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Diffstat (limited to 'runtime/module-template.h')
| -rw-r--r-- | runtime/module-template.h | 486 |
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diff --git a/runtime/module-template.h b/runtime/module-template.h new file mode 100644 index 00000000..eb39b587 --- /dev/null +++ b/runtime/module-template.h @@ -0,0 +1,486 @@ +/* module-template.h + * This header contains macros that can be used to implement the + * plumbing of modules. + * + * File begun on 2007-07-25 by RGerhards + * + * Copyright 2007 Rainer Gerhards and Adiscon GmbH. + * + * This file is part of the rsyslog runtime library. + * + * The rsyslog runtime library is free software: you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * The rsyslog runtime library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with the rsyslog runtime library. If not, see <http://www.gnu.org/licenses/>. + * + * A copy of the GPL can be found in the file "COPYING" in this distribution. + * A copy of the LGPL can be found in the file "COPYING.LESSER" in this distribution. + */ +#ifndef MODULE_TEMPLATE_H_INCLUDED +#define MODULE_TEMPLATE_H_INCLUDED 1 + +#include "modules.h" +#include "obj.h" +#include "objomsr.h" +#include "threads.h" + +/* macro to define standard output-module static data members + */ +#define DEF_MOD_STATIC_DATA \ + static __attribute__((unused)) rsRetVal (*omsdRegCFSLineHdlr)(); + +#define DEF_OMOD_STATIC_DATA \ + DEF_MOD_STATIC_DATA \ + DEFobjCurrIf(obj) +#define DEF_IMOD_STATIC_DATA \ + DEF_MOD_STATIC_DATA \ + DEFobjCurrIf(obj) +#define DEF_LMOD_STATIC_DATA \ + DEF_MOD_STATIC_DATA + + +/* Macro to define the module type. Each module can only have a single type. If + * a module provides multiple types, several separate modules must be created which + * then should share a single library containing the majority of code. This macro + * must be present in each module. -- rgerhards, 2007-12-14 + * Note that MODULE_TYPE_TESTBENCH is reserved for testbenches, but + * declared in their own header files (because the rest does not need these + * defines). -- rgerhards, 2008-06-13 + */ +#define MODULE_TYPE(x)\ +static rsRetVal modGetType(eModType_t *modType) \ + { \ + *modType = x; \ + return RS_RET_OK;\ + } + +#define MODULE_TYPE_INPUT MODULE_TYPE(eMOD_IN) +#define MODULE_TYPE_OUTPUT MODULE_TYPE(eMOD_OUT) +#define MODULE_TYPE_LIB \ + DEF_LMOD_STATIC_DATA \ + MODULE_TYPE(eMOD_LIB) + + +/* macro to define a unique module id. This must be able to fit in a void*. The + * module id must be unique inside a running rsyslogd application. It is used to + * track ownership of several objects. Most importantly, when the module is + * unloaded the module id value is used to find what needs to be destroyed. + * We currently use a pointer to modExit() as the module id. This sounds to be + * reasonable save, as each module must have this entry point AND there is no valid + * reason for twice this entry point being in memory. + * rgerhards, 2007-11-21 + */ +#define STD_LOADABLE_MODULE_ID ((void*) modExit) + + +/* macro to implement the "modGetID()" interface function + * rgerhards 2007-11-21 + */ +#define DEFmodGetID \ +static rsRetVal modGetID(void **pID) \ + { \ + *pID = STD_LOADABLE_MODULE_ID;\ + return RS_RET_OK;\ + } + +/* to following macros are used to generate function headers and standard + * functionality. It works as follows (described on the sample case of + * createInstance()): + * + * BEGINcreateInstance + * ... custom variable definitions (on stack) ... (if any) + * CODESTARTcreateInstance + * ... custom code ... (if any) + * ENDcreateInstance + */ + +/* createInstance() + */ +#define BEGINcreateInstance \ +static rsRetVal createInstance(instanceData **ppData)\ + {\ + DEFiRet; /* store error code here */\ + instanceData *pData; /* use this to point to data elements */ + +#define CODESTARTcreateInstance \ + if((pData = calloc(1, sizeof(instanceData))) == NULL) {\ + *ppData = NULL;\ + ENDfunc \ + return RS_RET_OUT_OF_MEMORY;\ + } + +#define ENDcreateInstance \ + *ppData = pData;\ + RETiRet;\ +} + +/* freeInstance() + * This is the cleanup function for the module instance. It is called immediately before + * the module instance is destroyed (unloaded). The module should do any cleanup + * here, e.g. close file, free instantance heap memory and the like. Control will + * not be passed back to the module once this function is finished. Keep in mind, + * however, that other instances may still be loaded and used. So do not destroy + * anything that may be used by another instance. If you have such a ressource, you + * currently need to do the instance counting yourself. + */ +#define BEGINfreeInstance \ +static rsRetVal freeInstance(void* pModData)\ +{\ + DEFiRet;\ + instanceData *pData; + +#define CODESTARTfreeInstance \ + pData = (instanceData*) pModData; + +#define ENDfreeInstance \ + if(pData != NULL)\ + free(pData); /* we need to free this in any case */\ + RETiRet;\ +} + +/* isCompatibleWithFeature() + */ +#define BEGINisCompatibleWithFeature \ +static rsRetVal isCompatibleWithFeature(syslogFeature __attribute__((unused)) eFeat)\ +{\ + rsRetVal iRet = RS_RET_INCOMPATIBLE; \ + BEGINfunc + +#define CODESTARTisCompatibleWithFeature + +#define ENDisCompatibleWithFeature \ + RETiRet;\ +} + +/* doAction() + */ +#define BEGINdoAction \ +static rsRetVal doAction(uchar __attribute__((unused)) **ppString, unsigned __attribute__((unused)) iMsgOpts, instanceData __attribute__((unused)) *pData)\ +{\ + DEFiRet; + +#define CODESTARTdoAction \ + /* ppString may be NULL if the output module requested no strings */ + +#define ENDdoAction \ + RETiRet;\ +} + + +/* dbgPrintInstInfo() + * Extra comments: + * Print debug information about this instance. + */ +#define BEGINdbgPrintInstInfo \ +static rsRetVal dbgPrintInstInfo(void *pModData)\ +{\ + DEFiRet;\ + instanceData *pData = NULL; + +#define CODESTARTdbgPrintInstInfo \ + pData = (instanceData*) pModData; + +#define ENDdbgPrintInstInfo \ + RETiRet;\ +} + + +/* parseSelectorAct() + * Extra comments: + * try to process a selector action line. Checks if the action + * applies to this module and, if so, processed it. If not, it + * is left untouched. The driver will then call another module. + * On exit, ppModData must point to instance data. Also, a string + * request object must be created and filled. A macro is defined + * for that. + * For the most usual case, we have defined a macro below. + * If more than one string is requested, the macro can be used together + * with own code that overwrites the entry count. In this case, the + * macro must come before the own code. It is recommended to be + * placed right after CODESTARTparseSelectorAct. + */ +#define BEGINparseSelectorAct \ +static rsRetVal parseSelectorAct(uchar **pp, void **ppModData, omodStringRequest_t **ppOMSR)\ +{\ + DEFiRet;\ + uchar *p;\ + instanceData *pData = NULL; + +#define CODESTARTparseSelectorAct \ + assert(pp != NULL);\ + assert(ppModData != NULL);\ + assert(ppOMSR != NULL);\ + p = *pp; + +#define CODE_STD_STRING_REQUESTparseSelectorAct(NumStrReqEntries) \ + CHKiRet(OMSRconstruct(ppOMSR, NumStrReqEntries)); + +#define CODE_STD_FINALIZERparseSelectorAct \ +finalize_it:\ + if(iRet == RS_RET_OK || iRet == RS_RET_SUSPENDED) {\ + *ppModData = pData;\ + *pp = p;\ + } else {\ + /* cleanup, we failed */\ + if(*ppOMSR != NULL) {\ + OMSRdestruct(*ppOMSR);\ + *ppOMSR = NULL;\ + }\ + if(pData != NULL) {\ + freeInstance(pData);\ + } \ + } + +#define ENDparseSelectorAct \ + RETiRet;\ +} + + +/* tryResume() + * This entry point is called to check if a module can resume operations. This + * happens when a module requested that it be suspended. In suspended state, + * the engine periodically tries to resume the module. If that succeeds, normal + * processing continues. If not, the module will not be called unless a + * tryResume() call succeeds. + * Returns RS_RET_OK, if resumption succeeded, RS_RET_SUSPENDED otherwise + * rgerhard, 2007-08-02 + */ +#define BEGINtryResume \ +static rsRetVal tryResume(instanceData __attribute__((unused)) *pData)\ +{\ + DEFiRet; + +#define CODESTARTtryResume \ + assert(pData != NULL); + +#define ENDtryResume \ + RETiRet;\ +} + + + +/* queryEtryPt() + */ +#define BEGINqueryEtryPt \ +DEFmodGetID \ +static rsRetVal queryEtryPt(uchar *name, rsRetVal (**pEtryPoint)())\ +{\ + DEFiRet; + +#define CODESTARTqueryEtryPt \ + if((name == NULL) || (pEtryPoint == NULL)) {\ + ENDfunc \ + return RS_RET_PARAM_ERROR;\ + } \ + *pEtryPoint = NULL; + +#define ENDqueryEtryPt \ + if(iRet == RS_RET_OK)\ + if(*pEtryPoint == NULL) { \ + dbgprintf("entry point '%s' not present in module\n", name); \ + iRet = RS_RET_MODULE_ENTRY_POINT_NOT_FOUND;\ + } \ + RETiRet;\ +} + +/* the following definition is the standard block for queryEtryPt for all types + * of modules. It should be included in any module, and typically is so by calling + * the module-type specific macros. + */ +#define CODEqueryEtryPt_STD_MOD_QUERIES \ + if(!strcmp((char*) name, "modExit")) {\ + *pEtryPoint = modExit;\ + } else if(!strcmp((char*) name, "modGetID")) {\ + *pEtryPoint = modGetID;\ + } else if(!strcmp((char*) name, "getType")) {\ + *pEtryPoint = modGetType;\ + } + +/* the following definition is the standard block for queryEtryPt for output + * modules. This can be used if no specific handling (e.g. to cover version + * differences) is needed. + */ +#define CODEqueryEtryPt_STD_OMOD_QUERIES \ + CODEqueryEtryPt_STD_MOD_QUERIES \ + else if(!strcmp((char*) name, "doAction")) {\ + *pEtryPoint = doAction;\ + } else if(!strcmp((char*) name, "dbgPrintInstInfo")) {\ + *pEtryPoint = dbgPrintInstInfo;\ + } else if(!strcmp((char*) name, "freeInstance")) {\ + *pEtryPoint = freeInstance;\ + } else if(!strcmp((char*) name, "parseSelectorAct")) {\ + *pEtryPoint = parseSelectorAct;\ + } else if(!strcmp((char*) name, "isCompatibleWithFeature")) {\ + *pEtryPoint = isCompatibleWithFeature;\ + } else if(!strcmp((char*) name, "tryResume")) {\ + *pEtryPoint = tryResume;\ + } + +/* the following definition is the standard block for queryEtryPt for INPUT + * modules. This can be used if no specific handling (e.g. to cover version + * differences) is needed. + */ +#define CODEqueryEtryPt_STD_IMOD_QUERIES \ + CODEqueryEtryPt_STD_MOD_QUERIES \ + else if(!strcmp((char*) name, "runInput")) {\ + *pEtryPoint = runInput;\ + } else if(!strcmp((char*) name, "willRun")) {\ + *pEtryPoint = willRun;\ + } else if(!strcmp((char*) name, "afterRun")) {\ + *pEtryPoint = afterRun;\ + } + +/* the following definition is the standard block for queryEtryPt for LIBRARY + * modules. This can be used if no specific handling (e.g. to cover version + * differences) is needed. + */ +#define CODEqueryEtryPt_STD_LIB_QUERIES \ + CODEqueryEtryPt_STD_MOD_QUERIES + +/* modInit() + * This has an extra parameter, which is the specific name of the modInit + * function. That is needed for built-in modules, which must have unique + * names in order to link statically. Please note that this is always only + * the case with modInit() and NO other entry point. The reason is that only + * modInit() is visible form a linker/loader point of view. All other entry + * points are passed via rsyslog-internal query functions and are defined + * static inside the modules source. This is an important concept, as it allows + * us to support different interface versions within a single module. (Granted, + * we do not currently have different interface versions, so we can not put + * it to a test - but our firm believe is that we can do all abstraction needed...) + * + * Extra Comments: + * initialize the module + * + * Later, much more must be done. So far, we only return a pointer + * to the queryEtryPt() function + * TODO: do interface version checking & handshaking + * iIfVersRequetsed is the version of the interface specification that the + * caller would like to see being used. ipIFVersProvided is what we + * decide to provide. + * rgerhards, 2007-11-21: see modExit() comment below for important information + * on the need to initialize static data with code. modInit() may be called on a + * cached, left-in-memory copy of a previous incarnation. + */ +#define BEGINmodInit(uniqName) \ +rsRetVal modInit##uniqName(int iIFVersRequested __attribute__((unused)), int *ipIFVersProvided, rsRetVal (**pQueryEtryPt)(), rsRetVal (*pHostQueryEtryPt)(uchar*, rsRetVal (**)()), modInfo_t __attribute__((unused)) *pModInfo)\ +{\ + DEFiRet; \ + rsRetVal (*pObjGetObjInterface)(obj_if_t *pIf); + +#define CODESTARTmodInit \ + assert(pHostQueryEtryPt != NULL);\ + iRet = pHostQueryEtryPt((uchar*)"objGetObjInterface", &pObjGetObjInterface); \ + if((iRet != RS_RET_OK) || (pQueryEtryPt == NULL) || (ipIFVersProvided == NULL) || (pObjGetObjInterface == NULL)) { \ + ENDfunc \ + return (iRet == RS_RET_OK) ? RS_RET_PARAM_ERROR : iRet; \ + } \ + /* now get the obj interface so that we can access other objects */ \ + CHKiRet(pObjGetObjInterface(&obj)); + +#define ENDmodInit \ +finalize_it:\ + *pQueryEtryPt = queryEtryPt;\ + RETiRet;\ +} + + +/* definitions for host API queries */ +#define CODEmodInit_QueryRegCFSLineHdlr \ + CHKiRet(pHostQueryEtryPt((uchar*)"regCfSysLineHdlr", &omsdRegCFSLineHdlr)); + +#endif /* #ifndef MODULE_TEMPLATE_H_INCLUDED */ + +/* modExit() + * This is the counterpart to modInit(). It destroys a module and makes it ready for + * unloading. It is similiar to freeInstance() for the instance data. Please note that + * this entry point needs to free any module-global data structures and registrations. + * For example, the CfSysLineHandlers a module has registered need to be unregistered + * here. This entry point is only called immediately before unloading of the module. So + * it is likely to be destroyed. HOWEVER, the caller may decide to keep the module cached. + * So a module must never assume that it is actually destroyed. A call to modInit() may + * happen immediately after modExit(). So a module can NOT assume that static data elements + * are being re-initialized by the loader - this must always be done by module code itself. + * It is suggested to do this in modInit(). - rgerhards, 2007-11-21 + */ +#define BEGINmodExit \ +static rsRetVal modExit(void)\ +{\ + DEFiRet; + +#define CODESTARTmodExit + +#define ENDmodExit \ + RETiRet;\ +} + + +/* runInput() + * This is the main function for input modules. It is used to gather data from the + * input source and submit it to the message queue. Each runInput() instance has its own + * thread. This is handled by the rsyslog engine. It needs to spawn off new threads only + * if there is a module-internal need to do so. + */ +#define BEGINrunInput \ +static rsRetVal runInput(thrdInfo_t __attribute__((unused)) *pThrd)\ +{\ + DEFiRet; + +#define CODESTARTrunInput \ + dbgSetThrdName((uchar*)__FILE__); /* we need to provide something better later */ + +#define ENDrunInput \ + RETiRet;\ +} + + +/* willRun() + * This is a function that will be replaced in the longer term. It is used so + * that a module can tell the caller if it will run or not. This is to be replaced + * when we introduce input module instances. However, these require config syntax + * changes and I may (or may not... ;)) hold that until another config file + * format is available. -- rgerhards, 2007-12-17 + * returns RS_RET_NO_RUN if it will not run (RS_RET_OK or error otherwise) + */ +#define BEGINwillRun \ +static rsRetVal willRun(void)\ +{\ + DEFiRet; + +#define CODESTARTwillRun + +#define ENDwillRun \ + RETiRet;\ +} + + +/* afterRun() + * This function is called after an input module has been run and its thread has + * been terminated. It shall do any necessary cleanup. + * This is expected to evolve into a freeInstance type of call once the input module + * interface evolves to support multiple instances. + * rgerhards, 2007-12-17 + */ +#define BEGINafterRun \ +static rsRetVal afterRun(void)\ +{\ + DEFiRet; + +#define CODESTARTafterRun + +#define ENDafterRun \ + RETiRet;\ +} + + +/* + * vi:set ai: + */ |