Implement an external locking interface.

lib/Makefile.in

@@ -39,6 +39,7 @@ SOURCES=\
 	label/label.c \
 	label/uuid-map.c \
 	locking/file_locking.c \
+	locking/external_locking.c \
 	locking/locking.c \
 	log/log.c \
 	metadata/lv_manip.c \

lib/locking/external_locking.c

@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2002 Sistina Software (UK) Limited.
+ *
+ * This file is released under the LGPL.
+ *
+ */
+
+#include "log.h"
+#include "locking.h"
+#include "locking_types.h"
+#include "activate.h"
+#include "config.h"
+#include "defaults.h"
+#include "lvm-file.h"
+#include "lvm-string.h"
+#include "dbg_malloc.h"
+
+#include <limits.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/file.h>
+#include <fcntl.h>
+#include <dlfcn.h>
+#include <signal.h>
+
+static void *locking_module = NULL;
+static void (*end_fn)(void) = NULL;
+static int  (*lock_fn)(struct cmd_context *cmd, const char *resource, int flags) = NULL;
+static int  (*init_fn)(int type, struct config_file *cf) = NULL;
+
+static int lock_resource(struct cmd_context *cmd, const char *resource, int flags)
+{
+    if (lock_fn)
+	return lock_fn(cmd, resource, flags);
+    else
+	return 0;
+}
+
+
+static void fin_external_locking(void)
+{
+    if (end_fn)
+	end_fn();
+
+    dlclose(locking_module);
+
+    locking_module = NULL;
+    end_fn = NULL;
+    lock_fn = NULL;
+}
+
+int init_external_locking(struct locking_type *locking, struct config_file *cf)
+{
+        char _lock_lib[PATH_MAX];
+
+	if (locking_module)
+	{
+	    log_error("External locking already initialised\n");
+	    return 1;
+	}
+	locking->lock_resource = lock_resource;
+	locking->fin_locking = fin_external_locking;
+
+	/* Get locking module name from config file */
+	strncpy(_lock_lib, find_config_str(cf->root, "global/locking_library",
+					   '/', "lvm2_locking.so"),
+		sizeof(_lock_lib));
+
+
+	/* If there is a module_dir in the config file then
+	   look for the locking module in there first and then
+	   using the normal dlopen(3) mechanism of looking
+	   down LD_LIBRARY_PATH and /lib, /usr/lib.
+	   If course, if the library name starts with a slash then
+	   just use the name... */
+	if (_lock_lib[0] != '/')
+	{
+	    struct stat st;
+	    char _lock_lib1[PATH_MAX];
+
+	    lvm_snprintf(_lock_lib1, sizeof(_lock_lib1),
+			 "%s/%s",
+			 find_config_str(cf->root, "global/module_dir",
+					 '/', "RUBBISH"),
+			 _lock_lib);
+
+	    /* Does it exist ? */
+	    if (stat(_lock_lib1, &st) == 0)
+	    {
+		strcpy(_lock_lib, _lock_lib1);
+	    }
+	}
+
+	log_very_verbose("Opening locking library %s\n", _lock_lib);
+
+	locking_module = dlopen(_lock_lib, RTLD_LAZY);
+	if (!locking_module)
+	{
+	    log_error("Unable to open external locking module %s\n", _lock_lib);
+	    return 0;
+	}
+
+	/* Get the functions we need */
+	init_fn = dlsym(locking_module, "init_locking");
+	lock_fn = dlsym(locking_module, "lock_resource");
+	end_fn  = dlsym(locking_module, "end_locking");
+
+	/* Are they all there ? */
+	if (!end_fn || !init_fn || !lock_fn)
+	{
+	    log_error("shared library %s does not contain locking functions\n", _lock_lib);
+	    dlclose(locking_module);
+	    return 0;
+	}
+
+	log_verbose("Opened external locking module %s\n", _lock_lib);
+	return init_fn(2, cf);
+}

lib/locking/locking.c

@@ -101,13 +101,13 @@ int init_locking(int type, struct config_file *cf)
 			return 0;
 		log_very_verbose("File-based locking enabled.");
 		break;
-/******
+
 	case 2:
-		if (!init_other_locking(&_locking, cf))
+		if (!init_external_locking(&_locking, cf))
 			return 0;
-		log_very_verbose("Other locking enabled.");
+		log_very_verbose("External locking enabled.");
 		break;
-******/
+
 	default:
 		log_error("Unknown locking type requested.");
 		return 0;

tools/Makefile.in

@@ -62,7 +62,7 @@ include ../make.tmpl
 
 lvm: $(OBJECTS) $(top_srcdir)/lib/liblvm.a
 	$(CC) -o lvm $(OBJECTS) $(LD_FLAGS) -L$(top_srcdir)/lib \
-	      -L$(DESTDIR)/lib -llvm -ldevmapper $(LIBS)
+	      -L$(DESTDIR)/lib -llvm -ldevmapper $(LIBS) -ldl -rdynamic
 
 .commands: commands.h cmdnames.h
 	$(CC) -E -P cmdnames.h | grep -v help > .commands