[RFC PATCH v2 1/3] multipath: add libmpathvalid library

[Benjamin Marzinski <bmarzins@redhat.com>]

This library allows other programs to check if a path should be claimed
by multipath. It exports an init function, that needs to be called
before and after all other library calls, an exit function, that needs
to be called after all library calls, a function to reread the multipath
configuration files, and two more functions.

mpath_get_mode() get the configured find_multipaths mode.
mpath_is_path() returns whether the device is claimed by multipath, and
optionally returns the wwid.  This code works slightly different than
the multipath -c/u code for SMART mode.  Instead of checking all the
existing paths to see if another has the same wwid, it expects the
caller to pass in an array of the already known path wwids, and checks
if the current path matches any of those.

The library also doesn't set up the device-mapper log fuctions. It
leaves this up to the caller.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 Makefile                            |   3 +-
 libmpathvalid/Makefile              |  38 ++++++
 libmpathvalid/libmpathvalid.version |  10 ++
 libmpathvalid/mpath_valid.c         | 199 ++++++++++++++++++++++++++++
 libmpathvalid/mpath_valid.h         |  61 +++++++++
 5 files changed, 310 insertions(+), 1 deletion(-)
 create mode 100644 libmpathvalid/Makefile
 create mode 100644 libmpathvalid/libmpathvalid.version
 create mode 100644 libmpathvalid/mpath_valid.c
 create mode 100644 libmpathvalid/mpath_valid.h

diff --git a/Makefile b/Makefile
index 4a3491da..f127ff91 100644
--- a/Makefile
+++ b/Makefile
@@ -9,6 +9,7 @@ BUILDDIRS := \
 	libmultipath/checkers \
 	libmultipath/foreign \
 	libmpathpersist \
+	libmpathvalid \
 	multipath \
 	multipathd \
 	mpathpersist \
@@ -29,7 +30,7 @@ $(BUILDDIRS):
 	$(MAKE) -C $@
 
 libmultipath libdmmp: libmpathcmd
-libmpathpersist multipath multipathd: libmultipath
+libmpathpersist libmpathvalid multipath multipathd: libmultipath
 mpathpersist multipathd:  libmpathpersist
 
 libmultipath/checkers.install \
diff --git a/libmpathvalid/Makefile b/libmpathvalid/Makefile
new file mode 100644
index 00000000..70b97eca
--- /dev/null
+++ b/libmpathvalid/Makefile
@@ -0,0 +1,38 @@
+include ../Makefile.inc
+
+SONAME = 0
+DEVLIB = libmpathvalid.so
+LIBS = $(DEVLIB).$(SONAME)
+
+CFLAGS += $(LIB_CFLAGS) -I$(multipathdir) -I$(mpathcmddir)
+
+LIBDEPS += -lpthread -ldevmapper -ldl -L$(multipathdir) \
+	   -lmultipath -L$(mpathcmddir) -lmpathcmd -ludev
+
+OBJS = mpath_valid.o
+
+all: $(LIBS)
+
+$(LIBS): $(OBJS)
+	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -Wl,-soname=$@ -o $@ $(OBJS) $(LIBDEPS) -Wl,--version-script=libmpathvalid.version
+	$(LN) $(LIBS) $(DEVLIB)
+
+install: $(LIBS)
+	$(INSTALL_PROGRAM) -m 755 -d $(DESTDIR)$(syslibdir)
+	$(INSTALL_PROGRAM) -m 755 $(LIBS) $(DESTDIR)$(syslibdir)/$(LIBS)
+	$(LN) $(LIBS) $(DESTDIR)$(syslibdir)/$(DEVLIB)
+	$(INSTALL_PROGRAM) -m 755 -d $(DESTDIR)$(includedir)
+	$(INSTALL_PROGRAM) -m 644 mpath_valid.h $(DESTDIR)$(includedir)
+
+uninstall:
+	$(RM) $(DESTDIR)$(syslibdir)/$(LIBS)
+	$(RM) $(DESTDIR)$(syslibdir)/$(DEVLIB)
+	$(RM) $(DESTDIR)$(includedir)/mpath_valid.h
+
+clean: dep_clean
+	$(RM) core *.a *.o *.so *.so.* *.gz
+
+include $(wildcard $(OBJS:.o=.d))
+
+dep_clean:
+	$(RM) $(OBJS:.o=.d)
diff --git a/libmpathvalid/libmpathvalid.version b/libmpathvalid/libmpathvalid.version
new file mode 100644
index 00000000..3bd0d3c5
--- /dev/null
+++ b/libmpathvalid/libmpathvalid.version
@@ -0,0 +1,10 @@
+MPATH_1.0 {
+	global:
+		mpathvalid_init;
+		mpathvalid_reload_config;
+		mpathvalid_exit;
+		mpathvalid_is_path;
+		mpathvalid_get_mode;
+	local:
+		*;
+};
diff --git a/libmpathvalid/mpath_valid.c b/libmpathvalid/mpath_valid.c
new file mode 100644
index 00000000..b9ec83a4
--- /dev/null
+++ b/libmpathvalid/mpath_valid.c
@@ -0,0 +1,199 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <libdevmapper.h>
+#include <libudev.h>
+#include <errno.h>
+
+#include "devmapper.h"
+#include "structs.h"
+#include "util.h"
+#include "config.h"
+#include "discovery.h"
+#include "wwids.h"
+#include "sysfs.h"
+#include "mpath_cmd.h"
+#include "valid.h"
+#include "mpath_valid.h"
+#include "debug.h"
+
+static unsigned int get_conf_mode(struct config *conf)
+{
+	if (conf->find_multipaths == FIND_MULTIPATHS_SMART)
+		return MPATH_SMART;
+	if (conf->find_multipaths == FIND_MULTIPATHS_GREEDY)
+		return MPATH_GREEDY;
+	return MPATH_STRICT;
+}
+
+static void set_conf_mode(struct config *conf, unsigned int mode)
+{
+	if (mode == MPATH_SMART)
+		conf->find_multipaths = FIND_MULTIPATHS_SMART;
+	else if (mode == MPATH_GREEDY)
+		conf->find_multipaths = FIND_MULTIPATHS_GREEDY;
+	else
+		conf->find_multipaths = FIND_MULTIPATHS_STRICT;
+}
+
+unsigned int mpathvalid_get_mode(void)
+{
+	int mode;
+	struct config *conf;
+
+	conf = get_multipath_config();
+	if (!conf)
+		return -1;
+	mode = get_conf_mode(conf);
+	put_multipath_config(conf);
+	return mode;
+}
+
+static int convert_result(int result) {
+	switch (result) {
+	case PATH_IS_ERROR:
+		return MPATH_IS_ERROR;
+	case PATH_IS_NOT_VALID:
+		return MPATH_IS_NOT_VALID;
+	case PATH_IS_VALID:
+		return MPATH_IS_VALID;
+	case PATH_IS_VALID_NO_CHECK:
+		return MPATH_IS_VALID_NO_CHECK;
+	case PATH_IS_MAYBE_VALID:
+		return MPATH_IS_MAYBE_VALID;
+	}
+	return MPATH_IS_ERROR;
+}
+
+static int load_default_config(int verbosity)
+{
+	struct config *conf;
+
+	/* need to set verbosity here to control logging during init_config() */
+	conf = get_multipath_config();
+	conf->verbosity = verbosity;
+	put_multipath_config(conf);
+
+	if (init_config(DEFAULT_CONFIGFILE))
+		return -1;
+
+	/* Need to override verbosity from init_config() */
+	conf = get_multipath_config();
+	conf->verbosity = verbosity;
+	put_multipath_config(conf);
+
+	return 0;
+}
+
+int
+mpathvalid_init(int verbosity, int log_style)
+{
+	unsigned int version[3];
+
+	logsink = log_style;
+	if (libmultipath_init())
+		return -1;
+
+	skip_libmp_dm_init();
+	if (load_default_config(verbosity))
+		goto fail;
+
+	if (dm_prereq(version))
+		goto fail_config;
+
+	return 0;
+
+fail_config:
+	uninit_config();
+fail:
+	libmultipath_exit();
+	return -1;
+}
+
+int
+mpathvalid_reload_config(void)
+{
+	int verbosity;
+	struct config *conf;
+
+	conf = get_multipath_config();
+	verbosity = conf->verbosity;
+	put_multipath_config(conf);
+
+	uninit_config();
+
+	return load_default_config(verbosity);
+}
+
+int
+mpathvalid_exit(void)
+{
+	uninit_config();
+	libmultipath_exit();
+	return 0;
+}
+
+/*
+ * name: name of path to check
+ * mode: mode to use for determination. MPATH_DEFAULT uses configured mode
+ * info: on success, contains the path wwid
+ * paths: array of the returned mpath_info from other claimed paths
+ * nr_paths: the size of the paths array
+ */
+int
+mpathvalid_is_path(const char *name, unsigned int mode, char **wwid,
+	           const char **path_wwids, unsigned int nr_paths)
+{
+	struct config *conf;
+	int r = MPATH_IS_ERROR;
+	unsigned int i;
+	struct path *pp;
+
+	if (!name || mode >= MPATH_MAX_MODE)
+		return r;
+	if (nr_paths > 0 && !path_wwids)
+		return r;
+	if (!udev)
+		return r;
+
+	pp = alloc_path();
+	if (!pp)
+		return r;
+
+	if (wwid) {
+		*wwid = (char *)malloc(WWID_SIZE);
+		if (!*wwid)
+			goto out;
+	}
+
+	conf = get_multipath_config();
+	if (!conf)
+		goto out_wwid;
+	if (mode != MPATH_DEFAULT)
+		set_conf_mode(conf, mode);
+	r = convert_result(is_path_valid(name, conf, pp, true));
+	put_multipath_config(conf);
+
+	if (r == MPATH_IS_MAYBE_VALID) {
+		for (i = 0; i < nr_paths; i++) {
+			if (strncmp(path_wwids[i], pp->wwid, WWID_SIZE) == 0) {
+				r = MPATH_IS_VALID;
+				break;
+			}
+		}
+	}
+
+out_wwid:
+	if (wwid) {
+		if (r == MPATH_IS_VALID || r == MPATH_IS_VALID_NO_CHECK ||
+		    r == MPATH_IS_MAYBE_VALID)
+			strlcpy(*wwid, pp->wwid, WWID_SIZE);
+		else {
+			free(*wwid);
+			*wwid = NULL;
+		}
+	}
+out:
+	free_path(pp);
+	return r;
+}
diff --git a/libmpathvalid/mpath_valid.h b/libmpathvalid/mpath_valid.h
new file mode 100644
index 00000000..c83b8da5
--- /dev/null
+++ b/libmpathvalid/mpath_valid.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * This file is part of the device-mapper multipath userspace tools.
+ *
+ * This program 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 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIB_MPATH_VALID_H
+#define LIB_MPATH_VALID_H
+
+#ifdef __cpluscplus
+extern "C" {
+#endif
+
+enum mpath_valid_mode {
+	MPATH_DEFAULT,
+	MPATH_STRICT,
+	MPATH_SMART,
+	MPATH_GREEDY,
+	MPATH_MAX_MODE,  /* used only for bounds checking */
+};
+
+/* MPATH_IS_VALID_NO_CHECK is used to skip checks to see if the device
+ * has already been unclaimed by multipath in the past */
+enum mpath_valid_result {
+	MPATH_IS_ERROR = -1,
+	MPATH_IS_NOT_VALID,
+	MPATH_IS_VALID,
+	MPATH_IS_VALID_NO_CHECK,
+	MPATH_IS_MAYBE_VALID,
+};
+
+enum mpath_valid_log_style {
+	MPATH_LOG_STDIO = -1,
+	MPATH_LOG_STDIO_TIMESTAMP,
+	MPATH_LOG_SYSLOG,
+};
+
+int mpathvalid_init(int verbosity, int log_style);
+int mpathvalid_reload_config(void);
+int mpathvalid_exit(void);
+unsigned int mpathvalid_get_mode(void);
+int mpathvalid_is_path(const char *name, unsigned int mode, char **wwid,
+		       const char **path_wwids, unsigned int nr_paths);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* LIB_PATH_VALID_H */
-- 
2.17.2