From 3822da837e4d531e8a9cd78ae76359a410f8d98d Mon Sep 17 00:00:00 2001

From: Jiri Vymazal <jvymazal@redhat.com>

Date: Thu, 31 May 2018 16:30:08 +0200

Subject: [PATCH] Symlink support for imfile

this introduces symlink detection and following as well

as monitoring changes on them. Also added test for the new

functionality and ensuring the original symlink behavior

stays as well.

---

 plugins/imfile/imfile.c       | 182 +++++++++++++++++++++++++++----------

 1 file changed, 133 insertions(+), 49 deletions(-)

diff --git a/plugins/imfile/imfile.c b/plugins/imfile/imfile.c

index 3c9308bfe..4ca23d2ca 100644

--- a/plugins/imfile/imfile.c

+++ b/plugins/imfile/imfile.c

@@ -152,6 +152,7 @@ struct act_obj_s {

 	fs_edge_t *edge;	/* edge which this object belongs to */

 	char *name;		/* full path name of active object */

 	char *basename;		/* only basename */ //TODO: remove when refactoring rename support

+	char *source_name;  /* if this object is target of a symlink, source_name is its name (else NULL) */

 	//char *statefile;	/* base name of state file (for move operations) */

 	int wd;

 #if defined(OS_SOLARIS) && defined (HAVE_PORT_SOURCE_FILE)

@@ -167,6 +168,7 @@ struct act_obj_s {

 	int nRecords; /**< How many records did we process before persisting the stream? */

 	ratelimit_t *ratelimiter;

 	multi_submit_t multiSub;

+	int is_symlink;

 };

 struct fs_edge_s {

 	fs_node_t *parent;

@@ -181,7 +182,8 @@ struct act_obj_s {

 	instanceConf_t **instarr;

 };

 struct fs_node_s {

-	fs_edge_t *edges;

+	fs_edge_t *edges;	/* NULL in leaf nodes */

+	fs_node_t *root;	/* node one level up (NULL for file system root) */

 };

@@ -189,7 +191,7 @@ static rsRetVal persistStrmState(act_obj_t *);

 static rsRetVal resetConfigVariables(uchar __attribute__((unused)) *pp, void __attribute__((unused)) *pVal);

 static rsRetVal ATTR_NONNULL(1) pollFile(act_obj_t *act);

 static int ATTR_NONNULL() getBasename(uchar *const __restrict__ basen, uchar *const __restrict__ path);

-static void ATTR_NONNULL() act_obj_unlink(act_obj_t *const act);

+static void ATTR_NONNULL() act_obj_unlink(act_obj_t *act);

 static uchar * ATTR_NONNULL(1, 2) getStateFileName(const act_obj_t *, uchar *, const size_t);

 static int ATTR_NONNULL() getFullStateFileName(const uchar *const, uchar *const pszout, const size_t ilenout);

@@ -483,14 +485,17 @@ in_setupWatch(act_obj_t *const act, const int is_file)

 		goto done;

 	wd = inotify_add_watch(ino_fd, act->name,

-		(is_file) ? IN_MODIFY : IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO);

+		(is_file) ? IN_MODIFY|IN_DONT_FOLLOW : IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO);

 	if(wd < 0) {

-		LogError(errno, RS_RET_IO_ERROR, "imfile: cannot watch object '%s'",

-			act->name);

+		if (errno == EACCES) { /* There is high probability of selinux denial on top-level paths */

+			DBGPRINTF("imfile: permission denied when adding watch for '%s'\n", act->name);

+		} else {

+			LogError(errno, RS_RET_IO_ERROR, "imfile: cannot watch object '%s'", act->name);

+		}

 		goto done;

 	}

 	wdmapAdd(wd, act);

-	DBGPRINTF("in_setupDirWatch: watch %d added for dir %s(%p)\n", wd, act->name, act);

+	DBGPRINTF("in_setupWatch: watch %d added for %s(object %p)\n", wd, act->name, act);

 done:	return wd;

 }

@@ -605,7 +610,7 @@ done:	return;

 static void ATTR_NONNULL()

 fen_setupWatch(act_obj_t *const act __attribute__((unused)))

 {

-	DBGPRINTF("fen_setupWatch: DUMMY CALLED - not on Solaris?");

+	DBGPRINTF("fen_setupWatch: DUMMY CALLED - not on Solaris?\n");

 }

 #endif /* FEN */

@@ -633,38 +638,48 @@ fs_node_print(const fs_node_t *const node, const int level)

 	}

 }

-

 /* add a new file system object if it not yet exists, ignore call

  * if it already does.

  */

-static rsRetVal ATTR_NONNULL()

+static rsRetVal ATTR_NONNULL(1,2)

 act_obj_add(fs_edge_t *const edge, const char *const name, const int is_file,

-	const ino_t ino)

+	const ino_t ino, const int is_symlink, const char *const source)

 {

 	act_obj_t *act;

 	char basename[MAXFNAME];

 	DEFiRet;

-	DBGPRINTF("act_obj_add: edge %p, name '%s'\n", edge, name);

+	DBGPRINTF("act_obj_add: edge %p, name '%s' (source '%s')\n", edge, name, source? source : "---");

 	for(act = edge->active ; act != NULL ; act = act->next) {

 		if(!strcmp(act->name, name)) {

-			DBGPRINTF("active object '%s' already exists in '%s' - no need to add\n",

-				name, edge->path);

-			FINALIZE;

+			if (!source || !act->source_name || !strcmp(act->source_name, source)) {

+				DBGPRINTF("active object '%s' already exists in '%s' - no need to add\n",

+					name, edge->path);

+				FINALIZE;

+			}

 		}

 	}

 	DBGPRINTF("add new active object '%s' in '%s'\n", name, edge->path);

 	CHKmalloc(act = calloc(sizeof(act_obj_t), 1));

 	CHKmalloc(act->name = strdup(name));

-	getBasename((uchar*)basename, (uchar*)name);

-	CHKmalloc(act->basename = strdup(basename));

+	if (-1 == getBasename((uchar*)basename, (uchar*)name)) {

+		CHKmalloc(act->basename = strdup(name)); /* assume basename is same as name */

+	} else {

+		CHKmalloc(act->basename = strdup(basename));

+	}

 	act->edge = edge;

 	act->ino = ino;

+	act->is_symlink = is_symlink;

+	if (source) { /* we are target of symlink */

+		CHKmalloc(act->source_name = strdup(source));

+	} else {

+		act->source_name = NULL;

+	}

 	#ifdef HAVE_INOTIFY_INIT

 	act->wd = in_setupWatch(act, is_file);

 	#endif

 	fen_setupWatch(act);

-	if(is_file) {

+	if(is_file && !is_symlink) {

 		const instanceConf_t *const inst = edge->instarr[0];// TODO: same file, multiple instances?

 		CHKiRet(ratelimitNew(&act->ratelimiter, "imfile", name));

 		CHKmalloc(act->multiSub.ppMsgs = MALLOC(inst->nMultiSub * sizeof(smsg_t *)));

@@ -702,27 +717,24 @@ detect_updates(fs_edge_t *const edge)

 {

 	act_obj_t *act;

 	struct stat fileInfo;

+	int restart = 0;

-	for(act = edge->active ; act != NULL ; ) {

+	for(act = edge->active ; act != NULL ; act = act->next) {

 		DBGPRINTF("detect_updates checking active obj '%s'\n", act->name);

-		const int r = stat(act->name, &fileInfo);

+		const int r = lstat(act->name, &fileInfo);

 		if(r == -1) { /* object gone away? */

 			DBGPRINTF("object gone away, unlinking: '%s'\n", act->name);

-			act_obj_t *toDel = act;

-			act = act->next;

-			DBGPRINTF("new next act %p\n", act);

-			act_obj_unlink(toDel);

-			continue;

+			act_obj_unlink(act);

+			restart = 1;

+			break;

 		}

 		// TODO: add inode check for change notification!

-		/* Note: active nodes may get deleted, so we need to do the

-		 * pointer advancement at the end of the for loop!

-		 */

-		act = act->next;

 	}

-

+	if (restart) {

+		detect_updates(edge);

+	}

 }

@@ -746,14 +758,52 @@ poll_active_files(fs_edge_t *const edge)

 	}

 }

+static rsRetVal ATTR_NONNULL()

+process_symlink(fs_edge_t *const chld, const char *symlink)

+{

+	DEFiRet;

+	char *target = NULL;

+	CHKmalloc(target = realpath(symlink, target));

+	struct stat fileInfo;

+	if(lstat(target, &fileInfo) != 0) {

+		LogError(errno, RS_RET_ERR,	"imfile: process_symlink: cannot stat file '%s' - ignored", target);

+		FINALIZE;

+	}

+	const int is_file = (S_ISREG(fileInfo.st_mode));

+	DBGPRINTF("process_symlink:  found '%s', File: %d (config file: %d), symlink: %d\n",

+		target, is_file, chld->is_file, 0);

+	if (act_obj_add(chld, target, is_file, fileInfo.st_ino, 0, symlink) == RS_RET_OK) {

+		/* need to watch parent target as well for proper rotation support */

+		uint idx = ustrlen(chld->active->name) - ustrlen(chld->active->basename);

+		if (idx) { /* basename is different from name */

+			char parent[MAXFNAME];

+			idx--; /* move past trailing slash */

+			memcpy(parent, chld->active->name, idx);

+			parent[idx] = '\0';

+			if(lstat(parent, &fileInfo) != 0) {

+				LogError(errno, RS_RET_ERR,

+					"imfile: process_symlink: cannot stat directory '%s' - ignored", parent);

+				FINALIZE;

+			}

+			if (chld->parent->root->edges) {

+				DBGPRINTF("process_symlink: adding parent '%s' of target '%s'\n", parent, target);

+				act_obj_add(chld->parent->root->edges, parent, 0, fileInfo.st_ino, 0, NULL);

+			}

+		}

+	}

+

+finalize_it:

+	free(target);

+	RETiRet;

+}

-static void ATTR_NONNULL() poll_tree(fs_edge_t *const chld);

 static void ATTR_NONNULL()

 poll_tree(fs_edge_t *const chld)

 {

 	struct stat fileInfo;

 	glob_t files;

 	int need_globfree = 0;

+	int issymlink;

 	DBGPRINTF("poll_tree: chld %p, name '%s', path: %s\n", chld, chld->name, chld->path);

 	detect_updates(chld);

 	const int ret = glob((char*)chld->path, runModConf->sortFiles|GLOB_BRACE, NULL, &files);

@@ -766,18 +803,27 @@ poll_tree(fs_edge_t *const chld)

 				goto done;

 			}

 			char *const file = files.gl_pathv[i];

-			if(stat(file, &fileInfo) != 0) {

+			if(lstat(file, &fileInfo) != 0) {

 				LogError(errno, RS_RET_ERR,

 					"imfile: poll_tree cannot stat file '%s' - ignored", file);

 				continue;

 			}

-			const int is_file = S_ISREG(fileInfo.st_mode);

-			DBGPRINTF("poll_tree:  found '%s', File: %d (config file: %d)\n",

-				file, is_file, chld->is_file);

+			if (S_ISLNK(fileInfo.st_mode)) {

+				rsRetVal slink_ret = process_symlink(chld, file);

+				if (slink_ret != RS_RET_OK) {

+					continue;

+				}

+				issymlink = 1;

+			} else {

+				issymlink = 0;

+			}

+			const int is_file = (S_ISREG(fileInfo.st_mode) || issymlink);

+			DBGPRINTF("poll_tree:  found '%s', File: %d (config file: %d), symlink: %d\n",

+				file, is_file, chld->is_file, issymlink);

 			if(!is_file && S_ISREG(fileInfo.st_mode)) {

 				LogMsg(0, RS_RET_ERR, LOG_WARNING,

-					"imfile: '%s' is neither a regular file nor a "

+					"imfile: '%s' is neither a regular file, symlink, nor a "

 					"directory - ignored", file);

 				continue;

 			}

@@ -788,7 +834,7 @@ poll_tree(fs_edge_t *const chld)

 					(chld->is_file) ? "FILE" : "DIRECTORY");

 				continue;

 			}

-			act_obj_add(chld, file, is_file, fileInfo.st_ino);

+			act_obj_add(chld, file, is_file, fileInfo.st_ino, issymlink, NULL);

 		}

 	}

@@ -829,8 +875,20 @@ act_obj_destroy(act_obj_t *const act, const int is_deleted)

 	if(act == NULL)

 		return;

-	DBGPRINTF("act_obj_destroy: act %p '%s', wd %d, pStrm %p, is_deleted %d, in_move %d\n",

-		act, act->name, act->wd, act->pStrm, is_deleted, act->in_move);

+	DBGPRINTF("act_obj_destroy: act %p '%s' (source '%s'), wd %d, pStrm %p, is_deleted %d, in_move %d\n",

+		act, act->name, act->source_name? act->source_name : "---", act->wd, act->pStrm, is_deleted,

+		act->in_move);

+	if(act->is_symlink && is_deleted) {

+		act_obj_t *target_act;

+		for(target_act = act->edge->active ; target_act != NULL ; target_act = target_act->next) {

+			if(target_act->source_name && !strcmp(target_act->source_name, act->name)) {

+				DBGPRINTF("act_obj_destroy: unlinking slink target %s of %s "

+						"symlink\n", target_act->name, act->name);

+				act_obj_unlink(target_act);

+				break;

+			}

+		}

+	}

 	if(act->ratelimiter != NULL) {

 		ratelimitDestruct(act->ratelimiter);

 	}

@@ -862,6 +920,7 @@ act_obj_destroy(act_obj_t *const act, const int is_deleted)

 	}

 	#endif

 	free(act->basename);

+	free(act->source_name);

 	//free(act->statefile);

 	free(act->multiSub.ppMsgs);

 	#if defined(OS_SOLARIS) && defined (HAVE_PORT_SOURCE_FILE)

@@ -909,7 +968,7 @@ chk_active(const act_obj_t *act, const act_obj_t *const deleted)

  * destruct it.

  */

 static void //ATTR_NONNULL()

-act_obj_unlink(act_obj_t *const act)

+act_obj_unlink(act_obj_t *act)

 {

 	DBGPRINTF("act_obj_unlink %p: %s\n", act, act->name);

 	if(act->prev == NULL) {

@@ -921,6 +980,7 @@ act_obj_unlink(act_obj_t *const act)

 		act->next->prev = act->prev;

 	}

 	act_obj_destroy(act, 1);

+	act = NULL;

 //dbgprintf("printout of fs tree post unlink\n");

 //fs_node_print(runModConf->conf_tree, 0);

 //dbg_wdmapPrint("wdmap after");

@@ -1025,6 +1038,7 @@ fs_node_walk(fs_node_t *const node,

  */

 static rsRetVal

 fs_node_add(fs_node_t *const node,

+	fs_node_t *const source,

 	const uchar *const toFind,

 	const size_t pathIdx,

 	instanceConf_t *const inst)

@@ -1053,6 +1067,7 @@ fs_node_add(fs_node_t *const node,

 	memcpy(name, toFind+pathIdx, len);

 	name[len] = '\0';

 	DBGPRINTF("fs_node_add: name '%s'\n", name);

+	node->root = source;

 	fs_edge_t *chld;

 	for(chld = node->edges ; chld != NULL ; chld = chld->next) {

@@ -1064,7 +1079,7 @@ fs_node_add(fs_node_t *const node,

 			chld->instarr[chld->ninst-1] = inst;

 			/* recurse */

 			if(!isFile) {

-				CHKiRet(fs_node_add(chld->node, toFind, nextPathIdx, inst));

+				CHKiRet(fs_node_add(chld->node, node, toFind, nextPathIdx, inst));

 			}

 			FINALIZE;

 		}

@@ -1086,7 +1101,7 @@ fs_node_add(fs_node_t *const node,

 	DBGPRINTF("fs_node_add(%p, '%s') returns %p\n", node, toFind, newchld->node);

 	if(!isFile) {

-		CHKiRet(fs_node_add(newchld->node, toFind, nextPathIdx, inst));

+		CHKiRet(fs_node_add(newchld->node, node, toFind, nextPathIdx, inst));

 	}

 	/* link to list */

@@ -1162,7 +1222,11 @@ enqLine(act_obj_t *const act,

 	msgSetPRI(pMsg, inst->iFacility | inst->iSeverity);

 	MsgSetRuleset(pMsg, inst->pBindRuleset);

 	if(inst->addMetadata) {

-		metadata_values[0] = (const uchar*)act->name;

+		if (act->source_name) {

+			metadata_values[0] = (const uchar*)act->source_name;

+		} else {

+			metadata_values[0] = (const uchar*)act->name;

+		}

 		snprintf((char *)file_offset, MAX_OFFSET_REPRESENTATION_NUM_BYTES+1, "%lld", strtOffs);

 		metadata_values[1] = file_offset;

 		msgAddMultiMetadata(pMsg, metadata_names, metadata_values, 2);

@@ -1389,13 +1453,16 @@ pollFile(act_obj_t *const act)

 {

 	cstr_t *pCStr = NULL;

 	DEFiRet;

+	if (act->is_symlink) {

+		FINALIZE;    /* no reason to poll symlink file */

+	}

 	/* Note: we must do pthread_cleanup_push() immediately, because the POSIX macros

 	 * otherwise do not work if I include the _cleanup_pop() inside an if... -- rgerhards, 2008-08-14

 	 */

 	pthread_cleanup_push(pollFileCancelCleanup, &pCStr);

 	iRet = pollFileReal(act, &pCStr);

 	pthread_cleanup_pop(0);

-	RETiRet;

+finalize_it: RETiRet;

 }

@@ -1931,7 +1946,7 @@ CODESTARTactivateCnf

 					"be processed. Reason", inst->pszFileName);

 			}

 		}

-		fs_node_add(runModConf->conf_tree, inst->pszFileName, 0, inst);

+		fs_node_add(runModConf->conf_tree, NULL, inst->pszFileName, 0, inst);

 	}

 	if(Debug) {

@@ -2031,6 +2113,9 @@ flag_in_move(fs_edge_t *const edge, const char *name_moved)

 			DBGPRINTF("name check fails, '%s' != '%s'\n", act->basename, name_moved);

 		}

 	}

+	if (!act && edge->next) {

+		flag_in_move(edge->next, name_moved);

+	}

 }

 static void ATTR_NONNULL(1)

@@ -2057,7 +2145,7 @@ in_processEvent(struct inotify_event *ev)

 	}

 	if(ev->mask & (IN_MOVED_FROM | IN_MOVED_TO))  {

 		fs_node_walk(etry->act->edge->node, poll_tree);

-	} else if(etry->act->edge->is_file) {

+	} else if(etry->act->edge->is_file && !(etry->act->is_symlink)) {

 		in_handleFileEvent(ev, etry); // esentially poll_file()!

 	} else {

 		fs_node_walk(etry->act->edge->node, poll_tree);