diamond_dependency_1v.sh

#! /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