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
666 the return values are also placed in the packet. In addition for Win32 systems
667 the plugin must return two additional values (described below).
679 int32_t pkt_size; /* Size of this packet */
680 int32_t func; /* Function code */
681 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 */
696 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.