--- file_not_specified_in_diff	
+++ file_not_specified_in_diff	
@@ -, +, @@ 
--- orig/src/internal.h
+++ mod/src/internal.h
@@ -5,6 +5,10 @@ 
 # define LIBRCC_DATA_DIR "/usr/lib/rcc"
 #endif /* LIBRCC_DATA_DIR */
 
+#ifndef LIBRCC_LOCK_WAIT
+# define LIBRCC_LOCK_WAIT 3000 /* ms */
+#endif /* LIBRCC_LOCK_WAIT */
+
 #define RCC_MAX_LANGUAGE_PARRENTS 4
 #define RCC_MAX_RELATIONS RCC_MAX_LANGUAGES
 
@@ -91,6 +95,9 @@ 
 };
 typedef struct rcc_context_t rcc_context_s;
 
+int rccLock();
+void rccUnLock();
+
 int rccConfigure(rcc_context ctx);
 char *rccCreateResult(rcc_context ctx, size_t len);
 
--- orig/src/librcc.c
+++ mod/src/librcc.c
@@ -1,6 +1,8 @@ 
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <time.h>
+#include <errno.h>
 
 #include "../config.h"
 
@@ -19,6 +21,11 @@ 
 # include <pwd.h>
 #endif /* HAVE_PWD_H */
 
+#ifdef HAVE_SYS_FILE_H
+# include <sys/file.h>
+#endif /* HAVE_SYS_FILE_H */
+
+
 #include "internal.h"
 #include "rccconfig.h"
 #include "rccenca.h"
@@ -135,6 +142,89 @@ 
     initialized = 0;
 }
 
+static int lockfd = -1;
+
+int rccLock() {
+# ifdef HAVE_SYS_FILE_H
+    int err, i;
+    int size;
+    char *stmp;
+    struct timespec wait = { 0, 10000000 };
+    
+    if (lockfd>=0) return -1;    
+    
+    size = strlen(rcc_home_dir) + 32;
+    stmp = (char*)malloc(size*sizeof(char));
+    if (!stmp) return -1;
+
+    sprintf(stmp,"%s/.rcc/", rcc_home_dir);
+    mkdir(stmp, 00755);
+    
+    sprintf(stmp,"%s/.rcc/locks/", rcc_home_dir);
+    mkdir(stmp, 00700);
+
+    sprintf(stmp,"%s/.rcc/locks/rcc.lock", rcc_home_dir);
+
+    lockfd = open(stmp, O_RDWR|O_CREAT, 0644);
+    if (lockfd >= 0) {
+	for (err = -1, i = 0; i < (LIBRCC_LOCK_WAIT/10); i++) {
+	    err = flock(lockfd, LOCK_EX|LOCK_NB);
+	    if ((err)&&(errno == EWOULDBLOCK)) nanosleep(&wait, NULL);
+	    else break;
+	}
+
+	if (err) {
+	    close(lockfd);
+
+		// Removing invalid lock
+	    if (i == (LIBRCC_LOCK_WAIT/10)) {
+		remove(stmp);
+
+		lockfd = open(stmp, O_RDWR|O_CREAT, 0644);
+		if (lockfd >= 0) {
+		    for (err = -1, i = 0; i < (LIBRCC_LOCK_WAIT/10); i++) {
+			err = flock(lockfd, LOCK_EX|LOCK_NB);
+			if ((err)&&(errno == EWOULDBLOCK)) nanosleep(&wait, NULL);
+			else break;
+		    }
+		    
+		    if (err) close(lockfd);
+		    else return 0;
+		} 
+	    }
+	    
+	    lockfd = -1;
+	    return -1;
+	} 
+
+	return 0;
+    }
+    
+    return -1;
+# else  /* HAVE_SYS_FILE_H */
+    return 0;
+# endif /* HAVE_SYS_FILE_H */
+}
+
+void rccUnLock() {
+#ifdef HAVE_SYS_FILE_H
+    int size;
+    char *stmp;
+
+    if (lockfd<0) return;
+    
+    size = strlen(rcc_home_dir) + 32;
+    stmp = (char*)malloc(size*sizeof(char));
+    if (!stmp) return;
+
+    sprintf(stmp,"%s/.rcc/locks/rcc.lock", rcc_home_dir);
+
+    flock(lockfd, LOCK_UN);
+    close(lockfd);
+    lockfd = -1;
+#endif /* HAVE_SYS_FILE_H */
+}
+
 rcc_context rccCreateContext(const char *locale_variable, unsigned int max_languages, unsigned int max_classes, rcc_class_ptr defclasses, rcc_init_flags flags) {
     unsigned int i;
     
--- orig/src/rccdb4.c
+++ mod/src/rccdb4.c
@@ -15,11 +15,35 @@ 
 #ifdef HAVE_DB_H
     DB_ENV *dbe;
     DB *db;
+
+    char stmp[160];
     
     err = db_env_create(&dbe, 0);
     if (err) return NULL;
+
+    err = dbe->open(dbe, dbpath, DB_CREATE|DB_INIT_CDB|DB_INIT_MPOOL, 00644);
+    if (err == DB_VERSION_MISMATCH) {
+
+	if (!rccLock()) {    
+	    err = dbe->open(dbe, dbpath, DB_CREATE|DB_INIT_LOCK|DB_INIT_LOG|DB_INIT_MPOOL|DB_INIT_TXN|DB_USE_ENVIRON|DB_PRIVATE|DB_RECOVER, 0);
+	    rccUnLock();
+	} else err = -1;
+
+	dbe->close(dbe, 0);
+	if (err) return NULL;
+
+	if (strlen(dbpath)<128) {
+	    sprintf(stmp, "%s/log.0000000001", dbpath);
+	    remove(stmp);
+	}
+	    
+	err = db_env_create(&dbe, 0);
+	if (err) return NULL;
+	    
+	err = dbe->open(dbe, dbpath, DB_CREATE|DB_INIT_CDB|DB_INIT_MPOOL, 00644);
+	
+    }
     
-    err = dbe->open(dbe, dbpath, DB_CREATE|DB_INIT_CDB|DB_INIT_MPOOL, 00755);
     if (err) {
 	dbe->close(dbe, 0);
 	return NULL;