Build: Add support for shared libraries and versioning.

These changes allow for the building of shared libraries by providing
the --enable-shared option to configure. In particular, lib/libopenvwitch.so,
lib/libsflow.so, ofproto/libofproto.so, and ovsdb/libovsdb.so will be built.
Original behavior of building static remains the same.

Additionally, versioning is introduced to each of the libraries objects
paving the way for APIs to be built around them. A detailed comment
outlining the rules for changing a version number is provided in
configure.ac. Note that at this time, the version number is set to
1.0.0, no API is specified yet, and there are no requirements to
maintain any sort of compatibility in any of the libraries.

Signed-off-by: Scott Mann <smann@noironetworks.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

.gitignore

@@ -16,6 +16,7 @@
 *.pyc
 *.so
 *.suo
+**/*.sym
 *~
 *,cover
 .#*

.travis/build.sh

@@ -24,6 +24,8 @@ function install_dpdk()
     cd dpdk-1.7.1
     find ./ -type f | xargs sed -i 's/max-inline-insns-single=100/max-inline-insns-single=400/'
     sed -ri 's,(CONFIG_RTE_BUILD_COMBINE_LIBS=).*,\1y,' config/common_linuxapp
+    sed -ri '/CONFIG_RTE_LIBNAME/a CONFIG_RTE_BUILD_FPIC=y' config/common_linuxapp
+    sed -ri '/EXECENV_CFLAGS  = -pthread -fPIC/{s/$/\nelse ifeq ($(CONFIG_RTE_BUILD_FPIC),y)/;s/$/\nEXECENV_CFLAGS  = -pthread -fPIC/}' mk/exec-env/linuxapp/rte.vars.mk
     make config CC=gcc T=x86_64-native-linuxapp-gcc
     make CC=gcc RTE_KERNELDIR=$KERNELSRC
     echo "Installed DPDK source in $(pwd)"

AUTHORS

@@ -131,6 +131,7 @@ Samuel Ghinet           sghinet@cloudbasesolutions.com
 Sanjay Sane             ssane@nicira.com
 Saurabh Shah            ssaurabh@nicira.com
 Scott Lowe              scott.lowe@scottlowe.org
+Scott Mann              sdmnix@gmail.com
 Selvamuthukumar         smkumar@merunetworks.com
 Shan Wei                davidshan@tencent.com
 Shih-Hao Li             shli@nicira.com

configure.ac

@@ -43,6 +43,41 @@ AC_SYS_LARGEFILE
 LT_INIT([disable-shared])
 m4_pattern_forbid([LT_INIT]) dnl Make autoconf fail if libtool is missing.
 
+# The following explanation may help to understand the use of the
+# version number fields: current, revision, and age.
+#
+# Consider that there are three possible kinds of reactions from
+# users of your library to changes in a shared library:
+#
+# 1. Programs using the previous version may use the new version as drop-in
+#    replacement, and programs using the new version can also work with the
+#    previous one. In other words, no recompiling nor relinking is needed.
+#    In short, there are no changes to any symbols, no symbols removed,
+#    and no symbols added. In this case, bump revision only, don't touch
+#    current nor age.
+#
+# 2. Programs using the previous version may use the new version as drop-in
+#    replacement, but programs using the new version may use APIs not
+#    present in the previous one. In other words, new symbols have been
+#    added and a program linking against the new version may fail with
+#    “unresolved symbols.” If linking against the old version at runtime:
+#    set revision to 0, bump current and age.
+#
+# 3. Programs may need to be changed, recompiled, relinked in order to use
+#    the new version. This is the case when symbols have been modified or
+#    deleted. Bump current, set revision and age to 0.
+
+m4_define([libopenvswitch_lt_current],    [1])
+m4_define([libopenvswitch_lt_revision],   [0])
+m4_define([libopenvswitch_lt_age],        [0])
+
+LT_CURRENT=libopenvswitch_lt_current
+AC_SUBST([LT_CURRENT])
+LT_REVISION=libopenvswitch_lt_revision
+AC_SUBST([LT_REVISION])
+LT_AGE=libopenvswitch_lt_age
+AC_SUBST([LT_AGE])
+
 AC_SEARCH_LIBS([pow], [m])
 AC_SEARCH_LIBS([clock_gettime], [rt])
 AC_SEARCH_LIBS([timer_create], [rt])
@@ -94,7 +129,13 @@ OVS_CHECK_LINUX_HOST
 AX_FUNC_POSIX_MEMALIGN
 
 OVS_CHECK_INCLUDE_NEXT([stdio.h string.h])
-AC_CONFIG_FILES([lib/stdio.h lib/string.h])
+AC_CONFIG_FILES([
+    lib/stdio.h
+    lib/string.h
+    ovsdb/libovsdb.sym
+    ofproto/libofproto.sym
+    lib/libsflow.sym
+    lib/libopenvswitch.sym])
 
 OVS_ENABLE_OPTION([-Wall])
 OVS_ENABLE_OPTION([-Wextra])

lib/automake.mk

@@ -13,7 +13,9 @@ if WIN32
 lib_libopenvswitch_la_LIBADD += ${PTHREAD_LIBS}
 endif
 
-lib_libopenvswitch_la_LDFLAGS = -release $(VERSION)
+lib_libopenvswitch_la_LDFLAGS = \
+        -version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE) \
+        -Wl,--version-script=$(top_builddir)/lib/libopenvswitch.sym
 
 lib_libopenvswitch_la_SOURCES = \
 	lib/aes128.c \
@@ -291,7 +293,9 @@ nodist_lib_libopenvswitch_la_SOURCES = \
 CLEANFILES += $(nodist_lib_libopenvswitch_la_SOURCES)
 
 lib_LTLIBRARIES += lib/libsflow.la
-lib_libsflow_la_LDFLAGS = -release $(VERSION)
+lib_libsflow_la_LDFLAGS = \
+        -version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE) \
+        -Wl,--version-script=$(top_builddir)/lib/libsflow.sym
 lib_libsflow_la_SOURCES = \
 	lib/sflow_api.h \
 	lib/sflow.h \

lib/libopenvswitch.sym.in

@@ -0,0 +1,4 @@
+libopenvswitch_@LT_CURRENT@ {
+global:
+        *;
+};

lib/libsflow.sym.in

@@ -0,0 +1,4 @@
+libsflow_@LT_CURRENT@ {
+global:
+        *;
+};

lib/util.c

@@ -471,9 +471,15 @@ set_program_name__(const char *argv0, const char *version, const char *date,
 
     assert_single_threaded();
     free(program_name);
+    /* Remove libtool prefix, if it is there */
+    if (strncmp(basename, "lt-", 3) == 0) {
+        char *tmp_name = basename;
+        basename = xstrdup(basename + 3);
+        free(tmp_name);
+    }
     program_name = basename;
-    free(program_version);
 
+    free(program_version);
     if (!strcmp(version, VERSION)) {
         program_version = xasprintf("%s (Open vSwitch) "VERSION"\n"
                                     "Compiled %s %s\n",

ofproto/automake.mk

@@ -6,7 +6,9 @@
 # without warranty of any kind.
 
 lib_LTLIBRARIES += ofproto/libofproto.la
-ofproto_libofproto_la_LDFLAGS = -release $(VERSION)
+ofproto_libofproto_la_LDFLAGS = \
+        -version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE) \
+        -Wl,--version-script=$(top_builddir)/ofproto/libofproto.sym
 ofproto_libofproto_la_SOURCES = \
 	ofproto/bond.c \
 	ofproto/bond.h \

ofproto/libofproto.sym.in

@@ -0,0 +1,4 @@
+libofproto_@LT_CURRENT@ {
+global:
+        *;
+};

ovsdb/automake.mk

@@ -1,6 +1,8 @@
 # libovsdb
 lib_LTLIBRARIES += ovsdb/libovsdb.la
-ovsdb_libovsdb_la_LDFLAGS = -release $(VERSION)
+ovsdb_libovsdb_la_LDFLAGS = \
+        -version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE) \
+        -Wl,--version-script=$(top_builddir)/ovsdb/libovsdb.sym
 ovsdb_libovsdb_la_SOURCES = \
 	ovsdb/column.c \
 	ovsdb/column.h \

ovsdb/libovsdb.sym.in

@@ -0,0 +1,4 @@
+libovsdb_@LT_CURRENT@ {
+global:
+        *;
+};