)}
547
Called when the first record is read from the Volume that was
548
previously written by the command plugin.
550
\subsection{createFile(bpContext *ctx, struct restore\_pkt *rp)}
551
Called for a command plugin to create a file during a Restore job before
553
This entry point is called before any I/O is done on the file. After
554
this call, Bacula will call pluginIO() to open the file for write.
557
restore\_pkt is passed to the plugin and is based on the data that was
558
originally given by the plugin during the backup and the current user
559
restore settings (e.g. where, RegexWhere, replace). This allows the
560
plugin to first create a file (if necessary) so that the data can
561
be transmitted to it. The next call to the plugin will be a
562
pluginIO command with a request to open the file write-only.
564
This call must return one of the following values:
568
CF_SKIP = 1, /* skip file (not newer or something) */
569
CF_ERROR, /* error creating file */
570
CF_EXTRACT, /* file created, data to extract */
571
CF_CREATED /* file created, no data to extract */
575
in the restore\_pkt value {\bf create\_status}. For a normal file,
576
unless there is an error, you must return {\bf CF\_EXTRACT}.
581
int32_t pkt_size; /* size of this packet */
582
int32_t stream; /* attribute stream id */
583
int32_t data_stream; /* id of data stream to follow */
584
int32_t type; /* file type FT */
585
int32_t file_index; /* file index */
586
int32_t LinkFI; /* file index to data if hard link */
587
uid_t uid; /* userid */
588
struct stat statp; /* decoded stat packet */
589
const char *attrEx; /* extended attributes if any */
590
const char *ofname; /* output filename */
591
const char *olname; /* output link name */
592
const char *where; /* where */
593
const char *RegexWhere; /* regex where */
594
int replace; /* replace flag */
595
int create_status; /* status from createFile() */
596
int32_t pkt_end; /* end packet sentinel */
601
Typical code to create a regular file would be the following:
604
struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext;
605
time_t now = time(NULL);
606
sp->fname = p_ctx->fname; /* set the full path/filename I want to create */
608
sp->statp.st_mode = 0700 | S_IFREG;
609
sp->statp.st_ctime = now;
610
sp->statp.st_mtime = now;
611
sp->statp.st_atime = now;
612
sp->statp.st_size = -1;
613
sp->statp.st_blksize = 4096;
614
sp->statp.st_blocks = 1;
618
This will create a virtual file. If you are creating a file that actually
619
exists, you will most likely want to fill the statp packet using the
622
Creating a directory is similar, but requires a few extra steps:
625
struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext;
626
time_t now = time(NULL);
627
sp->fname = p_ctx->fname; /* set the full path I want to create */
628
sp->link = xxx; where xxx is p_ctx->fname with a trailing forward slash
630
sp->statp.st_mode = 0700 | S_IFDIR;
631
sp->statp.st_ctime = now;
632
sp->statp.st_mtime = now;
633
sp->statp.st_atime = now;
634
sp->statp.st_size = -1;
635
sp->statp.st_blksize = 4096;
636
sp->statp.st_blocks = 1;
640
The link field must be set with the full cononical path name, which always
641
ends with a forward slash. If you do not terminate it with a forward slash,
642
you will surely have problems later.
644
As with the example that creates a file, if you are backing up a real
645
directory, you will want to do an stat() on the directory.
647
Note, if you want the directory permissions and times to be correctly
648
restored, you must create the directory {\bf after} all the file directories
649
have been sent to Bacula. That allows the restore process to restore all the
650
files in a directory using default directory options, then at the end, restore
651
the directory permissions. If you do it the other way around, each time you
652
restore a file, the OS will modify the time values for the directory entry.
654
\subsection{setFileAttributes(bpContext *ctx, struct restore\_pkt *rp)}
655
This is call not yet implemented. Called for a command plugin.
657
See the definition of {\bf restre\_pkt} in the above section.
659
\subsection{endRestoreFile(bpContext *ctx)}
660
Called when a command plugin is done restoring a file.
662
\subsection{pluginIO(bpContext *ctx, struct io\_pkt *io)}
663
Called to do the input (backup) or output (restore) of data from or to a file
664
for a command plugin. These routines simulate the Unix read(), write(), open(),
665
close(), and lseek() I/O calls, and the arguments are passed in the packet and
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the return values are also placed in the packet. In addition for Win32 systems
667
the plugin must return two additional values (described below).
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int32_t pkt_size; /* Size of this packet */
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int32_t func; /* Function code */
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int32_t count; /* read/write count */
682
mode_t mode; /* permissions for created files */
683
int32_t flags; /* Open flags */
684
char *buf; /* read/write buffer */
685
const char *fname; /* open filename */
686
int32_t status; /* return status */
687
int32_t io_errno; /* errno code */
688
int32_t lerror; /* Win32 error code */
689
int32_t whence; /* lseek argument */
690
boffset_t offset; /* lseek argument */
691
bool win32; /* Win32 GetLastError returned */
692
int32_t pkt_end; /* end packet sentinel */
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The particular Unix function being simulated is indicated by the {\bf func},
697
which will have one of the IO\_OPEN, IO\_READ, ... codes listed above. The
698
status code that would be returned from a Unix call is returned in {\bf status}
699
for IO\_OPEN, IO\_CLOSE, IO\_READ, and IO\_WRITE. The return value for IO\_SEEK
700
is returned in {\bf offset} which in general is a 64 bit value.
702
When there is an error on Unix systems, you must always set io\_error, and
703
on a Win32 system, you must always set win32, and the returned value from
704
the OS call GetLastError() in lerror.
706
For all except IO\_SEEK, {\bf status} is the return result. In general it is
707
a positive integer unless there is an error in which case it is -1.
709
The following describes each call and what you get and what you
714
You will be passed fname, mode, and flags.
715
You must set on return: status, and if there is a Unix error
716
io\_errno must be set to the errno value, and if there is a
717
Win32 error win32 and lerror.
720
You will be passed: count, and buf (buffer of size count).
721
You must set on return: status to the number of bytes
722
read into the buffer (buf) or -1 on an error,
723
and if there is a Unix error
724
io\_errno must be set to the errno value, and if there is a
725
Win32 error, win32 and lerror must be set.
728
You will be passed: count, and buf (buffer of size count).
729
You must set on return: status to the number of bytes
730
written from the buffer (buf) or -1 on an error,
731
and if there is a Unix error
732
io\_errno must be set to the errno value, and if there is a
733
Win32 error, win32 and lerror must be set.
736
Nothing will be passed to you. On return you must set
737
status to 0 on success and -1 on failure. If there is a Unix error
738
io\_errno must be set to the errno value, and if there is a
739
Win32 error, win32 and lerror must be set.
742
You will be passed: offset, and whence. offset is a 64 bit value
743
and is the position to seek to relative to whence. whence is one
744
of the following SEEK\_SET, SEEK\_CUR, or SEEK\_END indicating to
745
either to seek to an absolute possition, relative to the current
746
position or relative to the end of the file.
747
You must pass back in offset the absolute location to which you
748
seeked. If there is an error, offset should be set to -1.
749
If there is a Unix error
750
io\_errno must be set to the errno value, and if there is a
751
Win32 error, win32 and lerror must be set.
753
Note: Bacula will call IO\_SEEK only when writing a sparse file.
757
\subsection{bool checkFile(bpContext *ctx, char *fname)}
758
If this entry point is set, Bacula will call it after backing up all file
759
data during an Accurate backup. It will be passed the full filename for
760
each file that Bacula is proposing to mark as deleted. Only files
761
previously backed up but not backed up in the current session will be
762
marked to be deleted. If you return {\bf false}, the file will be be
763
marked deleted. If you return {\bf true} the file will not be marked
764
deleted. This permits a plugin to ensure that previously saved virtual
765
files or files controlled by your plugin that have not change (not backed
766
up in the current job) are not marked to be deleted. This entry point will
767
only be called during Accurate Incrmental and Differential backup jobs.
770
\section{Bacula Plugin Entrypoints}
771
When Bacula calls one of your plugin entrypoints, you can call back to
772
the entrypoints in Bacula that were supplied during the xxx plugin call
773
to get or set information within Bacula.
775
\subsection{bRC registerBaculaEvents(bpContext *ctx, ...)}
776
This Bacula entrypoint will allow you to register to receive events
777
that are not autmatically passed to your plugin by default. This
778
entrypoint currently is unimplemented.
780
\subsection{bRC getBaculaValue(bpContext *ctx, bVariable var, void *value)}
781
Calling this entrypoint, you can obtain specific values that are available
782
in Bacula. The following Variables can be referenced:
784
\item bVarJobId returns an int
785
\item bVarFDName returns a char *
786
\item bVarLevel returns an int
787
\item bVarClient returns a char *
788
\item bVarJobName returns a char *
789
\item bVarJobStatus returns an int
790
\item bVarSinceTime returns an int (time\_t)
791
\item bVarAccurate returns an int
794
\subsection{bRC setBaculaValue(bpContext *ctx, bVariable var, void *value)}
795
Calling this entrypoint allows you to set particular values in
796
Bacula. The only variable that can currently be set is
797
{\bf bVarFileSeen} and the value passed is a char * that points
798
to the full filename for a file that you are indicating has been
799
seen and hence is not deleted.
801
\subsection{bRC JobMessage(bpContext *ctx, const char *file, int line,
802
int type, utime\_t mtime, const char *fmt, ...)}
803
This call permits you to put a message in the Job Report.
806
\subsection{bRC DebugMessage(bpContext *ctx, const char *file, int line,
807
int level, const char *fmt, ...)}
808
This call permits you to print a debug message.
811
\subsection{void baculaMalloc(bpContext *ctx, const char *file, int line,
813
This call permits you to obtain memory from Bacula's memory allocator.
816
\subsection{void baculaFree(bpContext *ctx, const char *file, int line, void *mem)}
817
This call permits you to free memory obtained from Bacula's memory allocator.
819
\section{Building Bacula Plugins}
820
There is currently one sample program {\bf example-plugin-fd.c} and
821
one working plugin {\bf bpipe-fd.c} that can be found in the Bacula
822
{\bf src/plugins/fd} directory. Both are built with the following:
826
./configure <your-options>
834
After building Bacula and changing into the src/plugins/fd directory,
835
the {\bf make} command will build the {\bf bpipe-fd.so} plugin, which
836
is a very useful and working program.
838
The {\bf make test} command will build the {\bf example-plugin-fd.so}
839
plugin and a binary named {\bf main}, which is build from the source
840
code located in {\bf src/filed/fd\_plugins.c}.
842
If you execute {\bf ./main}, it will load and run the example-plugin-fd
843
plugin simulating a small number of the calling sequences that Bacula uses
844
in calling a real plugin. This allows you to do initial testing of
845
your plugin prior to trying it with Bacula.
847
You can get a good idea of how to write your own plugin by first
848
studying the example-plugin-fd, and actually running it. Then
849
it can also be instructive to read the bpipe-fd.c code as it is
850
a real plugin, which is still rather simple and small.
852
When actually writing your own plugin, you may use the example-plugin-fd.c
853
code as a template for your code.
added
removed
manuals/de/developers/pluginAPI.tex
