From ad37317739d30adef9e7be4787b908ee6129a3de Mon Sep 17 00:00:00 2001
From: thomas <kreitler@molgen.mpg.de>
Date: Fri, 7 Jun 2019 16:09:35 +0200
Subject: [PATCH] Working variant of diamond_dependency_1.sh

The trick is done by using versioned symbols in libcommon.
Well, this opens the next door towards dependency 'heaven' :)
---
 diamond_dependency_1v.sh | 101 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100755 diamond_dependency_1v.sh

diff --git a/diamond_dependency_1v.sh b/diamond_dependency_1v.sh
new file mode 100755
index 0000000..7b35628
--- /dev/null
+++ b/diamond_dependency_1v.sh
@@ -0,0 +1,101 @@
+#! /bin/bash
+
+# case 1:
+#
+#    main -----------------> libcommon
+#        \--- libmiddle ---> libcommon
+#
+# Now use versioned symbols, and tell libmiddle about libcommon
+#
+# 1) update libcommon
+# 2) rebuild libmiddle
+#
+# result: libmiddle uses new API
+
+set -e
+
+# install libcommon API 1
+
+cat >libcommon.c <<"_EOF_"
+#include <stdio.h>
+
+void libcommon_test(char *caller) {
+    printf("libcommon_test V1 called by %s\n",caller);
+}
+_EOF_
+cat >libcommon.h <<'_EOF_'
+#define API_VERSION "1"
+_EOF_
+cat >v1.lds <<'_EOF_'
+VER_1 { global: libcommon_test; };
+_EOF_
+gcc -shared -fPIC -Wl,-soname=libcommon-1.so,--version-script=v1.lds -o libcommon-1.so libcommon.c
+ln -sf libcommon-1.so libcommon.so
+
+# install libmiddle
+
+cat >libmiddle.c <<_EOF_
+#include <stdio.h>
+#include "libcommon.h"
+
+extern void libcommon_test(char *caller);
+
+void libmiddle_test(char *caller) {
+    printf("libmiddle_test called by %s\n",caller);
+    libcommon_test("libmiddle expecting V" API_VERSION " API");
+}
+_EOF_
+gcc -shared -fPIC -Wl,-soname=libmiddle-1.so -o libmiddle-1.so libmiddle.c
+ln -sf libmiddle-1.so libmiddle.so
+
+# install main
+
+cat >main.c <<_EOF_
+#include <stdio.h>
+#include "libcommon.h"
+
+extern void libcommon_test(char *caller);
+extern void libmiddle_test(char *caller);
+
+int main() {
+    libmiddle_test("main");
+    libcommon_test("main      expecting V" API_VERSION " API");
+}
+_EOF_
+
+gcc -o main -Wl,-rpath=. -lmiddle -L. -lcommon main.c
+
+echo "########### run main"
+
+./main
+
+echo "########### update libcommon"
+
+cat >libcommon.c <<"_EOF_"
+#include <stdio.h>
+
+void libcommon_test(char *caller) {
+    printf("libcommon_test V2 called by %s\n",caller);
+}
+_EOF_
+cat >libcommon.h <<'_EOF_'
+#define API_VERSION "2"
+_EOF_
+cat >v2.lds <<'_EOF_'
+VER_2 { global: libcommon_test; };
+_EOF_
+gcc -shared -fPIC -Wl,-soname=libcommon-2.so,--version-script=v2.lds -o libcommon-2.so libcommon.c
+ln -sf libcommon-2.so libcommon.so
+
+echo "########### run main"
+
+./main
+
+echo "########### rebuild libmiddle"
+
+gcc -shared -fPIC -Wl,-soname=libmiddle-1.so -o libmiddle-1.so libmiddle.c -L. -lcommon # better: -lcommon-2
+ln -sf libmiddle-1.so libmiddle.so
+
+echo "########### run main"
+
+./main