From: Kern Sibbald Date: Mon, 30 Mar 2009 14:02:14 +0000 (+0000) Subject: Update X-Git-Tag: Release-3.0.0~51 X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=ab0d54d05f5f39f3330e5a54236bc8412c127955;p=bacula%2Fdocs Update --- diff --git a/docs/manuals/en/concepts/concepts.tex b/docs/manuals/en/concepts/concepts.tex index 2f830e44..3d7bd17a 100644 --- a/docs/manuals/en/concepts/concepts.tex +++ b/docs/manuals/en/concepts/concepts.tex @@ -82,6 +82,7 @@ \pagenumbering{arabic} \include{general} \include{newfeatures} +\include{pluginAPI} \include{state} \include{requirements} \include{supportedoses} diff --git a/docs/manuals/en/concepts/license.tex b/docs/manuals/en/concepts/license.tex index 4e0a0d9d..2d58396d 100644 --- a/docs/manuals/en/concepts/license.tex +++ b/docs/manuals/en/concepts/license.tex @@ -33,11 +33,11 @@ at \elink{http://www.bacula.org}{\url{http://www.bacula.org}}. The vast bulk of the source code is released under the \ilink{GNU General Public License version 2.}{GplChapter}. -Most of this code is copyrighted: Copyright \copyright 2000-2007 +Most of this code is copyrighted: Copyright \copyright 2000-2009 Free Software Foundation Europe e.V. -Portions may be copyrighted by other people (ATT, the Free Software -Foundation, ...). These files are released under the GPL license. +Portions may be copyrighted by other people. These files are released +under different licenses which are compatible with the Bacula GPLv2 license. \section{LGPL} \index[general]{LGPL } @@ -79,15 +79,13 @@ is found on the Bacula web site at: and should be filled out then sent to: \begin{quote} - Free Software Foundation Europe \\ - Freedom Task Force \\ - Sumatrastrasse 25 \\ - 8006 Z\"{u}rich \\ + Kern Sibbald \\ + Cotes-de-Montmoiret 9 \\ + 1012 Lausanne \\ Switzerland \\ \end{quote} -Please note that the above address is different from the officially -registered office mentioned in the document. When you send in such a +When you send in such a complete document, please notify me: kern at sibbald dot com. diff --git a/docs/manuals/en/concepts/newfeatures.tex b/docs/manuals/en/concepts/newfeatures.tex index 5be276a6..275d08f8 100644 --- a/docs/manuals/en/concepts/newfeatures.tex +++ b/docs/manuals/en/concepts/newfeatures.tex @@ -351,8 +351,18 @@ writing it to a volume in a different pool. In some respects the Vbackup feature works similar to a Migration job, in that Bacula normally reads the data from the pool specified in the Job resource, and writes it to the {\bf Next Pool} specified in the -Job resource. The input Storage resource and the Output Storage resource -must be different. +Job resource. Note, this means that usually the output from the Virtual +Backup is written into a different pool from where your prior backups +are saved. Doing it this way guarantees that you will not get a deadlock +situation attempting to read and write to the same volume in the Storage +daemon. If you then want to do subsequent backups, you may need to +move the Virtual Full Volume back to your normal backup pool. +Alternatively, you can set your {\bf Next Pool} to point to the current +pool. This will cause Bacula to read and write to Volumes in the +current pool. In general, this will work, but doing the Virtual Full +requires reading more than one Volume, this procedure may cause a +deadlock where Bacula is writing on a Volume that is later needed +for reading. The Vbackup is enabled on a Job by Job in the Job resource by specifying a level of {\bf VirtualFull}. @@ -448,6 +458,8 @@ will be based on the Virtual Full, it will backup all files from the last Job included in the Virtual Full rather than from the time the Virtual Full was actually run. + + \section{Catalog Format} Bacula 3.0 comes with some changes on the catalog format. The upgrade operation will convert an essential field of the File table that permits to @@ -1124,7 +1136,9 @@ enhanced and stabilized. In particular, there are new table based status commands; it can now be easily localized using Qt4 Linguist. The Bat communications protocol has been significantly enhanced to improve -GUI handling. +GUI handling. Note, you {\bf must} use a the bat that is distributed with +the Director you are using otherwise the communications protocol will not +work. \subsection{RunScript Enhancements} The {\bf RunScript} resource has been enhanced to permit multiple @@ -1345,820 +1359,3 @@ When actually writing your own plugin, you may use the example-plugin-fd.c code as a template for your code. -%% -%% - -\chapter{Bacula FD Plugin API} -To write a Bacula plugin, you create a dynamic shared object program (or dll on -Win32) with a particular name and two exported entry points, place it in the -{\bf Plugins Directory}, which is defined in the {\bf bacula-fd.conf} file in -the {\bf Client} resource, and when the FD starts, it will load all the plugins -that end with {\bf -fd.so} (or {\bf -fd.dll} on Win32) found in that directory. - -\section{Normal vs Command Plugins} -In general, there are two ways that plugins are called. The first way, is when -a particular event is detected in Bacula, it will transfer control to each -plugin that is loaded in turn informing the plugin of the event. This is very -similar to how a {\bf RunScript} works, and the events are very similar. Once -the plugin gets control, it can interact with Bacula by getting and setting -Bacula variables. In this way, it behaves much like a RunScript. Currently -very few Bacula variables are defined, but they will be implemented as the need -arrises, and it is very extensible. - -We plan to have plugins register to receive events that they normally would -not receive, such as an event for each file examined for backup or restore. -This feature is not yet implemented. - -The second type of plugin, which is more useful and fully implemented in the -current version is what we call a command plugin. As with all plugins, it gets -notified of important events as noted above (details described below), but in -addition, this kind of plugin can accept a command line, which is a: - -\begin{verbatim} - Plugin = -\end{verbatim} - -directive that is placed in the Include section of a FileSet and is very -similar to the "File = " directive. When this Plugin directive is encountered -by Bacula during backup, it passes the "command" part of the Plugin directive -only to the plugin that is explicitly named in the first field of that command -string. This allows that plugin to backup any file or files on the system that -it wants. It can even create "virtual files" in the catalog that contain data -to be restored but do not necessarily correspond to actual files on the -filesystem. - -The important features of the command plugin entry points are: -\begin{itemize} - \item It is triggered by a "Plugin =" directive in the FileSet - \item Only a single plugin is called that is named on the "Plugin =" directive. - \item The full command string after the "Plugin =" is passed to the plugin - so that it can be told what to backup/restore. -\end{itemize} - - -\section{Loading Plugins} -Once the File daemon loads the plugins, it asks the OS for the -two entry points (loadPlugin and unloadPlugin) then calls the -{\bf loadPlugin} entry point (see below). - -Bacula passes information to the plugin through this call and it gets -back information that it needs to use the plugin. Later, Bacula - will call particular functions that are defined by the -{\bf loadPlugin} interface. - -When Bacula is finished with the plugin -(when Bacula is going to exit), it will call the {\bf unloadPlugin} -entry point. - -The two entry points are: - -\begin{verbatim} -bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs) - -and - -bRC unloadPlugin() -\end{verbatim} - -both these external entry points to the shared object are defined as C entry -points to avoid name mangling complications with C++. However, the shared -object can actually be written in any language (preferrably C or C++) providing -that it follows C language calling conventions. - -The definitions for {\bf bRC} and the arguments are {\bf -src/filed/fd-plugins.h} and so this header file needs to be included in -your plugin. It along with {\bf src/lib/plugins.h} define basically the whole -plugin interface. Within this header file, it includes the following -files: - -\begin{verbatim} -#include -#include "config.h" -#include "bc_types.h" -#include "lib/plugins.h" -#include -\end{verbatim} - -Aside from the {\bf bc\_types.h} and {\bf confit.h} headers, the plugin -definition uses the minimum code from Bacula. The bc\_types.h file is required -to ensure that the data type defintions in arguments correspond to the Bacula -core code. - -The return codes are defined as: -\begin{verbatim} -typedef enum { - bRC_OK = 0, /* OK */ - bRC_Stop = 1, /* Stop calling other plugins */ - bRC_Error = 2, /* Some kind of error */ - bRC_More = 3, /* More files to backup */ -} bRC; -\end{verbatim} - - -At a future point in time, we hope to make the Bacula libbac.a into a -shared object so that the plugin can use much more of Bacula's -infrastructure, but for this first cut, we have tried to minimize the -dependence on Bacula. - -\section{loadPlugin} -As previously mentioned, the {\bf loadPlugin} entry point in the plugin -is called immediately after Bacula loads the plugin when the File daemon -itself is first starting. This entry point is only called once during the -execution of the File daemon. In calling the -plugin, the first two arguments are information from Bacula that -is passed to the plugin, and the last two arguments are information -about the plugin that the plugin must return to Bacula. The call is: - -\begin{verbatim} -bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs) -\end{verbatim} - -and the arguments are: - -\begin{description} -\item [lbinfo] -This is information about Bacula in general. Currently, the only value -defined in the bInfo structure is the version, which is the Bacula plugin -interface version, currently defined as 1. The {\bf size} is set to the -byte size of the structure. The exact definition of the bInfo structure -as of this writing is: - -\begin{verbatim} -typedef struct s_baculaInfo { - uint32_t size; - uint32_t version; -} bInfo; -\end{verbatim} - -\item [lbfuncs] -The bFuncs structure defines the callback entry points within Bacula -that the plugin can use register events, get Bacula values, set -Bacula values, and send messages to the Job output or debug output. - -The exact definition as of this writing is: -\begin{verbatim} -typedef struct s_baculaFuncs { - uint32_t size; - uint32_t version; - bRC (*registerBaculaEvents)(bpContext *ctx, ...); - bRC (*getBaculaValue)(bpContext *ctx, bVariable var, void *value); - bRC (*setBaculaValue)(bpContext *ctx, bVariable var, void *value); - bRC (*JobMessage)(bpContext *ctx, const char *file, int line, - int type, utime_t mtime, const char *fmt, ...); - bRC (*DebugMessage)(bpContext *ctx, const char *file, int line, - int level, const char *fmt, ...); - void *(*baculaMalloc)(bpContext *ctx, const char *file, int line, - size_t size); - void (*baculaFree)(bpContext *ctx, const char *file, int line, void *mem); -} bFuncs; -\end{verbatim} - -We will discuss these entry points and how to use them a bit later when -describing the plugin code. - - -\item [pInfo] -When the loadPlugin entry point is called, the plugin must initialize -an information structure about the plugin and return a pointer to -this structure to Bacula. - -The exact definition as of this writing is: - -\begin{verbatim} -typedef struct s_pluginInfo { - uint32_t size; - uint32_t version; - const char *plugin_magic; - const char *plugin_license; - const char *plugin_author; - const char *plugin_date; - const char *plugin_version; - const char *plugin_description; -} pInfo; -\end{verbatim} - -Where: - \begin{description} - \item [version] is the current Bacula defined plugin interface version, currently - set to 1. If the interface version differs from the current version of - Bacula, the plugin will not be run (not yet implemented). - \item [plugin\_magic] is a pointer to the text string "*FDPluginData*", a - sort of sanity check. If this value is not specified, the plugin - will not be run (not yet implemented). - \item [plugin\_license] is a pointer to a text string that describes the - plugin license. Bacula will only accept compatible licenses (not yet - implemented). - \item [plugin\_author] is a pointer to the text name of the author of the program. - This string can be anything but is generally the author's name. - \item [plugin\_date] is the pointer text string containing the date of the plugin. - This string can be anything but is generally some human readable form of - the date. - \item [plugin\_version] is a pointer to a text string containing the version of - the plugin. The contents are determined by the plugin writer. - \item [plugin\_description] is a pointer to a string describing what the - plugin does. The contents are determined by the plugin writer. - \end{description} - -The pInfo structure must be defined in static memory because Bacula does not -copy it and may refer to the values at any time while the plugin is -loaded. All values must be supplied or the plugin will not run (not yet -implemented). All text strings must be either ASCII or UTF-8 strings that -are terminated with a zero byte. - -\item [pFuncs] -When the loadPlugin entry point is called, the plugin must initialize -an entry point structure about the plugin and return a pointer to -this structure to Bacula. This structure contains pointer to each -of the entry points that the plugin must provide for Bacula. When -Bacula is actually running the plugin, it will call the defined -entry points at particular times. All entry points must be defined. - -The pFuncs structure must be defined in static memory because Bacula does not -copy it and may refer to the values at any time while the plugin is -loaded. - -The exact definition as of this writing is: - -\begin{verbatim} -typedef struct s_pluginFuncs { - uint32_t size; - uint32_t version; - bRC (*newPlugin)(bpContext *ctx); - bRC (*freePlugin)(bpContext *ctx); - bRC (*getPluginValue)(bpContext *ctx, pVariable var, void *value); - bRC (*setPluginValue)(bpContext *ctx, pVariable var, void *value); - bRC (*handlePluginEvent)(bpContext *ctx, bEvent *event, void *value); - bRC (*startBackupFile)(bpContext *ctx, struct save_pkt *sp); - bRC (*endBackupFile)(bpContext *ctx); - bRC (*startRestoreFile)(bpContext *ctx, const char *cmd); - bRC (*endRestoreFile)(bpContext *ctx); - bRC (*pluginIO)(bpContext *ctx, struct io_pkt *io); - bRC (*createFile)(bpContext *ctx, struct restore_pkt *rp); - bRC (*setFileAttributes)(bpContext *ctx, struct restore_pkt *rp); - bRC (*checkFile)(bpContext *ctx, char *fname); -} pFuncs; -\end{verbatim} - -The details of the entry points will be presented in -separate sections below. - -Where: - \begin{description} - \item [size] is the byte size of the structure. - \item [version] is the plugin interface version currently set to 3. - \end{description} - -Sample code for loadPlugin: -\begin{verbatim} - bfuncs = lbfuncs; /* set Bacula funct pointers */ - binfo = lbinfo; - *pinfo = &pluginInfo; /* return pointer to our info */ - *pfuncs = &pluginFuncs; /* return pointer to our functions */ - - return bRC_OK; -\end{verbatim} - -where pluginInfo and pluginFuncs are statically defined structures. -See bpipe-fd.c for details. - - - -\end{description} - -\section{Plugin Entry Points} -This section will describe each of the entry points (subroutines) within -the plugin that the plugin must provide for Bacula, when they are called -and their arguments. As noted above, pointers to these subroutines are -passed back to Bacula in the pFuncs structure when Bacula calls the -loadPlugin() externally defined entry point. - -\subsection{newPlugin(bpContext *ctx)} - This is the entry point that Bacula will call - when a new "instance" of the plugin is created. This typically - happens at the beginning of a Job. If 10 Jobs are running - simultaneously, there will be at least 10 instances of the - plugin. - - The bpContext structure will be passed to the plugin, and - during this call, if the plugin needs to have its private - working storage that is associated with the particular - instance of the plugin, it should create it from the heap - (malloc the memory) and store a pointer to - its private working storage in the {\bf pContext} variable. - Note: since Bacula is a multi-threaded program, you must not - keep any variable data in your plugin unless it is truely meant - to apply globally to the whole plugin. In addition, you must - be aware that except the first and last call to the plugin - (loadPlugin and unloadPlugin) all the other calls will be - made by threads that correspond to a Bacula job. The - bpContext that will be passed for each thread will remain the - same throughout the Job thus you can keep your privat Job specific - data in it ({\bf bContext}). - -\begin{verbatim} -typedef struct s_bpContext { - void *pContext; /* Plugin private context */ - void *bContext; /* Bacula private context */ -} bpContext; - -\end{verbatim} - - This context pointer will be passed as the first argument to all - the entry points that Bacula calls within the plugin. Needless - to say, the plugin should not change the bContext variable, which - is Bacula's private context pointer for this instance (Job) of this - plugin. - -\subsection{freePlugin(bpContext *ctx)} -This entry point is called when the -this instance of the plugin is no longer needed (the Job is -ending), and the plugin should release all memory it may -have allocated for this particular instance (Job) i.e. the pContext. -This is not the final termination -of the plugin signaled by a call to {\bf unloadPlugin}. -Any other instances (Job) will -continue to run, and the entry point {\bf newPlugin} may be called -again if other jobs start. - -\subsection{getPluginValue(bpContext *ctx, pVariable var, void *value)} -Bacula will call this entry point to get -a value from the plugin. This entry point is currently not called. - -\subsection{setPluginValue(bpContext *ctx, pVariable var, void *value)} -Bacula will call this entry point to set -a value in the plugin. This entry point is currently not called. - -\subsection{handlePluginEvent(bpContext *ctx, bEvent *event, void *value)} -This entry point is called when Bacula -encounters certain events (discussed below). This is, in fact, the -main way that most plugins get control when a Job runs and how -they know what is happening in the job. It can be likened to the -{\bf RunScript} feature that calls external programs and scripts, -and is very similar to the Bacula Python interface. -When the plugin is called, Bacula passes it the pointer to an event -structure (bEvent), which currently has one item, the eventType: - -\begin{verbatim} -typedef struct s_bEvent { - uint32_t eventType; -} bEvent; -\end{verbatim} - - which defines what event has been triggered, and for each event, - Bacula will pass a pointer to a value associated with that event. - If no value is associated with a particular event, Bacula will - pass a NULL pointer, so the plugin must be careful to always check - value pointer prior to dereferencing it. - - The current list of events are: - -\begin{verbatim} -typedef enum { - bEventJobStart = 1, - bEventJobEnd = 2, - bEventStartBackupJob = 3, - bEventEndBackupJob = 4, - bEventStartRestoreJob = 5, - bEventEndRestoreJob = 6, - bEventStartVerifyJob = 7, - bEventEndVerifyJob = 8, - bEventBackupCommand = 9, - bEventRestoreCommand = 10, - bEventLevel = 11, - bEventSince = 12, -} bEventType; - -\end{verbatim} - -Most of the above are self-explanatory. - -\begin{description} - \item [bEventJobStart] is called whenever a Job starts. The value - passed is a pointer to a string that contains: "Jobid=nnn - Job=job-name". Where nnn will be replaced by the JobId and job-name - will be replaced by the Job name. The variable is temporary so if you - need the values, you must copy them. - - \item [bEventJobEnd] is called whenever a Job ends. No value is passed. - - \item [bEventStartBackupJob] is called when a Backup Job begins. No value - is passed. - - \item [bEventEndBackupJob] is called when a Backup Job ends. No value is - passed. - - \item [bEventStartRestoreJob] is called when a Restore Job starts. No value - is passed. - - \item [bEventEndRestoreJob] is called when a Restore Job ends. No value is - passed. - - \item [bEventStartVerifyJob] is called when a Verify Job starts. No value - is passed. - - \item [bEventEndVerifyJob] is called when a Verify Job ends. No value - is passed. - - \item [bEventBackupCommand] is called prior to the bEventStartBackupJob and - the plugin is passed the command string (everything after the equal sign - in "Plugin =" as the value. - - Note, if you intend to backup a file, this is an important first point to - write code that copies the command string passed into your pContext area - so that you will know that a backup is being performed and you will know - the full contents of the "Plugin =" command (i.e. what to backup and - what virtual filename the user wants to call it. - - \item [bEventRestoreCommand] is called prior to the bEventStartRestoreJob and - the plugin is passed the command string (everything after the equal sign - in "Plugin =" as the value. - - See the notes above concerning backup and the command string. This is the - point at which Bacula passes you the original command string that was - specified during the backup, so you will want to save it in your pContext - area for later use when Bacula calls the plugin again. - - \item [bEventLevel] is called when the level is set for a new Job. The value - is a 32 bit integer stored in the void*, which represents the Job Level code. - - \item [bEventSince] is called when the since time is set for a new Job. The - value is a time\_t time at which the last job was run. -\end{description} - -During each of the above calls, the plugin receives either no specific value or -only one value, which in some cases may not be sufficient. However, knowing -the context of the event, the plugin can call back to the Bacula entry points -it was passed during the {\bf loadPlugin} call and get to a number of Bacula -variables. (at the current time few Bacula variables are implemented, but it -easily extended at a future time and as needs require). - -\subsection{startBackupFile(bpContext *ctx, struct save\_pkt *sp)} -This entry point is called only if your plugin is a command plugin, and -it is called when Bacula encounters the "Plugin = " directive in -the Include section of the FileSet. -Called when beginning the backup of a file. Here Bacula provides you -with a pointer to the {\bf save\_pkt} structure and you must fill in -this packet with the "attribute" data of the file. - -\begin{verbatim} -struct save_pkt { - int32_t pkt_size; /* size of this packet */ - char *fname; /* Full path and filename */ - char *link; /* Link name if any */ - struct stat statp; /* System stat() packet for file */ - int32_t type; /* FT_xx for this file */ - uint32_t flags; /* Bacula internal flags */ - bool portable; /* set if data format is portable */ - char *cmd; /* command */ - int32_t pkt_end; /* end packet sentinel */ -}; -\end{verbatim} - -The second argument is a pointer to the {\bf save\_pkt} structure for the file -to be backed up. The plugin is responsible for filling in all the fields -of the {\bf save\_pkt}. If you are backing up -a real file, then generally, the statp structure can be filled in by doing -a {\bf stat} system call on the file. - -If you are backing up a database or -something that is more complex, you might want to create a virtual file. -That is a file that does not actually exist on the filesystem, but represents -say an object that you are backing up. In that case, you need to ensure -that the {\bf fname} string that you pass back is unique so that it -does not conflict with a real file on the system, and you need to -artifically create values in the statp packet. - -Example programs such as {\bf bpipe-fd.c} show how to set these fields. You -must take care not to store pointers the stack in the pointer fields such as -fname and link, because when you return from your function, your stack entries -will be destroyed. The solution in that case is to malloc() and return the -pointer to it. In order to not have memory leaks, you should store a pointer to -all memory allocated in your pContext structure so that in subsequent calls or -at termination, you can release it back to the system. - -Once the backup has begun, Bacula will call your plugin at the {\bf pluginIO} -entry point to "read" the data to be backed up. Please see the {\bf bpipe-fd.c} -plugin for how to do I/O. - -Example of filling in the save\_pkt as used in bpipe-fd.c: - -\begin{verbatim} - struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext; - time_t now = time(NULL); - sp->fname = p_ctx->fname; - sp->statp.st_mode = 0700 | S_IFREG; - sp->statp.st_ctime = now; - sp->statp.st_mtime = now; - sp->statp.st_atime = now; - sp->statp.st_size = -1; - sp->statp.st_blksize = 4096; - sp->statp.st_blocks = 1; - p_ctx->backup = true; - return bRC_OK; -\end{verbatim} - -Note: the filename to be created has already been created from the -command string previously sent to the plugin and is in the plugin -context (p\_ctx->fname) and is a malloc()ed string. This example -creates a regular file (S\_IFREG), with various fields being created. - -In general, the sequence of commands issued from Bacula to the plugin -to do a backup while processing the "Plugin = " directive are: - -\begin{enumerate} - \item generate a bEventBackupCommand event to the specified plugin - and pass it the command string. - \item make a startPluginBackup call to the plugin, which - fills in the data needed in save\_pkt to save as the file - attributes and to put on the Volume and in the catalog. - \item call Bacula's internal save\_file() subroutine to save the specified - file. The plugin will then be called at pluginIO() to "open" - the file, and then to read the file data. - Note, if you are dealing with a virtual file, the "open" operation - is something the plugin does internally and it doesn't necessarily - mean opening a file on the filesystem. For example in the case of - the bpipe-fd.c program, it initiates a pipe to the requested program. - Finally when the plugin signals to Bacula that all the data was read, - Bacula will call the plugin with the "close" pluginIO() function. -\end{enumerate} - - -\subsection{endBackupFile(bpContext *ctx)} -Called at the end of backing up a file for a command plugin. If the plugin's -work is done, it should return bRC\_OK. If the plugin wishes to create another -file and back it up, then it must return bRC\_More (not yet implemented). This -is probably a good time to release any malloc()ed memory you used to pass back -filenames. - -\subsection{startRestoreFile(bpContext *ctx, const char *cmd)} -Called when the first record is read from the Volume that was -previously written by the command plugin. - -\subsection{createFile(bpContext *ctx, struct restore\_pkt *rp)} -Called for a command plugin to create a file during a Restore job before -restoring the data. -This entry point is called before any I/O is done on the file. After -this call, Bacula will call pluginIO() to open the file for write. - -The data in the -restore\_pkt is passed to the plugin and is based on the data that was -originally given by the plugin during the backup and the current user -restore settings (e.g. where, RegexWhere, replace). This allows the -plugin to first create a file (if necessary) so that the data can -be transmitted to it. The next call to the plugin will be a -pluginIO command with a request to open the file write-only. - -This call must return one of the following values: - -\begin{verbatim} - enum { - CF_SKIP = 1, /* skip file (not newer or something) */ - CF_ERROR, /* error creating file */ - CF_EXTRACT, /* file created, data to extract */ - CF_CREATED /* file created, no data to extract */ -}; -\end{verbatim} - -in the restore\_pkt value {\bf create\_status}. For a normal file, -unless there is an error, you must return {\bf CF\_EXTRACT}. - -\begin{verbatim} - -struct restore_pkt { - int32_t pkt_size; /* size of this packet */ - int32_t stream; /* attribute stream id */ - int32_t data_stream; /* id of data stream to follow */ - int32_t type; /* file type FT */ - int32_t file_index; /* file index */ - int32_t LinkFI; /* file index to data if hard link */ - uid_t uid; /* userid */ - struct stat statp; /* decoded stat packet */ - const char *attrEx; /* extended attributes if any */ - const char *ofname; /* output filename */ - const char *olname; /* output link name */ - const char *where; /* where */ - const char *RegexWhere; /* regex where */ - int replace; /* replace flag */ - int create_status; /* status from createFile() */ - int32_t pkt_end; /* end packet sentinel */ - -}; -\end{verbatim} - -Typical code to create a regular file would be the following: - -\begin{verbatim} - struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext; - time_t now = time(NULL); - sp->fname = p_ctx->fname; /* set the full path/filename I want to create */ - sp->type = FT_REG; - sp->statp.st_mode = 0700 | S_IFREG; - sp->statp.st_ctime = now; - sp->statp.st_mtime = now; - sp->statp.st_atime = now; - sp->statp.st_size = -1; - sp->statp.st_blksize = 4096; - sp->statp.st_blocks = 1; - return bRC_OK; -\end{verbatim} - -This will create a virtual file. If you are creating a file that actually -exists, you will most likely want to fill the statp packet using the -stat() system call. - -Creating a directory is similar, but requires a few extra steps: - -\begin{verbatim} - struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext; - time_t now = time(NULL); - sp->fname = p_ctx->fname; /* set the full path I want to create */ - sp->link = xxx; where xxx is p_ctx->fname with a trailing forward slash - sp->type = FT_DIREND - sp->statp.st_mode = 0700 | S_IFDIR; - sp->statp.st_ctime = now; - sp->statp.st_mtime = now; - sp->statp.st_atime = now; - sp->statp.st_size = -1; - sp->statp.st_blksize = 4096; - sp->statp.st_blocks = 1; - return bRC_OK; -\end{verbatim} - -The link field must be set with the full cononical path name, which always -ends with a forward slash. If you do not terminate it with a forward slash, -you will surely have problems later. - -As with the example that creates a file, if you are backing up a real -directory, you will want to do an stat() on the directory. - -Note, if you want the directory permissions and times to be correctly -restored, you must create the directory {\bf after} all the file directories -have been sent to Bacula. That allows the restore process to restore all the -files in a directory using default directory options, then at the end, restore -the directory permissions. If you do it the other way around, each time you -restore a file, the OS will modify the time values for the directory entry. - -\subsection{setFileAttributes(bpContext *ctx, struct restore\_pkt *rp)} -This is call not yet implemented. Called for a command plugin. - -See the definition of {\bf restre\_pkt} in the above section. - -\subsection{endRestoreFile(bpContext *ctx)} -Called when a command plugin is done restoring a file. - -\subsection{pluginIO(bpContext *ctx, struct io\_pkt *io)} -Called to do the input (backup) or output (restore) of data from or to a file -for a command plugin. These routines simulate the Unix read(), write(), open(), -close(), and lseek() I/O calls, and the arguments are passed in the packet and -the return values are also placed in the packet. In addition for Win32 systems -the plugin must return two additional values (described below). - -\begin{verbatim} - enum { - IO_OPEN = 1, - IO_READ = 2, - IO_WRITE = 3, - IO_CLOSE = 4, - IO_SEEK = 5 -}; - -struct io_pkt { - int32_t pkt_size; /* Size of this packet */ - int32_t func; /* Function code */ - int32_t count; /* read/write count */ - mode_t mode; /* permissions for created files */ - int32_t flags; /* Open flags */ - char *buf; /* read/write buffer */ - const char *fname; /* open filename */ - int32_t status; /* return status */ - int32_t io_errno; /* errno code */ - int32_t lerror; /* Win32 error code */ - int32_t whence; /* lseek argument */ - boffset_t offset; /* lseek argument */ - bool win32; /* Win32 GetLastError returned */ - int32_t pkt_end; /* end packet sentinel */ -}; -\end{verbatim} - -The particular Unix function being simulated is indicated by the {\bf func}, -which will have one of the IO\_OPEN, IO\_READ, ... codes listed above. The -status code that would be returned from a Unix call is returned in {\bf status} -for IO\_OPEN, IO\_CLOSE, IO\_READ, and IO\_WRITE. The return value for IO\_SEEK -is returned in {\bf offset} which in general is a 64 bit value. - -When there is an error on Unix systems, you must always set io\_error, and -on a Win32 system, you must always set win32, and the returned value from -the OS call GetLastError() in lerror. - -For all except IO\_SEEK, {\bf status} is the return result. In general it is -a positive integer unless there is an error in which case it is -1. - -The following describes each call and what you get and what you -should return: - -\begin{description} - \item [IO\_OPEN] - You will be passed fname, mode, and flags. - You must set on return: status, and if there is a Unix error - io\_errno must be set to the errno value, and if there is a - Win32 error win32 and lerror. - - \item [IO\_READ] - You will be passed: count, and buf (buffer of size count). - You must set on return: status to the number of bytes - read into the buffer (buf) or -1 on an error, - and if there is a Unix error - io\_errno must be set to the errno value, and if there is a - Win32 error, win32 and lerror must be set. - - \item [IO\_WRITE] - You will be passed: count, and buf (buffer of size count). - You must set on return: status to the number of bytes - written from the buffer (buf) or -1 on an error, - and if there is a Unix error - io\_errno must be set to the errno value, and if there is a - Win32 error, win32 and lerror must be set. - - \item [IO\_CLOSE] - Nothing will be passed to you. On return you must set - status to 0 on success and -1 on failure. If there is a Unix error - io\_errno must be set to the errno value, and if there is a - Win32 error, win32 and lerror must be set. - - \item [IO\_LSEEK] - You will be passed: offset, and whence. offset is a 64 bit value - and is the position to seek to relative to whence. whence is one - of the following SEEK\_SET, SEEK\_CUR, or SEEK\_END indicating to - either to seek to an absolute possition, relative to the current - position or relative to the end of the file. - You must pass back in offset the absolute location to which you - seeked. If there is an error, offset should be set to -1. - If there is a Unix error - io\_errno must be set to the errno value, and if there is a - Win32 error, win32 and lerror must be set. - - Note: Bacula will call IO\_SEEK only when writing a sparse file. - -\end{description} - -\subsection{bool checkFile(bpContext *ctx, char *fname)} -If this entry point is set, Bacula will call it after backing up all file -data during an Accurate backup. It will be passed the full filename for -each file that Bacula is proposing to mark as deleted. Only files -previously backed up but not backed up in the current session will be -marked to be deleted. If you return {\bf false}, the file will be be -marked deleted. If you return {\bf true} the file will not be marked -deleted. This permits a plugin to ensure that previously saved virtual -files or files controlled by your plugin that have not change (not backed -up in the current job) are not marked to be deleted. This entry point will -only be called during Accurate Incrmental and Differential backup jobs. - - -\section{Bacula Plugin Entrypoints} -When Bacula calls one of your plugin entrypoints, you can call back to -the entrypoints in Bacula that were supplied during the xxx plugin call -to get or set information within Bacula. - -\subsection{bRC registerBaculaEvents(bpContext *ctx, ...)} -This Bacula entrypoint will allow you to register to receive events -that are not autmatically passed to your plugin by default. This -entrypoint currently is unimplemented. - -\subsection{bRC getBaculaValue(bpContext *ctx, bVariable var, void *value)} -Calling this entrypoint, you can obtain specific values that are available -in Bacula. The following Variables can be referenced: -\begin{itemize} -\item bVarJobId returns an int -\item bVarFDName returns a char * -\item bVarLevel returns an int -\item bVarClient returns a char * -\item bVarJobName returns a char * -\item bVarJobStatus returns an int -\item bVarSinceTime returns an int (time\_t) -\item bVarAccurate returns an int -\end{itemize} - -\subsection{bRC setBaculaValue(bpContext *ctx, bVariable var, void *value)} -Calling this entrypoint allows you to set particular values in -Bacula. The only variable that can currently be set is -{\bf bVarFileSeen} and the value passed is a char * that points -to the full filename for a file that you are indicating has been -seen and hence is not deleted. - -\subsection{bRC JobMessage(bpContext *ctx, const char *file, int line, - int type, utime\_t mtime, const char *fmt, ...)} -This call permits you to put a message in the Job Report. - - -\subsection{bRC DebugMessage(bpContext *ctx, const char *file, int line, - int level, const char *fmt, ...)} -This call permits you to print a debug message. - - -\subsection{void baculaMalloc(bpContext *ctx, const char *file, int line, - size\_t size)} -This call permits you to obtain memory from Bacula's memory allocator. - - -\subsection{void baculaFree(bpContext *ctx, const char *file, int line, void *mem)} -This call permits you to free memory obtained from Bacula's memory allocator. diff --git a/docs/manuals/en/concepts/plugin-API.tex b/docs/manuals/en/concepts/plugin-API.tex new file mode 100644 index 00000000..656fdc71 --- /dev/null +++ b/docs/manuals/en/concepts/plugin-API.tex @@ -0,0 +1,817 @@ +%% +%% + +\chapter{Bacula FD Plugin API} +To write a Bacula plugin, you create a dynamic shared object program (or dll on +Win32) with a particular name and two exported entry points, place it in the +{\bf Plugins Directory}, which is defined in the {\bf bacula-fd.conf} file in +the {\bf Client} resource, and when the FD starts, it will load all the plugins +that end with {\bf -fd.so} (or {\bf -fd.dll} on Win32) found in that directory. + +\section{Normal vs Command Plugins} +In general, there are two ways that plugins are called. The first way, is when +a particular event is detected in Bacula, it will transfer control to each +plugin that is loaded in turn informing the plugin of the event. This is very +similar to how a {\bf RunScript} works, and the events are very similar. Once +the plugin gets control, it can interact with Bacula by getting and setting +Bacula variables. In this way, it behaves much like a RunScript. Currently +very few Bacula variables are defined, but they will be implemented as the need +arrises, and it is very extensible. + +We plan to have plugins register to receive events that they normally would +not receive, such as an event for each file examined for backup or restore. +This feature is not yet implemented. + +The second type of plugin, which is more useful and fully implemented in the +current version is what we call a command plugin. As with all plugins, it gets +notified of important events as noted above (details described below), but in +addition, this kind of plugin can accept a command line, which is a: + +\begin{verbatim} + Plugin = +\end{verbatim} + +directive that is placed in the Include section of a FileSet and is very +similar to the "File = " directive. When this Plugin directive is encountered +by Bacula during backup, it passes the "command" part of the Plugin directive +only to the plugin that is explicitly named in the first field of that command +string. This allows that plugin to backup any file or files on the system that +it wants. It can even create "virtual files" in the catalog that contain data +to be restored but do not necessarily correspond to actual files on the +filesystem. + +The important features of the command plugin entry points are: +\begin{itemize} + \item It is triggered by a "Plugin =" directive in the FileSet + \item Only a single plugin is called that is named on the "Plugin =" directive. + \item The full command string after the "Plugin =" is passed to the plugin + so that it can be told what to backup/restore. +\end{itemize} + + +\section{Loading Plugins} +Once the File daemon loads the plugins, it asks the OS for the +two entry points (loadPlugin and unloadPlugin) then calls the +{\bf loadPlugin} entry point (see below). + +Bacula passes information to the plugin through this call and it gets +back information that it needs to use the plugin. Later, Bacula + will call particular functions that are defined by the +{\bf loadPlugin} interface. + +When Bacula is finished with the plugin +(when Bacula is going to exit), it will call the {\bf unloadPlugin} +entry point. + +The two entry points are: + +\begin{verbatim} +bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs) + +and + +bRC unloadPlugin() +\end{verbatim} + +both these external entry points to the shared object are defined as C entry +points to avoid name mangling complications with C++. However, the shared +object can actually be written in any language (preferrably C or C++) providing +that it follows C language calling conventions. + +The definitions for {\bf bRC} and the arguments are {\bf +src/filed/fd-plugins.h} and so this header file needs to be included in +your plugin. It along with {\bf src/lib/plugins.h} define basically the whole +plugin interface. Within this header file, it includes the following +files: + +\begin{verbatim} +#include +#include "config.h" +#include "bc_types.h" +#include "lib/plugins.h" +#include +\end{verbatim} + +Aside from the {\bf bc\_types.h} and {\bf confit.h} headers, the plugin +definition uses the minimum code from Bacula. The bc\_types.h file is required +to ensure that the data type defintions in arguments correspond to the Bacula +core code. + +The return codes are defined as: +\begin{verbatim} +typedef enum { + bRC_OK = 0, /* OK */ + bRC_Stop = 1, /* Stop calling other plugins */ + bRC_Error = 2, /* Some kind of error */ + bRC_More = 3, /* More files to backup */ +} bRC; +\end{verbatim} + + +At a future point in time, we hope to make the Bacula libbac.a into a +shared object so that the plugin can use much more of Bacula's +infrastructure, but for this first cut, we have tried to minimize the +dependence on Bacula. + +\section{loadPlugin} +As previously mentioned, the {\bf loadPlugin} entry point in the plugin +is called immediately after Bacula loads the plugin when the File daemon +itself is first starting. This entry point is only called once during the +execution of the File daemon. In calling the +plugin, the first two arguments are information from Bacula that +is passed to the plugin, and the last two arguments are information +about the plugin that the plugin must return to Bacula. The call is: + +\begin{verbatim} +bRC loadPlugin(bInfo *lbinfo, bFuncs *lbfuncs, pInfo **pinfo, pFuncs **pfuncs) +\end{verbatim} + +and the arguments are: + +\begin{description} +\item [lbinfo] +This is information about Bacula in general. Currently, the only value +defined in the bInfo structure is the version, which is the Bacula plugin +interface version, currently defined as 1. The {\bf size} is set to the +byte size of the structure. The exact definition of the bInfo structure +as of this writing is: + +\begin{verbatim} +typedef struct s_baculaInfo { + uint32_t size; + uint32_t version; +} bInfo; +\end{verbatim} + +\item [lbfuncs] +The bFuncs structure defines the callback entry points within Bacula +that the plugin can use register events, get Bacula values, set +Bacula values, and send messages to the Job output or debug output. + +The exact definition as of this writing is: +\begin{verbatim} +typedef struct s_baculaFuncs { + uint32_t size; + uint32_t version; + bRC (*registerBaculaEvents)(bpContext *ctx, ...); + bRC (*getBaculaValue)(bpContext *ctx, bVariable var, void *value); + bRC (*setBaculaValue)(bpContext *ctx, bVariable var, void *value); + bRC (*JobMessage)(bpContext *ctx, const char *file, int line, + int type, utime_t mtime, const char *fmt, ...); + bRC (*DebugMessage)(bpContext *ctx, const char *file, int line, + int level, const char *fmt, ...); + void *(*baculaMalloc)(bpContext *ctx, const char *file, int line, + size_t size); + void (*baculaFree)(bpContext *ctx, const char *file, int line, void *mem); +} bFuncs; +\end{verbatim} + +We will discuss these entry points and how to use them a bit later when +describing the plugin code. + + +\item [pInfo] +When the loadPlugin entry point is called, the plugin must initialize +an information structure about the plugin and return a pointer to +this structure to Bacula. + +The exact definition as of this writing is: + +\begin{verbatim} +typedef struct s_pluginInfo { + uint32_t size; + uint32_t version; + const char *plugin_magic; + const char *plugin_license; + const char *plugin_author; + const char *plugin_date; + const char *plugin_version; + const char *plugin_description; +} pInfo; +\end{verbatim} + +Where: + \begin{description} + \item [version] is the current Bacula defined plugin interface version, currently + set to 1. If the interface version differs from the current version of + Bacula, the plugin will not be run (not yet implemented). + \item [plugin\_magic] is a pointer to the text string "*FDPluginData*", a + sort of sanity check. If this value is not specified, the plugin + will not be run (not yet implemented). + \item [plugin\_license] is a pointer to a text string that describes the + plugin license. Bacula will only accept compatible licenses (not yet + implemented). + \item [plugin\_author] is a pointer to the text name of the author of the program. + This string can be anything but is generally the author's name. + \item [plugin\_date] is the pointer text string containing the date of the plugin. + This string can be anything but is generally some human readable form of + the date. + \item [plugin\_version] is a pointer to a text string containing the version of + the plugin. The contents are determined by the plugin writer. + \item [plugin\_description] is a pointer to a string describing what the + plugin does. The contents are determined by the plugin writer. + \end{description} + +The pInfo structure must be defined in static memory because Bacula does not +copy it and may refer to the values at any time while the plugin is +loaded. All values must be supplied or the plugin will not run (not yet +implemented). All text strings must be either ASCII or UTF-8 strings that +are terminated with a zero byte. + +\item [pFuncs] +When the loadPlugin entry point is called, the plugin must initialize +an entry point structure about the plugin and return a pointer to +this structure to Bacula. This structure contains pointer to each +of the entry points that the plugin must provide for Bacula. When +Bacula is actually running the plugin, it will call the defined +entry points at particular times. All entry points must be defined. + +The pFuncs structure must be defined in static memory because Bacula does not +copy it and may refer to the values at any time while the plugin is +loaded. + +The exact definition as of this writing is: + +\begin{verbatim} +typedef struct s_pluginFuncs { + uint32_t size; + uint32_t version; + bRC (*newPlugin)(bpContext *ctx); + bRC (*freePlugin)(bpContext *ctx); + bRC (*getPluginValue)(bpContext *ctx, pVariable var, void *value); + bRC (*setPluginValue)(bpContext *ctx, pVariable var, void *value); + bRC (*handlePluginEvent)(bpContext *ctx, bEvent *event, void *value); + bRC (*startBackupFile)(bpContext *ctx, struct save_pkt *sp); + bRC (*endBackupFile)(bpContext *ctx); + bRC (*startRestoreFile)(bpContext *ctx, const char *cmd); + bRC (*endRestoreFile)(bpContext *ctx); + bRC (*pluginIO)(bpContext *ctx, struct io_pkt *io); + bRC (*createFile)(bpContext *ctx, struct restore_pkt *rp); + bRC (*setFileAttributes)(bpContext *ctx, struct restore_pkt *rp); + bRC (*checkFile)(bpContext *ctx, char *fname); +} pFuncs; +\end{verbatim} + +The details of the entry points will be presented in +separate sections below. + +Where: + \begin{description} + \item [size] is the byte size of the structure. + \item [version] is the plugin interface version currently set to 3. + \end{description} + +Sample code for loadPlugin: +\begin{verbatim} + bfuncs = lbfuncs; /* set Bacula funct pointers */ + binfo = lbinfo; + *pinfo = &pluginInfo; /* return pointer to our info */ + *pfuncs = &pluginFuncs; /* return pointer to our functions */ + + return bRC_OK; +\end{verbatim} + +where pluginInfo and pluginFuncs are statically defined structures. +See bpipe-fd.c for details. + + + +\end{description} + +\section{Plugin Entry Points} +This section will describe each of the entry points (subroutines) within +the plugin that the plugin must provide for Bacula, when they are called +and their arguments. As noted above, pointers to these subroutines are +passed back to Bacula in the pFuncs structure when Bacula calls the +loadPlugin() externally defined entry point. + +\subsection{newPlugin(bpContext *ctx)} + This is the entry point that Bacula will call + when a new "instance" of the plugin is created. This typically + happens at the beginning of a Job. If 10 Jobs are running + simultaneously, there will be at least 10 instances of the + plugin. + + The bpContext structure will be passed to the plugin, and + during this call, if the plugin needs to have its private + working storage that is associated with the particular + instance of the plugin, it should create it from the heap + (malloc the memory) and store a pointer to + its private working storage in the {\bf pContext} variable. + Note: since Bacula is a multi-threaded program, you must not + keep any variable data in your plugin unless it is truely meant + to apply globally to the whole plugin. In addition, you must + be aware that except the first and last call to the plugin + (loadPlugin and unloadPlugin) all the other calls will be + made by threads that correspond to a Bacula job. The + bpContext that will be passed for each thread will remain the + same throughout the Job thus you can keep your privat Job specific + data in it ({\bf bContext}). + +\begin{verbatim} +typedef struct s_bpContext { + void *pContext; /* Plugin private context */ + void *bContext; /* Bacula private context */ +} bpContext; + +\end{verbatim} + + This context pointer will be passed as the first argument to all + the entry points that Bacula calls within the plugin. Needless + to say, the plugin should not change the bContext variable, which + is Bacula's private context pointer for this instance (Job) of this + plugin. + +\subsection{freePlugin(bpContext *ctx)} +This entry point is called when the +this instance of the plugin is no longer needed (the Job is +ending), and the plugin should release all memory it may +have allocated for this particular instance (Job) i.e. the pContext. +This is not the final termination +of the plugin signaled by a call to {\bf unloadPlugin}. +Any other instances (Job) will +continue to run, and the entry point {\bf newPlugin} may be called +again if other jobs start. + +\subsection{getPluginValue(bpContext *ctx, pVariable var, void *value)} +Bacula will call this entry point to get +a value from the plugin. This entry point is currently not called. + +\subsection{setPluginValue(bpContext *ctx, pVariable var, void *value)} +Bacula will call this entry point to set +a value in the plugin. This entry point is currently not called. + +\subsection{handlePluginEvent(bpContext *ctx, bEvent *event, void *value)} +This entry point is called when Bacula +encounters certain events (discussed below). This is, in fact, the +main way that most plugins get control when a Job runs and how +they know what is happening in the job. It can be likened to the +{\bf RunScript} feature that calls external programs and scripts, +and is very similar to the Bacula Python interface. +When the plugin is called, Bacula passes it the pointer to an event +structure (bEvent), which currently has one item, the eventType: + +\begin{verbatim} +typedef struct s_bEvent { + uint32_t eventType; +} bEvent; +\end{verbatim} + + which defines what event has been triggered, and for each event, + Bacula will pass a pointer to a value associated with that event. + If no value is associated with a particular event, Bacula will + pass a NULL pointer, so the plugin must be careful to always check + value pointer prior to dereferencing it. + + The current list of events are: + +\begin{verbatim} +typedef enum { + bEventJobStart = 1, + bEventJobEnd = 2, + bEventStartBackupJob = 3, + bEventEndBackupJob = 4, + bEventStartRestoreJob = 5, + bEventEndRestoreJob = 6, + bEventStartVerifyJob = 7, + bEventEndVerifyJob = 8, + bEventBackupCommand = 9, + bEventRestoreCommand = 10, + bEventLevel = 11, + bEventSince = 12, +} bEventType; + +\end{verbatim} + +Most of the above are self-explanatory. + +\begin{description} + \item [bEventJobStart] is called whenever a Job starts. The value + passed is a pointer to a string that contains: "Jobid=nnn + Job=job-name". Where nnn will be replaced by the JobId and job-name + will be replaced by the Job name. The variable is temporary so if you + need the values, you must copy them. + + \item [bEventJobEnd] is called whenever a Job ends. No value is passed. + + \item [bEventStartBackupJob] is called when a Backup Job begins. No value + is passed. + + \item [bEventEndBackupJob] is called when a Backup Job ends. No value is + passed. + + \item [bEventStartRestoreJob] is called when a Restore Job starts. No value + is passed. + + \item [bEventEndRestoreJob] is called when a Restore Job ends. No value is + passed. + + \item [bEventStartVerifyJob] is called when a Verify Job starts. No value + is passed. + + \item [bEventEndVerifyJob] is called when a Verify Job ends. No value + is passed. + + \item [bEventBackupCommand] is called prior to the bEventStartBackupJob and + the plugin is passed the command string (everything after the equal sign + in "Plugin =" as the value. + + Note, if you intend to backup a file, this is an important first point to + write code that copies the command string passed into your pContext area + so that you will know that a backup is being performed and you will know + the full contents of the "Plugin =" command (i.e. what to backup and + what virtual filename the user wants to call it. + + \item [bEventRestoreCommand] is called prior to the bEventStartRestoreJob and + the plugin is passed the command string (everything after the equal sign + in "Plugin =" as the value. + + See the notes above concerning backup and the command string. This is the + point at which Bacula passes you the original command string that was + specified during the backup, so you will want to save it in your pContext + area for later use when Bacula calls the plugin again. + + \item [bEventLevel] is called when the level is set for a new Job. The value + is a 32 bit integer stored in the void*, which represents the Job Level code. + + \item [bEventSince] is called when the since time is set for a new Job. The + value is a time\_t time at which the last job was run. +\end{description} + +During each of the above calls, the plugin receives either no specific value or +only one value, which in some cases may not be sufficient. However, knowing +the context of the event, the plugin can call back to the Bacula entry points +it was passed during the {\bf loadPlugin} call and get to a number of Bacula +variables. (at the current time few Bacula variables are implemented, but it +easily extended at a future time and as needs require). + +\subsection{startBackupFile(bpContext *ctx, struct save\_pkt *sp)} +This entry point is called only if your plugin is a command plugin, and +it is called when Bacula encounters the "Plugin = " directive in +the Include section of the FileSet. +Called when beginning the backup of a file. Here Bacula provides you +with a pointer to the {\bf save\_pkt} structure and you must fill in +this packet with the "attribute" data of the file. + +\begin{verbatim} +struct save_pkt { + int32_t pkt_size; /* size of this packet */ + char *fname; /* Full path and filename */ + char *link; /* Link name if any */ + struct stat statp; /* System stat() packet for file */ + int32_t type; /* FT_xx for this file */ + uint32_t flags; /* Bacula internal flags */ + bool portable; /* set if data format is portable */ + char *cmd; /* command */ + int32_t pkt_end; /* end packet sentinel */ +}; +\end{verbatim} + +The second argument is a pointer to the {\bf save\_pkt} structure for the file +to be backed up. The plugin is responsible for filling in all the fields +of the {\bf save\_pkt}. If you are backing up +a real file, then generally, the statp structure can be filled in by doing +a {\bf stat} system call on the file. + +If you are backing up a database or +something that is more complex, you might want to create a virtual file. +That is a file that does not actually exist on the filesystem, but represents +say an object that you are backing up. In that case, you need to ensure +that the {\bf fname} string that you pass back is unique so that it +does not conflict with a real file on the system, and you need to +artifically create values in the statp packet. + +Example programs such as {\bf bpipe-fd.c} show how to set these fields. You +must take care not to store pointers the stack in the pointer fields such as +fname and link, because when you return from your function, your stack entries +will be destroyed. The solution in that case is to malloc() and return the +pointer to it. In order to not have memory leaks, you should store a pointer to +all memory allocated in your pContext structure so that in subsequent calls or +at termination, you can release it back to the system. + +Once the backup has begun, Bacula will call your plugin at the {\bf pluginIO} +entry point to "read" the data to be backed up. Please see the {\bf bpipe-fd.c} +plugin for how to do I/O. + +Example of filling in the save\_pkt as used in bpipe-fd.c: + +\begin{verbatim} + struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext; + time_t now = time(NULL); + sp->fname = p_ctx->fname; + sp->statp.st_mode = 0700 | S_IFREG; + sp->statp.st_ctime = now; + sp->statp.st_mtime = now; + sp->statp.st_atime = now; + sp->statp.st_size = -1; + sp->statp.st_blksize = 4096; + sp->statp.st_blocks = 1; + p_ctx->backup = true; + return bRC_OK; +\end{verbatim} + +Note: the filename to be created has already been created from the +command string previously sent to the plugin and is in the plugin +context (p\_ctx->fname) and is a malloc()ed string. This example +creates a regular file (S\_IFREG), with various fields being created. + +In general, the sequence of commands issued from Bacula to the plugin +to do a backup while processing the "Plugin = " directive are: + +\begin{enumerate} + \item generate a bEventBackupCommand event to the specified plugin + and pass it the command string. + \item make a startPluginBackup call to the plugin, which + fills in the data needed in save\_pkt to save as the file + attributes and to put on the Volume and in the catalog. + \item call Bacula's internal save\_file() subroutine to save the specified + file. The plugin will then be called at pluginIO() to "open" + the file, and then to read the file data. + Note, if you are dealing with a virtual file, the "open" operation + is something the plugin does internally and it doesn't necessarily + mean opening a file on the filesystem. For example in the case of + the bpipe-fd.c program, it initiates a pipe to the requested program. + Finally when the plugin signals to Bacula that all the data was read, + Bacula will call the plugin with the "close" pluginIO() function. +\end{enumerate} + + +\subsection{endBackupFile(bpContext *ctx)} +Called at the end of backing up a file for a command plugin. If the plugin's +work is done, it should return bRC\_OK. If the plugin wishes to create another +file and back it up, then it must return bRC\_More (not yet implemented). This +is probably a good time to release any malloc()ed memory you used to pass back +filenames. + +\subsection{startRestoreFile(bpContext *ctx, const char *cmd)} +Called when the first record is read from the Volume that was +previously written by the command plugin. + +\subsection{createFile(bpContext *ctx, struct restore\_pkt *rp)} +Called for a command plugin to create a file during a Restore job before +restoring the data. +This entry point is called before any I/O is done on the file. After +this call, Bacula will call pluginIO() to open the file for write. + +The data in the +restore\_pkt is passed to the plugin and is based on the data that was +originally given by the plugin during the backup and the current user +restore settings (e.g. where, RegexWhere, replace). This allows the +plugin to first create a file (if necessary) so that the data can +be transmitted to it. The next call to the plugin will be a +pluginIO command with a request to open the file write-only. + +This call must return one of the following values: + +\begin{verbatim} + enum { + CF_SKIP = 1, /* skip file (not newer or something) */ + CF_ERROR, /* error creating file */ + CF_EXTRACT, /* file created, data to extract */ + CF_CREATED /* file created, no data to extract */ +}; +\end{verbatim} + +in the restore\_pkt value {\bf create\_status}. For a normal file, +unless there is an error, you must return {\bf CF\_EXTRACT}. + +\begin{verbatim} + +struct restore_pkt { + int32_t pkt_size; /* size of this packet */ + int32_t stream; /* attribute stream id */ + int32_t data_stream; /* id of data stream to follow */ + int32_t type; /* file type FT */ + int32_t file_index; /* file index */ + int32_t LinkFI; /* file index to data if hard link */ + uid_t uid; /* userid */ + struct stat statp; /* decoded stat packet */ + const char *attrEx; /* extended attributes if any */ + const char *ofname; /* output filename */ + const char *olname; /* output link name */ + const char *where; /* where */ + const char *RegexWhere; /* regex where */ + int replace; /* replace flag */ + int create_status; /* status from createFile() */ + int32_t pkt_end; /* end packet sentinel */ + +}; +\end{verbatim} + +Typical code to create a regular file would be the following: + +\begin{verbatim} + struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext; + time_t now = time(NULL); + sp->fname = p_ctx->fname; /* set the full path/filename I want to create */ + sp->type = FT_REG; + sp->statp.st_mode = 0700 | S_IFREG; + sp->statp.st_ctime = now; + sp->statp.st_mtime = now; + sp->statp.st_atime = now; + sp->statp.st_size = -1; + sp->statp.st_blksize = 4096; + sp->statp.st_blocks = 1; + return bRC_OK; +\end{verbatim} + +This will create a virtual file. If you are creating a file that actually +exists, you will most likely want to fill the statp packet using the +stat() system call. + +Creating a directory is similar, but requires a few extra steps: + +\begin{verbatim} + struct plugin_ctx *p_ctx = (struct plugin_ctx *)ctx->pContext; + time_t now = time(NULL); + sp->fname = p_ctx->fname; /* set the full path I want to create */ + sp->link = xxx; where xxx is p_ctx->fname with a trailing forward slash + sp->type = FT_DIREND + sp->statp.st_mode = 0700 | S_IFDIR; + sp->statp.st_ctime = now; + sp->statp.st_mtime = now; + sp->statp.st_atime = now; + sp->statp.st_size = -1; + sp->statp.st_blksize = 4096; + sp->statp.st_blocks = 1; + return bRC_OK; +\end{verbatim} + +The link field must be set with the full cononical path name, which always +ends with a forward slash. If you do not terminate it with a forward slash, +you will surely have problems later. + +As with the example that creates a file, if you are backing up a real +directory, you will want to do an stat() on the directory. + +Note, if you want the directory permissions and times to be correctly +restored, you must create the directory {\bf after} all the file directories +have been sent to Bacula. That allows the restore process to restore all the +files in a directory using default directory options, then at the end, restore +the directory permissions. If you do it the other way around, each time you +restore a file, the OS will modify the time values for the directory entry. + +\subsection{setFileAttributes(bpContext *ctx, struct restore\_pkt *rp)} +This is call not yet implemented. Called for a command plugin. + +See the definition of {\bf restre\_pkt} in the above section. + +\subsection{endRestoreFile(bpContext *ctx)} +Called when a command plugin is done restoring a file. + +\subsection{pluginIO(bpContext *ctx, struct io\_pkt *io)} +Called to do the input (backup) or output (restore) of data from or to a file +for a command plugin. These routines simulate the Unix read(), write(), open(), +close(), and lseek() I/O calls, and the arguments are passed in the packet and +the return values are also placed in the packet. In addition for Win32 systems +the plugin must return two additional values (described below). + +\begin{verbatim} + enum { + IO_OPEN = 1, + IO_READ = 2, + IO_WRITE = 3, + IO_CLOSE = 4, + IO_SEEK = 5 +}; + +struct io_pkt { + int32_t pkt_size; /* Size of this packet */ + int32_t func; /* Function code */ + int32_t count; /* read/write count */ + mode_t mode; /* permissions for created files */ + int32_t flags; /* Open flags */ + char *buf; /* read/write buffer */ + const char *fname; /* open filename */ + int32_t status; /* return status */ + int32_t io_errno; /* errno code */ + int32_t lerror; /* Win32 error code */ + int32_t whence; /* lseek argument */ + boffset_t offset; /* lseek argument */ + bool win32; /* Win32 GetLastError returned */ + int32_t pkt_end; /* end packet sentinel */ +}; +\end{verbatim} + +The particular Unix function being simulated is indicated by the {\bf func}, +which will have one of the IO\_OPEN, IO\_READ, ... codes listed above. The +status code that would be returned from a Unix call is returned in {\bf status} +for IO\_OPEN, IO\_CLOSE, IO\_READ, and IO\_WRITE. The return value for IO\_SEEK +is returned in {\bf offset} which in general is a 64 bit value. + +When there is an error on Unix systems, you must always set io\_error, and +on a Win32 system, you must always set win32, and the returned value from +the OS call GetLastError() in lerror. + +For all except IO\_SEEK, {\bf status} is the return result. In general it is +a positive integer unless there is an error in which case it is -1. + +The following describes each call and what you get and what you +should return: + +\begin{description} + \item [IO\_OPEN] + You will be passed fname, mode, and flags. + You must set on return: status, and if there is a Unix error + io\_errno must be set to the errno value, and if there is a + Win32 error win32 and lerror. + + \item [IO\_READ] + You will be passed: count, and buf (buffer of size count). + You must set on return: status to the number of bytes + read into the buffer (buf) or -1 on an error, + and if there is a Unix error + io\_errno must be set to the errno value, and if there is a + Win32 error, win32 and lerror must be set. + + \item [IO\_WRITE] + You will be passed: count, and buf (buffer of size count). + You must set on return: status to the number of bytes + written from the buffer (buf) or -1 on an error, + and if there is a Unix error + io\_errno must be set to the errno value, and if there is a + Win32 error, win32 and lerror must be set. + + \item [IO\_CLOSE] + Nothing will be passed to you. On return you must set + status to 0 on success and -1 on failure. If there is a Unix error + io\_errno must be set to the errno value, and if there is a + Win32 error, win32 and lerror must be set. + + \item [IO\_LSEEK] + You will be passed: offset, and whence. offset is a 64 bit value + and is the position to seek to relative to whence. whence is one + of the following SEEK\_SET, SEEK\_CUR, or SEEK\_END indicating to + either to seek to an absolute possition, relative to the current + position or relative to the end of the file. + You must pass back in offset the absolute location to which you + seeked. If there is an error, offset should be set to -1. + If there is a Unix error + io\_errno must be set to the errno value, and if there is a + Win32 error, win32 and lerror must be set. + + Note: Bacula will call IO\_SEEK only when writing a sparse file. + +\end{description} + +\subsection{bool checkFile(bpContext *ctx, char *fname)} +If this entry point is set, Bacula will call it after backing up all file +data during an Accurate backup. It will be passed the full filename for +each file that Bacula is proposing to mark as deleted. Only files +previously backed up but not backed up in the current session will be +marked to be deleted. If you return {\bf false}, the file will be be +marked deleted. If you return {\bf true} the file will not be marked +deleted. This permits a plugin to ensure that previously saved virtual +files or files controlled by your plugin that have not change (not backed +up in the current job) are not marked to be deleted. This entry point will +only be called during Accurate Incrmental and Differential backup jobs. + + +\section{Bacula Plugin Entrypoints} +When Bacula calls one of your plugin entrypoints, you can call back to +the entrypoints in Bacula that were supplied during the xxx plugin call +to get or set information within Bacula. + +\subsection{bRC registerBaculaEvents(bpContext *ctx, ...)} +This Bacula entrypoint will allow you to register to receive events +that are not autmatically passed to your plugin by default. This +entrypoint currently is unimplemented. + +\subsection{bRC getBaculaValue(bpContext *ctx, bVariable var, void *value)} +Calling this entrypoint, you can obtain specific values that are available +in Bacula. The following Variables can be referenced: +\begin{itemize} +\item bVarJobId returns an int +\item bVarFDName returns a char * +\item bVarLevel returns an int +\item bVarClient returns a char * +\item bVarJobName returns a char * +\item bVarJobStatus returns an int +\item bVarSinceTime returns an int (time\_t) +\item bVarAccurate returns an int +\end{itemize} + +\subsection{bRC setBaculaValue(bpContext *ctx, bVariable var, void *value)} +Calling this entrypoint allows you to set particular values in +Bacula. The only variable that can currently be set is +{\bf bVarFileSeen} and the value passed is a char * that points +to the full filename for a file that you are indicating has been +seen and hence is not deleted. + +\subsection{bRC JobMessage(bpContext *ctx, const char *file, int line, + int type, utime\_t mtime, const char *fmt, ...)} +This call permits you to put a message in the Job Report. + + +\subsection{bRC DebugMessage(bpContext *ctx, const char *file, int line, + int level, const char *fmt, ...)} +This call permits you to print a debug message. + + +\subsection{void baculaMalloc(bpContext *ctx, const char *file, int line, + size\_t size)} +This call permits you to obtain memory from Bacula's memory allocator. + + +\subsection{void baculaFree(bpContext *ctx, const char *file, int line, void *mem)} +This call permits you to free memory obtained from Bacula's memory allocator.