ndb: implement index regeneration if the index is out of sync

We compare the user generation stored in the index database with
the generation count from the package database. In case there
is a mismatch, we delete all the index databases and rely on the
already existing missing index creation code to rebuild the
database.

lib/backend/ndb/glue.c

@@ -80,6 +80,31 @@ static int ndb_Close(dbiIndex dbi, unsigned int flags)
     return 0;
 }
 
+static void ndb_CheckIndexSync(rpmpkgdb pkgdb, rpmxdb xdb)
+{
+    unsigned int generation, xdb_generation;
+    if (!pkgdb || !xdb)
+        return;
+    if (rpmpkgLock(pkgdb, 0))
+        return;
+    if (rpmpkgGeneration(pkgdb, &generation)) {
+        rpmpkgUnlock(pkgdb, 0);
+        return;
+    }
+    if (!rpmxdbGetUserGeneration(xdb, &xdb_generation) && generation == xdb_generation) {
+        rpmpkgUnlock(pkgdb, 0);
+        return;
+    }
+    rpmpkgUnlock(pkgdb, 0);
+    /* index corrupt or with different generation */
+    if (rpmxdbIsRdonly(xdb)) {
+	rpmlog(RPMLOG_WARNING, _("Detected outdated index databases\n"));
+    } else {
+	rpmlog(RPMLOG_WARNING, _("Rebuilding outdated index databases\n"));
+	rpmxdbDelAllBlobs(xdb);
+    }
+}
+
 static int ndb_Open(rpmdb rdb, rpmDbiTagVal rpmtag, dbiIndex * dbip, int flags)
 {
     const char *dbhome = rpmdbHome(rdb);
@@ -130,6 +155,7 @@ static int ndb_Open(rpmdb rdb, rpmDbiTagVal rpmtag, dbiIndex * dbip, int flags)
 	}
 	if (!ndbenv->xdb) {
 	    char *path = rstrscat(NULL, dbhome, "/Index.db", NULL);
+	    int created = 0;
 	    rpmlog(RPMLOG_DEBUG, "opening  db index       %s mode=0x%x\n", path, rdb->db_mode);
 
 	    /* Open indexes readwrite if possible */
@@ -144,6 +170,7 @@ static int ndb_Open(rpmdb rdb, rpmDbiTagVal rpmtag, dbiIndex * dbip, int flags)
 	    } else if (rc && errno == ENOENT) {
 		ioflags = O_CREAT|O_RDWR;
 		rc = rpmxdbOpen(&ndbenv->xdb, rdb->db_pkgs->dbi_db, path, ioflags, 0666);
+		created = 1;
 	    }
 	    if (rc) {
 		perror("rpmxdbOpen");
@@ -153,6 +180,8 @@ static int ndb_Open(rpmdb rdb, rpmDbiTagVal rpmtag, dbiIndex * dbip, int flags)
 	    }
 	    free(path);
 	    rpmxdbSetFsync(ndbenv->xdb, ndbenv->dofsync);
+	    if (!created)
+		ndb_CheckIndexSync(ndbenv->pkgdb, ndbenv->xdb);
 	}
 	if (rpmxdbLookupBlob(ndbenv->xdb, &id, rpmtag, 0, 0) == RPMRC_NOTFOUND) {
 	    dbi->dbi_flags |= DBI_CREATED;