multipath-tools: Introducing multipath C API

Features:

 * Use mpath_cmd.h for IPC connection and use output of 'show maps json'.
 * Library user guide will be 'man 3 libdmmp.h'.
 * Every public function has its own manpage in section 3 which is
   generated by linux 'kernel-doc' tool.

Usage:

    make -j5
    sudo make install \
            bindir=/usr/sbin/ \
            syslibdir=/usr/lib64/ \
            libdir=/usr/lib64/multipath \
            rcdir=/etc/rc.d/init.d \
            unitdir=/usr/lib/systemd/system \
            includedir=/usr/include
    make -C libdmmp check
    make -C libdmmp speed_test

    man libdmmp.h
    man dmmp_mpath_array_get
    man <dmmp function name>

Performance:

 * 10k scsi_debug sdX with 2 disks per mpath (i7-6820HQ 16GiB RAM):
   $ make -C libdmmp speed_test
   Got 5000 mpath
   real 3.22
   user 0.15
   sys 0.01

Misc:
 * Developer note is libdmmp/DEV_NOTES.

Signed-off-by: Gris Ge <fge@redhat.com>

.gitignore

@@ -12,3 +12,7 @@ mpathpersist/mpathpersist
 .nfs*
 *.swp
 *.patch
+libdmmp/docs/man/*.3.gz
+libdmmp/*.so.*
+libdmmp/test/libdmmp_test
+libdmmp/test/libdmmp_speed_test

Makefile

@@ -30,6 +30,7 @@ BUILDDIRS = \
 	libmultipath/prioritizers \
 	libmultipath/checkers \
 	libmpathpersist \
+	libdmmp \
 	multipath \
 	multipathd \
 	mpathpersist \

Makefile.inc

@@ -55,6 +55,9 @@ unitdir		= $(prefix)/$(SYSTEMDPATH)/systemd/system
 mpathpersistdir	= $(TOPDIR)/libmpathpersist
 mpathcmddir	= $(TOPDIR)/libmpathcmd
 thirdpartydir	= $(TOPDIR)/third-party
+libdmmpdir	= $(TOPDIR)/libdmmp
+includedir	= $(prefix)/usr/include
+pkgconfdir	= $(prefix)/usr/share/pkgconfig
 
 GZIP		= gzip -9 -c
 RM		= rm -f

libdmmp/DEV_NOTES

@@ -0,0 +1,41 @@
+== Planed features ==
+ * Expose all properties used by /usr/bin/multipath
+
+== Code style ==
+ * Keep things as simple as possible.
+ * Linux Kernel code style.
+ * Don't use typedef.
+ * Don't use enum.
+ * We are not smarter than API user, so don't create wrapping function like:
+
+    ```
+    dmmp_mpath_search_by_id(struct dmmp_context *ctx,
+                            struct dmmp_mpath **dmmp_mp,
+                            uint32_t dmmp_mp_count, const char *id)
+
+    dmmp_path_group_id_search(struct dmmp_mpath *dmmp_mp,
+                              const char *blk_name)
+    ```
+ * The performance is the same for query single mpath and query all mpaths,
+   so no `dmmp_mpath_of_wwid(struct dmmp_context *ctx, const char *wwid)` yet.
+
+== Naming scheme ==
+ * Public constants should be named as `DMMP_XXX_YYY`.
+ * Public functions should be named as `dmmp_<noun>_<verb>`.
+ * Private constants should be named as `_DMMP_XXX_YYY`.
+ * Private functions should be named as `_dmmp_<noun>_<verb>`.
+
+== Code Layout ==
+ * libdmmp_private.h
+    Internal functions or macros.
+ * libdmmp.c
+    Handling multipathd IPC and generate dmmp_context and
+    dmmp_mpath_array_get().
+ * libdmmp_mp.c
+    For `struct dmmp_mpath`
+ * libdmmp_pg.c
+    For `struct dmmp_path_group`
+ * libdmmp_path.c
+    For `struct dmmp_path`
+ * libdmmp_misc.c
+    Misc functions.

libdmmp/Makefile

@@ -0,0 +1,84 @@
+# Makefile
+#
+# Copyright (C) 2015 - 2016 Red Hat, Inc.
+# Gris Ge <fge@redhat.com>
+#
+include ../Makefile.inc
+
+LIBDMMP_VERSION=0.1.0
+SONAME=$(LIBDMMP_VERSION)
+DEVLIB = libdmmp.so
+LIBS = $(DEVLIB).$(SONAME)
+LIBDEPS = -pthread
+PKGFILE = libdmmp.pc
+EXTRA_MAN_FILES = libdmmp.h.3
+HEADERS = libdmmp/libdmmp.h
+OBJS = libdmmp.o libdmmp_mp.o libdmmp_pg.o libdmmp_path.o libdmmp_misc.o
+
+CFLAGS += -fvisibility=hidden -I$(libdmmpdir) -I$(mpathcmddir) \
+	  $(shell pkg-config --cflags json-c)
+LDFLAGS += $(shell pkg-config --libs json-c) -L$(mpathcmddir) -lmpathcmd
+
+all: $(LIBS) doc
+
+$(LIBS): $(OBJS)
+	$(CC) $(LDFLAGS) $(SHARED_FLAGS) \
+	-Wl,-soname=$@ $(CFLAGS) -o $@ $(OBJS) $(LIBDEPS)
+	$(LN) $@ $(DEVLIB)
+
+install:
+	$(INSTALL_PROGRAM) -m 755 $(LIBS) $(DESTDIR)$(syslibdir)/$(LIBS)
+	$(INSTALL_PROGRAM) -m 644 -D \
+		$(HEADERS) $(DESTDIR)/$(includedir)/$(HEADERS)
+	$(LN) $(LIBS) $(DESTDIR)/$(syslibdir)/$(DEVLIB)
+	$(INSTALL_PROGRAM) -m 644 -D \
+		$(PKGFILE).in $(DESTDIR)/$(pkgconfdir)/$(PKGFILE)
+	perl -i -pe 's|__VERSION__|$(LIBDMMP_VERSION)|g' \
+		$(DESTDIR)/$(pkgconfdir)/$(PKGFILE)
+	perl -i -pe 's|__LIBDIR__|$(syslibdir)|g' \
+		$(DESTDIR)/$(pkgconfdir)/$(PKGFILE)
+	perl -i -pe 's|__INCLUDEDIR__|$(includedir)|g' \
+		$(DESTDIR)/$(pkgconfdir)/$(PKGFILE)
+	@for file in docs/man/*.3.gz; do \
+		$(INSTALL_PROGRAM) -m 644 -D \
+			$$file \
+			$(DESTDIR)/$(man3dir)/ || exit $?; \
+	done
+
+uninstall:
+	$(RM) $(DESTDIR)$(syslibdir)/$(LIBS)
+	$(RM) $(DESTDIR)$(includedir)/$(HEADERS)
+	$(RM) $(DESTDIR)/$(syslibdir)/$(DEVLIB)
+	@for file in $(DESTDIR)/$(man3dir)/dmmp_*; do \
+		$(RM) $$file; \
+	done
+	$(RM) $(DESTDIR)$(man3dir)/libdmmp.h*
+
+clean:
+	$(RM) core *.a *.o *.gz *.so *.so.*
+	$(RM) docs/man/*.3.gz
+	$(MAKE) -C test clean
+
+check: all
+	$(MAKE) -C test check
+
+speed_test: all
+	$(MAKE) -C test speed_test
+
+doc: docs/man/$(EXTRA_MAN_FILES).gz
+
+TEMPFILE := $(shell mktemp)
+
+docs/man/$(EXTRA_MAN_FILES).gz: $(HEADERS)
+	@for file in $(EXTRA_MAN_FILES); do \
+		$(INSTALL_PROGRAM) -v -m 644 -D docs/$$file docs/man/$$file; \
+	done
+	cat $(HEADERS) | \
+	    perl docs/doc-preclean.pl > $(TEMPFILE)
+	perl docs/kernel-doc -man $(TEMPFILE) | \
+	    perl docs/split-man.pl docs/man
+	-rm -f $(TEMPFILE)
+	@for file in docs/man/*.3; do \
+		gzip -f $$file; \
+	done
+	find docs/man -type f -name \*[0-9].gz

libdmmp/docs/doc-preclean.pl

@@ -0,0 +1,28 @@
+#!/usr/bin/perl
+# Copyright (C) 2016 Red Hat, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# Author: Gris Ge <fge@redhat.com>
+
+use strict;
+
+my @REMOVE_KEY_LIST=("DMMP_DLL_EXPORT");
+
+while (<>) {
+    for my $key (@REMOVE_KEY_LIST) {
+        (s/$key//g);
+    }
+    print;
+}